diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index c5542c86..d9a8d8a1 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -2,7 +2,7 @@ name: C/C++ CI
 
 on:
   push:
-    branches: [ master, develop, issue-* ]
+    branches: [ master, develop, issue-*, feature/* ]
   pull_request:
     branches: [ master, develop ]
 
diff --git a/include/libipc/buffer.h b/include/libipc/buffer.h
index 3f8c229b..7185c021 100755
--- a/include/libipc/buffer.h
+++ b/include/libipc/buffer.h
@@ -5,12 +5,12 @@
 #include <vector>
 #include <type_traits>
 
-#include "libipc/export.h"
+#include "libipc/imp/export.h"
 #include "libipc/def.h"
 
 namespace ipc {
 
-class IPC_EXPORT buffer {
+class LIBIPC_EXPORT buffer {
 public:
     using destructor_t = void (*)(void*, std::size_t);
 
@@ -57,8 +57,8 @@ class IPC_EXPORT buffer {
         };
     }
 
-    friend IPC_EXPORT bool operator==(buffer const & b1, buffer const & b2);
-    friend IPC_EXPORT bool operator!=(buffer const & b1, buffer const & b2);
+    friend LIBIPC_EXPORT bool operator==(buffer const & b1, buffer const & b2);
+    friend LIBIPC_EXPORT bool operator!=(buffer const & b1, buffer const & b2);
 
 private:
     class buffer_;
diff --git a/include/libipc/concur/intrusive_stack.h b/include/libipc/concur/intrusive_stack.h
new file mode 100644
index 00000000..aa98a66d
--- /dev/null
+++ b/include/libipc/concur/intrusive_stack.h
@@ -0,0 +1,66 @@
+/**
+ * \file libconcur/intrusive_stack.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Define concurrent intrusive stack.
+ */
+#pragma once
+
+#include <atomic>
+
+namespace ipc {
+namespace concur {
+
+/// \brief Intrusive stack node.
+/// \tparam T The type of the value.
+template <typename T>
+struct intrusive_node {
+  T value;
+  std::atomic<intrusive_node *> next;
+};
+
+/// \brief Intrusive stack.
+/// \tparam T The type of the value.
+/// \tparam Node The type of the node.
+template <typename T, typename Node = intrusive_node<T>>
+class intrusive_stack {
+public:
+  using node = Node;
+
+private:
+  std::atomic<node *> top_{nullptr};
+
+public:
+  intrusive_stack(intrusive_stack const &) = delete;
+  intrusive_stack(intrusive_stack &&) = delete;
+  intrusive_stack &operator=(intrusive_stack const &) = delete;
+  intrusive_stack &operator=(intrusive_stack &&) = delete;
+
+  constexpr intrusive_stack() noexcept = default;
+
+  bool empty() const noexcept {
+    return top_.load(std::memory_order_acquire) == nullptr;
+  }
+
+  void push(node *n) noexcept {
+    node *old_top = top_.load(std::memory_order_acquire);
+    do {
+      n->next.store(old_top, std::memory_order_relaxed);
+    } while (!top_.compare_exchange_weak(old_top, n, std::memory_order_release
+                                                   , std::memory_order_acquire));
+  }
+
+  node *pop() noexcept {
+    node *old_top = top_.load(std::memory_order_acquire);
+    do {
+      if (old_top == nullptr) {
+        return nullptr;
+      }
+    } while (!top_.compare_exchange_weak(old_top, old_top->next.load(std::memory_order_relaxed)
+                                                , std::memory_order_release
+                                                , std::memory_order_acquire));
+    return old_top;
+  }
+};
+
+} // namespace concur
+} // namespace ipc
diff --git a/include/libipc/condition.h b/include/libipc/condition.h
index 072074a9..201c33fe 100644
--- a/include/libipc/condition.h
+++ b/include/libipc/condition.h
@@ -2,14 +2,14 @@
 
 #include <cstdint>  // std::uint64_t
 
-#include "libipc/export.h"
+#include "libipc/imp/export.h"
 #include "libipc/def.h"
 #include "libipc/mutex.h"
 
 namespace ipc {
 namespace sync {
 
-class IPC_EXPORT condition {
+class LIBIPC_EXPORT condition {
     condition(condition const &) = delete;
     condition &operator=(condition const &) = delete;
 
diff --git a/include/libipc/def.h b/include/libipc/def.h
index 45cd7801..fdda14a1 100755
--- a/include/libipc/def.h
+++ b/include/libipc/def.h
@@ -26,25 +26,26 @@ using uint_t = typename uint<N>::type;
 // constants
 
 enum : std::uint32_t {
-    invalid_value   = (std::numeric_limits<std::uint32_t>::max)(),
-    default_timeout = 100, // ms
+  invalid_value   = (std::numeric_limits<std::uint32_t>::max)(),
+  default_timeout = 100, // ms
 };
 
 enum : std::size_t {
-    data_length     = 64,
-    large_msg_limit = data_length,
-    large_msg_align = 1024,
-    large_msg_cache = 32,
+  central_cache_default_size = 1024 * 1024, ///< 1MB
+  data_length     = 64,
+  large_msg_limit = data_length,
+  large_msg_align = 1024,
+  large_msg_cache = 32,
 };
 
 enum class relat { // multiplicity of the relationship
-    single,
-    multi
+  single,
+  multi
 };
 
 enum class trans { // transmission
-    unicast,
-    broadcast
+  unicast,
+  broadcast
 };
 
 // producer-consumer policy flag
@@ -57,9 +58,9 @@ struct relat_trait;
 
 template <relat Rp, relat Rc, trans Ts>
 struct relat_trait<wr<Rp, Rc, Ts>> {
-    constexpr static bool is_multi_producer = (Rp == relat::multi);
-    constexpr static bool is_multi_consumer = (Rc == relat::multi);
-    constexpr static bool is_broadcast      = (Ts == trans::broadcast);
+  constexpr static bool is_multi_producer = (Rp == relat::multi);
+  constexpr static bool is_multi_consumer = (Rc == relat::multi);
+  constexpr static bool is_broadcast      = (Ts == trans::broadcast);
 };
 
 template <template <typename> class Policy, typename Flag>
@@ -67,7 +68,7 @@ struct relat_trait<Policy<Flag>> : relat_trait<Flag> {};
 
 // the prefix tag of a channel
 struct prefix {
-    char const *str;
+  char const *str;
 };
 
 } // namespace ipc
diff --git a/include/libipc/export.h b/include/libipc/export.h
deleted file mode 100755
index 6024f2f1..00000000
--- a/include/libipc/export.h
+++ /dev/null
@@ -1,54 +0,0 @@
-#pragma once
-
-#if defined(Q_DECL_EXPORT) && defined(Q_DECL_IMPORT)
-
-#   define IPC_DECL_EXPORT Q_DECL_EXPORT
-#   define IPC_DECL_IMPORT Q_DECL_IMPORT
-
-#else // defined(Q_DECL_EXPORT) && defined(Q_DECL_IMPORT)
-
-/*
- * Compiler & system detection for IPC_DECL_EXPORT & IPC_DECL_IMPORT.
- * Not using QtCore cause it shouldn't depend on Qt.
-*/
-
-#if defined(_MSC_VER)
-#   define IPC_DECL_EXPORT      __declspec(dllexport)
-#   define IPC_DECL_IMPORT      __declspec(dllimport)
-#elif defined(__ARMCC__) || defined(__CC_ARM)
-#   if defined(ANDROID) || defined(__linux__) || defined(__linux)
-#       define IPC_DECL_EXPORT  __attribute__((visibility("default")))
-#       define IPC_DECL_IMPORT  __attribute__((visibility("default")))
-#   else
-#       define IPC_DECL_EXPORT  __declspec(dllexport)
-#       define IPC_DECL_IMPORT  __declspec(dllimport)
-#   endif
-#elif defined(__GNUC__)
-#   if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__) || \
-       defined(WIN64) || defined(_WIN64) || defined(__WIN64__)
-#       define IPC_DECL_EXPORT  __declspec(dllexport)
-#       define IPC_DECL_IMPORT  __declspec(dllimport)
-#   else
-#       define IPC_DECL_EXPORT  __attribute__((visibility("default")))
-#       define IPC_DECL_IMPORT  __attribute__((visibility("default")))
-#   endif
-#else
-#   define IPC_DECL_EXPORT      __attribute__((visibility("default")))
-#   define IPC_DECL_IMPORT      __attribute__((visibility("default")))
-#endif
-
-#endif // defined(Q_DECL_EXPORT) && defined(Q_DECL_IMPORT)
-
-/*
- * Define IPC_EXPORT for exporting function & class.
-*/
-
-#ifndef IPC_EXPORT
-#if defined(LIBIPC_LIBRARY_SHARED_BUILDING__)
-#  define IPC_EXPORT IPC_DECL_EXPORT
-#elif defined(LIBIPC_LIBRARY_SHARED_USING__)
-#  define IPC_EXPORT IPC_DECL_IMPORT
-#else
-#  define IPC_EXPORT
-#endif
-#endif /*IPC_EXPORT*/
diff --git a/include/libipc/imp/aligned.h b/include/libipc/imp/aligned.h
new file mode 100644
index 00000000..e3da1671
--- /dev/null
+++ b/include/libipc/imp/aligned.h
@@ -0,0 +1,74 @@
+/**
+ * \file libipc/aligned.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Defines the type suitable for use as uninitialized storage for types of given type.
+ */
+#pragma once
+
+#include <array>
+#include <cstddef>
+
+#include "libipc/imp/byte.h"
+
+namespace ipc {
+
+/**
+ * \brief The type suitable for use as uninitialized storage for types of given type.
+ *        std::aligned_storage is deprecated in C++23, so we define our own.
+ * \tparam T The type to be aligned.
+ * \tparam AlignT The alignment of the type.
+ * \see https://en.cppreference.com/w/cpp/types/aligned_storage
+ *      https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1413r3.pdf
+ */
+template <typename T, std::size_t AlignT = alignof(T)>
+class aligned {
+  alignas(AlignT) std::array<ipc::byte, sizeof(T)> storage_;
+
+public:
+  /**
+   * \brief Returns a pointer to the aligned storage.
+   * \return A pointer to the aligned storage.
+   */
+  T *ptr() noexcept {
+    return reinterpret_cast<T *>(storage_.data());
+  }
+
+  /**
+   * \brief Returns a pointer to the aligned storage.
+   * \return A pointer to the aligned storage.
+   */
+  T const *ptr() const noexcept {
+    return reinterpret_cast<const T *>(storage_.data());
+  }
+
+  /**
+   * \brief Returns a reference to the aligned storage.
+   * \return A reference to the aligned storage.
+   */
+  T &ref() noexcept {
+    return *ptr();
+  }
+
+  /**
+   * \brief Returns a reference to the aligned storage.
+   * \return A reference to the aligned storage.
+   */
+  T const &ref() const noexcept {
+    return *ptr();
+  }
+};
+
+/**
+ * \brief Rounds up the given value to the given alignment.
+ * \tparam T The type of the value.
+ * \param value The value to be rounded up.
+ * \param alignment The alignment to be rounded up to.
+ * \return The rounded up value.
+ * \see https://stackoverflow.com/questions/3407012/c-rounding-up-to-the-nearest-multiple-of-a-number
+*/
+template <typename T>
+constexpr T round_up(T value, T alignment) noexcept {
+  return (value + alignment - 1) & ~(alignment - 1);
+}
+
+} // namespace ipc
diff --git a/include/libipc/imp/byte.h b/include/libipc/imp/byte.h
new file mode 100644
index 00000000..dec53697
--- /dev/null
+++ b/include/libipc/imp/byte.h
@@ -0,0 +1,178 @@
+/**
+ * \file libipc/byte.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Define the byte type.
+ */
+#pragma once
+
+#include <type_traits>
+#include <cstdint>
+#include <cstddef>  // std::byte (since C++17)
+
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/span.h"
+#include "libipc/imp/fmt.h"
+
+#if defined(LIBIPC_CPP_17) && defined(__cpp_lib_byte)
+#define LIBIPC_CPP_LIB_BYTE_
+#endif // __cpp_lib_byte
+
+namespace ipc {
+
+class byte;
+
+namespace detail_byte {
+
+template <typename T>
+using is_integral = 
+  typename std::enable_if<std::is_integral<T>::value>::type;
+
+template <typename T>
+using is_not_byte = 
+  typename std::enable_if<!std::is_same<
+  typename std::remove_cv<T>::type, byte>::value>::type;
+
+} // namespace detail_byte
+
+/**
+ * \brief A distinct type that implements the concept of byte as specified in the C++ language definition.
+ * \see https://en.cppreference.com/w/cpp/types/byte
+ */
+class byte {
+  std::uint8_t bits_;
+
+public:
+  byte() noexcept = default;
+
+  template <typename T, typename = detail_byte::is_integral<T>>
+  constexpr byte(T v) noexcept
+    : bits_(static_cast<std::uint8_t>(v)) {}
+
+#ifdef LIBIPC_CPP_LIB_BYTE_
+  constexpr byte(std::byte b) noexcept
+    : byte(std::to_integer<std::uint8_t>(b)) {}
+#endif // LIBIPC_CPP_LIB_BYTE_
+
+  template <typename T, typename = detail_byte::is_integral<T>>
+  constexpr operator T() const noexcept {
+    return static_cast<T>(bits_);
+  }
+
+#ifdef LIBIPC_CPP_LIB_BYTE_
+  constexpr operator std::byte() const noexcept {
+    /// \brief C++17 relaxed enum class initialization rules.
+    /// \see https://en.cppreference.com/w/cpp/language/enum#enum_relaxed_init_cpp17
+    return std::byte{bits_};
+  }
+#endif // LIBIPC_CPP_LIB_BYTE_
+
+  friend bool operator==(byte const &lhs, byte const &rhs) noexcept {
+    return lhs.bits_ == rhs.bits_;
+  }
+
+  friend bool operator!=(byte const &lhs, byte const &rhs) noexcept {
+    return !(lhs == rhs);
+  }
+};
+
+/**
+ * \brief Non-member functions.
+ */
+
+template <typename T, typename = detail_byte::is_integral<T>>
+constexpr T to_integer(byte b) noexcept {
+  return T(b);
+}
+
+/// \brief std::operator<<, operator>>
+
+template <typename T, typename = detail_byte::is_integral<T>>
+constexpr byte operator<<(byte b, T shift) noexcept {
+  return byte(to_integer<unsigned>(b) << shift);
+}
+
+template <typename T, typename = detail_byte::is_integral<T>>
+constexpr byte operator>>(byte b, T shift) noexcept {
+  return byte(to_integer<unsigned>(b) >> shift);
+}
+
+/// \brief std::operator<<=, operator>>=
+
+template <typename T, typename = detail_byte::is_integral<T>>
+constexpr byte &operator<<=(byte &b, T shift) noexcept {
+  return b = b << shift;
+}
+
+template <typename T, typename = detail_byte::is_integral<T>>
+constexpr byte &operator>>=(byte &b, T shift) noexcept {
+  return b = b >> shift;
+}
+
+/// \brief std::operator|, operator&, operator^, operator~
+
+constexpr byte operator|(byte l, byte r) noexcept { return byte(to_integer<unsigned>(l) | to_integer<unsigned>(r)); }
+constexpr byte operator&(byte l, byte r) noexcept { return byte(to_integer<unsigned>(l) & to_integer<unsigned>(r)); }
+constexpr byte operator^(byte l, byte r) noexcept { return byte(to_integer<unsigned>(l) ^ to_integer<unsigned>(r)); }
+constexpr byte operator~(byte b)         noexcept { return byte(~to_integer<unsigned>(b)); }
+
+/// \brief std::operator|=, operator&=, operator^=
+
+constexpr byte &operator|=(byte &l, byte r) noexcept { return l = l | r; }
+constexpr byte &operator&=(byte &l, byte r) noexcept { return l = l & r; }
+constexpr byte &operator^=(byte &l, byte r) noexcept { return l = l ^ r; }
+
+/// \brief Cast pointer to byte*.
+
+template <typename T, typename = detail_byte::is_not_byte<T>>
+byte *byte_cast(T *p) noexcept {
+  return reinterpret_cast<byte *>(p);
+}
+
+template <typename T, typename = detail_byte::is_not_byte<T>>
+byte const *byte_cast(T const *p) noexcept {
+  return reinterpret_cast<byte const *>(p);
+}
+
+/// \brief Cast byte* to a pointer of another type.
+
+template <typename T, typename = detail_byte::is_not_byte<T>>
+T *byte_cast(byte *p) noexcept {
+  if (reinterpret_cast<std::size_t>(p) % alignof(T) != 0) {
+    return nullptr;
+  }
+  return reinterpret_cast<T *>(p);
+}
+
+template <typename T, typename U = typename std::add_const<T>::type, 
+          typename = detail_byte::is_not_byte<T>>
+U *byte_cast(byte const *p) noexcept {
+  if (reinterpret_cast<std::size_t>(p) % alignof(T) != 0) {
+    return nullptr;
+  }
+  return reinterpret_cast<U *>(p);
+}
+
+/// \brief Converts a span into a view of its underlying bytes.
+/// \see https://en.cppreference.com/w/cpp/container/span/as_bytes
+
+template <typename T, 
+          typename Byte = typename std::conditional<std::is_const<T>::value, byte const, byte>::type>
+auto as_bytes(span<T> s) noexcept -> span<Byte> {
+  return {byte_cast(s.data()), s.size_bytes()};
+}
+
+/// \brief Custom defined fmt_to method for imp::fmt
+namespace detail_tag_invoke {
+
+inline bool tag_invoke(decltype(ipc::fmt_to), fmt_context &ctx, ipc::byte b) {
+  return ipc::to_string(ctx, static_cast<std::uint8_t>(b), "02x");
+}
+
+template <typename T, 
+          typename = std::enable_if_t<std::is_same<std::decay_t<T>, ipc::byte>::value>>
+bool tag_invoke(decltype(ipc::fmt_to), fmt_context &ctx, fmt_ref<T> arg) noexcept {
+  return ipc::to_string(ctx, static_cast<std::uint8_t>(arg.param), arg.fstr);
+}
+
+} // namespace detail_tag_invoke
+} // namespace ipc
diff --git a/include/libipc/imp/codecvt.h b/include/libipc/imp/codecvt.h
new file mode 100644
index 00000000..dda2b9f7
--- /dev/null
+++ b/include/libipc/imp/codecvt.h
@@ -0,0 +1,36 @@
+/**
+ * \file libipc/codecvt.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Character set conversion interface.
+ */
+#pragma once
+
+#include <string>
+#include <cstddef>
+
+#include "libipc/imp/export.h"
+
+namespace ipc {
+
+/**
+ * \brief The transform between UTF-8/16/32
+ * 
+ * \param des  The target string pointer can be nullptr
+ * \param dlen The target string length can be 0
+ */
+template <typename CharT, typename CharU>
+LIBIPC_EXPORT std::size_t cvt_cstr(CharT const *src, std::size_t slen, CharU *des, std::size_t dlen) noexcept;
+
+template <typename CharT, typename TraitsT, typename AllocT, 
+          typename CharU, typename TraitsU, typename AllocU>
+void cvt_sstr(std::basic_string<CharT, TraitsT, AllocT> const &src, std::basic_string<CharU, TraitsU, AllocU> &des) {
+  std::size_t dlen = cvt_cstr(src.c_str(), src.size(), (CharU *)nullptr, 0);
+  if (dlen == 0) {
+    des.clear();
+    return;
+  }
+  des.resize(dlen);
+  cvt_cstr(src.c_str(), src.size(), &des[0], des.size());
+}
+
+} // namespace ipc
diff --git a/include/libipc/imp/detect_plat.h b/include/libipc/imp/detect_plat.h
new file mode 100644
index 00000000..6095cec9
--- /dev/null
+++ b/include/libipc/imp/detect_plat.h
@@ -0,0 +1,226 @@
+/**
+ * \file libipc/detect_plat.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Define platform detection related interfaces.
+ */
+#pragma once
+
+/// \brief OS check.
+
+#if defined(WINCE) || defined(_WIN32_WCE)
+# define LIBIPC_OS_WINCE
+#elif defined(WIN64) || defined(_WIN64) || defined(__WIN64__) || \
+     (defined(__x86_64) && defined(__MSYS__))
+#define LIBIPC_OS_WIN64
+#elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || \
+      defined(__NT__) || defined(__MSYS__)
+# define LIBIPC_OS_WIN32
+#elif defined(__QNX__) || defined(__QNXNTO__)
+# define LIBIPC_OS_QNX
+#elif defined(__APPLE__)
+# define LIBIPC_OS_APPLE
+#elif defined(ANDROID) || defined(__ANDROID__)
+# define LIBIPC_OS_ANDROID
+#elif defined(__linux__) || defined(__linux)
+# define LIBIPC_OS_LINUX
+#elif defined(_POSIX_VERSION)
+# define LIBIPC_OS_POSIX
+#else
+# error "This OS is unsupported."
+#endif
+
+#if defined(LIBIPC_OS_WIN32) || defined(LIBIPC_OS_WIN64) || \
+    defined(LIBIPC_OS_WINCE)
+# define LIBIPC_OS_WIN
+#endif
+
+/// \brief Compiler check.
+
+#if defined(_MSC_VER)
+# define LIBIPC_CC_MSVC      _MSC_VER
+# define LIBIPC_CC_MSVC_2015 1900
+# define LIBIPC_CC_MSVC_2017 1910
+# define LIBIPC_CC_MSVC_2019 1920
+# define LIBIPC_CC_MSVC_2022 1930
+#elif defined(__GNUC__)
+# define LIBIPC_CC_GNUC __GNUC__
+# if defined(__clang__)
+#   define LIBIPC_CC_CLANG
+#endif
+#else
+# error "This compiler is unsupported."
+#endif
+
+/// \brief Instruction set.
+/// \see https://sourceforge.net/p/predef/wiki/Architectures/
+
+#if defined(_M_X64) || defined(_M_AMD64) || \
+    defined(__x86_64__) || defined(__x86_64) || \
+    defined(__amd64__) || defined(__amd64)
+# define LIBIPC_INSTR_X64
+#elif defined(_M_IA64) || defined(__IA64__) || defined(_IA64) || \
+      defined(__ia64__) || defined(__ia64)
+# define LIBIPC_INSTR_I64
+#elif defined(_M_IX86) || defined(_X86_) || defined(__i386__) || defined(__i386)
+# define LIBIPC_INSTR_X86
+#elif defined(_M_ARM64) || defined(__arm64__) || defined(__aarch64__)
+# define LIBIPC_INSTR_ARM64
+#elif defined(_M_ARM) || defined(_ARM) || defined(__arm__) || defined(__arm)
+# define LIBIPC_INSTR_ARM32
+#else
+# error "This instruction set is unsupported."
+#endif
+
+#if defined(LIBIPC_INSTR_X86) || defined(LIBIPC_INSTR_X64)
+# define LIBIPC_INSTR_X86_64
+#elif defined(LIBIPC_INSTR_ARM32) || defined(LIBIPC_INSTR_ARM64)
+# define LIBIPC_INSTR_ARM
+#endif
+
+/// \brief Byte order.
+
+#if defined(__BYTE_ORDER__)
+# define LIBIPC_ENDIAN_BIG   (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
+# define LIBIPC_ENDIAN_LIT   (!LIBIPC_ENDIAN_BIG)
+#else
+# define LIBIPC_ENDIAN_BIG   (0)
+# define LIBIPC_ENDIAN_LIT   (1)
+#endif
+
+/// \brief C++ version.
+
+#if (__cplusplus >= 202002L) && !defined(LIBIPC_CPP_20)
+# define LIBIPC_CPP_20
+#endif
+#if (__cplusplus >= 201703L) && !defined(LIBIPC_CPP_17)
+# define LIBIPC_CPP_17
+#endif
+#if /*(__cplusplus >= 201402L) &&*/ !defined(LIBIPC_CPP_14)
+# define LIBIPC_CPP_14
+#endif
+
+#if !defined(LIBIPC_CPP_20) && \
+    !defined(LIBIPC_CPP_17) && \
+    !defined(LIBIPC_CPP_14)
+# error "This C++ version is unsupported."
+#endif
+
+/// \brief Feature cross-platform adaptation.
+
+#if defined(LIBIPC_CPP_17)
+# define LIBIPC_INLINE_CONSTEXPR inline constexpr
+#else
+# define LIBIPC_INLINE_CONSTEXPR constexpr
+#endif
+
+/// \brief C++ attributes.
+/// \see https://en.cppreference.com/w/cpp/language/attributes
+
+#if defined(__has_cpp_attribute)
+# if __has_cpp_attribute(fallthrough)
+#   define LIBIPC_FALLTHROUGH [[fallthrough]]
+# endif
+# if __has_cpp_attribute(maybe_unused)
+#   define LIBIPC_UNUSED [[maybe_unused]]
+# endif
+# if __has_cpp_attribute(likely)
+#   define LIBIPC_LIKELY(...) (__VA_ARGS__) [[likely]]
+# endif
+# if __has_cpp_attribute(unlikely)
+#   define LIBIPC_UNLIKELY(...) (__VA_ARGS__) [[unlikely]]
+# endif
+# if __has_cpp_attribute(nodiscard)
+#   define LIBIPC_NODISCARD [[nodiscard]]
+# endif
+# if __has_cpp_attribute(assume)
+#   define LIBIPC_ASSUME(...) [[assume(__VA_ARGS__)]]
+# endif
+#endif
+
+#if !defined(LIBIPC_FALLTHROUGH)
+# if defined(LIBIPC_CC_GNUC)
+#   define LIBIPC_FALLTHROUGH __attribute__((__fallthrough__))
+# else
+#   define LIBIPC_FALLTHROUGH
+# endif
+#endif
+
+#if !defined(LIBIPC_UNUSED)
+# if defined(LIBIPC_CC_GNUC)
+#   define LIBIPC_UNUSED __attribute__((__unused__))
+# elif defined(LIBIPC_CC_MSVC)
+#   define LIBIPC_UNUSED __pragma(warning(suppress: 4100 4101 4189))
+# else
+#   define LIBIPC_UNUSED
+# endif
+#endif
+
+#if !defined(LIBIPC_LIKELY)
+# if defined(__has_builtin)
+#   if __has_builtin(__builtin_expect)
+#     define LIBIPC_LIKELY(...) (__builtin_expect(!!(__VA_ARGS__), 1))
+#   endif
+# endif
+#endif
+
+#if !defined(LIBIPC_LIKELY)
+# define LIBIPC_LIKELY(...) (__VA_ARGS__)
+#endif
+
+#if !defined(LIBIPC_UNLIKELY)
+# if defined(__has_builtin)
+#   if __has_builtin(__builtin_expect)
+#     define LIBIPC_UNLIKELY(...) (__builtin_expect(!!(__VA_ARGS__), 0))
+#   endif
+# endif
+#endif
+
+#if !defined(LIBIPC_UNLIKELY)
+# define LIBIPC_UNLIKELY(...) (__VA_ARGS__)
+#endif
+
+#if !defined(LIBIPC_NODISCARD)
+/// \see https://stackoverflow.com/questions/4226308/msvc-equivalent-of-attribute-warn-unused-result
+# if defined(LIBIPC_CC_GNUC) && (LIBIPC_CC_GNUC >= 4)
+#   define LIBIPC_NODISCARD __attribute__((warn_unused_result))
+# elif defined(LIBIPC_CC_MSVC) && (LIBIPC_CC_MSVC >= 1700)
+#   define LIBIPC_NODISCARD _Check_return_
+# else
+#   define LIBIPC_NODISCARD
+# endif
+#endif
+
+#if !defined(LIBIPC_ASSUME)
+# if defined(__has_builtin)
+#   if __has_builtin(__builtin_assume)
+      /// \see https://clang.llvm.org/docs/LanguageExtensions.html#langext-builtin-assume
+#     define LIBIPC_ASSUME(...) __builtin_assume(__VA_ARGS__)
+#   elif __has_builtin(__builtin_unreachable)
+      /// \see https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005funreachable
+#     define LIBIPC_ASSUME(...) do { if (!(__VA_ARGS__)) __builtin_unreachable(); } while (false)
+#   endif
+# endif
+#endif
+
+#if !defined(LIBIPC_ASSUME)
+# if defined(LIBIPC_CC_MSVC)
+    /// \see https://learn.microsoft.com/en-us/cpp/intrinsics/assume?view=msvc-140
+#   define LIBIPC_ASSUME(...) __assume(__VA_ARGS__)
+# else
+#   define LIBIPC_ASSUME(...)
+# endif
+#endif
+
+/// \see https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_exceptions.html
+///      https://learn.microsoft.com/en-us/cpp/preprocessor/predefined-macros
+///      https://stackoverflow.com/questions/6487013/programmatically-determine-whether-exceptions-are-enabled
+#if defined(__cpp_exceptions) && __cpp_exceptions || \
+    defined(__EXCEPTIONS) || defined(_CPPUNWIND)
+# define LIBIPC_TRY                    try
+# define LIBIPC_CATCH(...)             catch (__VA_ARGS__)
+# define LIBIPC_THROW($EXCEPTION, ...) throw $EXCEPTION
+#else
+# define LIBIPC_TRY                    if (true)
+# define LIBIPC_CATCH(...)             else if (false)
+# define LIBIPC_THROW($EXCEPTION, ...) return __VA_ARGS__
+#endif
diff --git a/include/libipc/imp/error.h b/include/libipc/imp/error.h
new file mode 100644
index 00000000..6493b0b4
--- /dev/null
+++ b/include/libipc/imp/error.h
@@ -0,0 +1,27 @@
+/**
+ * \file libipc/error.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief A platform-dependent error code.
+ */
+#pragma once
+
+#include <system_error>
+#include <string>
+#include <cstdint>
+
+#include "libipc/imp/export.h"
+#include "libipc/imp/fmt_cpo.h"
+
+namespace ipc {
+
+/**
+ * \brief Custom defined fmt_to method for imp::fmt
+ */
+namespace detail_tag_invoke {
+
+inline bool tag_invoke(decltype(ipc::fmt_to), fmt_context &ctx, std::error_code const &ec) noexcept {
+  return fmt_to(ctx, '[', ec.value(), ": ", ec.message(), ']');
+}
+
+} // namespace detail_tag_invoke
+} // namespace ipc
diff --git a/include/libipc/imp/expected.h b/include/libipc/imp/expected.h
new file mode 100644
index 00000000..a56aed46
--- /dev/null
+++ b/include/libipc/imp/expected.h
@@ -0,0 +1,392 @@
+/**
+ * \file libipc/expected.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Provides a way to store either of two values.
+ */
+#pragma once
+
+#include <type_traits>
+#include <utility>  // std::exchange
+#include <array>
+#include <memory>   // std::addressof
+#include <cstddef>  // std::nullptr_t
+
+#include "libipc/imp/uninitialized.h"
+#include "libipc/imp/generic.h"
+#include "libipc/imp/byte.h"
+
+namespace ipc {
+
+/**
+ * \brief In-place construction tag for unexpected value in expected.
+ * \see https://en.cppreference.com/w/cpp/utility/expected/unexpect_t
+ */
+struct unexpected_t {
+  explicit unexpected_t() = default;
+};
+constexpr unexpected_t unexpected{};
+
+/**
+ * \class template <typename T, typename E> expected
+ * \brief Provides a way to store either of two values.
+ * \see https://en.cppreference.com/w/cpp/utility/expected
+ * \tparam T - the type of the expected value.
+ * \tparam E - the type of the unexpected value.
+ */
+template <typename T, typename E>
+class expected;
+
+namespace detail_expected {
+
+template <typename T, typename E>
+struct data_union {
+  using const_value_t = typename std::add_const<T>::type;
+  using const_error_t = typename std::add_const<E>::type;
+
+  union {
+    T value_;  ///< the expected value
+    E error_;  ///< the unexpected value
+  };
+
+  data_union(data_union const &) = delete;
+  data_union &operator=(data_union const &) = delete;
+
+  data_union(std::nullptr_t) noexcept {}
+  ~data_union() {}
+
+  template <typename... A>
+  data_union(in_place_t, A &&...args) : value_{std::forward<A>(args)...} {}
+  template <typename... A>
+  data_union(unexpected_t, A &&...args) : error_{std::forward<A>(args)...} {}
+
+  void destruct_value() noexcept { destroy(&value_); }
+  void destruct_error() noexcept { destroy(&error_); }
+
+  const_value_t & value() const &  noexcept { return value_; }
+  T &             value() &        noexcept { return value_; }
+  const_value_t &&value() const && noexcept { return std::move(value_); }
+  T &&            value() &&       noexcept { return std::move(value_); }
+
+  const_error_t & error() const &  noexcept { return error_; }
+  E &             error() &        noexcept { return error_; }
+  const_error_t &&error() const && noexcept { return std::move(error_); }
+  E &&            error() &&       noexcept { return std::move(error_); }
+};
+
+template <typename E>
+struct data_union<void, E> {
+  using const_error_t = typename std::add_const<E>::type;
+
+  alignas(E) std::array<byte, sizeof(E)> error_;  ///< the unexpected value
+
+  data_union(data_union const &) = delete;
+  data_union &operator=(data_union const &) = delete;
+
+  data_union(std::nullptr_t) noexcept {}
+
+  template <typename... A>
+  data_union(in_place_t, A &&...) noexcept {}
+  template <typename... A>
+  data_union(unexpected_t, A &&...args) {
+    construct<E>(&error_, std::forward<A>(args)...);
+  }
+
+  void destruct_value() noexcept {}
+  void destruct_error() noexcept { destroy(reinterpret_cast<E *>(&error_)); }
+
+  const_error_t & error() const &  noexcept { return *reinterpret_cast<E *>(error_.data()); }
+  E &             error() &        noexcept { return *reinterpret_cast<E *>(error_.data()); }
+  const_error_t &&error() const && noexcept { return std::move(*reinterpret_cast<E *>(error_.data())); }
+  E &&            error() &&       noexcept { return std::move(*reinterpret_cast<E *>(error_.data())); }
+};
+
+template <typename T, typename E>
+auto destruct(bool /*has_value*/, data_union<T, E> &/*data*/) noexcept
+  -> typename std::enable_if<std::is_trivially_destructible<T>::value &&
+                             std::is_trivially_destructible<E>::value>::type {
+  // Do nothing.
+}
+
+template <typename T, typename E>
+auto destruct(bool has_value, data_union<T, E> &data) noexcept
+  -> typename std::enable_if<!std::is_trivially_destructible<T>::value &&
+                              std::is_trivially_destructible<E>::value>::type {
+  if (has_value) data.destruct_value();
+}
+
+template <typename T, typename E>
+auto destruct(bool has_value, data_union<T, E> &data) noexcept
+  -> typename std::enable_if< std::is_trivially_destructible<T>::value &&
+                             !std::is_trivially_destructible<E>::value>::type {
+  if (!has_value) data.destruct_error();
+}
+
+template <typename T, typename E>
+auto destruct(bool has_value, data_union<T, E> &data) noexcept
+  -> typename std::enable_if<!std::is_trivially_destructible<T>::value &&
+                             !std::is_trivially_destructible<E>::value>::type {
+  if (has_value) {
+    data.destruct_value();
+  } else {
+    data.destruct_error();
+  }
+}
+
+template <typename S, typename T, typename E>
+struct value_getter : data_union<T, E> {
+  using data_union<T, E>::data_union;
+
+  template <typename U>
+  value_getter(U &&other) : data_union<T, E>(nullptr) {
+    if (other) {
+      construct<data_union<T, E>>(this, in_place, std::forward<U>(other).value());
+    } else {
+      construct<data_union<T, E>>(this, unexpected, std::forward<U>(other).error());
+    }
+  }
+
+  T const *operator->() const noexcept { return std::addressof(this->value()); }
+  T *      operator->()       noexcept { return std::addressof(this->value()); }
+
+  T const & operator*() const &  noexcept { return this->value(); }
+  T &       operator*()       &  noexcept { return this->value(); }
+  T const &&operator*() const && noexcept { return std::move(this->value()); }
+  T &&      operator*()       && noexcept { return std::move(this->value()); }
+
+  template <typename U>
+  T value_or(U &&def) const & {
+    return bool(*static_cast<S *>(this)) ? **this : static_cast<T>(std::forward<U>(def));
+  }
+  template <typename U>
+  T value_or(U &&def) && {
+    return bool(*static_cast<S *>(this)) ? std::move(**this) : static_cast<T>(std::forward<U>(def));
+  }
+
+  template <typename... A>
+  T &emplace(A &&...args) {
+    static_cast<S *>(this)->reconstruct(in_place, std::forward<A>(args)...);
+    return this->value();
+  }
+
+  void swap(S &other) {
+    if (bool(*static_cast<S *>(this)) && bool(other)) {
+      std::swap(this->value(), other.value());
+    } else if (!*static_cast<S *>(this) && !other) {
+      std::swap(this->error(), other.error());
+    } else if (!*static_cast<S *>(this) && bool(other)) {
+      E err(std::move(this->error()));
+      this->emplace(std::move(other.value()));
+      other.reconstruct(unexpected, std::move(err));
+    } else /*if (bool(*this) && !other)*/ {
+      E err(std::move(other.error()));
+      other.emplace(std::move(this->value()));
+      static_cast<S *>(this)->reconstruct(unexpected, std::move(err));
+    }
+  }
+};
+
+template <typename S, typename E>
+struct value_getter<S, void, E> : data_union<void, E> {
+  using data_union<void, E>::data_union;
+
+  template <typename U>
+  value_getter(U &&other) : data_union<void, E>(nullptr) {
+    if (other) {
+      construct<data_union<void, E>>(this, in_place);
+    } else {
+      construct<data_union<void, E>>(this, unexpected, std::forward<U>(other).error());
+    }
+  }
+
+  void emplace() noexcept {
+    static_cast<S *>(this)->reconstruct(in_place);
+  }
+
+  void swap(S &other) {
+    if (bool(*static_cast<S *>(this)) && bool(other)) {
+      return;
+    } else if (!*static_cast<S *>(this) && !other) {
+      std::swap(this->error(), other.error());
+    } else if (!*static_cast<S *>(this) && bool(other)) {
+      E err(std::move(this->error()));
+      this->emplace();
+      other.reconstruct(unexpected, std::move(err));
+    } else /*if (bool(*this) && !other)*/ {
+      E err(std::move(other.error()));
+      other.emplace();
+      static_cast<S *>(this)->reconstruct(unexpected, std::move(err));
+    }
+  }
+};
+
+/**
+ * \brief Define the expected storage.
+ */
+template <typename T, typename E>
+struct storage : value_getter<storage<T, E>, T, E> {
+  using getter_t = value_getter<storage<T, E>, T, E>;
+
+  bool has_value_;
+
+  template <typename... A>
+  storage(in_place_t, A &&...args)
+    : getter_t(in_place, std::forward<A>(args)...)
+    , has_value_(true) {}
+
+  template <typename... A>
+  storage(unexpected_t, A &&...args)
+    : getter_t(unexpected, std::forward<A>(args)...)
+    , has_value_(false) {}
+
+  storage(storage const &other)
+    : getter_t(other)
+    , has_value_(other.has_value_) {}
+
+  storage(storage &&other)
+    : getter_t(std::move(other))
+    /// After construction, has_value() is equal to other.has_value().
+    , has_value_(other.has_value_) {}
+
+  template <typename T_, typename E_>
+  storage(storage<T_, E_> const &other)
+    : getter_t(other)
+    , has_value_(other.has_value_) {}
+
+  template <typename T_, typename E_>
+  storage(storage<T_, E_> &&other)
+    : getter_t(std::move(other))
+    /// After construction, has_value() is equal to other.has_value().
+    , has_value_(other.has_value_) {}
+
+  bool has_value() const noexcept {
+    return has_value_;
+  }
+
+  explicit operator bool() const noexcept {
+    return this->has_value();
+  }
+
+protected:
+  friend getter_t;
+
+  template <typename... A>
+  void reconstruct(A &&...args) {
+    destroy(this);
+    construct<storage>(this, std::forward<A>(args)...);
+  }
+};
+
+/// \brief The invoke forwarding helper.
+
+template <typename F, typename... A>
+auto invoke(F &&f, A &&...args) noexcept(
+     noexcept(std::forward<F>(f)(std::forward<A>(args)...)))
+  -> decltype(std::forward<F>(f)(std::forward<A>(args)...)) {
+  return std::forward<F>(f)(std::forward<A>(args)...);
+}
+
+template <typename F, typename... A>
+auto invoke(F &&f, A &&...args) noexcept(
+     noexcept(std::forward<F>(f)()))
+  -> decltype(std::forward<F>(f)()) {
+  return std::forward<F>(f)();
+}
+
+/// \brief and_then helper.
+
+template <typename E, typename F,
+          typename R = decltype(invoke(std::declval<F>(), *std::declval<E>()))>
+R and_then(E &&exp, F &&f) {
+  static_assert(is_specialized<expected, R>::value, "F must return an `expected`.");
+  return bool(exp) ? invoke(std::forward<F>(f), *std::forward<E>(exp))
+                   : R(unexpected, std::forward<E>(exp).error());
+}
+
+/// \brief or_else helper.
+
+template <typename E, typename F,
+          typename R = decltype(invoke(std::declval<F>(), std::declval<E>().error()))>
+R or_else(E &&exp, F &&f) {
+  static_assert(is_specialized<expected, R>::value, "F must return an `expected`.");
+  return bool(exp) ? std::forward<E>(exp)
+                   : invoke(std::forward<F>(f), std::forward<E>(exp).error());
+}
+
+} // namespace detail_expected
+
+/**
+ * \class template <typename T, typename E> expected
+ * \brief Provides a way to store either of two values.
+ */
+template <typename T, typename E>
+class expected : public detail_expected::storage<typename std::remove_cv<T>::type, E> {
+public:
+  using value_type = typename std::remove_cv<T>::type;
+  using error_type = E;
+
+  using detail_expected::storage<value_type, E>::storage;
+
+  expected(expected const &) = default;
+  expected(expected &&) = default;
+
+  expected()
+    : detail_expected::storage<value_type, E>(in_place) {}
+
+  expected &operator=(expected other) {
+    this->swap(other);
+    return *this;
+  }
+
+  // Monadic operations
+
+  template <typename F>
+  auto and_then(F &&f) & {
+    return detail_expected::and_then(*this, std::forward<F>(f));
+  }
+
+  template <typename F>
+  auto and_then(F &&f) const & {
+    return detail_expected::and_then(*this, std::forward<F>(f));
+  }
+
+  template <typename F>
+  auto and_then(F &&f) && {
+    return detail_expected::and_then(std::move(*this), std::forward<F>(f));
+  }
+
+  template <typename F>
+  auto or_else(F &&f) & {
+    return detail_expected::or_else(*this, std::forward<F>(f));
+  }
+
+  template <typename F>
+  auto or_else(F &&f) const & {
+    return detail_expected::or_else(*this, std::forward<F>(f));
+  }
+
+  template <typename F>
+  auto or_else(F &&f) && {
+    return detail_expected::or_else(std::move(*this), std::forward<F>(f));
+  }
+};
+
+// Compares
+
+template <typename T1, typename E1, typename T2, typename E2>
+bool operator==(expected<T1, E1> const &lhs, expected<T2, E2> const &rhs) {
+  return (lhs.has_value() == rhs.has_value())
+      && (lhs.has_value() ? *lhs == *rhs : lhs.error() == rhs.error());
+}
+
+template <typename E1, typename E2>
+bool operator==(expected<void, E1> const &lhs, expected<void, E2> const &rhs) {
+  return (lhs.has_value() == rhs.has_value())
+      && (lhs.has_value() || lhs.error() == rhs.error());
+}
+
+template <typename T1, typename E1, typename T2, typename E2>
+bool operator!=(expected<T1, E1> const &lhs, expected<T2, E2> const &rhs) {
+  return !(lhs == rhs);
+}
+
+} // namespace ipc
diff --git a/include/libipc/imp/export.h b/include/libipc/imp/export.h
new file mode 100755
index 00000000..027fd002
--- /dev/null
+++ b/include/libipc/imp/export.h
@@ -0,0 +1,45 @@
+/**
+ * \file libipc/export.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Define the symbol export interfaces.
+ */
+#pragma once
+
+#include "libipc/imp/detect_plat.h"
+
+#if defined(Q_DECL_EXPORT) && defined(Q_DECL_IMPORT)
+
+# define LIBIPC_DECL_EXPORT Q_DECL_EXPORT
+# define LIBIPC_DECL_IMPORT Q_DECL_IMPORT
+
+#else // defined(Q_DECL_EXPORT) && defined(Q_DECL_IMPORT)
+
+/**
+ * \brief Compiler & system detection for LIBIPC_DECL_EXPORT & LIBIPC_DECL_IMPORT.
+ * Not using QtCore cause it shouldn't depend on Qt.
+ */
+# if defined(LIBIPC_CC_MSVC) || defined(LIBIPC_OS_WIN)
+#   define LIBIPC_DECL_EXPORT __declspec(dllexport)
+#   define LIBIPC_DECL_IMPORT __declspec(dllimport)
+# elif defined(LIBIPC_OS_ANDROID) || defined(LIBIPC_OS_LINUX) || defined(LIBIPC_CC_GNUC)
+#   define LIBIPC_DECL_EXPORT __attribute__((visibility("default")))
+#   define LIBIPC_DECL_IMPORT __attribute__((visibility("default")))
+# else
+#   define LIBIPC_DECL_EXPORT __attribute__((visibility("default")))
+#   define LIBIPC_DECL_IMPORT __attribute__((visibility("default")))
+# endif
+
+#endif // defined(Q_DECL_EXPORT) && defined(Q_DECL_IMPORT)
+
+/**
+ * \brief Define LIBIPC_EXPORT for exporting function & class.
+ */
+#ifndef LIBIPC_EXPORT
+# if defined(LIBIPC_LIBRARY_SHARED_BUILDING__)
+#   define LIBIPC_EXPORT LIBIPC_DECL_EXPORT
+# elif defined(LIBIPC_LIBRARY_SHARED_USING__)
+#   define LIBIPC_EXPORT LIBIPC_DECL_IMPORT
+# else
+#   define LIBIPC_EXPORT
+# endif
+#endif /*LIBIPC_EXPORT*/
diff --git a/include/libipc/imp/fmt.h b/include/libipc/imp/fmt.h
new file mode 100644
index 00000000..c9d7af29
--- /dev/null
+++ b/include/libipc/imp/fmt.h
@@ -0,0 +1,177 @@
+/**
+ * \file libipc/fmt.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief String formatting.
+ * 
+ * \remarks The current performance is not high, 
+ * because I use std::sprintf directly for formatting for convenience.
+ */
+#pragma once
+
+#include <string>
+#include <utility>
+#include <type_traits>
+#include <chrono>   // std::chrono::time_point
+#include <tuple>
+#include <cstddef>
+#include <ctime>    // std::tm, std::localtime
+
+#include "libipc/imp/fmt_cpo.h"
+#include "libipc/imp/span.h"
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/export.h"
+
+namespace ipc {
+
+/**
+ * \brief The format string reference wrapper.
+ */
+template <typename T>
+struct fmt_ref {
+  span<char const> fstr;
+  T param;
+};
+
+/**
+ * \brief Conversion specifiers.
+ * 
+ * \remarks Just like printf, the format string is of the form
+ * [flags][field_width][.precision][conversion_character]
+ * 
+ * \see http://personal.ee.surrey.ac.uk/Personal/R.Bowden/C/printf.html
+ */
+template <std::size_t N>
+auto spec(char const (&fstr)[N]) noexcept {
+  return [&fstr](auto &&arg) noexcept {
+    using arg_t = decltype(arg);
+    return fmt_ref<arg_t> {{fstr}, static_cast<arg_t>(arg)};
+  };
+}
+
+/**
+ * \brief String formatting function.
+ * 
+ * \param args arguments that support the fmt output
+ * \return an empty string if the fmt output fails 
+ */
+template <typename... A>
+LIBIPC_NODISCARD std::string fmt(A &&...args) {
+  std::string joined;
+  fmt_context ctx(joined);
+  if (fmt_to(ctx, std::forward<A>(args)...)) {
+    return ctx.finish() ? joined : "";
+  }
+  return {};
+}
+
+/// \brief String types.
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, char const *       a) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, std::string const &a) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, char const *       a, span<char const> fstr) noexcept;
+       inline bool to_string(fmt_context &ctx, std::string const &a, span<char const> fstr) noexcept { return to_string(ctx, a.c_str(), fstr); }
+
+/// \brief Character to string conversion.
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, char     a) noexcept;
+#if defined(LIBIPC_CPP_20)
+       inline bool to_string(fmt_context &ctx, char8_t  a) noexcept { return to_string(ctx, (char)a); }
+#endif // defined(LIBIPC_CPP_20)
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, wchar_t  a) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, char16_t a) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, char32_t a) noexcept;
+
+/// \brief Conversion of numeric types to strings.
+LIBIPC_EXPORT bool to_string(fmt_context &ctx,   signed short     a, span<char const> fstr = {}) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, unsigned short     a, span<char const> fstr = {}) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx,   signed int       a, span<char const> fstr = {}) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, unsigned int       a, span<char const> fstr = {}) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx,   signed long      a, span<char const> fstr = {}) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, unsigned long      a, span<char const> fstr = {}) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx,   signed long long a, span<char const> fstr = {}) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, unsigned long long a, span<char const> fstr = {}) noexcept;
+       inline bool to_string(fmt_context &ctx,   signed char      a, span<char const> fstr = {}) noexcept { return to_string(ctx,      (int)a, fstr); }
+       inline bool to_string(fmt_context &ctx, unsigned char      a, span<char const> fstr = {}) noexcept { return to_string(ctx, (unsigned)a, fstr); }
+
+/// \brief Conversion of floating point type to strings.
+LIBIPC_EXPORT bool to_string(fmt_context &ctx,      double a, span<char const> fstr = {}) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, long double a, span<char const> fstr = {}) noexcept;
+       inline bool to_string(fmt_context &ctx, float       a, span<char const> fstr = {}) noexcept { return to_string(ctx, (double)a, fstr); }
+
+/// \brief Pointer.
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, std::nullptr_t) noexcept;
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, void const volatile *a) noexcept;
+template <typename T,
+          typename = std::enable_if_t<!std::is_same<T, char>::value>>
+inline bool to_string(fmt_context &ctx, T const volatile *a) noexcept { return to_string(ctx, (void *)a); }
+
+/// \brief Date and time.
+LIBIPC_EXPORT bool to_string(fmt_context &ctx, std::tm const &a, span<char const> fstr = {}) noexcept;
+
+namespace detail_fmt {
+
+/**
+ * \brief Convert std::time_t to std::string.
+ * \return an empty string if the conversion fails
+ */
+inline bool time_to_string(fmt_context &ctx, std::time_t tt, span<char const> fstr) noexcept {
+#if defined(LIBIPC_CC_MSVC)
+  /// \see https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/localtime-s-localtime32-s-localtime64-s
+  std::tm tm{};
+  if (::localtime_s(&tm, &tt) != 0) {
+    return {};
+  }
+  return to_string(ctx, tm, fstr);
+#else
+  return to_string(ctx, *std::localtime(&tt), fstr);
+#endif
+}
+
+} // namespace detail_fmt
+
+template <class Clock, class Duration>
+bool to_string(fmt_context &ctx, std::chrono::time_point<Clock, Duration> const &a, span<char const> fstr = {}) noexcept {
+  return detail_fmt::time_to_string(ctx, std::chrono::system_clock::to_time_t(a), fstr);
+}
+
+/**
+ * \brief Predefined fmt_to method
+ */
+namespace detail_tag_invoke {
+
+template <typename T>
+auto tag_invoke(decltype(ipc::fmt_to), fmt_context &ctx, T &&arg) noexcept
+  -> decltype(ipc::to_string(ctx, std::forward<T>(arg))) {
+  return ipc::to_string(ctx, std::forward<T>(arg));
+}
+
+template <typename T>
+auto tag_invoke(decltype(ipc::fmt_to), fmt_context &ctx, fmt_ref<T> arg) noexcept
+  -> decltype(ipc::to_string(ctx, static_cast<T>(arg.param), arg.fstr)) {
+  return ipc::to_string(ctx, static_cast<T>(arg.param), arg.fstr);
+}
+
+template <typename T>
+bool tag_invoke(decltype(ipc::fmt_to), fmt_context &ctx, span<T> s) {
+  if (s.empty()) {
+    return false;
+  }
+  if (!fmt_to(ctx, s[0])) {
+    return false;
+  }
+  for (std::size_t i = 1; i < s.size(); ++i) {
+    if (!fmt_to(ctx, ' ', s[i])) return false;
+  }
+  return true;
+}
+
+template <typename Tp, std::size_t... I>
+bool unfold_tuple_fmt_to(fmt_context &ctx, Tp const &tp, std::index_sequence<I...>) {
+  return fmt_to(ctx, std::get<I>(tp)...);
+}
+
+template <typename... T>
+bool tag_invoke(decltype(ipc::fmt_to), fmt_context &ctx, std::tuple<T...> const &tp) {
+  return unfold_tuple_fmt_to(ctx, tp, std::index_sequence_for<T...>{});
+}
+
+} // namespace detail_tag_invoke
+} // namespace ipc
diff --git a/include/libipc/imp/fmt_cpo.h b/include/libipc/imp/fmt_cpo.h
new file mode 100644
index 00000000..463ef8be
--- /dev/null
+++ b/include/libipc/imp/fmt_cpo.h
@@ -0,0 +1,66 @@
+/**
+ * \file libipc/fmt_cpo.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief String formatting CPO.
+ */
+#pragma once
+
+#include <string>
+#include <cstddef>
+#include <array>
+
+#include "libipc/imp/generic.h"
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/span.h"
+#include "libipc/imp/export.h"
+
+namespace ipc {
+
+/**
+ * \class class LIBIPC_EXPORT fmt_context
+ * \brief The context of fmt.
+ */
+class LIBIPC_EXPORT fmt_context {
+  std::array<char, 2048U> sbuf_; ///< stack buffer
+
+  std::string &joined_;
+  std::size_t  offset_;
+
+public:
+  fmt_context(std::string &j) noexcept;
+
+  std::size_t capacity() noexcept;
+  void reset() noexcept;
+  bool finish() noexcept;
+  span<char> buffer(std::size_t sz) noexcept;
+  void expend(std::size_t sz) noexcept;
+  bool append(span<char const> const &str) noexcept;
+};
+
+/// \brief Supports custom fmt_to methods for ipc::fmt.
+namespace detail_tag_invoke {
+
+class fmt_to_t {
+  template <typename A1>
+  bool get_result(fmt_context &ctx, A1 && a1) const {
+    return ipc::tag_invoke(fmt_to_t{}, ctx, std::forward<A1>(a1));
+  }
+
+  template <typename A1, typename... A>
+  bool get_result(fmt_context &ctx, A1 && a1, A &&...args) const {
+    return get_result(ctx, std::forward<A1>(a1))
+        && get_result(ctx, std::forward<A>(args)...);
+  }
+
+public:
+  template <typename... A>
+  bool operator()(fmt_context &ctx, A &&...args) const {
+    return get_result(ctx, std::forward<A>(args)...);
+  }
+};
+
+} // namespace detail_tag_invoke
+
+constexpr detail_tag_invoke::fmt_to_t fmt_to{};
+
+} // namespace ipc
diff --git a/include/libipc/imp/generic.h b/include/libipc/imp/generic.h
new file mode 100644
index 00000000..c3b63ed5
--- /dev/null
+++ b/include/libipc/imp/generic.h
@@ -0,0 +1,301 @@
+/**
+ * \file libipc/generic.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Tools for generic programming.
+ */
+#pragma once
+
+#include <utility>
+#include <type_traits>  // std::declval, std::true_type, std::false_type
+#include <cstddef>      // std::size_t
+
+#include "libipc/imp/detect_plat.h"
+
+namespace ipc {
+
+/**
+ * \brief Utility metafunction that maps a sequence of any types to the type void
+ * \see https://en.cppreference.com/w/cpp/types/void_t
+ */
+template <typename...>
+using void_t = void;
+
+/**
+ * \brief A type-list for generic programming.
+*/
+template <typename...>
+struct types {};
+
+/**
+ * \brief To indicate that the contained object should be constructed in-place.
+ * \see https://en.cppreference.com/w/cpp/utility/in_place
+ */
+#if defined(LIBIPC_CPP_17)
+using std::in_place_t;
+using std::in_place;
+#else /*!LIBIPC_CPP_17*/
+struct in_place_t {
+  explicit in_place_t() = default;
+};
+constexpr in_place_t in_place{};
+#endif/*!LIBIPC_CPP_17*/
+
+/**
+ * \brief A general pattern for supporting customisable functions
+ * \see https://www.open-std.org/jtc1/sc22/WG21/docs/papers/2019/p1895r0.pdf
+ */
+namespace detail_tag_invoke {
+
+void tag_invoke();
+
+struct tag_invoke_t {
+  template <typename T, typename... A>
+  constexpr auto operator()(T tag, A &&...args) const
+    noexcept(noexcept(tag_invoke(std::forward<T>(tag), std::forward<A>(args)...)))
+          -> decltype(tag_invoke(std::forward<T>(tag), std::forward<A>(args)...)) {
+    return tag_invoke(std::forward<T>(tag), std::forward<A>(args)...);
+  }
+};
+
+} // namespace detail_tag_invoke
+
+constexpr detail_tag_invoke::tag_invoke_t tag_invoke{};
+
+/**
+ * \brief Circumventing forwarding reference may override copy and move constructs.
+ * \see https://mpark.github.io/programming/2014/06/07/beware-of-perfect-forwarding-constructors/
+ */
+namespace detail_not_match {
+
+template <typename T, typename... A>
+struct is_same_first : std::false_type {};
+
+template <typename T>
+struct is_same_first<T, T> : std::true_type {};
+
+} // namespace detail_not_match
+
+template <typename T, typename... A>
+using not_match = 
+  typename std::enable_if<!detail_not_match::is_same_first<T, 
+  typename std::decay<A>::type...>::value, bool>::type;
+
+/**
+ * \brief Determines whether a type is specialized from a particular template.
+ */
+template <template <typename...> class Tt, typename T>
+struct is_specialized : std::false_type {};
+
+template <template <typename...> class Tt, typename... A>
+struct is_specialized<Tt, Tt<A...>> : std::true_type {};
+
+/**
+ * \brief Copy the cv qualifier and reference of the source type to the target type.
+ */
+template <typename Src, typename Des>
+struct copy_cvref {
+  using type = Des;
+};
+
+template <typename Src, typename Des>
+struct copy_cvref<Src const, Des> {
+  using type = typename std::add_const<Des>::type;
+};
+
+template <typename Src, typename Des>
+struct copy_cvref<Src volatile, Des> {
+  using type = typename std::add_volatile<Des>::type;
+};
+
+template <typename Src, typename Des>
+struct copy_cvref<Src const volatile, Des> {
+  using type = typename std::add_cv<Des>::type;
+};
+
+template <typename Src, typename Des>
+struct copy_cvref<Src &, Des> {
+  using type = typename std::add_lvalue_reference<
+               typename copy_cvref<Src, Des>::type>::type;
+};
+
+template <typename Src, typename Des>
+struct copy_cvref<Src &&, Des> {
+  using type = typename std::add_rvalue_reference<
+               typename copy_cvref<Src, Des>::type>::type;
+};
+
+template <typename Src, typename Des>
+using copy_cvref_t = typename copy_cvref<Src, Des>::type;
+
+/**
+ * \brief Returns the size of the given range.
+ * \see https://en.cppreference.com/w/cpp/iterator/size
+*/
+namespace detail_countof {
+
+template <typename T>
+struct trait_has_size {
+private:
+  template <typename Type>
+  static std::true_type check(decltype(std::declval<Type>().size())*);
+  template <typename Type>
+  static std::false_type check(...);
+public:
+  using type = decltype(check<T>(nullptr));
+  static constexpr auto value = type::value;
+};
+
+template <typename T>
+struct trait_has_Size {
+private:
+  template <typename Type>
+  static std::true_type check(decltype(std::declval<Type>().Size())*);
+  template <typename Type>
+  static std::false_type check(...);
+public:
+  using type = decltype(check<T>(nullptr));
+  static constexpr auto value = type::value;
+};
+
+template <typename C, bool = trait_has_size<C>::value
+                    , bool = trait_has_Size<C>::value>
+struct trait;
+
+template <typename T, std::size_t N>
+struct trait<T[N], false, false> {
+  static constexpr auto countof(T const (&)[N]) noexcept {
+    return N;
+  }
+};
+
+template <typename C, bool B>
+struct trait<C, true, B> {
+  static constexpr auto countof(C const &c) noexcept(noexcept(c.size())) {
+    return c.size();
+  }
+};
+
+template <typename C>
+struct trait<C, false, true> {
+  static constexpr auto countof(C const &c) noexcept(noexcept(c.Size())) {
+    return c.Size();
+  }
+};
+
+} // namespace detail_countof
+
+template <typename C, 
+          typename T = detail_countof::trait<C>, 
+          typename R = decltype(T::countof(std::declval<C const &>()))>
+constexpr R countof(C const &c) noexcept(noexcept(T::countof(c))) {
+  return T::countof(c);
+}
+
+/**
+ * \brief Returns the data pointer of the given range.
+ * \see https://en.cppreference.com/w/cpp/iterator/data
+*/
+
+namespace detail_dataof {
+
+template <typename T>
+struct trait_has_data {
+private:
+  template <typename Type>
+  static std::true_type check(decltype(std::declval<Type>().data())*);
+  template <typename Type>
+  static std::false_type check(...);
+public:
+  using type = decltype(check<T>(nullptr));
+  static constexpr auto value = type::value;
+};
+
+template <typename T>
+struct trait_has_Data {
+private:
+  template <typename Type>
+  static std::true_type check(decltype(std::declval<Type>().Data())*);
+  template <typename Type>
+  static std::false_type check(...);
+public:
+  using type = decltype(check<T>(nullptr));
+  static constexpr auto value = type::value;
+};
+
+template <typename C, bool = trait_has_data<C>::value
+                    , bool = trait_has_Data<C>::value>
+struct trait;
+
+template <typename T, std::size_t N>
+struct trait<T[N], false, false> {
+  static constexpr T const *dataof(T const (&arr)[N]) noexcept {
+    return arr;
+  }
+  static constexpr T *dataof(T (&arr)[N]) noexcept {
+    return arr;
+  }
+};
+
+template <typename C, bool B>
+struct trait<C, true, B> {
+  template <typename T>
+  static constexpr auto dataof(T &&c) noexcept(noexcept(c.data())) {
+    return std::forward<T>(c).data();
+  }
+};
+
+template <typename C>
+struct trait<C, false, true> {
+  template <typename T>
+  static constexpr auto dataof(T &&c) noexcept(noexcept(c.Data())) {
+    return std::forward<T>(c).Data();
+  }
+};
+
+template <typename C>
+struct trait<C, false, false> {
+  template <typename T>
+  static constexpr T const *dataof(std::initializer_list<T> il) noexcept {
+    return il.begin();
+  }
+  template <typename T>
+  static constexpr T const *dataof(T const *p) noexcept {
+    return p;
+  }
+};
+
+} // namespace detail_dataof
+
+template <typename C, 
+          typename T = detail_dataof::trait<std::remove_cv_t<std::remove_reference_t<C>>>, 
+          typename R = decltype(T::dataof(std::declval<C>()))>
+constexpr R dataof(C &&c) noexcept(noexcept(T::dataof(std::forward<C>(c)))) {
+  return T::dataof(std::forward<C>(c));
+}
+
+/// \brief Returns after converting the value to the underlying type of E.
+/// \see https://en.cppreference.com/w/cpp/types/underlying_type
+///      https://en.cppreference.com/w/cpp/utility/to_underlying
+template <typename E>
+constexpr auto underlyof(E e) noexcept {
+  return static_cast<std::underlying_type_t<E>>(e);
+}
+
+namespace detail_horrible_cast {
+
+template <typename T, typename U>
+union temp {
+  U in;
+  T out;
+};
+
+} // namespace detail_horrible_cast
+
+template <typename T, typename U>
+constexpr auto horrible_cast(U &&in) noexcept
+  -> typename std::enable_if<std::is_trivially_copyable<T>::value
+                          && std::is_trivially_copyable<std::decay_t<U>>::value, T>::type {
+  return detail_horrible_cast::temp<T, std::decay_t<U>>{std::forward<U>(in)}.out;
+}
+
+} // namespace ipc
diff --git a/include/libipc/imp/log.h b/include/libipc/imp/log.h
new file mode 100644
index 00000000..7ad31aac
--- /dev/null
+++ b/include/libipc/imp/log.h
@@ -0,0 +1,195 @@
+/**
+ * \file libipc/log.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Simple log output component.
+ */
+#pragma once
+
+#include <string>
+#include <type_traits>
+#include <chrono>
+#include <tuple>
+#include <utility>
+#include <exception>
+
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/export.h"
+#include "libipc/imp/fmt.h"
+#include "libipc/imp/generic.h"
+
+namespace ipc {
+namespace log {
+
+enum class level : std::int32_t {
+  trace,
+  debug,
+  info,
+  warning,
+  error,
+  failed,
+};
+
+/// \struct template <typename... T> struct context
+/// \brief Logging context.
+/// \tparam ...T - a log records all parameter types passed
+template <typename... T>
+struct context {
+  log::level level;
+  std::chrono::system_clock::time_point tp;
+  char const *func;
+  std::tuple<T...> params;
+};
+
+/// \brief Custom defined fmt_to method for imp::fmt
+namespace detail_log {
+
+template <typename Tp, std::size_t... I, typename... A>
+bool unfold_tuple_fmt_to(fmt_context &ctx, Tp const &tp, std::index_sequence<I...>, A &&...args) {
+  return fmt_to(ctx, std::forward<A>(args)..., std::get<I>(tp)...);
+}
+
+} // namespace detail_log
+
+template <typename... T>
+bool context_to_string(fmt_context &f_ctx, context<T...> const &l_ctx) {
+  static constexpr char types[] = {
+    'T', 'D', 'I', 'W', 'E', 'F',
+  };
+  auto ms = std::chrono::time_point_cast<std::chrono::milliseconds>(l_ctx.tp).time_since_epoch().count() % 1000;
+  return detail_log::unfold_tuple_fmt_to(f_ctx, l_ctx.params, std::index_sequence_for<T...>{},
+                                        "[", types[underlyof(l_ctx.level)], "]"
+                                        "[", l_ctx.tp, ".", spec("03")(ms), "]"
+                                        "[", l_ctx.func, "] ");
+}
+
+template <typename... T>
+std::string context_to_string(context<T...> const &l_ctx) {
+  std::string log_txt;
+  fmt_context f_ctx(log_txt);
+  LIBIPC_TRY {
+    if (!context_to_string(f_ctx, l_ctx)) {
+      return {};
+    }
+    f_ctx.finish();
+    return log_txt;
+  } LIBIPC_CATCH(...) {
+    f_ctx.finish();
+    throw;
+  }
+}
+
+/// \brief Standard console output object.
+inline auto &make_std_out() noexcept {
+  static auto std_out = [](auto const &ctx) {
+    auto s = context_to_string(ctx);
+    switch (ctx.level) {
+    case level::trace:
+    case level::debug:
+    case level::info:
+      std::fprintf(stdout, "%s\n", s.c_str());
+      break;
+    case level::warning:
+    case level::error:
+    case level::failed:
+      std::fprintf(stderr, "%s\n", s.c_str());
+      break;
+    default:
+      break;
+    }
+  };
+  return std_out;
+}
+
+/// \brief Get the exception information.
+inline char const *exception_string(std::exception_ptr eptr) noexcept {
+  LIBIPC_TRY {
+    if (eptr) {
+      std::rethrow_exception(eptr);
+    }
+  } LIBIPC_CATCH(std::exception const &e) {
+    return e.what();
+  } LIBIPC_CATCH(...) {
+    return "unknown";
+  }
+  return "none";
+}
+
+/// \brief Record the last information when an exception occurs.
+inline void exception_print(char const *func, std::exception_ptr eptr) noexcept {
+  if (func == nullptr) {
+    func = "-";
+  }
+  std::fprintf(stderr, "[F][%s] exception: %s\n", func, exception_string(eptr));
+}
+
+/**
+ * \brief Log information base class.
+ */
+class logger_base {
+protected:
+  char const *func_;
+  level level_limit_;
+
+  logger_base(char const *func, level level_limit) noexcept
+    : func_       (func)
+    , level_limit_(level_limit) {}
+};
+
+/**
+ * \brief Log information grips.
+ */
+template <typename Outputer>
+class logger : public logger_base {
+  Outputer out_;
+
+public:
+  template <typename O>
+  logger(char const *func, O &&out, level level_limit) noexcept
+    : logger_base(func, level_limit)
+    , out_       (std::forward<O>(out)) {}
+
+  template <typename... A>
+  logger const &operator()(log::level l, A &&...args) const noexcept {
+    if (underlyof(l) < underlyof(level_limit_)) {
+      return *this;
+    }
+    LIBIPC_TRY {
+      out_(context<A &&...> {
+        l, std::chrono::system_clock::now(), func_,
+        std::forward_as_tuple(std::forward<A>(args)...),
+      });
+    } LIBIPC_CATCH(...) {
+      exception_print(func_, std::current_exception());
+    }
+    return *this;
+  }
+
+  template <typename... A> logger const &trace  (A &&...args) const noexcept { return (*this)(log::level::trace  , std::forward<A>(args)...); }
+  template <typename... A> logger const &debug  (A &&...args) const noexcept { return (*this)(log::level::debug  , std::forward<A>(args)...); }
+  template <typename... A> logger const &info   (A &&...args) const noexcept { return (*this)(log::level::info   , std::forward<A>(args)...); }
+  template <typename... A> logger const &warning(A &&...args) const noexcept { return (*this)(log::level::warning, std::forward<A>(args)...); }
+  template <typename... A> logger const &error  (A &&...args) const noexcept { return (*this)(log::level::error  , std::forward<A>(args)...); }
+  template <typename... A> logger const &failed (A &&...args) const noexcept { return (*this)(log::level::failed , std::forward<A>(args)...); }
+};
+
+template <typename O>
+inline auto make_logger(char const *func, O &&out, level level_limit = level::info) noexcept {
+  return logger<std::decay_t<O>>(func, std::forward<O>(out), level_limit);
+}
+
+inline auto make_logger(char const *func, level level_limit = level::info) noexcept {
+  return make_logger(func, make_std_out(), level_limit);
+}
+
+inline auto make_logger(char const * /*ignore*/, char const *name, level level_limit = level::info) noexcept {
+  return make_logger(name, make_std_out(), level_limit);
+}
+
+#define LIBIPC_LOG(...) \
+  auto log \
+    = [](auto &&...args) noexcept { \
+        return ::ipc::log::make_logger(__func__, std::forward<decltype(args)>(args)...); \
+      }(__VA_ARGS__)
+
+} // namespace log
+} // namespace ipc
diff --git a/include/libipc/imp/nameof.h b/include/libipc/imp/nameof.h
new file mode 100644
index 00000000..ec7b4b2b
--- /dev/null
+++ b/include/libipc/imp/nameof.h
@@ -0,0 +1,43 @@
+/**
+ * \file libipc/nameof.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Gets the name string of a type.
+ */
+#pragma once
+
+#include <typeinfo>
+#include <string>
+#include <cstring>
+
+#include "libipc/imp/export.h"
+#include "libipc/imp/span.h"
+#include "libipc/imp/detect_plat.h"
+
+namespace ipc {
+
+/**
+ * \brief The conventional way to obtain demangled symbol name.
+ * \see https://www.boost.org/doc/libs/1_80_0/libs/core/doc/html/core/demangle.html
+ * 
+ * \param name the mangled name
+ * \return std::string a human-readable demangled type name
+ */
+LIBIPC_EXPORT std::string demangle(std::string name) noexcept;
+
+/**
+ * \brief Returns an implementation defined string containing the name of the type.
+ * \see https://en.cppreference.com/w/cpp/types/type_info/name
+ * 
+ * \tparam T a type
+ * \return std::string a human-readable demangled type name
+ */
+template <typename T>
+std::string nameof() noexcept {
+  LIBIPC_TRY {
+    return demangle(typeid(T).name());
+  } LIBIPC_CATCH(...) {
+    return {};
+  }
+}
+
+} // namespace ipc
diff --git a/include/libipc/imp/result.h b/include/libipc/imp/result.h
new file mode 100644
index 00000000..d5685e20
--- /dev/null
+++ b/include/libipc/imp/result.h
@@ -0,0 +1,138 @@
+/**
+ * \file libipc/result.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Define the return value type with an error status code.
+ */
+#pragma once
+
+#include <type_traits>
+#include <utility>
+#include <cstdint>
+
+#include "libipc/imp/expected.h"
+#include "libipc/imp/error.h"
+#include "libipc/imp/generic.h"
+#include "libipc/imp/fmt.h"
+
+namespace ipc {
+namespace detail_result {
+
+template <typename T>
+struct generic_initializer {
+  using storage_t = expected<T, std::error_code>;
+  
+  /// \brief Custom initialization.
+  static constexpr storage_t init_code() noexcept {
+    return {unexpected, std::error_code(-1, std::generic_category())};
+  }
+
+  static constexpr storage_t init_code(T value) noexcept {
+    return {in_place, value};
+  }
+
+  static constexpr storage_t init_code(std::error_code const &ec) noexcept {
+    return {unexpected, ec};
+  }
+};
+
+template <typename T, typename = void>
+struct result_base;
+
+template <typename T>
+struct result_base<T, std::enable_if_t<std::is_pointer<T>::value>>
+  : generic_initializer<T> {
+
+  using storage_t = typename generic_initializer<T>::storage_t;
+  using generic_initializer<T>::init_code;
+
+  static constexpr storage_t init_code(std::nullptr_t, std::error_code const &ec) noexcept {
+    return {unexpected, ec};
+  }
+
+  static constexpr storage_t init_code(std::nullptr_t) noexcept {
+    return {unexpected, std::error_code(-1, std::generic_category())};
+  }
+};
+
+template <typename T>
+struct result_base<T, std::enable_if_t<std::is_integral<T>::value || std::is_enum<T>::value>>
+  : generic_initializer<T> {
+
+  using storage_t = typename generic_initializer<T>::storage_t;
+  using generic_initializer<T>::init_code;
+};
+
+} // namespace detail_result
+
+/**
+ * \class class result
+ * \brief The generic wrapper for the result type.
+ */
+template <typename T>
+class result : public detail_result::result_base<T> {
+private:
+  using base_t    = detail_result::result_base<T>;
+  using storage_t = typename base_t::storage_t;
+
+  storage_t ret_; ///< internal data
+
+public:
+  template <typename... A, 
+            typename = not_match<result, A...>,
+            typename = decltype(base_t::init_code(std::declval<A>()...))>
+  result(A &&...args) noexcept
+    : ret_(base_t::init_code(std::forward<A>(args)...)) {}
+
+  std::string format_string() const {
+    if LIBIPC_LIKELY(ret_) {
+      return fmt("value = ", ret_.value());
+    } else {
+      return fmt("error = ", ret_.error());
+    }
+  }
+
+  T               value() const noexcept { return ret_ ? ret_.value() : T{}; }
+  bool            ok   () const noexcept { return ret_.has_value(); }
+  std::error_code error() const noexcept { return ret_.error(); }
+
+         T operator *   () const noexcept { return value(); }
+  explicit operator bool() const noexcept { return ok   (); }
+
+  friend bool operator==(result const &lhs, result const &rhs) noexcept { return lhs.ret_ == rhs.ret_; }
+  friend bool operator!=(result const &lhs, result const &rhs) noexcept { return !(lhs == rhs); }
+};
+
+template <>
+class result<void> {
+private:
+  std::error_code ret_; ///< internal data
+
+public:
+  result() noexcept
+    : ret_(-1, std::generic_category()) {}
+  
+  result(std::error_code const &ec) noexcept
+    : ret_(ec) {}
+
+  std::string format_string() const {
+    return fmt("error = ", error());
+  }
+
+  bool              ok   () const noexcept { return !ret_; }
+  std::error_code   error() const noexcept { return  ret_; }
+  explicit operator bool () const noexcept { return  ok(); }
+
+  friend bool operator==(result const &lhs, result const &rhs) noexcept { return lhs.ret_ == rhs.ret_; }
+  friend bool operator!=(result const &lhs, result const &rhs) noexcept { return !(lhs == rhs); }
+};
+
+/// \brief Custom defined fmt_to method for imp::fmt
+namespace detail_tag_invoke {
+
+template <typename T>
+inline bool tag_invoke(decltype(ipc::fmt_to), fmt_context &ctx, result<T> const &r) {
+  return fmt_to(ctx, (r ? "succ" : "fail"), ", ", r.format_string());
+}
+
+} // namespace detail_tag_invoke
+} // namespace ipc
diff --git a/include/libipc/imp/scope_exit.h b/include/libipc/imp/scope_exit.h
new file mode 100644
index 00000000..f1c00651
--- /dev/null
+++ b/include/libipc/imp/scope_exit.h
@@ -0,0 +1,77 @@
+/**
+ * \file libipc/scope_exit.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Execute guard function when the enclosing scope exits.
+ */
+#pragma once
+
+#include <utility>      // std::forward, std::move
+#include <functional>   // std::function
+#include <type_traits>
+
+#include "libipc/imp/detect_plat.h"
+
+namespace ipc {
+
+template <typename F = std::function<void()>>
+class scope_exit {
+  F destructor_;
+  mutable bool released_;
+
+public:
+  template <typename G>
+  explicit scope_exit(G &&destructor) noexcept
+    : destructor_(std::forward<G>(destructor))
+    , released_  (false) {}
+
+  scope_exit(scope_exit &&other) noexcept
+    : destructor_(std::move(other.destructor_))
+    , released_  (std::exchange(other.released_, true)) /*release rhs*/ {}
+
+  scope_exit &operator=(scope_exit &&other) noexcept {
+    destructor_ = std::move(other.destructor_);
+    released_   = std::exchange(other.released_, true);
+    return *this;
+  }
+
+  ~scope_exit() noexcept {
+    if (!released_) destructor_();
+  }
+
+  void release() const noexcept {
+    released_ = true;
+  }
+
+  void do_exit() noexcept {
+    if (released_) return;
+    destructor_();
+    released_ = true;
+  }
+
+  void swap(scope_exit &other) noexcept {
+    std::swap(destructor_, other.destructor_);
+    std::swap(released_  , other.released_);
+  }
+};
+
+/// \brief Creates a scope_exit object.
+template <typename F>
+auto make_scope_exit(F &&destructor) noexcept {
+  return scope_exit<std::decay_t<F>>(std::forward<F>(destructor));
+}
+
+namespace detail_scope_exit {
+
+struct scope_exit_helper {
+  template <typename F>
+  auto operator=(F &&f) const noexcept {
+    return make_scope_exit(std::forward<F>(f));
+  }
+};
+
+} // namespace detail_scope_exit
+
+#define LIBIPC_SCOPE_EXIT($VAL) \
+  LIBIPC_UNUSED auto $VAL = ::ipc::detail_scope_exit::scope_exit_helper{}
+
+} // namespace ipc
diff --git a/include/libipc/imp/span.h b/include/libipc/imp/span.h
new file mode 100644
index 00000000..f3c545b7
--- /dev/null
+++ b/include/libipc/imp/span.h
@@ -0,0 +1,281 @@
+/**
+ * \file libipc/span.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Describes an object that can refer to a contiguous sequence of objects.
+ */
+#pragma once
+
+#include <type_traits>
+#include <cstddef>
+#include <iterator>
+#include <array>
+#include <vector>
+#include <string>
+#include <limits>
+#include <algorithm>
+#include <cstdint>
+#include <initializer_list>
+
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/generic.h"
+
+#if defined(LIBIPC_CPP_20) && defined(__cpp_lib_span)
+#include <span>
+#define LIBIPC_CPP_LIB_SPAN_
+#endif // __cpp_lib_span
+
+namespace ipc {
+namespace detail_span {
+
+/// \brief Helper trait for span.
+
+template <typename From, typename To>
+using array_convertible = std::is_convertible<From(*)[], To(*)[]>;
+
+template <typename From, typename To>
+using is_array_convertible = 
+  typename std::enable_if<array_convertible<From, To>::value>::type;
+
+template <typename T, typename Ref>
+using compatible_ref = array_convertible<typename std::remove_reference<Ref>::type, T>;
+
+template <typename It>
+using iter_reference_t = decltype(*std::declval<It&>());
+
+template <typename T, typename It>
+using is_compatible_iter = 
+  typename std::enable_if<compatible_ref<T, iter_reference_t<It>>::value>::type;
+
+template <typename From, typename To>
+using is_inconvertible = 
+  typename std::enable_if<!std::is_convertible<From, To>::value>::type;
+
+template <typename S, typename I>
+using is_sized_sentinel_for = 
+  typename std::enable_if<std::is_convertible<decltype(std::declval<S>() - std::declval<I>()), 
+                          std::ptrdiff_t>::value>::type;
+
+template <typename T>
+using is_continuous_container =
+  decltype(dataof(std::declval<T>()), countof(std::declval<T>()));
+
+/// \brief Obtain the address represented by p 
+///        without forming a reference to the object pointed to by p.
+/// \see https://en.cppreference.com/w/cpp/memory/to_address
+
+template<typename T>
+constexpr T *to_address(T *ptr) noexcept {
+  static_assert(!std::is_function<T>::value, "ptr shouldn't a function pointer");
+  return ptr;
+}
+
+template<typename T>
+constexpr auto to_address(T const &ptr) 
+  noexcept(noexcept(ptr.operator->()))
+        -> decltype(ptr.operator->()) {
+  return to_address(ptr.operator->());
+}
+
+} // namespace detail_span
+
+/**
+ * \brief A simple implementation of span.
+ * \see https://en.cppreference.com/w/cpp/container/span
+ */
+template <typename T>
+class span {
+public:
+  using element_type     = T;
+  using value_type       = typename std::remove_cv<element_type>::type;
+  using size_type        = std::size_t;
+  using difference_type  = std::ptrdiff_t;
+  using pointer          = element_type *;
+  using const_pointer    = typename std::remove_const<element_type>::type const *;
+  using reference        = element_type &;
+  using const_reference  = typename std::remove_const<element_type>::type const &;
+  using iterator         = pointer;
+  using reverse_iterator = std::reverse_iterator<iterator>;
+
+private:
+  pointer   ptr_    {nullptr};
+  size_type extent_ {0};
+
+public:
+  constexpr span() noexcept = default;
+  constexpr span(span const &) noexcept = default;
+#if (LIBIPC_CC_MSVC > LIBIPC_CC_MSVC_2015)
+  constexpr
+#endif
+  span & operator=(span const &) noexcept = default;
+
+  template <typename It, 
+            typename = detail_span::is_compatible_iter<T, It>>
+  constexpr span(It first, size_type count) noexcept
+    : ptr_   (detail_span::to_address(first))
+    , extent_(count) {}
+
+  template <typename It, typename End,
+            typename = detail_span::is_compatible_iter<T, It>,
+            typename = detail_span::is_sized_sentinel_for<End, It>,
+            typename = detail_span::is_inconvertible<End, size_type>>
+  constexpr span(It first, End last) noexcept(noexcept(last - first))
+    : ptr_   (detail_span::to_address(first))
+    , extent_(static_cast<size_type>(last - first)) {}
+
+  template <typename U,
+            typename = detail_span::is_continuous_container<U>,
+            typename = detail_span::is_array_convertible<std::remove_pointer_t<
+              decltype(dataof(std::declval<U>()))>, element_type>>
+  constexpr span(U &&u) noexcept(noexcept(dataof (std::forward<U>(u)), 
+                                          countof(std::forward<U>(u))))
+    : ptr_   (dataof (std::forward<U>(u)))
+    , extent_(countof(std::forward<U>(u))) {}
+
+  template <typename U, std::size_t E,
+            typename = detail_span::is_array_convertible<U, element_type>>
+  constexpr span(U (&arr)[E]) noexcept
+    : span(static_cast<pointer>(arr), E) {}
+
+  template <typename U, std::size_t E,
+            typename = detail_span::is_array_convertible<U, element_type>>
+  constexpr span(std::array<U, E> &arr) noexcept
+	  : span(static_cast<pointer>(arr.data()), E) {}
+
+  template <typename U, std::size_t E,
+            typename = detail_span::is_array_convertible<typename std::add_const<U>::type, element_type>>
+  constexpr span(std::array<U, E> const &arr) noexcept
+	  : span(static_cast<pointer>(arr.data()), E) {}
+
+  template <typename U,
+            typename = detail_span::is_array_convertible<U, T>>
+  constexpr span(span<U> const &s) noexcept
+    : ptr_   (s.data())
+    , extent_(s.size()) {}
+
+#ifdef LIBIPC_CPP_LIB_SPAN_
+  template <typename U, std::size_t E,
+            typename = detail_span::is_array_convertible<U, T>>
+  constexpr span(std::span<U, E> const &s) noexcept
+    : ptr_   (s.data())
+    , extent_(s.size()) {}
+#endif // LIBIPC_CPP_LIB_SPAN_
+
+  constexpr size_type size() const noexcept {
+    return extent_;
+  }
+
+  constexpr size_type size_bytes() const noexcept {
+    return size() * sizeof(element_type);
+  }
+
+  constexpr bool empty() const noexcept {
+    return size() == 0;
+  }
+
+  constexpr pointer data() const noexcept {
+    return this->ptr_;
+  }
+
+  constexpr reference front() const noexcept {
+    return *data();
+  }
+
+  constexpr reference back() const noexcept {
+    return *(data() + (size() - 1));
+  }
+
+  constexpr reference operator[](size_type idx) const noexcept {
+    return *(data() + idx);
+  }
+
+  constexpr iterator begin() const noexcept {
+    return iterator(data());
+  }
+
+  constexpr iterator end() const noexcept {
+    return iterator(data() + this->size());
+  }
+
+  constexpr reverse_iterator rbegin() const noexcept {
+    return reverse_iterator(this->end());
+  }
+
+  constexpr reverse_iterator rend() const noexcept {
+    return reverse_iterator(this->begin());
+  }
+
+  constexpr span first(size_type count) const noexcept {
+    return span(begin(), count);
+  }
+
+  constexpr span last(size_type count) const noexcept {
+    return span(end() - count, count);
+  }
+
+  constexpr span subspan(size_type offset, size_type count = (std::numeric_limits<size_type>::max)()) const noexcept {
+    return (offset >= size()) ? span() : span(begin() + offset, (std::min)(size() - offset, count));
+  }
+};
+
+/// \brief Support for span equals comparison.
+
+template <typename T, typename U, 
+          typename = decltype(std::declval<T>() == std::declval<U>())>
+bool operator==(span<T> a, span<U> b) noexcept {
+  if (a.size() != b.size()) {
+    return false;
+  }
+  for (std::size_t i = 0; i < a.size(); ++i) {
+    if (a[i] != b[i]) return false;
+  }
+  return true;
+}
+
+/// \brief Constructs an object of type T and wraps it in a span.
+/// Before C++17, template argument deduction for class templates was not supported.
+/// \see https://en.cppreference.com/w/cpp/language/template_argument_deduction
+
+template <typename T>
+auto make_span(T *arr, std::size_t count) noexcept -> span<T> {
+  return {arr, count};
+}
+
+template <typename T, std::size_t E>
+auto make_span(T (&arr)[E]) noexcept -> span<T> {
+  return {arr};
+}
+
+template <typename T, std::size_t E>
+auto make_span(std::array<T, E> &arr) noexcept -> span<T> {
+  return {arr};
+}
+
+template <typename T, std::size_t E>
+auto make_span(std::array<T, E> const &arr) noexcept -> span<typename std::add_const<T>::type> {
+  return {arr};
+}
+
+template <typename T>
+auto make_span(std::vector<T> &arr) noexcept -> span<T> {
+  return {arr.data(), arr.size()};
+}
+
+template <typename T>
+auto make_span(std::vector<T> const &arr) noexcept -> span<typename std::add_const<T>::type> {
+  return {arr.data(), arr.size()};
+}
+
+template <typename T>
+auto make_span(std::initializer_list<T> list) noexcept -> span<typename std::add_const<T>::type> {
+  return {list.begin(), list.end()};
+}
+
+inline auto make_span(std::string &str) noexcept -> span<char> {
+  return {const_cast<char *>(str.data()), str.size()};
+}
+
+inline auto make_span(std::string const &str) noexcept -> span<char const> {
+  return {str.data(), str.size()};
+}
+
+} // namespace ipc
diff --git a/include/libipc/imp/system.h b/include/libipc/imp/system.h
new file mode 100644
index 00000000..1ecbb9c0
--- /dev/null
+++ b/include/libipc/imp/system.h
@@ -0,0 +1,33 @@
+/**
+ * \file libipc/system.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Isolation and encapsulation of system APIs.
+ */
+#pragma once
+
+#include <string>
+#include <ostream>  // std::ostream
+#include <cstdint>
+
+#include "libipc/imp/export.h"
+#include "libipc/imp/error.h"
+#include "libipc/imp/result.h"
+
+namespace ipc {
+namespace sys {
+
+/// \brief A platform-dependent error code.
+LIBIPC_EXPORT std::error_code error() noexcept;
+
+/// \enum The name of the `conf()` argument used to inquire about its value.
+/// \brief Certain options are supported, 
+/// or what the value is of certain configurable constants or limits.
+enum class info : std::int32_t {
+  page_size,
+};
+
+/// \brief Get system configuration information at run time.
+LIBIPC_EXPORT result<std::int64_t> conf(info) noexcept;
+
+} // namespace sys
+} // namespace ipc
diff --git a/include/libipc/imp/uninitialized.h b/include/libipc/imp/uninitialized.h
new file mode 100644
index 00000000..01b69c8d
--- /dev/null
+++ b/include/libipc/imp/uninitialized.h
@@ -0,0 +1,151 @@
+/**
+ * \file libipc/uninitialized.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Uninitialized memory algorithms.
+ */
+#pragma once
+
+#include <new>          // placement-new
+#include <type_traits>  // std::enable_if_t
+#include <utility>      // std::forward
+#include <memory>       // std::construct_at, std::destroy_at, std::addressof
+#include <cstddef>
+
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/generic.h"
+
+namespace ipc {
+
+/**
+ * \brief Creates an object at a given address, like 'construct_at' in c++20
+ * \see https://en.cppreference.com/w/cpp/memory/construct_at
+*/
+
+template <typename T, typename... A>
+auto construct(void *p, A &&...args)
+  -> std::enable_if_t<::std::is_constructible<T, A...>::value, T *> {
+#if defined(LIBIPC_CPP_20)
+  return std::construct_at(static_cast<T *>(p), std::forward<A>(args)...);
+#else
+  return ::new (p) T(std::forward<A>(args)...);
+#endif
+}
+
+template <typename T, typename... A>
+auto construct(void *p, A &&...args)
+  -> std::enable_if_t<!::std::is_constructible<T, A...>::value, T *> {
+  return ::new (p) T{std::forward<A>(args)...};
+}
+
+/**
+ * \brief Destroys an object at a given address, like 'destroy_at' in c++17
+ * \see https://en.cppreference.com/w/cpp/memory/destroy_at
+*/
+
+template <typename T>
+void *destroy(T *p) noexcept {
+  if (p == nullptr) return nullptr;
+#if defined(LIBIPC_CPP_17)
+  std::destroy_at(p);
+#else
+  p->~T();
+#endif
+  return p;
+}
+
+template <>
+inline void *destroy<void>(void *p) noexcept {
+  return p;
+}
+
+template <typename T, std::size_t N>
+void *destroy(T (*p)[N]) noexcept {
+  if (p == nullptr) return nullptr;
+#if defined(LIBIPC_CPP_20)
+  std::destroy_at(p);
+#elif defined(LIBIPC_CPP_17)
+  std::destroy(std::begin(*p), std::end(*p));
+#else
+  for (auto &elem : *p) destroy(std::addressof(elem));
+#endif
+  return p;
+}
+
+/**
+ * \brief Destroys a range of objects.
+ * \see https://en.cppreference.com/w/cpp/memory/destroy
+*/
+template <typename ForwardIt>
+void destroy(ForwardIt first, ForwardIt last) noexcept {
+#if defined(LIBIPC_CPP_17)
+  std::destroy(first, last);
+#else
+  for (; first != last; ++first) {
+    destroy(std::addressof(*first));
+  }
+#endif
+}
+
+/**
+ * \brief Destroys a number of objects in a range.
+ * \see https://en.cppreference.com/w/cpp/memory/destroy_n
+*/
+template <typename ForwardIt, typename Size>
+ForwardIt destroy_n(ForwardIt first, Size n) noexcept {
+#if defined(LIBIPC_CPP_17)
+  return std::destroy_n(first, n);
+#else
+  for (; n > 0; (void) ++first, --n)
+    destroy(std::addressof(*first));
+  return first;
+#endif
+}
+
+/**
+ * \brief Constructs objects by default-initialization 
+ *        in an uninitialized area of memory, defined by a start and a count.
+ * \see https://en.cppreference.com/w/cpp/memory/uninitialized_default_construct_n
+*/
+template <typename ForwardIt, typename Size>
+ForwardIt uninitialized_default_construct_n(ForwardIt first, Size n) {
+#if defined(LIBIPC_CPP_17)
+  return std::uninitialized_default_construct_n(first, n);
+#else
+  using T = typename std::iterator_traits<ForwardIt>::value_type;
+  ForwardIt current = first;
+  LIBIPC_TRY {
+    for (; n > 0; (void) ++current, --n)
+      ::new (horrible_cast<void *>(std::addressof(*current))) T;
+    return current;
+  } LIBIPC_CATCH(...) {
+    destroy(first, current);
+    LIBIPC_THROW(, first);
+  }
+#endif
+}
+
+/**
+* \brief Moves a number of objects to an uninitialized area of memory.
+* \see https://en.cppreference.com/w/cpp/memory/uninitialized_move_n
+*/
+template <typename InputIt, typename Size, typename NoThrowForwardIt>
+auto uninitialized_move_n(InputIt first, Size count, NoThrowForwardIt d_first)
+  -> std::pair<InputIt, NoThrowForwardIt> {
+#if defined(LIBIPC_CPP_17)
+  return std::uninitialized_move_n(first, count, d_first);
+#else
+  using Value = typename std::iterator_traits<NoThrowForwardIt>::value_type;
+  NoThrowForwardIt current = d_first;
+  LIBIPC_TRY {
+    for (; count > 0; ++first, (void) ++current, --count) {
+      ::new (static_cast<void *>(std::addressof(*current))) Value(std::move(*first));
+    }
+  } LIBIPC_CATCH(...) {
+    destroy(d_first, current);
+    LIBIPC_THROW(, {first, d_first});
+  }
+  return {first, current};
+#endif
+}
+
+} // namespace ipc
diff --git a/include/libipc/ipc.h b/include/libipc/ipc.h
index e6fe61a4..c7827ee9 100755
--- a/include/libipc/ipc.h
+++ b/include/libipc/ipc.h
@@ -2,7 +2,7 @@
 
 #include <string>
 
-#include "libipc/export.h"
+#include "libipc/imp/export.h"
 #include "libipc/def.h"
 #include "libipc/buffer.h"
 #include "libipc/shm.h"
@@ -18,7 +18,7 @@ enum : unsigned {
 };
 
 template <typename Flag>
-struct IPC_EXPORT chan_impl {
+struct LIBIPC_EXPORT chan_impl {
     static ipc::handle_t init_first();
 
     static bool connect   (ipc::handle_t * ph, char const * name, unsigned mode);
diff --git a/include/libipc/mem/block_pool.h b/include/libipc/mem/block_pool.h
new file mode 100644
index 00000000..9906a610
--- /dev/null
+++ b/include/libipc/mem/block_pool.h
@@ -0,0 +1,121 @@
+/**
+ * \file libipc/block_pool.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief The fixed-length memory block pool.
+ */
+#pragma once
+
+#include <cstddef>
+
+#include "libipc/mem/central_cache_pool.h"
+
+namespace ipc {
+namespace mem {
+
+/**
+ * \brief Fixed-length memory block pool.
+ * \tparam BlockSize specifies the memory block size
+ * \tparam BlockPoolExpansion specifies the default number of blocks to expand when the block pool is exhausted
+ */
+template <std::size_t BlockSize, std::size_t BlockPoolExpansion>
+class block_pool;
+
+/// \brief General-purpose block pool for any size of memory block.
+/// \note This block pool can only be used to deallocate a group of memory blocks of unknown but consistent size, 
+///       and cannot be used for memory block allocation.
+template <>
+class block_pool<0, 0> {
+
+  template <std::size_t BlockSize, std::size_t BlockPoolExpansion>
+  friend class block_pool;
+
+  /// \brief The block type.
+  struct block_t {
+    block_t *next;
+  };
+
+  /// \brief The central cache pool type.
+  using central_cache_pool_t = central_cache_pool<block_t, 0>;
+
+public:
+  static constexpr std::size_t block_size = 0;
+
+  block_pool() noexcept : cursor_(central_cache_pool_t::instance().aqueire()) {}
+  ~block_pool() noexcept {
+    central_cache_pool_t::instance().release(cursor_);
+  }
+
+  block_pool(block_pool const &) = delete;
+  block_pool& operator=(block_pool const &) = delete;
+
+  block_pool(block_pool &&rhs) noexcept : cursor_(std::exchange(rhs.cursor_, nullptr)) {}
+  block_pool &operator=(block_pool &&) noexcept = delete;
+
+  void deallocate(void *p) noexcept {
+    if (p == nullptr) return;
+    block_t *b = static_cast<block_t *>(p);
+    b->next = cursor_;
+    cursor_ = b;
+  }
+
+private:
+  block_t *cursor_;
+};
+
+/// \brief A block pool for a block of memory of a specific size.
+template <std::size_t BlockSize, std::size_t BlockPoolExpansion>
+class block_pool {
+
+  /// \brief The block type.
+  using block_t = block<BlockSize>;
+  /// \brief The central cache pool type.
+  using central_cache_pool_t = central_cache_pool<block_t, BlockPoolExpansion>;
+
+  /// \brief Expand the block pool when it is exhausted.
+  block_t *expand() noexcept {
+    return central_cache_pool_t::instance().aqueire();
+  }
+
+public:
+  static constexpr std::size_t block_size = BlockSize;
+
+  block_pool() noexcept : cursor_(expand()) {}
+  ~block_pool() noexcept {
+    central_cache_pool_t::instance().release(cursor_);
+  }
+
+  block_pool(block_pool const &) = delete;
+  block_pool& operator=(block_pool const &) = delete;
+
+  block_pool(block_pool &&rhs) noexcept
+    : cursor_(std::exchange(rhs.cursor_, nullptr)) {}
+  block_pool &operator=(block_pool &&) noexcept = delete;
+
+  /// \brief Used to take all memory blocks from within a general-purpose block pool.
+  /// \note Of course, the actual memory blocks they manage must be the same size.
+  block_pool(block_pool<0, 0> &&rhs) noexcept
+    : cursor_(reinterpret_cast<block_t *>(std::exchange(rhs.cursor_, nullptr))) {}
+
+  void *allocate() noexcept {
+    if (cursor_ == nullptr) {
+      cursor_ = expand();
+      if (cursor_ == nullptr) return nullptr;
+    }
+    block_t *p = cursor_;
+    cursor_ = cursor_->next;
+    return p->storage.data();
+  }
+
+  void deallocate(void *p) noexcept {
+    if (p == nullptr) return;
+    block_t *b = static_cast<block_t *>(p);
+    b->next = cursor_;
+    cursor_ = b;
+  }
+
+private:
+  block_t *cursor_;
+};
+
+} // namespace mem
+} // namespace ipc
diff --git a/include/libipc/mem/bytes_allocator.h b/include/libipc/mem/bytes_allocator.h
new file mode 100644
index 00000000..c9c6322a
--- /dev/null
+++ b/include/libipc/mem/bytes_allocator.h
@@ -0,0 +1,163 @@
+/**
+ * \file libipc/bytes_allocator.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief A generic polymorphic memory allocator.
+ */
+#pragma once
+
+#include <type_traits>
+#include <array>
+#include <limits>   // std::numeric_limits
+#include <utility>  // std::forward
+#include <tuple>    // std::ignore
+#include <cstddef>
+
+#include "libipc/imp/export.h"
+#include "libipc/imp/uninitialized.h"
+#include "libipc/imp/byte.h"
+
+namespace ipc {
+namespace mem {
+
+/// \brief Helper trait for memory resource.
+
+template <typename T, typename = void>
+struct has_allocate : std::false_type {};
+
+template <typename T>
+struct has_allocate<T, 
+  typename std::enable_if<std::is_convertible<
+  decltype(std::declval<T &>().allocate(std::declval<std::size_t>(), 
+                                        std::declval<std::size_t>())), void *
+  >::value>::type> : std::true_type {};
+
+template <typename T, typename = void>
+struct has_deallocate : std::false_type {};
+
+template <typename T>
+struct has_deallocate<T, 
+  decltype(std::declval<T &>().deallocate(std::declval<void *>(), 
+                                          std::declval<std::size_t>(), 
+                                          std::declval<std::size_t>()))
+  > : std::true_type {};
+
+template <typename T>
+using is_memory_resource = 
+  std::enable_if_t<has_allocate  <T>::value && 
+                   has_deallocate<T>::value, bool>;
+
+/**
+ * \brief An allocator which exhibits different allocation behavior 
+ *        depending upon the memory resource from which it is constructed.
+ * 
+ * \note Unlike `std::pmr::container_allocator`, it does not 
+ *       rely on a specific inheritance relationship and only restricts 
+ *       the interface behavior of the incoming memory resource object to 
+ *       conform to `std::pmr::memory_resource`.
+ * 
+ * \see https://en.cppreference.com/w/cpp/memory/memory_resource
+ *      https://en.cppreference.com/w/cpp/memory/container_allocator
+ */
+class LIBIPC_EXPORT bytes_allocator {
+
+  class holder_mr_base {
+  public:
+    virtual ~holder_mr_base() noexcept = default;
+    virtual void *alloc(std::size_t, std::size_t) const = 0;
+    virtual void  dealloc(void *, std::size_t, std::size_t) const = 0;
+  };
+
+  template <typename MR, typename = bool>
+  class holder_mr;
+
+  /**
+   * \brief An empty holding class used to calculate a reasonable memory size for the holder.
+   * \tparam MR cannot be converted to the type of memory resource
+   */
+  template <typename MR, typename U>
+  class holder_mr : public holder_mr_base {
+  protected:
+    MR *res_;
+
+  public:
+    holder_mr(MR *p_mr) noexcept
+      : res_(p_mr) {}
+
+    // [MSVC] error C2259: 'bytes_allocator::holder_mr<void *,bool>': cannot instantiate abstract class.
+    void *alloc(std::size_t s, std::size_t a) const override { return nullptr; }
+    void dealloc(void *p, std::size_t s, std::size_t a) const override {}
+  };
+
+  /**
+   * \brief A memory resource pointer holder class for type erasure.
+   * \tparam MR memory resource type
+   */
+  template <typename MR>
+  class holder_mr<MR, is_memory_resource<MR>> : public holder_mr<MR, void> {
+    using base_t = holder_mr<MR, void>;
+
+  public:
+    holder_mr(MR *p_mr) noexcept
+      : base_t{p_mr} {}
+
+    void *alloc(std::size_t s, std::size_t a) const override {
+      return base_t::res_->allocate(s, a);
+    }
+
+    void dealloc(void *p, std::size_t s, std::size_t a) const override {
+      base_t::res_->deallocate(p, s, a);
+    }
+  };
+
+  using void_holder_t = holder_mr<void *>;
+  alignas(void_holder_t) std::array<ipc::byte, sizeof(void_holder_t)> holder_;
+
+  holder_mr_base &      get_holder() noexcept;
+  holder_mr_base const &get_holder() const noexcept;
+
+  void init_default_resource() noexcept;
+
+public:
+  /// \brief Constructs an `bytes_allocator` using the return value of 
+  ///       `new_delete_resource::get()` as the underlying memory resource.
+  bytes_allocator() noexcept;
+  ~bytes_allocator() noexcept;
+
+  bytes_allocator(bytes_allocator const &other) noexcept = default;
+  bytes_allocator &operator=(bytes_allocator const &other) & noexcept = default;
+
+  bytes_allocator(bytes_allocator &&other) noexcept = default;
+  bytes_allocator &operator=(bytes_allocator &&other) & noexcept = default;
+
+  /// \brief Constructs a `bytes_allocator` from a memory resource pointer.
+  /// \note The lifetime of the pointer must be longer than that of bytes_allocator.
+  template <typename T, is_memory_resource<T> = true>
+  bytes_allocator(T *p_mr) noexcept {
+    if (p_mr == nullptr) {
+      init_default_resource();
+      return;
+    }
+    std::ignore = ipc::construct<holder_mr<T>>(holder_.data(), p_mr);
+  }
+
+  void swap(bytes_allocator &other) noexcept;
+
+  /// \brief Allocate/deallocate memory.
+  void *allocate(std::size_t s, std::size_t = alignof(std::max_align_t)) const;
+  void  deallocate(void *p, std::size_t s, std::size_t = alignof(std::max_align_t)) const;
+
+  /// \brief Allocates uninitialized memory and constructs an object of type T in the memory.
+  template <typename T, typename... A>
+  T *construct(A &&...args) const {
+    return ipc::construct<T>(allocate(sizeof(T), alignof(T)), std::forward<A>(args)...);
+  }
+
+  /// \brief Calls the destructor of the object pointed to by p and deallocates the memory.
+  template <typename T>
+  void destroy(T *p) const noexcept {
+    deallocate(ipc::destroy(p), sizeof(T), alignof(T));
+  }
+};
+
+} // namespace mem
+} // namespace ipc
diff --git a/include/libipc/mem/central_cache_allocator.h b/include/libipc/mem/central_cache_allocator.h
new file mode 100644
index 00000000..02992a05
--- /dev/null
+++ b/include/libipc/mem/central_cache_allocator.h
@@ -0,0 +1,20 @@
+/**
+ * \file libipc/central_cache_allocator.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief The central cache allocator getter.
+ */
+#pragma once
+
+#include "libipc/imp/export.h"
+#include "libipc/mem/bytes_allocator.h"
+
+namespace ipc {
+namespace mem {
+
+/// \brief Get the central cache allocator.
+/// \note The central cache allocator is used to allocate memory for the central cache pool.
+///       The underlying memory resource is a `monotonic_buffer_resource` with a fixed-size buffer.
+LIBIPC_EXPORT bytes_allocator &central_cache_allocator() noexcept;
+
+} // namespace mem
+} // namespace ipc
diff --git a/include/libipc/mem/central_cache_pool.h b/include/libipc/mem/central_cache_pool.h
new file mode 100644
index 00000000..e6a3bd08
--- /dev/null
+++ b/include/libipc/mem/central_cache_pool.h
@@ -0,0 +1,132 @@
+/**
+ * \file libipc/central_cache_pool.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief The fixed-length memory block central cache pool.
+ */
+#pragma once
+
+#include <cstddef>
+#include <deque>
+#include <utility>
+#include <array>
+
+#include "libipc/imp/byte.h"
+#include "libipc/concur/intrusive_stack.h"
+#include "libipc/mem/central_cache_allocator.h"
+
+namespace ipc {
+namespace mem {
+
+/**
+ * \brief The block type.
+ * \tparam BlockSize specifies the memory block size
+*/
+template <std::size_t BlockSize>
+union block {
+  block *next;
+  alignas(std::max_align_t) std::array<byte, BlockSize> storage;
+};
+
+/**
+ * \brief A fixed-length memory block central cache pool.
+ * \tparam BlockT specifies the memory block type
+ */
+template <typename BlockT, std::size_t BlockPoolExpansion>
+class central_cache_pool {
+
+  /// \brief The block type, which should be a union of a pointer and a storage.
+  using block_t = BlockT;
+  /// \brief The chunk type, which is an array of blocks.
+  using chunk_t = std::array<block_t, BlockPoolExpansion>;
+  /// \brief The node type, which is used to store the block pointer.
+  using node_t  = typename concur::intrusive_stack<block_t *>::node;
+
+  /// \brief The central cache stack.
+  concur::intrusive_stack<block_t *> cached_;
+  concur::intrusive_stack<block_t *> aqueired_;
+
+  central_cache_pool() noexcept = default;
+
+public:
+  block_t *aqueire() noexcept {
+    auto *n = cached_.pop();
+    if (n != nullptr) {
+      aqueired_.push(n);
+      return n->value;
+    }
+    auto *chunk = central_cache_allocator().construct<chunk_t>();
+    if (chunk == nullptr) {
+      return nullptr;
+    }
+    for (std::size_t i = 0; i < BlockPoolExpansion - 1; ++i) {
+      (*chunk)[i].next = &(*chunk)[i + 1];
+    }
+    chunk->back().next = nullptr;
+    return chunk->data();
+  }
+
+  void release(block_t *p) noexcept {
+    if (p == nullptr) return;
+    auto *a = aqueired_.pop();
+    if (a == nullptr) {
+      a = central_cache_allocator().construct<node_t>();
+      if (a == nullptr) return;
+    }
+    a->value = p;
+    cached_.push(a);
+  }
+
+  /// \brief Get the singleton instance.
+  static central_cache_pool &instance() noexcept {
+    static central_cache_pool pool;
+    return pool;
+  }
+};
+
+/// \brief A fixed-length memory block central cache pool with no default expansion size.
+template <typename BlockT>
+class central_cache_pool<BlockT, 0> {
+
+  /// \brief The block type, which should be a union of a pointer and a storage.
+  using block_t = BlockT;
+  /// \brief The node type, which is used to store the block pointer.
+  using node_t = typename concur::intrusive_stack<block_t *>::node;
+
+  /// \brief The central cache stack.
+  concur::intrusive_stack<block_t *> cached_;
+  concur::intrusive_stack<block_t *> aqueired_;
+
+  central_cache_pool() noexcept = default;
+
+public:
+  block_t *aqueire() noexcept {
+    auto *n = cached_.pop();
+    if (n != nullptr) {
+      aqueired_.push(n);
+      return n->value;
+    }
+    // For pools with no default expansion size, 
+    // the central cache pool is only buffered, not allocated.
+    return nullptr;
+  }
+
+  void release(block_t *p) noexcept {
+    if (p == nullptr) return;
+    auto *a = aqueired_.pop();
+    if (a == nullptr) {
+      a = central_cache_allocator().construct<node_t>();
+      if (a == nullptr) return;
+    }
+    a->value = p;
+    cached_.push(a);
+  }
+
+  /// \brief Get the singleton instance.
+  static central_cache_pool &instance() noexcept {
+    static central_cache_pool pool;
+    return pool;
+  }
+};
+
+} // namespace mem
+} // namespace ipc
diff --git a/include/libipc/mem/container_allocator.h b/include/libipc/mem/container_allocator.h
new file mode 100644
index 00000000..4087b009
--- /dev/null
+++ b/include/libipc/mem/container_allocator.h
@@ -0,0 +1,109 @@
+/**
+ * \file libipc/container_allocator.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief An allocator that can be used by all standard library containers.
+ */
+#pragma once
+
+#include <cstddef>
+#include <utility>
+#include <limits>
+
+#include "libipc/imp/uninitialized.h"
+#include "libipc/mem/new.h"
+
+namespace ipc {
+namespace mem {
+
+/**
+ * \brief An allocator that can be used by all standard library containers.
+ * 
+ * \see https://en.cppreference.com/w/cpp/memory/allocator
+ *      https://en.cppreference.com/w/cpp/memory/polymorphic_allocator
+ */
+template <typename T>
+class container_allocator {
+
+  template <typename U>
+  friend class container_allocator;
+
+public:
+  // type definitions
+  typedef T                 value_type;
+  typedef value_type *      pointer;
+  typedef const value_type *const_pointer;
+  typedef value_type &      reference;
+  typedef const value_type &const_reference;
+  typedef std::size_t       size_type;
+  typedef std::ptrdiff_t    difference_type;
+
+  // the other type of std_allocator
+  template <typename U>
+  struct rebind { 
+    using other = container_allocator<U>;
+  };
+
+  container_allocator() noexcept {}
+
+  // construct by copying (do nothing)
+  container_allocator           (container_allocator<T> const &) noexcept {}
+  container_allocator& operator=(container_allocator<T> const &) noexcept { return *this; }
+
+  // construct from a related allocator (do nothing)
+  template <typename U> container_allocator           (container_allocator<U> const &) noexcept {}
+  template <typename U> container_allocator &operator=(container_allocator<U> const &) noexcept { return *this; }
+
+  container_allocator           (container_allocator &&) noexcept = default;
+  container_allocator& operator=(container_allocator &&) noexcept = default;
+
+  constexpr size_type max_size() const noexcept {
+    return (std::numeric_limits<size_type>::max)() / sizeof(value_type);
+  }
+
+  pointer allocate(size_type count) noexcept {
+    if (count == 0) return nullptr;
+    if (count > this->max_size()) return nullptr;
+    if (count == 1) {
+      return mem::$new<value_type>();
+    } else {
+      void *p = mem::alloc(sizeof(value_type) * count);
+      if (p == nullptr) return nullptr;
+      for (std::size_t i = 0; i < count; ++i) {
+        std::ignore = ipc::construct<value_type>(static_cast<byte *>(p) + sizeof(value_type) * i);
+      }
+      return static_cast<pointer>(p);
+    }
+  }
+
+  void deallocate(pointer p, size_type count) noexcept {
+    if (count == 0) return;
+    if (count > this->max_size()) return;
+    if (count == 1) {
+      mem::$delete(p);
+    } else {
+      mem::free(ipc::destroy_n(p, count), sizeof(value_type) * count);
+    }
+  }
+
+  template <typename... P>
+  static void construct(pointer p, P && ... params) {
+    std::ignore = ipc::construct<T>(p, std::forward<P>(params)...);
+  }
+
+  static void destroy(pointer p) {
+    std::ignore = ipc::destroy(p);
+  }
+};
+
+template <typename T, typename U>
+constexpr bool operator==(container_allocator<T> const &, container_allocator<U> const &) noexcept {
+  return true;
+}
+
+template <typename T, typename U>
+constexpr bool operator!=(container_allocator<T> const &, container_allocator<U> const &) noexcept {
+  return false;
+}
+
+} // namespace mem
+} // namespace ipc
diff --git a/include/libipc/mem/memory_resource.h b/include/libipc/mem/memory_resource.h
new file mode 100644
index 00000000..0d2012fc
--- /dev/null
+++ b/include/libipc/mem/memory_resource.h
@@ -0,0 +1,83 @@
+/**
+ * \file libipc/memory_resource.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Implement memory allocation strategies that can be used by ipc::mem::bytes_allocator.
+ */
+#pragma once
+
+#include <type_traits>
+#include <cstddef>  // std::size_t, std::max_align_t
+
+#include "libipc/imp/export.h"
+#include "libipc/imp/span.h"
+#include "libipc/imp/byte.h"
+#include "libipc/mem/bytes_allocator.h"
+
+namespace ipc {
+namespace mem {
+
+/**
+ * \class LIBIPC_EXPORT new_delete_resource
+ * \brief A memory resource that uses the 
+ *        standard memory allocation and deallocation interface to allocate memory.
+ * \see https://en.cppreference.com/w/cpp/memory/new_delete_resource
+ */
+class LIBIPC_EXPORT new_delete_resource {
+public:
+  /// \brief Returns a pointer to a `new_delete_resource`.
+  static new_delete_resource *get() noexcept;
+
+  /// \brief Allocates storage with a size of at least bytes bytes, aligned to the specified alignment.
+  /// \remark Returns nullptr if storage of the requested size and alignment cannot be obtained.
+  /// \see https://en.cppreference.com/w/cpp/memory/memory_resource/do_allocate
+  void *allocate(std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
+
+  /// \brief Deallocates the storage pointed to by p.
+  /// \see https://en.cppreference.com/w/cpp/memory/memory_resource/deallocate
+  void deallocate(void *p, std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
+};
+
+/**
+ * \class LIBIPC_EXPORT monotonic_buffer_resource
+ * \brief A special-purpose memory resource class 
+ *        that releases the allocated memory only when the resource is destroyed.
+ * \see https://en.cppreference.com/w/cpp/memory/monotonic_buffer_resource
+ */
+class LIBIPC_EXPORT monotonic_buffer_resource {
+
+  bytes_allocator upstream_;
+
+  struct node {
+    node *next;
+    std::size_t size;
+  } *free_list_;
+
+  ipc::byte * head_;
+  ipc::byte * tail_;
+  std::size_t next_size_;
+
+  ipc::byte * const initial_buffer_;
+  std::size_t const initial_size_;
+
+public:
+  monotonic_buffer_resource() noexcept;
+  explicit monotonic_buffer_resource(bytes_allocator upstream) noexcept;
+  explicit monotonic_buffer_resource(std::size_t initial_size) noexcept;
+  monotonic_buffer_resource(std::size_t initial_size, bytes_allocator upstream) noexcept;
+  monotonic_buffer_resource(ipc::span<ipc::byte> buffer) noexcept;
+  monotonic_buffer_resource(ipc::span<ipc::byte> buffer, bytes_allocator upstream) noexcept;
+
+  ~monotonic_buffer_resource() noexcept;
+
+  monotonic_buffer_resource(monotonic_buffer_resource const &) = delete;
+  monotonic_buffer_resource &operator=(monotonic_buffer_resource const &) = delete;
+
+  bytes_allocator upstream_resource() const noexcept;
+  void release() noexcept;
+
+  void *allocate(std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
+  void deallocate(void *p, std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
+};
+
+} // namespace mem
+} // namespace ipc
diff --git a/include/libipc/mem/new.h b/include/libipc/mem/new.h
new file mode 100644
index 00000000..cf246a4f
--- /dev/null
+++ b/include/libipc/mem/new.h
@@ -0,0 +1,117 @@
+/**
+ * \file libipc/mem.h
+ * \author mutouyun (orz@orzz.org)
+ * \brief Global memory management.
+ */
+#pragma once
+
+#include <cstddef>
+#include <algorithm>
+#include <type_traits>
+#include <limits>
+#include <tuple>
+
+#include "libipc/imp/aligned.h"
+#include "libipc/imp/uninitialized.h"
+#include "libipc/imp/byte.h"
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/export.h"
+#include "libipc/mem/memory_resource.h"
+#include "libipc/mem/block_pool.h"
+
+namespace ipc {
+namespace mem {
+
+/// \brief Defines the memory block collector interface.
+class LIBIPC_EXPORT block_collector {
+public:
+  virtual ~block_collector() noexcept = default;
+  virtual void *allocate(std::size_t /*bytes*/) noexcept = 0;
+  virtual void deallocate(void */*p*/, std::size_t /*bytes*/) noexcept = 0;
+};
+
+/// \brief Matches the appropriate memory block resource based on a specified size.
+LIBIPC_EXPORT block_collector &get_regular_resource(std::size_t s) noexcept;
+
+/// \brief Allocates storage with a size of at least bytes bytes.
+LIBIPC_EXPORT void *alloc(std::size_t bytes) noexcept;
+LIBIPC_EXPORT void  free (void *p, std::size_t bytes) noexcept;
+
+namespace detail_new {
+
+#if defined(LIBIPC_CPP_17)
+using recycle_t = void (*)(void *p) noexcept;
+#else
+using recycle_t = void (*)(void *p);
+#endif
+
+static constexpr std::size_t recycler_size     = round_up(sizeof(recycle_t), alignof(std::size_t));
+static constexpr std::size_t allocated_size    = sizeof(std::size_t);
+static constexpr std::size_t regular_head_size = round_up(recycler_size + allocated_size, alignof(std::max_align_t));
+
+template <typename T>
+struct do_allocate {
+  template <typename... A>
+  static T *apply(A &&... args) noexcept {
+    void *b = mem::alloc(regular_head_size + sizeof(T));
+    auto *p = static_cast<byte *>(b) + regular_head_size;
+    LIBIPC_TRY {
+      T *t = construct<T>(p, std::forward<A>(args)...);
+      *reinterpret_cast<recycle_t *>(b)
+        = [](void *p) noexcept {
+            mem::free(static_cast<byte *>(destroy(static_cast<T *>(p))) - regular_head_size
+                    , regular_head_size + sizeof(T));
+          };
+      return t;
+    } LIBIPC_CATCH(...) {
+      return nullptr;
+    }
+  }
+};
+
+template <>
+struct do_allocate<void> {
+  static void *apply(std::size_t bytes) noexcept {
+    if (bytes == 0) return nullptr;
+    std::size_t rbz = regular_head_size + bytes;
+    void *b = mem::alloc(rbz);
+    *reinterpret_cast<recycle_t *>(b)
+      = [](void *p) noexcept {
+          auto *b = static_cast<byte *>(p) - regular_head_size;
+          mem::free(b, *reinterpret_cast<std::size_t *>(b + recycler_size));
+        };
+    auto *z = static_cast<byte *>(b) + recycler_size;
+    *reinterpret_cast<std::size_t *>(z) = rbz;
+    return static_cast<byte *>(b) + regular_head_size;
+  }
+};
+
+} // namespace detail_new
+
+/// \brief Creates an object based on the specified type and parameters with block pool resource.
+/// \note This function is thread-safe.
+template <typename T, typename... A>
+T *$new(A &&... args) noexcept {
+  return detail_new::do_allocate<T>::apply(std::forward<A>(args)...);
+}
+
+/// \brief Destroys object previously allocated by the `$new` and releases obtained memory area.
+/// \note This function is thread-safe. If the pointer type passed in is different from `$new`, 
+///       additional performance penalties may be incurred.
+inline void $delete(void *p) noexcept {
+  if (p == nullptr) return;
+  auto *r = reinterpret_cast<detail_new::recycle_t *>(static_cast<byte *>(p) - detail_new::regular_head_size);
+  (*r)(p);
+}
+
+/// \brief The destruction policy used by std::unique_ptr.
+/// \see https://en.cppreference.com/w/cpp/memory/default_delete
+struct deleter {
+  template <typename T>
+  void operator()(T *p) const noexcept {
+    $delete(p);
+  }
+};
+
+} // namespace mem
+} // namespace ipc
diff --git a/include/libipc/mutex.h b/include/libipc/mutex.h
index 0b2a0e41..422e496c 100644
--- a/include/libipc/mutex.h
+++ b/include/libipc/mutex.h
@@ -3,13 +3,13 @@
 #include <cstdint>  // std::uint64_t
 #include <system_error>
 
-#include "libipc/export.h"
+#include "libipc/imp/export.h"
 #include "libipc/def.h"
 
 namespace ipc {
 namespace sync {
 
-class IPC_EXPORT mutex {
+class LIBIPC_EXPORT mutex {
     mutex(mutex const &) = delete;
     mutex &operator=(mutex const &) = delete;
 
diff --git a/include/libipc/pool_alloc.h b/include/libipc/pool_alloc.h
deleted file mode 100755
index c6be5a05..00000000
--- a/include/libipc/pool_alloc.h
+++ /dev/null
@@ -1,103 +0,0 @@
-#pragma once
-
-#include <new>
-#include <utility>
-
-#include "libipc/export.h"
-#include "libipc/def.h"
-
-namespace ipc {
-namespace mem {
-
-class IPC_EXPORT pool_alloc {
-public:
-    static void* alloc(std::size_t size) noexcept;
-    static void  free (void* p, std::size_t size) noexcept;
-};
-
-////////////////////////////////////////////////////////////////
-/// construct/destruct an object
-////////////////////////////////////////////////////////////////
-
-namespace detail {
-
-template <typename T>
-struct impl {
-    template <typename... P>
-    static T* construct(T* p, P&&... params) {
-        ::new (p) T(std::forward<P>(params)...);
-        return p;
-    }
-
-    static void destruct(T* p) {
-        reinterpret_cast<T*>(p)->~T();
-    }
-};
-
-template <typename T, size_t N>
-struct impl<T[N]> {
-    using type = T[N];
-
-    template <typename... P>
-    static type* construct(type* p, P&&... params) {
-        for (size_t i = 0; i < N; ++i) {
-            impl<T>::construct(&((*p)[i]), std::forward<P>(params)...);
-        }
-        return p;
-    }
-
-    static void destruct(type* p) {
-        for (size_t i = 0; i < N; ++i) {
-            impl<T>::destruct(&((*p)[i]));
-        }
-    }
-};
-
-} // namespace detail
-
-template <typename T, typename... P>
-T* construct(T* p, P&&... params) {
-    return detail::impl<T>::construct(p, std::forward<P>(params)...);
-}
-
-template <typename T, typename... P>
-T* construct(void* p, P&&... params) {
-    return construct(static_cast<T*>(p), std::forward<P>(params)...);
-}
-
-template <typename T>
-void destruct(T* p) {
-    return detail::impl<T>::destruct(p);
-}
-
-template <typename T>
-void destruct(void* p) {
-    destruct(static_cast<T*>(p));
-}
-
-////////////////////////////////////////////////////////////////
-/// general alloc/free
-////////////////////////////////////////////////////////////////
-
-inline void* alloc(std::size_t size) {
-    return pool_alloc::alloc(size);
-}
-
-template <typename T, typename... P>
-T* alloc(P&&... params) {
-    return construct<T>(pool_alloc::alloc(sizeof(T)), std::forward<P>(params)...);
-}
-
-inline void free(void* p, std::size_t size) {
-    pool_alloc::free(p, size);
-}
-
-template <typename T>
-void free(T* p) {
-    if (p == nullptr) return;
-    destruct(p);
-    pool_alloc::free(p, sizeof(T));
-}
-
-} // namespace mem
-} // namespace ipc
diff --git a/include/libipc/semaphore.h b/include/libipc/semaphore.h
index 397ec3e3..8be73e8e 100644
--- a/include/libipc/semaphore.h
+++ b/include/libipc/semaphore.h
@@ -2,13 +2,13 @@
 
 #include <cstdint>  // std::uint64_t
 
-#include "libipc/export.h"
+#include "libipc/imp/export.h"
 #include "libipc/def.h"
 
 namespace ipc {
 namespace sync {
 
-class IPC_EXPORT semaphore {
+class LIBIPC_EXPORT semaphore {
     semaphore(semaphore const &) = delete;
     semaphore &operator=(semaphore const &) = delete;
 
diff --git a/include/libipc/shm.h b/include/libipc/shm.h
index dc24ab43..47169c01 100755
--- a/include/libipc/shm.h
+++ b/include/libipc/shm.h
@@ -3,7 +3,7 @@
 #include <cstddef>
 #include <cstdint>
 
-#include "libipc/export.h"
+#include "libipc/imp/export.h"
 
 namespace ipc {
 namespace shm {
@@ -15,16 +15,16 @@ enum : unsigned {
     open   = 0x02
 };
 
-IPC_EXPORT id_t         acquire(char const * name, std::size_t size, unsigned mode = create | open);
-IPC_EXPORT void *       get_mem(id_t id, std::size_t * size);
-IPC_EXPORT std::int32_t release(id_t id) noexcept;
-IPC_EXPORT void         remove (id_t id) noexcept;
-IPC_EXPORT void         remove (char const * name) noexcept;
+LIBIPC_EXPORT id_t         acquire(char const * name, std::size_t size, unsigned mode = create | open);
+LIBIPC_EXPORT void *       get_mem(id_t id, std::size_t * size);
+LIBIPC_EXPORT std::int32_t release(id_t id) noexcept;
+LIBIPC_EXPORT void         remove (id_t id) noexcept;
+LIBIPC_EXPORT void         remove (char const * name) noexcept;
 
-IPC_EXPORT std::int32_t get_ref(id_t id);
-IPC_EXPORT void sub_ref(id_t id);
+LIBIPC_EXPORT std::int32_t get_ref(id_t id);
+LIBIPC_EXPORT void sub_ref(id_t id);
 
-class IPC_EXPORT handle {
+class LIBIPC_EXPORT handle {
 public:
     handle();
     handle(char const * name, std::size_t size, unsigned mode = create | open);
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0d167321..2af39810 100755
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -5,6 +5,8 @@ set (PACKAGE_VERSION 1.3.0)
 aux_source_directory(${LIBIPC_PROJECT_DIR}/src/libipc SRC_FILES)
 aux_source_directory(${LIBIPC_PROJECT_DIR}/src/libipc/sync SRC_FILES)
 aux_source_directory(${LIBIPC_PROJECT_DIR}/src/libipc/platform SRC_FILES)
+aux_source_directory(${LIBIPC_PROJECT_DIR}/src/libipc/imp SRC_FILES)
+aux_source_directory(${LIBIPC_PROJECT_DIR}/src/libipc/mem SRC_FILES)
 
 file(GLOB HEAD_FILES
   ${LIBIPC_PROJECT_DIR}/include/libipc/*.h
diff --git a/src/libipc/circ/elem_def.h b/src/libipc/circ/elem_def.h
index 40039480..20d55cd2 100755
--- a/src/libipc/circ/elem_def.h
+++ b/src/libipc/circ/elem_def.h
@@ -33,7 +33,7 @@ class conn_head_base {
     void init() {
         /* DCLP */
         if (!constructed_.load(std::memory_order_acquire)) {
-            IPC_UNUSED_ auto guard = ipc::detail::unique_lock(lc_);
+            LIBIPC_UNUSED auto guard = ipc::detail::unique_lock(lc_);
             if (!constructed_.load(std::memory_order_relaxed)) {
                 ::new (this) conn_head_base;
                 constructed_.store(true, std::memory_order_release);
diff --git a/src/libipc/imp/codecvt.cpp b/src/libipc/imp/codecvt.cpp
new file mode 100644
index 00000000..bd34daa2
--- /dev/null
+++ b/src/libipc/imp/codecvt.cpp
@@ -0,0 +1,365 @@
+
+#include <algorithm>
+#include <type_traits>
+#include <cstring>
+#include <cstdint>
+
+#include "libipc/imp/codecvt.h"
+#include "libipc/imp/detect_plat.h"
+
+#if defined(LIBIPC_OS_WIN)
+# include "libipc/platform/win/codecvt.h"
+#endif
+
+namespace ipc {
+
+/**
+ * \brief The transform between local-character-set(UTF-8/GBK/...) and UTF-16/32.
+ * 
+ * Modified from UnicodeConverter.
+ * Copyright (c) 2010. Jianhui Qin (http://blog.csdn.net/jhqin).
+ * 
+ * \remarks codecvt_utf8_utf16/std::wstring_convert is deprecated.
+ * \see https://codingtidbit.com/2020/02/09/c17-codecvt_utf8-is-deprecated/
+ *      https://stackoverflow.com/questions/42946335/deprecated-header-codecvt-replacement
+ *      https://en.cppreference.com/w/cpp/locale/codecvt/in
+*/
+namespace {
+
+/// \brief X-bit unicode transformation format
+enum class ufmt {
+  utf8,
+  utf16,
+  utf32,
+};
+
+template <typename T, ufmt, typename = void>
+struct utf_compatible : std::false_type {};
+
+template <typename T>
+struct utf_compatible<T, ufmt::utf8, 
+  std::enable_if_t<std::is_fundamental<T>::value && (sizeof(T) == 1)>> : std::true_type {};
+
+template <typename T>
+struct utf_compatible<T, ufmt::utf16, 
+  std::enable_if_t<std::is_fundamental<T>::value && (sizeof(T) == 2)>> : std::true_type {};
+
+template <typename T>
+struct utf_compatible<T, ufmt::utf32, 
+  std::enable_if_t<std::is_fundamental<T>::value && (sizeof(T) == 4)>> : std::true_type {};
+
+template <typename T, ufmt Fmt>
+constexpr bool utf_compatible_v = utf_compatible<T, Fmt>::value;
+
+/**
+ * \brief UTF-32 --> UTF-8
+ */
+template <typename T, typename U>
+auto cvt_char(T src, U* des, std::size_t dlen) noexcept
+  -> std::enable_if_t<utf_compatible_v<T, ufmt::utf32> &&
+                      utf_compatible_v<U, ufmt::utf8>, std::size_t> {
+  if (src == 0) return 0;
+
+  constexpr std::uint8_t prefix[] = {
+    0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC
+  };
+  constexpr std::uint32_t codeup[] = {
+    0x80,      // U+00000000 - U+0000007F
+    0x800,     // U+00000080 - U+000007FF
+    0x10000,   // U+00000800 - U+0000FFFF
+    0x200000,  // U+00010000 - U+001FFFFF
+    0x4000000, // U+00200000 - U+03FFFFFF
+    0x80000000 // U+04000000 - U+7FFFFFFF
+  };
+
+  std::size_t i, len = sizeof(codeup) / sizeof(std::uint32_t);
+  for(i = 0; i < len; ++i) {
+    if (static_cast<std::uint32_t>(src) < codeup[i]) break;
+  }
+  if (i == len) return 0; // the src is invalid
+
+  len = i + 1;
+  if (des != nullptr) {
+    if (dlen > i) for (; i > 0; --i) {
+      des[i] = static_cast<U>((src & 0x3F) | 0x80);
+      src >>= 6;
+    }
+    des[0] = static_cast<U>(src | prefix[len - 1]);
+  }
+  return len;
+}
+
+/**
+ * \brief UTF-8 --> UTF-32
+ */
+template <typename T, typename U>
+auto cvt_char(T const *src, std::size_t slen, U &des) noexcept
+  -> std::enable_if_t<utf_compatible_v<T, ufmt::utf8> &&
+                      utf_compatible_v<U, ufmt::utf32>, std::size_t> {
+  if ((src == nullptr) || (*src) == 0) return 0;
+  if (slen == 0) return 0;
+
+  std::uint8_t b = (std::uint8_t)*(src++);
+
+  if (b < 0x80) {
+    des = b;
+    return 1;
+  }
+
+  if (b < 0xC0 || b > 0xFD) return 0; // the src is invalid
+
+  std::size_t len;
+  if (b < 0xE0) {
+    des = b & 0x1F;
+    len = 2;
+  } else if (b < 0xF0) {
+    des = b & 0x0F;
+    len = 3;
+  } else if (b < 0xF8) {
+    des = b & 0x07;
+    len = 4;
+  } else if (b < 0xFC) {
+    des = b & 0x03;
+    len = 5;
+  } else {
+    des = b & 0x01;
+    len = 6;
+  }
+
+  if (slen < len) return 0;
+  std::size_t i = 1;
+  for(; i < len; ++i) {
+    b = *(src++);
+    if ((b < 0x80) || (b > 0xBF)) return 0; // the src is invalid
+    des = (des << 6) + (b & 0x3F);
+  }
+  return len;
+}
+
+/**
+ * \brief UTF-32 --> UTF-16
+ */
+template <typename T, typename U>
+auto cvt_char(T src, U *des, std::size_t dlen) noexcept
+  -> std::enable_if_t<utf_compatible_v<T, ufmt::utf32> &&
+                      utf_compatible_v<U, ufmt::utf16>, std::size_t> {
+  if (src == 0) return 0;
+
+  if (src <= 0xFFFF) {
+    if ((des != nullptr) && (dlen != 0)) {
+      (*des) = static_cast<U>(src);
+    }
+    return 1;
+  } else if (src <= 0xEFFFF) {
+    if ((des != nullptr) && (dlen > 1)) {
+      des[0] = static_cast<U>(0xD800 + (src >> 10) - 0x40);  // high
+      des[1] = static_cast<U>(0xDC00 + (src & 0x03FF));      // low
+    }
+    return 2;
+  }
+  return 0;
+}
+
+/**
+ * \brief UTF-16 --> UTF-32
+*/
+template <typename T, typename U>
+auto cvt_char(T const *src, std::size_t slen, U &des)
+  -> std::enable_if_t<utf_compatible_v<T, ufmt::utf16> &&
+                      utf_compatible_v<U, ufmt::utf32>, std::size_t> {
+  if ((src == nullptr) || (*src) == 0) return 0;
+  if (slen == 0) return 0;
+
+  std::uint16_t w1 = src[0];
+  if ((w1 >= 0xD800) && (w1 <= 0xDFFF)) {
+    if (w1 < 0xDC00) {
+      if (slen < 2) return 0;
+      std::uint16_t w2 = src[1];
+      if ((w2 >= 0xDC00) && (w2 <= 0xDFFF)) {
+        des = (w2 & 0x03FF) + (((w1 & 0x03FF) + 0x40) << 10);
+        return 2;
+      }
+    }
+    return 0; // the src is invalid
+  }
+  des = w1;
+  return 1;
+}
+
+/**
+ * \brief UTF-16 --> UTF-8
+*/
+template <typename T, typename U>
+auto cvt_char(T src, U *des, std::size_t dlen) noexcept
+  -> std::enable_if_t<utf_compatible_v<T, ufmt::utf16> &&
+                      utf_compatible_v<U, ufmt::utf8>, std::size_t> {
+  // make utf-16 to utf-32
+  std::uint32_t tmp;
+  if (cvt_char(&src, 1, tmp) != 1) return 0;
+  // make utf-32 to utf-8
+  return cvt_char(tmp, des, dlen);
+}
+
+/**
+ * \brief UTF-8 --> UTF-16
+*/
+template <typename T, typename U>
+auto cvt_char(T const *src, std::size_t slen, U &des)
+  -> std::enable_if_t<utf_compatible_v<T, ufmt::utf8> &&
+                      utf_compatible_v<U, ufmt::utf16>, std::size_t> {
+  // make utf-8 to utf-32
+  std::uint32_t tmp;
+  std::size_t len = cvt_char(src, slen, tmp);
+  if (len == 0) return 0;
+  // make utf-32 to utf-16
+  if (cvt_char(tmp, &des, 1) != 1) return 0;
+  return len;
+}
+
+/**
+ * \brief UTF-32 string --> UTF-8/16 string
+*/
+template <typename T, typename U>
+auto cvt_cstr_utf(T const *src, std::size_t slen, U *des, std::size_t dlen) noexcept
+  -> std::enable_if_t<utf_compatible_v<T, ufmt::utf32> &&
+                     (utf_compatible_v<U, ufmt::utf16> || utf_compatible_v<U, ufmt::utf8>), std::size_t> {
+  if ((src == nullptr) || ((*src) == 0) || (slen == 0)) {
+    // source string is empty
+    return 0;
+  }
+  std::size_t num = 0, len = 0;
+  for (std::size_t i = 0; (i < slen) && ((*src) != 0); ++src, ++i) {
+    len = cvt_char(*src, des, dlen);
+    if (len == 0) return 0;
+    if (des != nullptr) {
+      des += len;
+      if (dlen < len) {
+        dlen = 0;
+      } else {
+        dlen -= len;
+      }
+    }
+    num += len;
+  }
+  return num;
+}
+
+/**
+ * \brief UTF-8/16 string --> UTF-32 string
+*/
+template <typename T, typename U>
+auto cvt_cstr_utf(T const *src, std::size_t slen, U *des, std::size_t dlen) noexcept
+  -> std::enable_if_t<utf_compatible_v<U, ufmt::utf32> &&
+                     (utf_compatible_v<T, ufmt::utf16> || utf_compatible_v<T, ufmt::utf8>), std::size_t> {
+  if ((src == nullptr) || ((*src) == 0) || (slen == 0)) {
+    // source string is empty
+    return 0;
+  }
+  std::size_t num = 0;
+  for (std::size_t i = 0; (i < slen) && ((*src) != 0);) {
+    std::uint32_t tmp;
+    std::size_t len = cvt_char(src, slen - i, tmp);
+    if (len == 0) return 0;
+    if ((des != nullptr) && (dlen > 0)) {
+      (*des) = tmp;
+      ++des;
+      dlen -= 1;
+    }
+    src += len;
+    i   += len;
+    num += 1;
+  }
+  return num;
+}
+
+/**
+ * \brief UTF-8/16 string --> UTF-16/8 string
+*/
+template <typename T, typename U>
+auto cvt_cstr_utf(T const *src, std::size_t slen, U *des, std::size_t dlen) noexcept
+  -> std::enable_if_t<(utf_compatible_v<T, ufmt::utf8>  && utf_compatible_v<U, ufmt::utf16>) ||
+                      (utf_compatible_v<T, ufmt::utf16> && utf_compatible_v<U, ufmt::utf8>), std::size_t> {
+  if ((src == nullptr) || ((*src) == 0) || (slen == 0)) {
+    // source string is empty
+    return 0;
+  }
+  std::size_t num = 0;
+  for (std::size_t i = 0; (i < slen) && ((*src) != 0);) {
+    // make utf-x to utf-32
+    std::uint32_t tmp;
+    std::size_t len = cvt_char(src, slen - i, tmp);
+    if (len == 0) return 0;
+    src += len;
+    i   += len;
+    // make utf-32 to utf-y
+    len = cvt_char(tmp, des, dlen);
+    if (len == 0) return 0;
+    if (des != nullptr) {
+      des += len;
+      if (dlen < len) {
+        dlen = 0;
+      } else {
+        dlen -= len;
+      }
+    }
+    num += len;
+  }
+  return num;
+}
+
+template <typename T, typename U>
+auto cvt_cstr_utf(T const *src, std::size_t slen, U *des, std::size_t dlen) noexcept
+  -> std::enable_if_t<(sizeof(T) == sizeof(U)), std::size_t> {
+  if ((des == nullptr) || (dlen == 0)) {
+    return slen;
+  }
+  std::size_t r = (std::min)(slen, dlen);
+  std::memcpy(des, src, r * sizeof(T));
+  return r;
+}
+
+} // namespace
+
+#define LIBIPC_DEF_CVT_CSTR_($CHAR_T, $CHAR_U) \
+  template <> \
+  std::size_t cvt_cstr($CHAR_T const *src, std::size_t slen, $CHAR_U *des, std::size_t dlen) noexcept { \
+    return cvt_cstr_utf(src, slen, des, dlen); \
+  }
+// #define LIBIPC_DEF_CVT_CSTR_($CHAR_T, $CHAR_U)
+
+LIBIPC_DEF_CVT_CSTR_(char    , char)
+LIBIPC_DEF_CVT_CSTR_(char    , char16_t)
+LIBIPC_DEF_CVT_CSTR_(char    , char32_t)
+LIBIPC_DEF_CVT_CSTR_(wchar_t , wchar_t)
+LIBIPC_DEF_CVT_CSTR_(char16_t, char16_t)
+LIBIPC_DEF_CVT_CSTR_(char16_t, char)
+LIBIPC_DEF_CVT_CSTR_(char16_t, char32_t)
+LIBIPC_DEF_CVT_CSTR_(char32_t, char32_t)
+LIBIPC_DEF_CVT_CSTR_(char32_t, char)
+LIBIPC_DEF_CVT_CSTR_(char32_t, char16_t)
+#if !defined(LIBIPC_OS_WIN)
+LIBIPC_DEF_CVT_CSTR_(char    , wchar_t)
+LIBIPC_DEF_CVT_CSTR_(wchar_t , char)
+LIBIPC_DEF_CVT_CSTR_(wchar_t , char16_t)
+LIBIPC_DEF_CVT_CSTR_(wchar_t , char32_t)
+LIBIPC_DEF_CVT_CSTR_(char16_t, wchar_t)
+LIBIPC_DEF_CVT_CSTR_(char32_t, wchar_t)
+#endif // !defined(LIBIPC_OS_WIN)
+
+#if defined(LIBIPC_CPP_20)
+LIBIPC_DEF_CVT_CSTR_(char8_t , char8_t)
+LIBIPC_DEF_CVT_CSTR_(char8_t , char)
+LIBIPC_DEF_CVT_CSTR_(char8_t , char16_t)
+LIBIPC_DEF_CVT_CSTR_(char8_t , char32_t)
+LIBIPC_DEF_CVT_CSTR_(char    , char8_t)
+LIBIPC_DEF_CVT_CSTR_(char16_t, char8_t)
+LIBIPC_DEF_CVT_CSTR_(char32_t, char8_t)
+#if !defined(LIBIPC_OS_WIN)
+LIBIPC_DEF_CVT_CSTR_(char8_t , wchar_t)
+LIBIPC_DEF_CVT_CSTR_(wchar_t , char8_t)
+#endif // !defined(LIBIPC_OS_WIN)
+#endif // defined(LIBIPC_CPP_20)
+
+#undef LIBIPC_DEF_CVT_CSTR_
+
+} // namespace ipc
diff --git a/src/libipc/imp/fmt.cpp b/src/libipc/imp/fmt.cpp
new file mode 100644
index 00000000..cc16821e
--- /dev/null
+++ b/src/libipc/imp/fmt.cpp
@@ -0,0 +1,329 @@
+
+#include <cstdio>     // std::snprintf
+#include <iomanip>    // std::put_time
+#include <sstream>    // std::ostringstream
+#include <array>
+#include <cstring>    // std::memcpy
+#include <algorithm>  // std::min
+#include <initializer_list>
+#include <cstdint>
+
+#include "libipc/imp/fmt.h"
+#include "libipc/imp/codecvt.h"
+#include "libipc/imp/detect_plat.h"
+
+namespace ipc {
+
+/**
+ * \brief Format conversions helpers.
+ * \see http://personal.ee.surrey.ac.uk/Personal/R.Bowden/C/printf.html
+ *      https://en.cppreference.com/w/cpp/io/c/fprintf
+ */
+namespace {
+
+struct sfmt_policy {
+  static constexpr std::size_t aligned_size = 32U;
+};
+
+template <typename Policy = sfmt_policy>
+span<char> local_fmt_sbuf() noexcept {
+  thread_local std::array<char, Policy::aligned_size> sbuf;
+  return sbuf;
+}
+
+span<char const> normalize(span<char const> const &a) {
+  if (a.empty()) return {};
+  return a.first(a.size() - (a.back() == '\0' ? 1 : 0));
+}
+
+span<char> smem_cpy(span<char> const &sbuf, span<char const> a) noexcept {
+  if (sbuf.empty()) return {};
+  a = normalize(a);
+  auto sz = (std::min)(sbuf.size() - 1, a.size());
+  if (sz != 0) std::memcpy(sbuf.data(), a.data(), sz);
+  return sbuf.first(sz);
+}
+
+span<char> sbuf_cpy(span<char> sbuf, span<char const> const &a) noexcept {
+  sbuf = smem_cpy(sbuf, a);
+  *sbuf.end() = '\0';
+  return sbuf;
+}
+
+span<char> sbuf_cat(span<char> const &sbuf, std::initializer_list<span<char const>> args) noexcept {
+  std::size_t remain = sbuf.size();
+  for (auto s : args) {
+    remain -= smem_cpy(sbuf.last(remain), s).size();
+  }
+  auto sz = sbuf.size() - remain;
+  sbuf[sz] = '\0';
+  return sbuf.first(sz);
+}
+
+char const *as_cstr(span<char const> const &a) {
+  if (a.empty()) return "";
+  if (a.back() == '\0') return a.data();
+  return sbuf_cpy(local_fmt_sbuf(), a).data();
+}
+
+span<char> fmt_of(span<char const> const &fstr, span<char const> const &s) {
+  return sbuf_cat(local_fmt_sbuf(), {"%", fstr, s});
+}
+
+span<char> fmt_of_unsigned(span<char const> fstr, span<char const> const &l) {
+  if (fstr.empty()) {
+    return fmt_of(l, "u");
+  }
+  fstr = normalize(fstr);
+  switch (fstr.back()) {
+    case 'o':
+    case 'x':
+    case 'X':
+    case 'u': return sbuf_cat(local_fmt_sbuf(), {"%", fstr.first(fstr.size() - 1), l, fstr.last(1)});
+    default : return sbuf_cat(local_fmt_sbuf(), {"%", fstr, l, "u"});
+  }
+}
+
+span<char> fmt_of_signed(span<char const> fstr, span<char const> const &l) {
+  if (fstr.empty()) {
+    return fmt_of(l, "d");
+  }
+  fstr = normalize(fstr);
+  switch (fstr.back()) {
+    case 'o':
+    case 'x':
+    case 'X':
+    case 'u': return fmt_of_unsigned(fstr, l);
+    default : return sbuf_cat(local_fmt_sbuf(), {"%", fstr, l, "d"});
+  }
+}
+
+span<char> fmt_of_float(span<char const> fstr, span<char const> const &l) {
+  if (fstr.empty()) {
+    return fmt_of(l, "f");
+  }
+  fstr = normalize(fstr);
+  switch (fstr.back()) {
+    case 'e':
+    case 'E':
+    case 'g':
+    case 'G': return sbuf_cat(local_fmt_sbuf(), {"%", fstr.first(fstr.size() - 1), l, fstr.last(1)});
+    default : return sbuf_cat(local_fmt_sbuf(), {"%", fstr, l, "f"});
+  }
+}
+
+template <typename A /*a fundamental or pointer type*/>
+int sprintf(fmt_context &ctx, span<char const> const &sfmt, A a) {
+  for (std::int32_t sz = -1;;) {
+    auto sbuf = ctx.buffer(sz + 1);
+    if (sbuf.size() < std::size_t(sz + 1)) {
+      return -1;
+    }
+    sz = std::snprintf(sbuf.data(), sbuf.size(), sfmt.data(), a);
+    if (sz <= 0) {
+      return sz;
+    }
+    if (std::size_t(sz) < sbuf.size()) {
+      ctx.expend(sz);
+      return sz;
+    }
+  }
+}
+
+template <typename F /*a function pointer*/, 
+          typename A /*a fundamental or pointer type*/>
+bool sprintf(fmt_context &ctx, F fop, span<char const> const &fstr, span<char const> const &s, A a) noexcept {
+  LIBIPC_TRY {
+    return ipc::sprintf(ctx, fop(fstr, s), a) >= 0;
+  } LIBIPC_CATCH(...) {
+    return false;
+  }
+}
+
+} // namespace
+
+/// \brief The context of fmt.
+
+fmt_context::fmt_context(std::string &j) noexcept
+  : joined_(j)
+  , offset_(0) {}
+
+std::size_t fmt_context::capacity() noexcept {
+  return (offset_ < sbuf_.size()) ? sbuf_.size() : joined_.size();
+}
+
+void fmt_context::reset() noexcept {
+  offset_ = 0;
+}
+
+bool fmt_context::finish() noexcept {
+  LIBIPC_TRY {
+    if (offset_ < sbuf_.size()) {
+      joined_.assign(sbuf_.data(), offset_);
+    } else {
+      joined_.resize(offset_);
+    }
+    return true;
+  } LIBIPC_CATCH(...) {
+    return false;
+  }
+}
+
+span<char> fmt_context::buffer(std::size_t sz) noexcept {
+  auto roundup = [](std::size_t sz) noexcept {
+    constexpr std::size_t fmt_context_aligned_size = 512U;
+    return (sz & ~(fmt_context_aligned_size - 1)) + fmt_context_aligned_size;
+  };
+  auto sbuf = make_span(sbuf_);
+  LIBIPC_TRY {
+    if (offset_ < sbuf.size()) {
+      if ((offset_ + sz) < sbuf.size()) {
+        return sbuf.subspan(offset_);
+      } else {
+        /// \remark switch the cache to std::string
+        joined_.assign(sbuf.data(), offset_);
+        joined_.resize(roundup(offset_ + sz));
+      }
+    } else if ((offset_ + sz) >= joined_.size()) {
+      joined_.resize(roundup(offset_ + sz));
+    }
+    return {&joined_[offset_], joined_.size() - offset_};
+  } LIBIPC_CATCH(...) {
+    return {};
+  }
+}
+
+void fmt_context::expend(std::size_t sz) noexcept {
+  offset_ += sz;
+}
+
+bool fmt_context::append(span<char const> const &str) noexcept {
+  auto sz = str.size();
+  if (sz == 0) return true;
+  if (str.back() == '\0') --sz;
+  auto sbuf = buffer(sz);
+  if (sbuf.size() < sz) {
+    return false;
+  }
+  std::memcpy(sbuf.data(), str.data(), sz);
+  offset_ += sz;
+  return true;
+}
+
+/// \brief To string conversion.
+
+bool to_string(fmt_context &ctx, char const *a) noexcept {
+  return to_string(ctx, a, {});
+}
+
+bool to_string(fmt_context &ctx, std::string const &a) noexcept {
+  return ctx.append(a);
+}
+
+bool to_string(fmt_context &ctx, char const *a, span<char const> fstr) noexcept {
+  if (a == nullptr) {
+    return ipc::sprintf(ctx, fmt_of, fstr, "s", "");
+  } else {
+    return ipc::sprintf(ctx, fmt_of, fstr, "s", a);
+  }
+}
+
+bool to_string(fmt_context &ctx, char a) noexcept {
+  return ipc::sprintf(ctx, fmt_of, {}, "c", a);
+}
+
+bool to_string(fmt_context &ctx, wchar_t a) noexcept {
+  LIBIPC_TRY {
+    std::string des;
+    cvt_sstr(std::wstring{a}, des);
+    return ctx.append(des);
+  } LIBIPC_CATCH(...) {
+    return false;
+  }
+}
+
+bool to_string(fmt_context &ctx, char16_t a) noexcept {
+  LIBIPC_TRY {
+    std::string des;
+    cvt_sstr(std::u16string{a}, des);
+    return ctx.append(des);
+  } LIBIPC_CATCH(...) {
+    return false;
+  }
+}
+
+bool to_string(fmt_context &ctx, char32_t a) noexcept {
+  LIBIPC_TRY {
+    std::string des;
+    cvt_sstr(std::u32string{a}, des);
+    return ctx.append(des);
+  } LIBIPC_CATCH(...) {
+    return false;
+  }
+}
+
+bool to_string(fmt_context &ctx, signed short a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_signed, fstr, "h", a);
+}
+
+bool to_string(fmt_context &ctx, unsigned short a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_unsigned, fstr, "h", a);
+}
+
+bool to_string(fmt_context &ctx, signed int a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_signed, fstr, "", a);
+}
+
+bool to_string(fmt_context &ctx, unsigned int a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_unsigned, fstr, "", a);
+}
+
+bool to_string(fmt_context &ctx, signed long a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_signed, fstr, "l", a);
+}
+
+bool to_string(fmt_context &ctx, unsigned long a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_unsigned, fstr, "l", a);
+}
+
+bool to_string(fmt_context &ctx, signed long long a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_signed, fstr, "ll", a);
+}
+
+bool to_string(fmt_context &ctx, unsigned long long a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_unsigned, fstr, "ll", a);
+}
+
+bool to_string(fmt_context &ctx, double a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_float, fstr, "", a);
+}
+
+bool to_string(fmt_context &ctx, long double a, span<char const> fstr) noexcept {
+  return ipc::sprintf(ctx, fmt_of_float, fstr, "L", a);
+}
+
+bool to_string(fmt_context &ctx, std::nullptr_t) noexcept {
+  return ctx.append("null");
+}
+
+bool to_string(fmt_context &ctx, void const volatile *a) noexcept {
+  if (a == nullptr) {
+    return to_string(ctx, nullptr);
+  }
+  return ipc::sprintf(ctx, fmt_of, "", "p", a);
+}
+
+bool to_string(fmt_context &ctx, std::tm const &a, span<char const> fstr) noexcept {
+  if (fstr.empty()) {
+    fstr = "%Y-%m-%d %H:%M:%S";
+  }
+  LIBIPC_TRY {
+    std::ostringstream ss;
+    ss << std::put_time(&a, as_cstr(fstr));
+    return ctx.append(ss.str());
+  } LIBIPC_CATCH(...) {
+    return {};
+  }
+}
+
+} // namespace ipc
diff --git a/src/libipc/imp/nameof.cpp b/src/libipc/imp/nameof.cpp
new file mode 100644
index 00000000..462473bc
--- /dev/null
+++ b/src/libipc/imp/nameof.cpp
@@ -0,0 +1,7 @@
+
+#include "libipc/imp/detect_plat.h"
+#if defined(LIBIPC_CC_GNUC)
+# include "libipc/platform/gnuc/demangle.h"
+#else
+# include "libipc/platform/win/demangle.h"
+#endif
diff --git a/src/libipc/imp/system.cpp b/src/libipc/imp/system.cpp
new file mode 100644
index 00000000..c05975ce
--- /dev/null
+++ b/src/libipc/imp/system.cpp
@@ -0,0 +1,7 @@
+
+#include "libipc/imp/detect_plat.h"
+#if defined(LIBIPC_OS_WIN)
+# include "libipc/platform/win/system.h"
+#else
+# include "libipc/platform/posix/system.h"
+#endif
diff --git a/src/libipc/ipc.cpp b/src/libipc/ipc.cpp
index 7d919dda..51086483 100755
--- a/src/libipc/ipc.cpp
+++ b/src/libipc/ipc.cpp
@@ -14,7 +14,6 @@
 #include "libipc/ipc.h"
 #include "libipc/def.h"
 #include "libipc/shm.h"
-#include "libipc/pool_alloc.h"
 #include "libipc/queue.h"
 #include "libipc/policy.h"
 #include "libipc/rw_lock.h"
@@ -25,7 +24,8 @@
 #include "libipc/utility/scope_guard.h"
 #include "libipc/utility/utility.h"
 
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
+#include "libipc/mem/new.h"
 #include "libipc/platform/detail.h"
 #include "libipc/circ/elem_array.h"
 
@@ -64,25 +64,30 @@ struct msg_t : msg_t<0, AlignSize> {
 };
 
 template <typename T>
-ipc::buff_t make_cache(T& data, std::size_t size) {
-    auto ptr = ipc::mem::alloc(size);
+ipc::buff_t make_cache(T &data, std::size_t size) {
+    auto *ptr = ipc::mem::$new<void>(size);
     std::memcpy(ptr, &data, (ipc::detail::min)(sizeof(data), size));
-    return { ptr, size, ipc::mem::free };
+    return {
+        ptr, size, 
+        [](void *p, std::size_t) noexcept {
+            ipc::mem::$delete(p);
+        }
+    };
 }
 
-acc_t *cc_acc(ipc::string const &pref) {
-    static ipc::unordered_map<ipc::string, ipc::shm::handle> handles;
+acc_t *cc_acc(std::string const &pref) {
+    static auto *phs = new ipc::unordered_map<std::string, ipc::shm::handle>; // no delete
     static std::mutex lock;
     std::lock_guard<std::mutex> guard {lock};
-    auto it = handles.find(pref);
-    if (it == handles.end()) {
-        ipc::string shm_name {ipc::make_prefix(pref, {"CA_CONN__"})};
+    auto it = phs->find(pref);
+    if (it == phs->end()) {
+        std::string shm_name {ipc::make_prefix(pref, "CA_CONN__")};
         ipc::shm::handle h;
         if (!h.acquire(shm_name.c_str(), sizeof(acc_t))) {
             ipc::error("[cc_acc] acquire failed: %s\n", shm_name.c_str());
             return nullptr;
         }
-        it = handles.emplace(pref, std::move(h)).first;
+        it = phs->emplace(pref, std::move(h)).first;
     }
     return static_cast<acc_t *>(it->second.get());
 }
@@ -105,8 +110,8 @@ struct cache_t {
 
 struct conn_info_head {
 
-    ipc::string prefix_;
-    ipc::string name_;
+    std::string prefix_;
+    std::string name_;
     msg_id_t    cc_id_; // connection-info id
     ipc::detail::waiter cc_waiter_, wt_waiter_, rd_waiter_;
     ipc::shm::handle acc_h_;
@@ -117,10 +122,10 @@ struct conn_info_head {
         , cc_id_ {} {}
 
     void init() {
-        if (!cc_waiter_.valid()) cc_waiter_.open(ipc::make_prefix(prefix_, {"CC_CONN__", name_}).c_str());
-        if (!wt_waiter_.valid()) wt_waiter_.open(ipc::make_prefix(prefix_, {"WT_CONN__", name_}).c_str());
-        if (!rd_waiter_.valid()) rd_waiter_.open(ipc::make_prefix(prefix_, {"RD_CONN__", name_}).c_str());
-        if (!acc_h_.valid()) acc_h_.acquire(ipc::make_prefix(prefix_, {"AC_CONN__", name_}).c_str(), sizeof(acc_t));
+        if (!cc_waiter_.valid()) cc_waiter_.open(ipc::make_prefix(prefix_, "CC_CONN__", name_).c_str());
+        if (!wt_waiter_.valid()) wt_waiter_.open(ipc::make_prefix(prefix_, "WT_CONN__", name_).c_str());
+        if (!rd_waiter_.valid()) rd_waiter_.open(ipc::make_prefix(prefix_, "RD_CONN__", name_).c_str());
+        if (!acc_h_.valid()) acc_h_.acquire(ipc::make_prefix(prefix_, "AC_CONN__", name_).c_str(), sizeof(acc_t));
         if (cc_id_ != 0) {
             return;
         }
@@ -146,10 +151,10 @@ struct conn_info_head {
     static void clear_storage(char const * prefix, char const * name) noexcept {
         auto p = ipc::make_string(prefix);
         auto n = ipc::make_string(name);
-        ipc::detail::waiter::clear_storage(ipc::make_prefix(p, {"CC_CONN__", n}).c_str());
-        ipc::detail::waiter::clear_storage(ipc::make_prefix(p, {"WT_CONN__", n}).c_str());
-        ipc::detail::waiter::clear_storage(ipc::make_prefix(p, {"RD_CONN__", n}).c_str());
-        ipc::shm::handle::clear_storage(ipc::make_prefix(p, {"AC_CONN__", n}).c_str());
+        ipc::detail::waiter::clear_storage(ipc::make_prefix(p, "CC_CONN__", n).c_str());
+        ipc::detail::waiter::clear_storage(ipc::make_prefix(p, "WT_CONN__", n).c_str());
+        ipc::detail::waiter::clear_storage(ipc::make_prefix(p, "RD_CONN__", n).c_str());
+        ipc::shm::handle::clear_storage(ipc::make_prefix(p, "AC_CONN__", n).c_str());
     }
 
     void quit_waiting() {
@@ -208,10 +213,10 @@ struct chunk_info_t {
 
 auto& chunk_storages() {
     class chunk_handle_t {
-        ipc::unordered_map<ipc::string, ipc::shm::handle> handles_;
+        ipc::unordered_map<std::string, ipc::shm::handle> handles_;
         std::mutex lock_;
 
-        static bool make_handle(ipc::shm::handle &h, ipc::string const &shm_name, std::size_t chunk_size) {
+        static bool make_handle(ipc::shm::handle &h, std::string const &shm_name, std::size_t chunk_size) {
             if (!h.valid() &&
                 !h.acquire( shm_name.c_str(), 
                             sizeof(chunk_info_t) + chunk_info_t::chunks_mem_size(chunk_size) )) {
@@ -223,8 +228,8 @@ auto& chunk_storages() {
 
     public:
         chunk_info_t *get_info(conn_info_head *inf, std::size_t chunk_size) {
-            ipc::string pref {(inf == nullptr) ? ipc::string{} : inf->prefix_};
-            ipc::string shm_name {ipc::make_prefix(pref, {"CHUNK_INFO__", ipc::to_string(chunk_size)})};
+            std::string pref {(inf == nullptr) ? std::string{} : inf->prefix_};
+            std::string shm_name {ipc::make_prefix(pref, "CHUNK_INFO__", chunk_size)};
             ipc::shm::handle *h;
             {
                 std::lock_guard<std::mutex> guard {lock_};
@@ -243,8 +248,8 @@ auto& chunk_storages() {
     };
     using deleter_t = void (*)(chunk_handle_t*);
     using chunk_handle_ptr_t = std::unique_ptr<chunk_handle_t, deleter_t>;
-    static ipc::map<std::size_t, chunk_handle_ptr_t> chunk_hs;
-    return chunk_hs;
+    static auto *chunk_hs = new ipc::map<std::size_t, chunk_handle_ptr_t>; // no delete
+    return *chunk_hs;
 }
 
 chunk_info_t *chunk_storage_info(conn_info_head *inf, std::size_t chunk_size) {
@@ -252,15 +257,15 @@ chunk_info_t *chunk_storage_info(conn_info_head *inf, std::size_t chunk_size) {
     std::decay_t<decltype(storages)>::iterator it;
     {
         static ipc::rw_lock lock;
-        IPC_UNUSED_ std::shared_lock<ipc::rw_lock> guard {lock};
+        LIBIPC_UNUSED std::shared_lock<ipc::rw_lock> guard {lock};
         if ((it = storages.find(chunk_size)) == storages.end()) {
             using chunk_handle_ptr_t = std::decay_t<decltype(storages)>::value_type::second_type;
             using chunk_handle_t     = chunk_handle_ptr_t::element_type;
             guard.unlock();
-            IPC_UNUSED_ std::lock_guard<ipc::rw_lock> guard {lock};
+            LIBIPC_UNUSED std::lock_guard<ipc::rw_lock> guard {lock};
             it = storages.emplace(chunk_size, chunk_handle_ptr_t{
-                ipc::mem::alloc<chunk_handle_t>(), [](chunk_handle_t *p) {
-                    ipc::mem::destruct(p);
+                ipc::mem::$new<chunk_handle_t>(), [](chunk_handle_t *p) {
+                    ipc::mem::$delete(p);
                 }}).first;
         }
     }
@@ -394,11 +399,11 @@ struct queue_generator {
         void init() {
             conn_info_head::init();
             if (!que_.valid()) {
-                que_.open(ipc::make_prefix(prefix_, {
+                que_.open(ipc::make_prefix(prefix_, 
                           "QU_CONN__", 
                           this->name_, 
-                          "__", ipc::to_string(DataSize), 
-                          "__", ipc::to_string(AlignSize)}).c_str());
+                          "__", DataSize, 
+                          "__", AlignSize).c_str());
             }
         }
 
@@ -408,11 +413,11 @@ struct queue_generator {
         }
 
         static void clear_storage(char const * prefix, char const * name) noexcept {
-            queue_t::clear_storage(ipc::make_prefix(ipc::make_string(prefix), {
+            queue_t::clear_storage(ipc::make_prefix(prefix, 
                                    "QU_CONN__", 
-                                   ipc::make_string(name), 
-                                   "__", ipc::to_string(DataSize), 
-                                   "__", ipc::to_string(AlignSize)}).c_str());
+                                   name, 
+                                   "__", DataSize, 
+                                   "__", AlignSize).c_str());
             conn_info_head::clear_storage(prefix, name);
         }
 
@@ -447,7 +452,7 @@ constexpr static queue_t* queue_of(ipc::handle_t h) noexcept {
 static bool connect(ipc::handle_t * ph, ipc::prefix pref, char const * name, bool start_to_recv) {
     assert(ph != nullptr);
     if (*ph == nullptr) {
-        *ph = ipc::mem::alloc<conn_info_t>(pref.str, name);
+        *ph = ipc::mem::$new<conn_info_t>(pref.str, name);
     }
     return reconnect(ph, start_to_recv);
 }
@@ -490,7 +495,7 @@ static bool reconnect(ipc::handle_t * ph, bool start_to_recv) {
 }
 
 static void destroy(ipc::handle_t h) noexcept {
-    ipc::mem::free(info_of(h));
+    ipc::mem::$delete(info_of(h));
 }
 
 static std::size_t recv_count(ipc::handle_t h) noexcept {
@@ -654,20 +659,20 @@ static ipc::buff_t recv(ipc::handle_t h, std::uint64_t tm) {
                     conn_info_t *     inf;
                     ipc::circ::cc_t   curr_conns;
                     ipc::circ::cc_t   conn_id;
-                } *r_info = ipc::mem::alloc<recycle_t>(recycle_t{
+                } *r_info = ipc::mem::$new<recycle_t>(recycle_t{
                     buf_id, 
                     inf, 
                     que->elems()->connections(std::memory_order_relaxed), 
                     que->connected_id()
                 });
                 if (r_info == nullptr) {
-                    ipc::log("fail: ipc::mem::alloc<recycle_t>.\n");
+                    ipc::log("fail: ipc::mem::$new<recycle_t>.\n");
                     return ipc::buff_t{buf, msg_size}; // no recycle
                 } else {
                     return ipc::buff_t{buf, msg_size, [](void* p_info, std::size_t size) {
                         auto r_info = static_cast<recycle_t *>(p_info);
-                        IPC_UNUSED_ auto finally = ipc::guard([r_info] {
-                            ipc::mem::free(r_info);
+                        LIBIPC_UNUSED auto finally = ipc::guard([r_info] {
+                            ipc::mem::$delete(r_info);
                         });
                         recycle_storage<flag_t>(r_info->storage_id, 
                                                 r_info->inf, 
diff --git a/src/libipc/mem/bytes_allocator.cpp b/src/libipc/mem/bytes_allocator.cpp
new file mode 100644
index 00000000..133f642a
--- /dev/null
+++ b/src/libipc/mem/bytes_allocator.cpp
@@ -0,0 +1,53 @@
+
+#include <algorithm>  // std::swap
+
+#include "libipc/imp/log.h"
+#include "libipc/mem/bytes_allocator.h"
+#include "libipc/mem/memory_resource.h"
+
+namespace ipc {
+namespace mem {
+
+bytes_allocator::holder_mr_base &bytes_allocator::get_holder() noexcept {
+  return *reinterpret_cast<holder_mr_base *>(holder_.data());
+}
+
+bytes_allocator::holder_mr_base const &bytes_allocator::get_holder() const noexcept {
+  return *reinterpret_cast<holder_mr_base const *>(holder_.data());
+}
+
+void bytes_allocator::init_default_resource() noexcept {
+  std::ignore = ipc::construct<holder_mr<new_delete_resource>>(holder_.data(), new_delete_resource::get());
+}
+
+bytes_allocator::bytes_allocator() noexcept
+  : bytes_allocator(new_delete_resource::get()) {}
+
+bytes_allocator::~bytes_allocator() noexcept {
+  ipc::destroy(&get_holder());
+}
+
+void bytes_allocator::swap(bytes_allocator &other) noexcept {
+  std::swap(this->holder_, other.holder_);
+}
+
+void *bytes_allocator::allocate(std::size_t s, std::size_t a) const {
+  LIBIPC_LOG();
+  if ((a & (a - 1)) != 0) {
+    log.error("failed: allocate alignment is not a power of 2.");
+    return nullptr;
+  }
+  return get_holder().alloc(s, a);
+}
+
+void bytes_allocator::deallocate(void *p, std::size_t s, std::size_t a) const {
+  LIBIPC_LOG();
+  if ((a & (a - 1)) != 0) {
+    log.error("failed: allocate alignment is not a power of 2.");
+    return;
+  }
+  get_holder().dealloc(p, s, a);
+}
+
+} // namespace mem
+} // namespace ipc
diff --git a/src/libipc/mem/central_cache_allocator.cpp b/src/libipc/mem/central_cache_allocator.cpp
new file mode 100644
index 00000000..d4a11b5d
--- /dev/null
+++ b/src/libipc/mem/central_cache_allocator.cpp
@@ -0,0 +1,47 @@
+
+#include <mutex>
+#include <array>
+#include <cstddef>
+
+#include "libipc/def.h"
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/byte.h"
+#include "libipc/mem/bytes_allocator.h"
+#include "libipc/mem/memory_resource.h"
+
+namespace ipc {
+namespace mem {
+
+class thread_safe_resource : public monotonic_buffer_resource {
+public:
+  thread_safe_resource(span<byte> buffer) noexcept
+      : monotonic_buffer_resource(buffer) {}
+
+  ~thread_safe_resource() noexcept {
+    LIBIPC_UNUSED std::lock_guard<std::mutex> lock(mutex_);
+    monotonic_buffer_resource::release();
+  }
+
+  void *allocate(std::size_t bytes, std::size_t alignment) noexcept {
+    LIBIPC_UNUSED std::lock_guard<std::mutex> lock(mutex_);
+    return monotonic_buffer_resource::allocate(bytes, alignment);
+  }
+
+  void deallocate(void *p, std::size_t bytes, std::size_t alignment) noexcept {
+    LIBIPC_UNUSED std::lock_guard<std::mutex> lock(mutex_);
+    monotonic_buffer_resource::deallocate(p, bytes, alignment);
+  }
+
+private:
+  std::mutex mutex_;
+};
+
+bytes_allocator &central_cache_allocator() noexcept {
+  static std::array<byte, central_cache_default_size> buf;
+  static thread_safe_resource res(buf);
+  static bytes_allocator a(&res);
+  return a;
+}
+
+} // namespace mem
+} // namespace ipc
diff --git a/src/libipc/mem/monotonic_buffer_resource.cpp b/src/libipc/mem/monotonic_buffer_resource.cpp
new file mode 100644
index 00000000..dc717f5e
--- /dev/null
+++ b/src/libipc/mem/monotonic_buffer_resource.cpp
@@ -0,0 +1,140 @@
+
+#include <utility>
+#include <memory>
+#include <algorithm>
+
+#include "libipc/imp/log.h"
+#include "libipc/imp/aligned.h"
+#include "libipc/imp/detect_plat.h"
+#include "libipc/mem/memory_resource.h"
+
+namespace ipc {
+namespace mem {
+namespace {
+
+template <typename Node>
+Node *make_node(bytes_allocator const &upstream, std::size_t initial_size, std::size_t alignment) noexcept {
+  LIBIPC_LOG();
+  auto sz = ipc::round_up(sizeof(Node), alignment) + initial_size;
+  LIBIPC_TRY {
+    auto *node = static_cast<Node *>(upstream.allocate(sz));
+    if (node == nullptr) {
+      log.error("failed: allocate memory for `monotonic_buffer_resource`'s node.", 
+                " bytes = ", initial_size, ", alignment = ", alignment);
+      return nullptr;
+    }
+    node->next = nullptr;
+    node->size = sz;
+    return node;
+  } LIBIPC_CATCH(...) {
+    log.error("failed: allocate memory for `monotonic_buffer_resource`'s node.", 
+              " bytes = ", initial_size, ", alignment = ", alignment,
+              "\n\texception: ", ipc::log::exception_string(std::current_exception()));
+    return nullptr;
+  }
+}
+
+std::size_t next_buffer_size(std::size_t size) noexcept {
+  return size * 3 / 2;
+}
+
+} // namespace
+
+monotonic_buffer_resource::monotonic_buffer_resource() noexcept
+  : monotonic_buffer_resource(bytes_allocator{}) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(bytes_allocator upstream) noexcept
+  : monotonic_buffer_resource(0, std::move(upstream)) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(std::size_t initial_size) noexcept
+  : monotonic_buffer_resource(initial_size, bytes_allocator{}) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(std::size_t initial_size, bytes_allocator upstream) noexcept
+  : upstream_      (std::move(upstream))
+  , free_list_     (nullptr)
+  , head_          (nullptr)
+  , tail_          (nullptr)
+  , next_size_     (initial_size)
+  , initial_buffer_(nullptr)
+  , initial_size_  (initial_size) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(ipc::span<ipc::byte> buffer) noexcept
+  : monotonic_buffer_resource(buffer, bytes_allocator{}) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(ipc::span<ipc::byte> buffer, bytes_allocator upstream) noexcept
+  : upstream_      (std::move(upstream))
+  , free_list_     (nullptr)
+  , head_          (buffer.begin())
+  , tail_          (buffer.end())
+  , next_size_     (next_buffer_size(buffer.size()))
+  , initial_buffer_(buffer.begin())
+  , initial_size_  (buffer.size()) {}
+
+monotonic_buffer_resource::~monotonic_buffer_resource() noexcept {
+  release();
+}
+
+bytes_allocator monotonic_buffer_resource::upstream_resource() const noexcept {
+  return upstream_;
+}
+
+void monotonic_buffer_resource::release() noexcept {
+  LIBIPC_LOG();
+  LIBIPC_TRY {
+    while (free_list_ != nullptr) {
+      auto *next = free_list_->next;
+      upstream_.deallocate(free_list_, free_list_->size);
+      free_list_ = next;
+    }
+  } LIBIPC_CATCH(...) {
+    log.error("failed: deallocate memory for `monotonic_buffer_resource`.",
+              "\n\texception: ", ipc::log::exception_string(std::current_exception()));
+  }
+  // reset to initial state at contruction
+  if ((head_ = initial_buffer_) != nullptr) {
+    tail_ = head_ + initial_size_;
+    next_size_ = next_buffer_size(initial_size_);
+  } else {
+    tail_ = nullptr;
+    next_size_ = initial_size_;
+  }
+}
+
+void *monotonic_buffer_resource::allocate(std::size_t bytes, std::size_t alignment) noexcept {
+  LIBIPC_LOG();
+  if (bytes == 0) {
+    log.error("failed: allocate bytes = 0.");
+    return nullptr;
+  }
+  void *p = head_;
+  auto  s = static_cast<std::size_t>(tail_ - head_);
+  if (std::align(alignment, bytes, p, s) == nullptr) {
+    next_size_ = (std::max)(next_size_, bytes);
+    auto *node = make_node<monotonic_buffer_resource::node>(upstream_, next_size_, alignment);
+    if (node == nullptr) return nullptr;
+    node->next = free_list_;
+    free_list_ = node;
+    next_size_ = next_buffer_size(next_size_);
+    // try again
+    s = node->size - sizeof(monotonic_buffer_resource::node);
+    p = std::align(alignment, bytes, (p = node + 1), s);
+    if (p == nullptr) {
+      log.error("failed: allocate memory for `monotonic_buffer_resource`.", 
+                " bytes = ", bytes, ", alignment = ", alignment);
+      return nullptr;
+    }
+    tail_ = static_cast<ipc::byte *>(p) + s;
+  }
+  head_ = static_cast<ipc::byte *>(p) + bytes;
+  return p;
+}
+
+void monotonic_buffer_resource::deallocate(void *p, std::size_t bytes, std::size_t alignment) noexcept {
+  static_cast<void>(p);
+  static_cast<void>(bytes);
+  static_cast<void>(alignment);
+  // Do nothing.
+}
+
+} // namespace mem
+} // namespace ipc
diff --git a/src/libipc/mem/new.cpp b/src/libipc/mem/new.cpp
new file mode 100644
index 00000000..a8f6e2e1
--- /dev/null
+++ b/src/libipc/mem/new.cpp
@@ -0,0 +1,121 @@
+
+#include "libipc/mem/new.h"
+
+namespace ipc {
+namespace mem {
+
+/// \brief Select the incremental level based on the size.
+constexpr inline std::size_t regular_level(std::size_t s) noexcept {
+  return (s <= 128  ) ? 0 :
+         (s <= 1024 ) ? 1 :
+         (s <= 8192 ) ? 2 :
+         (s <= 65536) ? 3 : 4;
+}
+
+/// \brief Use block pools to handle memory less than 64K.
+template <std::size_t BlockSize, std::size_t BlockPoolExpansion>
+class block_resource_base : public block_pool<BlockSize, BlockPoolExpansion>
+                          , public block_collector {
+public:
+  void *allocate(std::size_t /*bytes*/) noexcept override {
+    return block_pool<BlockSize, BlockPoolExpansion>::allocate();
+  }
+
+  void deallocate(void *p, std::size_t /*bytes*/) noexcept override {
+    block_pool<BlockSize, BlockPoolExpansion>::deallocate(p);
+  }
+};
+
+/// \brief Use `new`/`delete` to handle memory larger than 64K.
+template <>
+class block_resource_base<0, 0> : public new_delete_resource
+                                , public block_collector {
+public:
+  void *allocate(std::size_t bytes) noexcept override {
+    return new_delete_resource::allocate(bytes);
+  }
+
+  void deallocate(void *p, std::size_t bytes) noexcept override {
+    new_delete_resource::deallocate(p, bytes);
+  }
+};
+
+/// \brief Defines block pool memory resource based on block pool.
+template <std::size_t BlockSize, std::size_t BlockPoolExpansion>
+class block_pool_resource : public block_resource_base<BlockSize, BlockPoolExpansion> {
+public:
+  static block_collector &get() noexcept {
+    thread_local block_pool_resource instance;
+    return instance;
+  }
+};
+
+/// \brief Matches the appropriate memory block resource based on a specified size.
+block_collector &get_regular_resource(std::size_t s) noexcept {
+  std::size_t l = regular_level(s);
+  switch (l) {
+  case 0:
+    switch (round_up<std::size_t>(s, 16)) {
+    case 16 : return block_pool_resource<16 , 512>::get();
+    case 32 : return block_pool_resource<32 , 512>::get();
+    case 48 : return block_pool_resource<48 , 512>::get();
+    case 64 : return block_pool_resource<64 , 512>::get();
+    case 80 : return block_pool_resource<80 , 512>::get();
+    case 96 : return block_pool_resource<96 , 512>::get();
+    case 112: return block_pool_resource<112, 512>::get();
+    case 128: return block_pool_resource<128, 512>::get();
+    default : break;
+    }
+    break;
+  case 1:
+    switch (round_up<std::size_t>(s, 128)) {
+    case 256 : return block_pool_resource<256 , 256>::get();
+    case 384 : return block_pool_resource<384 , 256>::get();
+    case 512 : return block_pool_resource<512 , 256>::get();
+    case 640 : return block_pool_resource<640 , 256>::get();
+    case 768 : return block_pool_resource<768 , 256>::get();
+    case 896 : return block_pool_resource<896 , 256>::get();
+    case 1024: return block_pool_resource<1024, 256>::get();
+    default  : break;
+    }
+    break;
+  case 2:
+    switch (round_up<std::size_t>(s, 1024)) {
+    case 2048: return block_pool_resource<2048, 128>::get();
+    case 3072: return block_pool_resource<3072, 128>::get();
+    case 4096: return block_pool_resource<4096, 128>::get();
+    case 5120: return block_pool_resource<5120, 128>::get();
+    case 6144: return block_pool_resource<6144, 128>::get();
+    case 7168: return block_pool_resource<7168, 128>::get();
+    case 8192: return block_pool_resource<8192, 128>::get();
+    default  : break;
+    }
+    break;
+  case 3:
+    switch (round_up<std::size_t>(s, 8192)) {
+    case 16384: return block_pool_resource<16384, 64>::get();
+    case 24576: return block_pool_resource<24576, 64>::get();
+    case 32768: return block_pool_resource<32768, 64>::get();
+    case 40960: return block_pool_resource<40960, 64>::get();
+    case 49152: return block_pool_resource<49152, 64>::get();
+    case 57344: return block_pool_resource<57344, 64>::get();
+    case 65536: return block_pool_resource<65536, 64>::get();
+    default   : break;
+    }
+    break;
+  default:
+    break;
+  }
+  return block_pool_resource<0, 0>::get();
+}
+
+void *alloc(std::size_t bytes) noexcept {
+  return get_regular_resource(bytes).allocate(bytes);
+}
+
+void free(void *p, std::size_t bytes) noexcept {
+  return get_regular_resource(bytes).deallocate(p, bytes);
+}
+
+} // namespace mem
+} // namespace ipc
diff --git a/src/libipc/mem/new_delete_resource.cpp b/src/libipc/mem/new_delete_resource.cpp
new file mode 100644
index 00000000..b2d270cb
--- /dev/null
+++ b/src/libipc/mem/new_delete_resource.cpp
@@ -0,0 +1,101 @@
+
+#include <cstdlib>  // std::aligned_alloc
+
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/aligned.h"
+#include "libipc/imp/system.h"
+#include "libipc/imp/log.h"
+#include "libipc/mem/memory_resource.h"
+#include "libipc/mem/verify_args.h"
+
+namespace ipc {
+namespace mem {
+
+/**
+ * \brief Returns a pointer to a new_delete_resource.
+ * 
+ * \return new_delete_resource* 
+ */
+new_delete_resource *new_delete_resource::get() noexcept {
+  static new_delete_resource mem_res;
+  return &mem_res;
+}
+
+/**
+ * \brief Allocates storage with a size of at least bytes bytes, aligned to the specified alignment.
+ * Alignment shall be a power of two.
+ * 
+ * \see https://en.cppreference.com/w/cpp/memory/memory_resource/do_allocate
+ *      https://www.cppstories.com/2019/08/newnew-align/
+ * 
+ * \return void * - nullptr if storage of the requested size and alignment cannot be obtained.
+ */
+void *new_delete_resource::allocate(std::size_t bytes, std::size_t alignment) noexcept {
+  LIBIPC_LOG();
+  if (!verify_args(bytes, alignment)) {
+    log.error("invalid bytes = ", bytes, ", alignment = ", alignment);
+    return nullptr;
+  }
+#if defined(LIBIPC_CPP_17)
+  /// \see https://en.cppreference.com/w/cpp/memory/c/aligned_alloc
+  /// \remark The size parameter must be an integral multiple of alignment.
+  return std::aligned_alloc(alignment, ipc::round_up(bytes, alignment));
+#else
+  if (alignment <= alignof(std::max_align_t)) {
+    /// \see https://en.cppreference.com/w/cpp/memory/c/malloc
+    return std::malloc(bytes);
+  }
+#if defined(LIBIPC_OS_WIN)
+  /// \see https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/aligned-malloc
+  return ::_aligned_malloc(bytes, alignment);
+#else // try posix
+  /// \see https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_memalign.html
+  void *p = nullptr;
+  int ret = ::posix_memalign(&p, alignment, bytes);
+  if (ret != 0) {
+    log.error("failed: posix_memalign(alignment = ", alignment, 
+                                       ", bytes = ", bytes, 
+                                      "). error = ", sys::error(ret));
+    return nullptr;
+  }
+  return p;
+#endif
+#endif // defined(LIBIPC_CPP_17)
+}
+
+/**
+ * \brief Deallocates the storage pointed to by p.
+ * The storage it points to must not yet have been deallocated, otherwise the behavior is undefined.
+ * 
+ * \see https://en.cppreference.com/w/cpp/memory/memory_resource/do_deallocate
+ * 
+ * \param p must have been returned by a prior call to new_delete_resource::do_allocate(bytes, alignment).
+ */
+void new_delete_resource::deallocate(void *p, std::size_t bytes, std::size_t alignment) noexcept {
+  LIBIPC_LOG();
+  if (p == nullptr) {
+    return;
+  }
+  if (!verify_args(bytes, alignment)) {
+    log.error("invalid bytes = ", bytes, ", alignment = ", alignment);
+    return;
+  }
+#if defined(LIBIPC_CPP_17)
+  /// \see https://en.cppreference.com/w/cpp/memory/c/free
+  std::free(p);
+#else
+  if (alignment <= alignof(std::max_align_t)) {
+    std::free(p);
+    return;
+  }
+#if defined(LIBIPC_OS_WIN)
+  /// \see https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/aligned-free
+  ::_aligned_free(p);
+#else // try posix
+  ::free(p);
+#endif
+#endif // defined(LIBIPC_CPP_17)
+}
+
+} // namespace mem
+} // namespace ipc
diff --git a/src/libipc/mem/resource.h b/src/libipc/mem/resource.h
new file mode 100755
index 00000000..cc59a33a
--- /dev/null
+++ b/src/libipc/mem/resource.h
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <unordered_map>
+#include <map>
+#include <string>
+
+#include "libipc/def.h"
+#include "libipc/imp/fmt.h"
+#include "libipc/mem/container_allocator.h"
+
+namespace ipc {
+
+template <typename Key, typename T>
+using unordered_map = std::unordered_map<
+  Key, T, std::hash<Key>, std::equal_to<Key>, ipc::mem::container_allocator<std::pair<Key const, T>>
+>;
+
+template <typename Key, typename T>
+using map = std::map<
+  Key, T, std::less<Key>, ipc::mem::container_allocator<std::pair<Key const, T>>
+>;
+
+/// \brief Check string validity.
+constexpr bool is_valid_string(char const *str) noexcept {
+  return (str != nullptr) && (str[0] != '\0');
+}
+
+/// \brief Make a valid string.
+inline std::string make_string(char const *str) {
+  return is_valid_string(str) ? std::string{str} : std::string{};
+}
+
+/// \brief Combine prefix from a list of strings.
+template <typename A1, typename... A>
+inline std::string make_prefix(A1 &&prefix, A &&...args) {
+  return ipc::fmt(std::forward<A1>(prefix), "__IPC_SHM__", std::forward<A>(args)...);
+}
+
+} // namespace ipc
diff --git a/src/libipc/mem/verify_args.h b/src/libipc/mem/verify_args.h
new file mode 100644
index 00000000..a818bb52
--- /dev/null
+++ b/src/libipc/mem/verify_args.h
@@ -0,0 +1,16 @@
+#pragma once
+
+#include <cstddef>
+
+namespace ipc {
+namespace mem {
+
+/**
+ * \brief Check that bytes is not 0 and that the alignment is a power of two.
+ */
+inline constexpr bool verify_args(std::size_t bytes, std::size_t alignment) noexcept {
+  return (bytes > 0) && (alignment > 0) && ((alignment & (alignment - 1)) == 0);
+}
+
+} // namespace mem
+} // namespace ipc
diff --git a/src/libipc/memory/alloc.h b/src/libipc/memory/alloc.h
deleted file mode 100755
index 3a4ce201..00000000
--- a/src/libipc/memory/alloc.h
+++ /dev/null
@@ -1,424 +0,0 @@
-#pragma once
-
-#include <algorithm>
-#include <utility>
-#include <iterator>
-#include <limits>       // std::numeric_limits
-#include <cstdlib>
-#include <cassert>      // assert
-
-#include "libipc/def.h"
-#include "libipc/rw_lock.h"
-
-#include "libipc/utility/concept.h"
-#include "libipc/memory/allocator_wrapper.h"
-#include "libipc/platform/detail.h"
-
-namespace ipc {
-namespace mem {
-
-class static_alloc {
-public:
-    static void swap(static_alloc&) noexcept {}
-
-    static void* alloc(std::size_t size) noexcept {
-        return size ? std::malloc(size) : nullptr;
-    }
-
-    static void free(void* p) noexcept {
-        std::free(p);
-    }
-
-    static void free(void* p, std::size_t /*size*/) noexcept {
-        free(p);
-    }
-};
-
-////////////////////////////////////////////////////////////////
-/// Scope allocation -- The destructor will release all allocated blocks.
-////////////////////////////////////////////////////////////////
-
-namespace detail {
-
-constexpr std::size_t aligned(std::size_t size, size_t alignment) noexcept {
-    return ( (size - 1) & ~(alignment - 1) ) + alignment;
-}
-
-IPC_CONCEPT_(has_take, take(std::move(std::declval<Type>())));
-
-class scope_alloc_base {
-protected:
-    struct block_t {
-        std::size_t size_;
-        block_t   * next_;
-    } * head_ = nullptr, * tail_ = nullptr;
-
-    enum : std::size_t {
-        aligned_block_size = aligned(sizeof(block_t), alignof(std::max_align_t))
-    };
-
-public:
-    void swap(scope_alloc_base & rhs) {
-        std::swap(head_, rhs.head_);
-        std::swap(tail_, rhs.tail_);
-    }
-
-    bool empty() const noexcept {
-        return head_ == nullptr;
-    }
-
-    void take(scope_alloc_base && rhs) {
-        if (rhs.empty()) return;
-        if (empty()) swap(rhs);
-        else {
-            std::swap(tail_->next_, rhs.head_);
-            // rhs.head_ should be nullptr here
-            tail_ = rhs.tail_;
-            rhs.tail_ = nullptr;
-        }
-    }
-
-    void free(void* /*p*/) {}
-    void free(void* /*p*/, std::size_t) {}
-};
-
-} // namespace detail
-
-template <typename AllocP = static_alloc>
-class scope_alloc : public detail::scope_alloc_base {
-public:
-    using base_t = detail::scope_alloc_base;
-    using alloc_policy = AllocP;
-
-private:
-    alloc_policy alloc_;
-
-    void free_all() {
-        while (!empty()) {
-            auto curr = head_;
-            head_ = head_->next_;
-            alloc_.free(curr, curr->size_);
-        }
-        // now head_ is nullptr
-    }
-
-public:
-    scope_alloc() = default;
-
-    scope_alloc(scope_alloc && rhs)         { swap(rhs); }
-    scope_alloc& operator=(scope_alloc rhs) { swap(rhs); return (*this); }
-
-    ~scope_alloc() { free_all(); }
-
-    void swap(scope_alloc& rhs) {
-        alloc_.swap(rhs.alloc_);
-        base_t::swap(rhs);
-    }
-
-    template <typename A = AllocP>
-    auto take(scope_alloc && rhs) -> ipc::require<detail::has_take<A>::value> {
-        base_t::take(std::move(rhs));
-        alloc_.take(std::move(rhs.alloc_));
-    }
-
-    template <typename A = AllocP>
-    auto take(scope_alloc && rhs) -> ipc::require<!detail::has_take<A>::value> {
-        base_t::take(std::move(rhs));
-    }
-
-    void* alloc(std::size_t size) {
-        std::size_t real_size = aligned_block_size + size;
-        auto curr = static_cast<block_t*>(alloc_.alloc(real_size));
-        curr->size_ = real_size;
-        curr->next_ = head_;
-        head_ = curr;
-        if (tail_ == nullptr) {
-            tail_ = curr;
-        }
-        return (reinterpret_cast<byte_t*>(curr) + aligned_block_size);
-    }
-};
-
-////////////////////////////////////////////////////////////////
-/// Fixed-size blocks allocation
-////////////////////////////////////////////////////////////////
-
-namespace detail {
-
-class fixed_alloc_base {
-protected:
-    std::size_t block_size_;
-    std::size_t init_expand_;
-    void      * cursor_;
-
-    void init(std::size_t block_size, std::size_t init_expand) {
-        block_size_  = block_size;
-        init_expand_ = init_expand;
-        cursor_      = nullptr;
-    }
-
-    static void** node_p(void* node) {
-        return reinterpret_cast<void**>(node);
-    }
-
-    static auto& next(void* node) {
-        return *node_p(node);
-    }
-
-public:
-    bool operator<(fixed_alloc_base const & right) const {
-        return init_expand_ < right.init_expand_;
-    }
-
-    void set_block_size(std::size_t block_size) {
-        block_size_ = block_size;
-    }
-
-    void swap(fixed_alloc_base& rhs) {
-        std::swap(block_size_ , rhs.block_size_);
-        std::swap(init_expand_, rhs.init_expand_);
-        std::swap(cursor_     , rhs.cursor_);
-    }
-
-    bool empty() const noexcept {
-        return cursor_ == nullptr;
-    }
-
-    void take(fixed_alloc_base && rhs) {
-        assert(block_size_ == rhs.block_size_);
-        init_expand_ = (ipc::detail::max)(init_expand_, rhs.init_expand_);
-        if (rhs.empty()) return;
-        auto curr = cursor_;
-        if (curr != nullptr) while (1) {
-            auto next_cur = next(curr);
-            if (next_cur == nullptr) {
-                std::swap(next(curr), rhs.cursor_);
-                return;
-            }
-            // next_cur != nullptr
-            else curr = next_cur;
-        }
-        // curr == nullptr, means cursor_ == nullptr
-        else std::swap(cursor_, rhs.cursor_);
-        // rhs.cursor_ must be nullptr
-    }
-
-    void free(void* p) {
-        if (p == nullptr) return;
-        next(p) = cursor_;
-        cursor_ = p;
-    }
-
-    void free(void* p, std::size_t) {
-        free(p);
-    }
-};
-
-template <typename AllocP, typename ExpandP>
-class fixed_alloc : public detail::fixed_alloc_base {
-public:
-    using base_t = detail::fixed_alloc_base;
-    using alloc_policy = AllocP;
-
-private:
-    alloc_policy alloc_;
-
-    void* try_expand() {
-        if (empty()) {
-            auto size = ExpandP::next(block_size_, init_expand_);
-            auto p = node_p(cursor_ = alloc_.alloc(size));
-            for (std::size_t i = 0; i < (size / block_size_) - 1; ++i)
-                p = node_p((*p) = reinterpret_cast<byte_t*>(p) + block_size_);
-            (*p) = nullptr;
-        }
-        return cursor_;
-    }
-
-public:
-    explicit fixed_alloc(std::size_t block_size, std::size_t init_expand = 1) {
-        init(block_size, init_expand);
-    }
-
-    fixed_alloc(fixed_alloc && rhs) {
-        init(0, 0);
-        swap(rhs);
-    }
-
-    fixed_alloc& operator=(fixed_alloc rhs) {
-        swap(rhs);
-        return (*this);
-    }
-
-    void swap(fixed_alloc& rhs) {
-        alloc_.swap(rhs.alloc_);
-        base_t::swap(rhs);
-    }
-
-    template <typename A = AllocP>
-    auto take(fixed_alloc && rhs) -> ipc::require<detail::has_take<A>::value> {
-        base_t::take(std::move(rhs));
-        alloc_.take(std::move(rhs.alloc_));
-    }
-
-    void* alloc() {
-        void* p = try_expand();
-        cursor_ = next(p);
-        return p;
-    }
-
-    void* alloc(std::size_t) {
-        return alloc();
-    }
-};
-
-} // namespace detail
-
-template <std::size_t BaseSize  = sizeof(void*) * 1024, 
-          std::size_t LimitSize = (std::numeric_limits<std::uint32_t>::max)()>
-struct fixed_expand_policy {
-
-    enum : std::size_t {
-        base_size  = BaseSize,
-        limit_size = LimitSize
-    };
-
-    constexpr static std::size_t prev(std::size_t e) noexcept {
-        return ((e / 2) == 0) ? 1 : (e / 2);
-    }
-
-    constexpr static std::size_t next(std::size_t e) noexcept {
-        return e * 2;
-    }
-
-    static std::size_t next(std::size_t block_size, std::size_t & e) {
-        auto n = ipc::detail::max<std::size_t>(block_size, base_size) * e;
-             e = ipc::detail::min<std::size_t>(limit_size, next(e));
-        return n;
-    }
-};
-
-template <std::size_t BlockSize,
-          typename AllocP  = scope_alloc<>,
-          typename ExpandP = fixed_expand_policy<>>
-class fixed_alloc : public detail::fixed_alloc<AllocP, ExpandP> {
-public:
-    using base_t = detail::fixed_alloc<AllocP, ExpandP>;
-
-    enum : std::size_t {
-        block_size = ipc::detail::max<std::size_t>(BlockSize, sizeof(void*))
-    };
-
-public:
-    explicit fixed_alloc(std::size_t init_expand)
-        : base_t(block_size, init_expand) {
-    }
-
-    fixed_alloc() : fixed_alloc(1) {}
-
-    fixed_alloc(fixed_alloc && rhs)
-        : base_t(std::move(rhs)) {
-    }
-
-    fixed_alloc& operator=(fixed_alloc rhs) {
-        swap(rhs);
-        return (*this);
-    }
-
-    void swap(fixed_alloc& rhs) {
-        base_t::swap(rhs);
-    }
-};
-
-////////////////////////////////////////////////////////////////
-/// Variable-size blocks allocation (without alignment)
-////////////////////////////////////////////////////////////////
-
-namespace detail {
-
-class variable_alloc_base {
-protected:
-    byte_t * head_ = nullptr, * tail_ = nullptr;
-
-public:
-    void swap(variable_alloc_base & rhs) {
-        std::swap(head_, rhs.head_);
-        std::swap(tail_, rhs.tail_);
-    }
-
-    std::size_t remain() const noexcept {
-        return static_cast<std::size_t>(tail_ - head_);
-    }
-
-    bool empty() const noexcept {
-        return remain() == 0;
-    }
-
-    void take(variable_alloc_base && rhs) {
-        if (remain() < rhs.remain()) {
-            // replace this by rhs
-            head_ = rhs.head_;
-            tail_ = rhs.tail_;
-        }
-        // discard rhs
-        rhs.head_ = rhs.tail_ = nullptr;
-    }
-
-    void free(void* /*p*/) {}
-    void free(void* /*p*/, std::size_t) {}
-};
-
-} // namespace detail
-
-template <std::size_t ChunkSize = (sizeof(void*) * 1024), typename AllocP = scope_alloc<>>
-class variable_alloc : public detail::variable_alloc_base {
-public:
-    using base_t       = detail::variable_alloc_base;
-    using alloc_policy = AllocP;
-
-    enum : std::size_t {
-        aligned_chunk_size = detail::aligned(ChunkSize, alignof(std::max_align_t))
-    };
-
-private:
-    alloc_policy alloc_;
-
-public:
-    variable_alloc() = default;
-
-    variable_alloc(variable_alloc && rhs)         { swap(rhs); }
-    variable_alloc& operator=(variable_alloc rhs) { swap(rhs); return (*this); }
-
-    void swap(variable_alloc& rhs) {
-        alloc_.swap(rhs.alloc_);
-        base_t::swap(rhs);
-    }
-
-    template <typename A = AllocP>
-    auto take(variable_alloc && rhs) -> ipc::require<detail::has_take<A>::value> {
-        base_t::take(std::move(rhs));
-        alloc_.take(std::move(rhs.alloc_));
-    }
-
-    void* alloc(std::size_t size) {
-        /*
-         * byte alignment is always alignof(std::max_align_t).
-        */
-        size = detail::aligned(size, alignof(std::max_align_t));
-        void* ptr;
-        // size would never be 0 here
-        if (remain() < size) {
-            std::size_t chunk_size = ipc::detail::max<std::size_t>(aligned_chunk_size, size);
-            ptr   = alloc_.alloc(chunk_size);
-            tail_ = static_cast<byte_t*>(ptr) + chunk_size;
-            head_ = tail_ - (chunk_size - size);
-        }
-        else {
-            ptr   = head_;
-            head_ += size;
-        }
-        return ptr;
-    }
-};
-
-} // namespace mem
-} // namespace ipc
diff --git a/src/libipc/memory/allocator_wrapper.h b/src/libipc/memory/allocator_wrapper.h
deleted file mode 100755
index d1c3ea36..00000000
--- a/src/libipc/memory/allocator_wrapper.h
+++ /dev/null
@@ -1,121 +0,0 @@
-#pragma once
-
-#include <limits>   // std::numeric_limits
-#include <utility>  // std::forward
-#include <cstddef>
-
-#include "libipc/pool_alloc.h"
-
-namespace ipc {
-namespace mem {
-
-////////////////////////////////////////////////////////////////
-/// The allocator wrapper class for STL
-////////////////////////////////////////////////////////////////
-
-namespace detail {
-
-template <typename T, typename AllocP>
-struct rebind {
-    template <typename U>
-    using alloc_t = AllocP;
-};
-
-template <typename T, template <typename> class AllocT>
-struct rebind<T, AllocT<T>> {
-    template <typename U>
-    using alloc_t = AllocT<U>;
-};
-
-} // namespace detail
-
-template <typename T, typename AllocP>
-class allocator_wrapper {
-
-    template <typename U, typename AllocU>
-    friend class allocator_wrapper;
-
-public:
-    // type definitions
-    typedef T                 value_type;
-    typedef value_type*       pointer;
-    typedef const value_type* const_pointer;
-    typedef value_type&       reference;
-    typedef const value_type& const_reference;
-    typedef std::size_t       size_type;
-    typedef std::ptrdiff_t    difference_type;
-    typedef AllocP            alloc_policy;
-
-private:
-    alloc_policy alloc_;
-
-public:
-    allocator_wrapper() noexcept {}
-
-    // construct by copying (do nothing)
-    allocator_wrapper           (const allocator_wrapper<T, AllocP>&) noexcept {}
-    allocator_wrapper& operator=(const allocator_wrapper<T, AllocP>&) noexcept { return *this; }
-	
-    // construct from a related allocator (do nothing)
-    template <typename U, typename AllocU> allocator_wrapper           (const allocator_wrapper<U, AllocU>&) noexcept {}
-    template <typename U, typename AllocU> allocator_wrapper& operator=(const allocator_wrapper<U, AllocU>&) noexcept { return *this; }
-
-    allocator_wrapper           (allocator_wrapper && rhs) noexcept : alloc_ ( std::move(rhs.alloc_) ) {}
-    allocator_wrapper& operator=(allocator_wrapper && rhs) noexcept { alloc_ = std::move(rhs.alloc_); return *this; }
-
-public:
-    // the other type of std_allocator
-    template <typename U>
-    struct rebind { 
-        using other = allocator_wrapper< U, typename detail::rebind<T, AllocP>::template alloc_t<U> >;
-    };
-
-    constexpr size_type max_size(void) const noexcept {
-        return (std::numeric_limits<size_type>::max)() / sizeof(value_type);
-    }
-
-public:
-    pointer allocate(size_type count) noexcept {
-        if (count == 0) return nullptr;
-        if (count > this->max_size()) return nullptr;
-        return static_cast<pointer>(alloc_.alloc(count * sizeof(value_type)));
-    }
-
-    void deallocate(pointer p, size_type count) noexcept {
-        alloc_.free(p, count * sizeof(value_type));
-    }
-
-    template <typename... P>
-    static void construct(pointer p, P && ... params) {
-        ipc::mem::construct(p, std::forward<P>(params)...);
-    }
-
-    static void destroy(pointer p) {
-        ipc::mem::destruct(p);
-    }
-};
-
-template <class AllocP>
-class allocator_wrapper<void, AllocP> {
-public:
-    // type definitions
-    typedef void              value_type;
-    typedef value_type*       pointer;
-    typedef const value_type* const_pointer;
-    typedef std::size_t       size_type;
-    typedef std::ptrdiff_t    difference_type;
-    typedef AllocP            alloc_policy;
-};
-
-template <typename T, typename U, class AllocP>
-constexpr bool operator==(const allocator_wrapper<T, AllocP>&, const allocator_wrapper<U, AllocP>&) noexcept {
-    return true;
-}
-
-template <typename T, typename U, class AllocP>
-constexpr bool operator!=(const allocator_wrapper<T, AllocP>&, const allocator_wrapper<U, AllocP>&) noexcept {
-    return false;
-}
-
-} // namespace mem
-} // namespace ipc
diff --git a/src/libipc/memory/resource.h b/src/libipc/memory/resource.h
deleted file mode 100755
index cb50c92c..00000000
--- a/src/libipc/memory/resource.h
+++ /dev/null
@@ -1,110 +0,0 @@
-#pragma once
-
-#include <type_traits>
-#include <limits>
-#include <utility>
-#include <functional>
-#include <unordered_map>
-#include <map>
-#include <string>
-#include <cstdio>
-
-#include "libipc/def.h"
-
-#include "libipc/memory/alloc.h"
-#include "libipc/memory/wrapper.h"
-#include "libipc/platform/detail.h"
-
-namespace ipc {
-namespace mem {
-
-//using async_pool_alloc = static_wrapper<variable_wrapper<async_wrapper<
-//    detail::fixed_alloc<
-//        variable_alloc                           <sizeof(void*) * 1024 * 256>, 
-//        fixed_expand_policy<sizeof(void*) * 1024, sizeof(void*) * 1024 * 256>
-//    >, 
-//    default_recycler >>>;
-using async_pool_alloc = ipc::mem::static_alloc;
-
-template <typename T>
-using allocator = allocator_wrapper<T, async_pool_alloc>;
-
-} // namespace mem
-
-namespace {
-
-constexpr char const * pf(int)                { return "%d"  ; }
-constexpr char const * pf(long)               { return "%ld" ; }
-constexpr char const * pf(long long)          { return "%lld"; }
-constexpr char const * pf(unsigned int)       { return "%u"  ; }
-constexpr char const * pf(unsigned long)      { return "%lu" ; }
-constexpr char const * pf(unsigned long long) { return "%llu"; }
-constexpr char const * pf(float)              { return "%f"  ; }
-constexpr char const * pf(double)             { return "%f"  ; }
-constexpr char const * pf(long double)        { return "%Lf" ; }
-
-} // internal-linkage
-
-template <typename T>
-struct hash : public std::hash<T> {};
-
-template <typename Key, typename T>
-using unordered_map = std::unordered_map<
-    Key, T, ipc::hash<Key>, std::equal_to<Key>, ipc::mem::allocator<std::pair<Key const, T>>
->;
-
-template <typename Key, typename T>
-using map = std::map<
-    Key, T, std::less<Key>, ipc::mem::allocator<std::pair<Key const, T>>
->;
-
-template <typename Char>
-using basic_string = std::basic_string<
-    Char, std::char_traits<Char>, ipc::mem::allocator<Char>
->;
-
-using string  = basic_string<char>;
-using wstring = basic_string<wchar_t>;
-
-template <> struct hash<string> {
-    std::size_t operator()(string const &val) const noexcept {
-        return std::hash<char const *>{}(val.c_str());
-    }
-};
-
-template <> struct hash<wstring> {
-    std::size_t operator()(wstring const &val) const noexcept {
-        return std::hash<wchar_t const *>{}(val.c_str());
-    }
-};
-
-template <typename T>
-ipc::string to_string(T val) {
-    char buf[std::numeric_limits<T>::digits10 + 1] {};
-    if (std::snprintf(buf, sizeof(buf), pf(val), val) > 0) {
-        return buf;
-    }
-    return {};
-}
-
-/// \brief Check string validity.
-constexpr bool is_valid_string(char const *str) noexcept {
-    return (str != nullptr) && (str[0] != '\0');
-}
-
-/// \brief Make a valid string.
-inline ipc::string make_string(char const *str) {
-    return is_valid_string(str) ? ipc::string{str} : ipc::string{};
-}
-
-/// \brief Combine prefix from a list of strings.
-inline ipc::string make_prefix(ipc::string prefix, std::initializer_list<ipc::string> args) {
-    prefix += "__IPC_SHM__";
-    for (auto const &txt: args) {
-        if (txt.empty()) continue;
-        prefix += txt;
-    }
-    return prefix;
-}
-
-} // namespace ipc
diff --git a/src/libipc/memory/wrapper.h b/src/libipc/memory/wrapper.h
deleted file mode 100755
index b0b7c588..00000000
--- a/src/libipc/memory/wrapper.h
+++ /dev/null
@@ -1,327 +0,0 @@
-#pragma once
-
-#include <tuple>
-#include <thread>
-#include <deque>        // std::deque
-#include <functional>   // std::function
-#include <utility>      // std::forward
-#include <cstddef>
-#include <cassert>      // assert
-#include <type_traits>  // std::aligned_storage_t
-
-#include "libipc/def.h"
-#include "libipc/rw_lock.h"
-#include "libipc/pool_alloc.h"
-
-#include "libipc/utility/concept.h"
-#include "libipc/memory/alloc.h"
-#include "libipc/platform/detail.h"
-
-namespace ipc {
-namespace mem {
-
-////////////////////////////////////////////////////////////////
-/// Thread-safe allocation wrapper
-////////////////////////////////////////////////////////////////
-
-namespace detail {
-
-IPC_CONCEPT_(is_comparable, operator<(std::declval<Type>()));
-
-} // namespace detail
-
-template <typename AllocP, bool = detail::is_comparable<AllocP>::value>
-class limited_recycler;
-
-template <typename AllocP>
-class limited_recycler<AllocP, true> {
-public:
-    using alloc_policy = AllocP;
-
-protected:
-    std::deque<alloc_policy> master_allocs_;
-    ipc::spin_lock master_lock_;
-
-    template <typename F>
-    void take_first_do(F && pred) {
-        auto it = master_allocs_.begin();
-        pred(const_cast<alloc_policy&>(*it));
-        master_allocs_.erase(it);
-    }
-
-public:
-    void try_recover(alloc_policy & alc) {
-        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(master_lock_);
-        if (master_allocs_.empty()) return;
-        take_first_do([&alc](alloc_policy & first) { alc.swap(first); });
-    }
-
-    void collect(alloc_policy && alc) {
-        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(master_lock_);
-        if (master_allocs_.size() >= 32) {
-            take_first_do([](alloc_policy &) {}); // erase first
-        }
-        master_allocs_.emplace_back(std::move(alc));
-    }
-
-    IPC_CONSTEXPR_ auto try_replenish(alloc_policy&, std::size_t) noexcept {}
-};
-
-template <typename AllocP>
-class default_recycler : public limited_recycler<AllocP> {
-
-    IPC_CONCEPT_(has_remain, remain());
-    IPC_CONCEPT_(has_empty , empty());
-
-    template <typename A>
-    void try_fill(A & alc) {
-        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(this->master_lock_);
-        if (this->master_allocs_.empty()) return;
-        this->take_first_do([&alc](alloc_policy & first) { alc.take(std::move(first)); });
-    }
-
-public:
-    using alloc_policy = typename limited_recycler<AllocP>::alloc_policy;
-
-    template <typename A = AllocP>
-    auto try_replenish(alloc_policy & alc, std::size_t size)
-        -> ipc::require<detail::has_take<A>::value && has_remain<A>::value> {
-        if (alc.remain() >= size) return;
-        this->try_fill(alc);
-    }
-
-    template <typename A = AllocP>
-    auto try_replenish(alloc_policy & alc, std::size_t /*size*/)
-        -> ipc::require<detail::has_take<A>::value && !has_remain<A>::value && has_empty<A>::value> {
-        if (!alc.empty()) return;
-        this->try_fill(alc);
-    }
-
-    template <typename A = AllocP>
-    auto try_replenish(alloc_policy & alc, std::size_t /*size*/)
-        -> ipc::require<!detail::has_take<A>::value && has_empty<A>::value> {
-        if (!alc.empty()) return;
-        this->try_recover(alc);
-    }
-
-    template <typename A = AllocP>
-    IPC_CONSTEXPR_ auto try_replenish(alloc_policy & /*alc*/, std::size_t /*size*/) noexcept
-        -> ipc::require<(!detail::has_take<A>::value || !has_remain<A>::value) && !has_empty<A>::value> {
-        // Do Nothing.
-    }
-};
-
-template <typename AllocP>
-class empty_recycler {
-public:
-    using alloc_policy = AllocP;
-
-    IPC_CONSTEXPR_ void try_recover(alloc_policy&)                noexcept {}
-    IPC_CONSTEXPR_ auto try_replenish(alloc_policy&, std::size_t) noexcept {}
-    IPC_CONSTEXPR_ void collect(alloc_policy&&)                   noexcept {}
-};
-
-template <typename AllocP,
-          template <typename> class RecyclerP = default_recycler>
-class async_wrapper {
-public:
-    using alloc_policy = AllocP;
-
-private:
-    RecyclerP<alloc_policy> recycler_;
-
-    class alloc_proxy : public AllocP {
-        async_wrapper * w_ = nullptr;
-
-    public:
-        alloc_proxy(alloc_proxy && rhs) = default;
-
-        template <typename ... P>
-        alloc_proxy(async_wrapper* w, P && ... pars)
-            : AllocP(std::forward<P>(pars) ...), w_(w) {
-            assert(w_ != nullptr);
-            w_->recycler_.try_recover(*this);
-        }
-
-        ~alloc_proxy() {
-            w_->recycler_.collect(std::move(*this));
-        }
-
-        auto alloc(std::size_t size) {
-            w_->recycler_.try_replenish(*this, size);
-            return AllocP::alloc(size);
-        }
-    };
-
-    friend class alloc_proxy;
-    using ref_t = alloc_proxy&;
-
-    std::function<ref_t()> get_alloc_;
-
-public:
-    template <typename ... P>
-    async_wrapper(P ... pars) {
-        get_alloc_ = [this, pars ...]()->ref_t {
-            thread_local alloc_proxy tls(pars ...);
-            return tls;
-        };
-    }
-
-    void* alloc(std::size_t size) {
-        return get_alloc_().alloc(size);
-    }
-
-    void free(void* p, std::size_t size) {
-        get_alloc_().free(p, size);
-    }
-};
-
-////////////////////////////////////////////////////////////////
-/// Thread-safe allocation wrapper (with spin_lock)
-////////////////////////////////////////////////////////////////
-
-template <typename AllocP, typename MutexT = ipc::spin_lock>
-class sync_wrapper {
-public:
-    using alloc_policy = AllocP;
-    using mutex_type   = MutexT;
-
-private:
-    mutex_type   lock_;
-    alloc_policy alloc_;
-
-public:
-    template <typename ... P>
-    sync_wrapper(P && ... pars)
-        : alloc_(std::forward<P>(pars) ...)
-    {}
-
-    void swap(sync_wrapper& rhs) {
-        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(lock_);
-        alloc_.swap(rhs.alloc_);
-    }
-
-    void* alloc(std::size_t size) {
-        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(lock_);
-        return alloc_.alloc(size);
-    }
-
-    void free(void* p, std::size_t size) {
-        IPC_UNUSED_ auto guard = ipc::detail::unique_lock(lock_);
-        alloc_.free(p, size);
-    }
-};
-
-////////////////////////////////////////////////////////////////
-/// Variable memory allocation wrapper
-////////////////////////////////////////////////////////////////
-
-template <std::size_t BaseSize = 0, std::size_t IterSize = sizeof(void*)>
-struct default_mapping_policy {
-
-    enum : std::size_t {
-        base_size    = BaseSize,
-        iter_size    = IterSize,
-        classes_size = 64
-    };
-
-    template <typename F, typename ... P>
-    IPC_CONSTEXPR_ static void foreach(F && f, P && ... params) {
-        for (std::size_t i = 0; i < classes_size; ++i) {
-            f(i, std::forward<P>(params)...);
-        }
-    }
-
-    IPC_CONSTEXPR_ static std::size_t block_size(std::size_t id) noexcept {
-        return (id < classes_size) ? (base_size + (id + 1) * iter_size) : 0;
-    }
-
-    template <typename F, typename D, typename ... P>
-    IPC_CONSTEXPR_ static auto classify(F && f, D && d, std::size_t size, P && ... params) {
-        std::size_t id = (size - base_size - 1) / iter_size;
-        return (id < classes_size) ? 
-            f(id, size, std::forward<P>(params)...) : 
-            d(size, std::forward<P>(params)...);
-    }
-};
-
-template <typename FixedAlloc,
-          typename DefaultAlloc = mem::static_alloc,
-          typename MappingP     = default_mapping_policy<>>
-class variable_wrapper {
-
-    struct initiator {
-
-        using falc_t = std::aligned_storage_t<sizeof(FixedAlloc), alignof(FixedAlloc)>;
-        falc_t arr_[MappingP::classes_size];
-
-        initiator() {
-            MappingP::foreach([](std::size_t id, falc_t * a) {
-                ipc::mem::construct(&initiator::at(a, id), MappingP::block_size(id));
-            }, arr_);
-        }
-
-        ~initiator() {
-            MappingP::foreach([](std::size_t id, falc_t * a) {
-                ipc::mem::destruct(&initiator::at(a, id));
-            }, arr_);
-        }
-
-        static FixedAlloc & at(falc_t * arr, std::size_t id) noexcept {
-            return reinterpret_cast<FixedAlloc&>(arr[id]);
-        }
-    } init_;
-
-    using falc_t = typename initiator::falc_t;
-
-public:
-    void swap(variable_wrapper & other) {
-        MappingP::foreach([](std::size_t id, falc_t * in, falc_t * ot) {
-            initiator::at(in, id).swap(initiator::at(ot, id));
-        }, init_.arr_, other.init_.arr_);
-    }
-
-    void* alloc(std::size_t size) {
-        return MappingP::classify([](std::size_t id, std::size_t size, falc_t * a) {
-            return initiator::at(a, id).alloc(size);
-        }, [](std::size_t size, falc_t *) {
-            return DefaultAlloc::alloc(size);
-        }, size, init_.arr_);
-    }
-
-    void free(void* p, std::size_t size) {
-        MappingP::classify([](std::size_t id, std::size_t size, void* p, falc_t * a) {
-            initiator::at(a, id).free(p, size);
-        }, [](std::size_t size, void* p, falc_t *) {
-            DefaultAlloc::free(p, size);
-        }, size, p, init_.arr_);
-    }
-};
-
-////////////////////////////////////////////////////////////////
-/// Static allocation wrapper
-////////////////////////////////////////////////////////////////
-
-template <typename AllocP>
-class static_wrapper {
-public:
-    using alloc_policy = AllocP;
-
-    static alloc_policy& instance() {
-        static alloc_policy alloc;
-        return alloc;
-    }
-
-    static void swap(static_wrapper&) {}
-
-    static void* alloc(std::size_t size) {
-        return instance().alloc(size);
-    }
-
-    static void free(void* p, std::size_t size) {
-        instance().free(p, size);
-    }
-};
-
-} // namespace mem
-} // namespace ipc
diff --git a/src/libipc/platform/detail.h b/src/libipc/platform/detail.h
index 4d6a27cf..97b7b296 100755
--- a/src/libipc/platform/detail.h
+++ b/src/libipc/platform/detail.h
@@ -1,20 +1,7 @@
 #ifndef LIBIPC_SRC_PLATFORM_DETAIL_H_
 #define LIBIPC_SRC_PLATFORM_DETAIL_H_
 
-// detect platform
-
-#if defined(WIN64) || defined(_WIN64) || defined(__WIN64__) || \
-    defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__) || \
-    defined(WINCE) || defined(_WIN32_WCE)
-#   define IPC_OS_WINDOWS_
-#elif defined(__linux__) || defined(__linux)
-#   define IPC_OS_LINUX_
-#elif defined(__QNX__)
-#   define IPC_OS_QNX_
-#elif defined(__APPLE__)
-#elif defined(__ANDROID__)
-// TBD
-#endif
+#include "libipc/imp/detect_plat.h"
 
 #if defined(__cplusplus)
 
@@ -27,12 +14,6 @@
 
 // pre-defined
 
-#ifdef IPC_UNUSED_
-#   error "IPC_UNUSED_ has been defined."
-#endif
-#ifdef IPC_FALLTHROUGH_
-#   error "IPC_FALLTHROUGH_ has been defined."
-#endif
 #ifdef IPC_STBIND_
 #   error "IPC_STBIND_ has been defined."
 #endif
@@ -42,23 +23,11 @@
 
 #if __cplusplus >= 201703L
 
-#define IPC_UNUSED_      [[maybe_unused]]
-#define IPC_FALLTHROUGH_ [[fallthrough]]
 #define IPC_STBIND_(A, B, ...) auto [A, B] = __VA_ARGS__
 #define IPC_CONSTEXPR_   constexpr
 
 #else /*__cplusplus < 201703L*/
 
-#if defined(_MSC_VER)
-#   define IPC_UNUSED_ __pragma(warning(suppress: 4100 4101 4189))
-#elif defined(__GNUC__)
-#   define IPC_UNUSED_ __attribute__((__unused__))
-#else
-#   define IPC_UNUSED_
-#endif
-
-#define IPC_FALLTHROUGH_
-
 #define IPC_STBIND_(A, B, ...)       \
     auto tp___ = __VA_ARGS__         \
     auto A     = std::get<0>(tp___); \
diff --git a/src/libipc/platform/gnuc/demangle.h b/src/libipc/platform/gnuc/demangle.h
new file mode 100644
index 00000000..888b6191
--- /dev/null
+++ b/src/libipc/platform/gnuc/demangle.h
@@ -0,0 +1,43 @@
+/**
+ * \file libipc/platform/gnuc/demangle.h
+ * \author mutouyun (orz@orzz.org)
+ */
+#pragma once
+
+#include <cxxabi.h> // abi::__cxa_demangle
+#include <cstdlib>  // std::malloc
+
+#include "libipc/imp/nameof.h"
+#include "libipc/imp/scope_exit.h"
+#include "libipc/imp/detect_plat.h"
+
+namespace ipc {
+
+/**
+ * \brief The conventional way to obtain demangled symbol name.
+ * \see https://www.boost.org/doc/libs/1_80_0/libs/core/doc/html/core/demangle.html
+ * 
+ * \param name the mangled name
+ * \return std::string a human-readable demangled type name
+ */
+std::string demangle(std::string name) noexcept {
+  /// \see https://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-4.3/a01696.html
+  std::size_t sz = name.size() + 1;
+  char *buffer = static_cast<char *>(std::malloc(sz));
+  int status = 0;
+  char *realname = abi::__cxa_demangle(name.data(), buffer, &sz, &status);
+  if (realname == nullptr) {
+    std::free(buffer);
+    return {};
+  }
+  LIBIPC_SCOPE_EXIT(guard) = [realname] {
+    std::free(realname);
+  };
+  LIBIPC_TRY {
+    return std::move(name.assign(realname, sz));
+  } LIBIPC_CATCH(...) {
+    return {};
+  }
+}
+
+} // namespace ipc
diff --git a/src/libipc/platform/linux/mutex.h b/src/libipc/platform/linux/mutex.h
index 8fd84d59..6dd7ca3d 100644
--- a/src/libipc/platform/linux/mutex.h
+++ b/src/libipc/platform/linux/mutex.h
@@ -7,7 +7,7 @@
 
 #include "libipc/platform/detail.h"
 #include "libipc/utility/log.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 #include "libipc/shm.h"
 
 #include "get_wait_time.h"
@@ -108,7 +108,7 @@ class mutex {
             shm_data(init arg)
                 : mtx{}, ref{0} { mtx.open(arg.name); }
         };
-        ipc::map<ipc::string, shm_data> mutex_handles;
+        ipc::map<std::string, shm_data> mutex_handles;
         std::mutex lock;
 
         static curr_prog &get() {
@@ -122,7 +122,7 @@ class mutex {
             return;
         }
         auto &info = curr_prog::get();
-        IPC_UNUSED_ std::lock_guard<std::mutex> guard {info.lock};
+        LIBIPC_UNUSED std::lock_guard<std::mutex> guard {info.lock};
         auto it = info.mutex_handles.find(name);
         if (it == info.mutex_handles.end()) {
             it = info.mutex_handles
@@ -136,10 +136,10 @@ class mutex {
     }
 
     template <typename F>
-    static void release_mutex(ipc::string const &name, F &&clear) {
+    static void release_mutex(std::string const &name, F &&clear) {
         if (name.empty()) return;
         auto &info = curr_prog::get();
-        IPC_UNUSED_ std::lock_guard<std::mutex> guard {info.lock};
+        LIBIPC_UNUSED std::lock_guard<std::mutex> guard {info.lock};
         auto it = info.mutex_handles.find(name);
         if (it == info.mutex_handles.end()) {
             return;
diff --git a/src/libipc/platform/platform.c b/src/libipc/platform/platform.c
index 49cc977b..7b225bc7 100644
--- a/src/libipc/platform/platform.c
+++ b/src/libipc/platform/platform.c
@@ -1,13 +1,13 @@
 
 #include "libipc/platform/detail.h"
-#if defined(IPC_OS_WINDOWS_)
-#elif defined(IPC_OS_LINUX_)
+#if defined(LIBIPC_OS_WIN)
+#elif defined(LIBIPC_OS_LINUX)
 #include "libipc/platform/linux/a0/err.c"
 #include "libipc/platform/linux/a0/mtx.c"
 #include "libipc/platform/linux/a0/strconv.c"
 #include "libipc/platform/linux/a0/tid.c"
 #include "libipc/platform/linux/a0/time.c"
-#elif defined(IPC_OS_QNX_)
+#elif defined(LIBIPC_OS_QNX)
 #else/*IPC_OS*/
 #   error "Unsupported platform."
 #endif
diff --git a/src/libipc/platform/platform.cpp b/src/libipc/platform/platform.cpp
index b77cbc97..0e31553c 100644
--- a/src/libipc/platform/platform.cpp
+++ b/src/libipc/platform/platform.cpp
@@ -1,8 +1,8 @@
 
 #include "libipc/platform/detail.h"
-#if defined(IPC_OS_WINDOWS_)
+#if defined(LIBIPC_OS_WIN)
 #include "libipc/platform/win/shm_win.cpp"
-#elif defined(IPC_OS_LINUX_) || defined(IPC_OS_QNX_)
+#elif defined(LIBIPC_OS_LINUX) || defined(LIBIPC_OS_QNX)
 #include "libipc/platform/posix/shm_posix.cpp"
 #else/*IPC_OS*/
 #   error "Unsupported platform."
diff --git a/src/libipc/platform/posix/condition.h b/src/libipc/platform/posix/condition.h
index 521f9fe9..686ff4ed 100644
--- a/src/libipc/platform/posix/condition.h
+++ b/src/libipc/platform/posix/condition.h
@@ -63,7 +63,7 @@ class condition {
             ipc::error("fail pthread_condattr_init[%d]\n", eno);
             return false;
         }
-        IPC_UNUSED_ auto guard_cond_attr = guard([&cond_attr] { ::pthread_condattr_destroy(&cond_attr); });
+        LIBIPC_UNUSED auto guard_cond_attr = guard([&cond_attr] { ::pthread_condattr_destroy(&cond_attr); });
         if ((eno = ::pthread_condattr_setpshared(&cond_attr, PTHREAD_PROCESS_SHARED)) != 0) {
             ipc::error("fail pthread_condattr_setpshared[%d]\n", eno);
             return false;
diff --git a/src/libipc/platform/posix/mutex.h b/src/libipc/platform/posix/mutex.h
index d84736f0..12679be5 100644
--- a/src/libipc/platform/posix/mutex.h
+++ b/src/libipc/platform/posix/mutex.h
@@ -12,7 +12,7 @@
 #include "libipc/platform/detail.h"
 #include "libipc/utility/log.h"
 #include "libipc/utility/scope_guard.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 #include "libipc/shm.h"
 
 #include "get_wait_time.h"
@@ -38,7 +38,7 @@ class mutex {
             shm_data(init arg)
                 : shm{arg.name, arg.size}, ref{0} {}
         };
-        ipc::map<ipc::string, shm_data> mutex_handles;
+        ipc::map<std::string, shm_data> mutex_handles;
         std::mutex lock;
 
         static curr_prog &get() {
@@ -52,7 +52,7 @@ class mutex {
             return nullptr;
         }
         auto &info = curr_prog::get();
-        IPC_UNUSED_ std::lock_guard<std::mutex> guard {info.lock};
+        LIBIPC_UNUSED std::lock_guard<std::mutex> guard {info.lock};
         auto it = info.mutex_handles.find(name);
         if (it == info.mutex_handles.end()) {
           it = info.mutex_handles
@@ -71,10 +71,10 @@ class mutex {
     }
 
     template <typename F>
-    static void release_mutex(ipc::string const &name, F &&clear) {
+    static void release_mutex(std::string const &name, F &&clear) {
         if (name.empty()) return;
         auto &info = curr_prog::get();
-        IPC_UNUSED_ std::lock_guard<std::mutex> guard {info.lock};
+        LIBIPC_UNUSED std::lock_guard<std::mutex> guard {info.lock};
         auto it = info.mutex_handles.find(name);
         if (it == info.mutex_handles.end()) {
             return;
@@ -130,7 +130,7 @@ class mutex {
             ipc::error("fail pthread_mutexattr_init[%d]\n", eno);
             return false;
         }
-        IPC_UNUSED_ auto guard_mutex_attr = guard([&mutex_attr] { ::pthread_mutexattr_destroy(&mutex_attr); });
+        LIBIPC_UNUSED auto guard_mutex_attr = guard([&mutex_attr] { ::pthread_mutexattr_destroy(&mutex_attr); });
         if ((eno = ::pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED)) != 0) {
             ipc::error("fail pthread_mutexattr_setpshared[%d]\n", eno);
             return false;
diff --git a/src/libipc/platform/posix/shm_posix.cpp b/src/libipc/platform/posix/shm_posix.cpp
index 968a2027..65eb5db1 100644
--- a/src/libipc/platform/posix/shm_posix.cpp
+++ b/src/libipc/platform/posix/shm_posix.cpp
@@ -13,10 +13,10 @@
 
 #include "libipc/shm.h"
 #include "libipc/def.h"
-#include "libipc/pool_alloc.h"
 
 #include "libipc/utility/log.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
+#include "libipc/mem/new.h"
 
 namespace {
 
@@ -28,7 +28,7 @@ struct id_info_t {
     int         fd_   = -1;
     void*       mem_  = nullptr;
     std::size_t size_ = 0;
-    ipc::string name_;
+    std::string name_;
 };
 
 constexpr std::size_t calc_size(std::size_t size) {
@@ -51,7 +51,7 @@ id_t acquire(char const * name, std::size_t size, unsigned mode) {
     }
     // For portable use, a shared memory object should be identified by name of the form /somename.
     // see: https://man7.org/linux/man-pages/man3/shm_open.3.html
-    ipc::string op_name = ipc::string{"/"} + name;
+    std::string op_name = std::string{"/"} + name;
     // Open the object for read-write access.
     int flag = O_RDWR;
     switch (mode) {
@@ -81,7 +81,7 @@ id_t acquire(char const * name, std::size_t size, unsigned mode) {
     ::fchmod(fd, S_IRUSR | S_IWUSR | 
                  S_IRGRP | S_IWGRP | 
                  S_IROTH | S_IWOTH);
-    auto ii = mem::alloc<id_info_t>();
+    auto ii = mem::$new<id_info_t>();
     ii->fd_   = fd;
     ii->size_ = size;
     ii->name_ = std::move(op_name);
@@ -177,7 +177,7 @@ std::int32_t release(id_t id) noexcept {
         }
     }
     else ::munmap(ii->mem_, ii->size_);
-    mem::free(ii);
+    mem::$delete(ii);
     return ret;
 }
 
diff --git a/src/libipc/platform/posix/system.h b/src/libipc/platform/posix/system.h
new file mode 100644
index 00000000..cae48987
--- /dev/null
+++ b/src/libipc/platform/posix/system.h
@@ -0,0 +1,49 @@
+/**
+ * \file libipc/platform/posix/system.h
+ * \author mutouyun (orz@orzz.org)
+ */
+#pragma once
+
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "libipc/imp/system.h"
+#include "libipc/imp/log.h"
+
+namespace ipc {
+namespace sys {
+
+/**
+ * \brief Get the system error number.
+ * \see https://en.cppreference.com/w/cpp/error/generic_category
+ *      https://man7.org/linux/man-pages/man3/errno.3.html
+*/
+std::error_code error() noexcept {
+  return std::error_code(errno, std::generic_category());
+}
+
+/**
+ * \brief Gets configuration information at run time
+ * https://man7.org/linux/man-pages/man2/getpagesize.2.html
+ * https://man7.org/linux/man-pages/man3/sysconf.3.html
+ */
+result<std::int64_t> conf(info r) noexcept {
+  LIBIPC_LOG();
+  switch (r) {
+  case info::page_size: {
+    auto val = ::sysconf(_SC_PAGESIZE);
+    if (val >= 0) return static_cast<std::int64_t>(val);
+    break;
+  }
+  default:
+    log.error("invalid info = ", underlyof(r));
+    return std::make_error_code(std::errc::invalid_argument);
+  }
+  auto err = sys::error();
+  log.error("info = ", underlyof(r), ", error = ", err);
+  return err;
+}
+
+} // namespace sys
+} // namespace ipc
diff --git a/src/libipc/platform/win/codecvt.h b/src/libipc/platform/win/codecvt.h
new file mode 100644
index 00000000..f617cc5f
--- /dev/null
+++ b/src/libipc/platform/win/codecvt.h
@@ -0,0 +1,95 @@
+/**
+ * \file libipc/platform/win/codecvt.h
+ * \author mutouyun (orz@orzz.org)
+ */
+#pragma once
+
+#include <Windows.h>
+
+#include "libipc/imp/codecvt.h"
+#include "libipc/imp/detect_plat.h"
+
+namespace ipc {
+
+/**
+ * \see https://docs.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-multibytetowidechar
+ *      https://docs.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-widechartomultibyte
+ * 
+ *      CP_ACP       : The system default Windows ANSI code page.
+ *      CP_MACCP     : The current system Macintosh code page.
+ *      CP_OEMCP     : The current system OEM code page.
+ *      CP_SYMBOL    : Symbol code page (42).
+ *      CP_THREAD_ACP: The Windows ANSI code page for the current thread.
+ *      CP_UTF7      : UTF-7. Use this value only when forced by a 7-bit transport mechanism. Use of UTF-8 is preferred.
+ *      CP_UTF8      : UTF-8.
+*/
+
+template <>
+std::size_t cvt_cstr(char const *src, std::size_t slen, wchar_t *des, std::size_t dlen) noexcept {
+  if ((src == nullptr) || ((*src) == 0) || (slen == 0)) {
+    // source string is empty
+    return 0;
+  }
+  int cch_wc = (des == nullptr) ? 0 : (int)dlen;
+  int size_needed = ::MultiByteToWideChar(CP_ACP, 0, src, (int)slen, des, cch_wc);
+  if (size_needed <= 0) {
+    // failed: MultiByteToWideChar(CP_ACP).
+    return 0;
+  }
+  return size_needed;
+}
+
+template <>
+std::size_t cvt_cstr(wchar_t const *src, std::size_t slen, char *des, std::size_t dlen) noexcept {
+  if ((src == nullptr) || ((*src) == 0) || (slen == 0)) {
+    // source string is empty
+    return 0;
+  }
+  int cb_mb = (des == nullptr) ? 0 : (int)dlen;
+  int size_needed = ::WideCharToMultiByte(CP_ACP, 0, src, (int)slen, des, cb_mb, NULL, NULL);
+  if (size_needed <= 0) {
+    // failed: WideCharToMultiByte(CP_ACP).
+    return 0;
+  }
+  return size_needed;
+}
+
+/**
+ * \brief Used for char8_t (since C++20) to wchar_t conversion.
+ * 
+ * There is no ut to guarantee correctness (I'm a little lazy here), 
+ * so if there are any bugs, please contact me in time.
+ */
+#if defined(LIBIMP_CPP_20)
+template <>
+std::size_t cvt_cstr(char8_t const *src, std::size_t slen, wchar_t *des, std::size_t dlen) noexcept {
+  if ((src == nullptr) || ((*src) == 0) || (slen == 0)) {
+    // source string is empty
+    return 0;
+  }
+  int cch_wc = (des == nullptr) ? 0 : (int)dlen;
+  int size_needed = ::MultiByteToWideChar(CP_UTF8, 0, (char *)src, (int)slen, des, cch_wc);
+  if (size_needed <= 0) {
+    // failed: MultiByteToWideChar(CP_UTF8).
+    return 0;
+  }
+  return size_needed;
+}
+
+template <>
+std::size_t cvt_cstr(wchar_t const *src, std::size_t slen, char8_t *des, std::size_t dlen) noexcept {
+  if ((src == nullptr) || ((*src) == 0) || (slen == 0)) {
+    // source string is empty
+    return 0;
+  }
+  int cb_mb = (des == nullptr) ? 0 : (int)dlen;
+  int size_needed = ::WideCharToMultiByte(CP_UTF8, 0, src, (int)slen, (char *)des, cb_mb, NULL, NULL);
+  if (size_needed <= 0) {
+    // failed: WideCharToMultiByte(CP_UTF8).
+    return 0;
+  }
+  return size_needed;
+}
+#endif // defined(LIBIMP_CPP_20)
+
+} // namespace ipc
diff --git a/src/libipc/platform/win/condition.h b/src/libipc/platform/win/condition.h
index 9c89633e..43dc1123 100644
--- a/src/libipc/platform/win/condition.h
+++ b/src/libipc/platform/win/condition.h
@@ -81,7 +81,7 @@ class condition {
         if (!valid()) return false;
         auto &cnt = counter();
         {
-            IPC_UNUSED_ std::lock_guard<ipc::sync::mutex> guard {lock_};
+            LIBIPC_UNUSED std::lock_guard<ipc::sync::mutex> guard {lock_};
             cnt = (cnt < 0) ? 1 : cnt + 1;
         }
         DWORD ms = (tm == invalid_value) ? INFINITE : static_cast<DWORD>(tm);
@@ -93,7 +93,7 @@ class condition {
         bool rs = ::SignalObjectAndWait(mtx.native(), sem_.native(), ms, FALSE) == WAIT_OBJECT_0;
         bool rl = mtx.lock(); // INFINITE
         if (!rs) {
-            IPC_UNUSED_ std::lock_guard<ipc::sync::mutex> guard {lock_};
+            LIBIPC_UNUSED std::lock_guard<ipc::sync::mutex> guard {lock_};
             cnt -= 1;
         }
         return rs && rl;
diff --git a/src/libipc/platform/win/demangle.h b/src/libipc/platform/win/demangle.h
new file mode 100644
index 00000000..791f64d4
--- /dev/null
+++ b/src/libipc/platform/win/demangle.h
@@ -0,0 +1,15 @@
+/**
+ * \file libipc/platform/win/demangle.h
+ * \author mutouyun (orz@orzz.org)
+ */
+#pragma once
+
+#include "libipc/imp/nameof.h"
+
+namespace ipc {
+
+std::string demangle(std::string name) noexcept {
+  return std::move(name);
+}
+
+} // namespace ipc
diff --git a/src/libipc/platform/win/mutex.h b/src/libipc/platform/win/mutex.h
index e9b61cd7..22c191fa 100644
--- a/src/libipc/platform/win/mutex.h
+++ b/src/libipc/platform/win/mutex.h
@@ -84,7 +84,7 @@ class mutex {
             return false;
         case WAIT_ABANDONED:
             unlock();
-            IPC_FALLTHROUGH_;
+            LIBIPC_FALLTHROUGH;
         default:
             ipc::error("fail WaitForSingleObject[%lu]: 0x%08X\n", ::GetLastError(), ret);
             throw std::system_error{static_cast<int>(ret), std::system_category()};
diff --git a/src/libipc/platform/win/shm_win.cpp b/src/libipc/platform/win/shm_win.cpp
index b19245fd..c082dace 100755
--- a/src/libipc/platform/win/shm_win.cpp
+++ b/src/libipc/platform/win/shm_win.cpp
@@ -6,10 +6,10 @@
 
 #include "libipc/shm.h"
 #include "libipc/def.h"
-#include "libipc/pool_alloc.h"
 
 #include "libipc/utility/log.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
+#include "libipc/mem/new.h"
 
 #include "to_tchar.h"
 #include "get_sa.h"
@@ -58,7 +58,7 @@ id_t acquire(char const * name, std::size_t size, unsigned mode) {
           return nullptr;
         }
     }
-    auto ii = mem::alloc<id_info_t>();
+    auto ii = mem::$new<id_info_t>();
     ii->h_    = h;
     ii->size_ = size;
     return ii;
@@ -116,7 +116,7 @@ std::int32_t release(id_t id) noexcept {
         ipc::error("fail release: invalid id (h = null)\n");
     }
     else ::CloseHandle(ii->h_);
-    mem::free(ii);
+    mem::$delete(ii);
     return 0;
 }
 
diff --git a/src/libipc/platform/win/system.h b/src/libipc/platform/win/system.h
new file mode 100644
index 00000000..25a7add9
--- /dev/null
+++ b/src/libipc/platform/win/system.h
@@ -0,0 +1,88 @@
+/**
+ * \file libipc/platform/win/system.h
+ * \author mutouyun (orz@orzz.org)
+ */
+#pragma once
+
+#include <exception>
+#include <type_traits>
+
+#include <Windows.h>
+#include <tchar.h>
+
+#include "libipc/imp/system.h"
+#include "libipc/imp/log.h"
+#include "libipc/imp/codecvt.h"
+#include "libipc/imp/generic.h"
+#include "libipc/imp/detect_plat.h"
+#include "libipc/imp/scope_exit.h"
+
+namespace ipc {
+namespace sys {
+
+/**
+ * \brief Gets a text description of the system error
+ * \see https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-formatmessage
+ */
+std::string error_string(DWORD code) noexcept {
+  LIBIPC_LOG();
+  LIBIPC_TRY {
+    LPTSTR lpErrText = NULL;
+    if (::FormatMessage(
+          FORMAT_MESSAGE_ALLOCATE_BUFFER | 
+          FORMAT_MESSAGE_FROM_SYSTEM | 
+          FORMAT_MESSAGE_IGNORE_INSERTS,
+          NULL,
+          code,
+          MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+          (LPTSTR)&lpErrText,
+          0, NULL) == 0) {
+      log.error("failed: FormatMessage(dwMessageId = ", code, "). error = ", ::GetLastError());
+      return {};
+    }
+    LIBIPC_SCOPE_EXIT(finally) = [lpErrText] { ::LocalFree(lpErrText); };
+    std::size_t msg_len = ::_tcslen(lpErrText);
+    std::size_t len = cvt_cstr(lpErrText, msg_len, (char *)nullptr, 0);
+    if (len == 0) {
+      return {};
+    }
+    std::string ret(len, '\0');
+    cvt_cstr(lpErrText, msg_len, &ret[0], ret.size());
+    return ret;
+  } LIBIPC_CATCH(...) {
+    log.error("failed: FormatMessage(dwMessageId = ", code, ").",
+              "\n\texception: ", log::exception_string(std::current_exception()));
+  }
+  return {};
+}
+
+/**
+ * \brief Get the system error number.
+ * \see https://en.cppreference.com/w/cpp/error/system_category
+ *      https://docs.microsoft.com/en-us/windows/win32/api/errhandlingapi/nf-errhandlingapi-getlasterror
+*/
+std::error_code error() noexcept {
+  return std::error_code(::GetLastError(), std::system_category());
+}
+
+/**
+ * \brief Retrieves information about the current system.
+ * \see https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsysteminfo
+ *      https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getnativesysteminfo
+ */
+result<std::int64_t> conf(info r) noexcept {
+  LIBIPC_LOG();
+  switch (r) {
+  case info::page_size: {
+    ::SYSTEM_INFO info{};
+    ::GetNativeSystemInfo(&info);
+    return (std::int64_t)info.dwPageSize;
+  }
+  default:
+    log.error("invalid info = ", underlyof(r));
+    return std::make_error_code(std::errc::invalid_argument);
+  }
+}
+
+} // namespace sys
+} // namespace ipc
diff --git a/src/libipc/platform/win/to_tchar.h b/src/libipc/platform/win/to_tchar.h
index 94bc83e8..d557f6c2 100755
--- a/src/libipc/platform/win/to_tchar.h
+++ b/src/libipc/platform/win/to_tchar.h
@@ -11,7 +11,7 @@
 #include <cstddef>
 
 #include "libipc/utility/concept.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 #include "libipc/platform/detail.h"
 
 namespace ipc {
@@ -36,7 +36,7 @@ using IsSameChar = ipc::require<is_same_char<T, S>::value, R>;
 ////////////////////////////////////////////////////////////////
 
 template <typename T = TCHAR>
-constexpr auto to_tchar(ipc::string &&str) -> IsSameChar<T, ipc::string, ipc::string &&> {
+constexpr auto to_tchar(std::string &&str) -> IsSameChar<T, std::string, std::string &&> {
     return std::move(str); // noconv
 }
 
@@ -48,7 +48,7 @@ constexpr auto to_tchar(ipc::string &&str) -> IsSameChar<T, ipc::string, ipc::st
  *      https://docs.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-multibytetowidechar
 */
 template <typename T = TCHAR>
-auto to_tchar(ipc::string &&external) -> IsSameChar<T, ipc::wstring> {
+auto to_tchar(std::string &&external) -> IsSameChar<T, std::wstring> {
     if (external.empty()) {
         return {}; // noconv
     }
@@ -65,7 +65,7 @@ auto to_tchar(ipc::string &&external) -> IsSameChar<T, ipc::wstring> {
     if (size_needed <= 0) {
         return {};
     }
-    ipc::wstring internal(size_needed, L'\0');
+    std::wstring internal(size_needed, L'\0');
     ::MultiByteToWideChar(CP_UTF8, 0, &external[0], (int)external.size(), &internal[0], size_needed);
     return internal;
 }
diff --git a/src/libipc/pool_alloc.cpp b/src/libipc/pool_alloc.cpp
deleted file mode 100755
index 9824df91..00000000
--- a/src/libipc/pool_alloc.cpp
+++ /dev/null
@@ -1,17 +0,0 @@
-#include "libipc/pool_alloc.h"
-
-#include "libipc/memory/resource.h"
-
-namespace ipc {
-namespace mem {
-
-void* pool_alloc::alloc(std::size_t size) noexcept {
-    return async_pool_alloc::alloc(size);
-}
-
-void pool_alloc::free(void* p, std::size_t size) noexcept {
-    async_pool_alloc::free(p, size);
-}
-
-} // namespace mem
-} // namespace ipc
diff --git a/src/libipc/queue.h b/src/libipc/queue.h
index 71dc170e..343454bb 100755
--- a/src/libipc/queue.h
+++ b/src/libipc/queue.h
@@ -18,7 +18,7 @@
 #include "libipc/utility/log.h"
 #include "libipc/platform/detail.h"
 #include "libipc/circ/elem_def.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 
 namespace ipc {
 namespace detail {
diff --git a/src/libipc/shm.cpp b/src/libipc/shm.cpp
index a6a00c76..40a374e4 100755
--- a/src/libipc/shm.cpp
+++ b/src/libipc/shm.cpp
@@ -6,7 +6,7 @@
 
 #include "libipc/utility/pimpl.h"
 #include "libipc/utility/log.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 
 namespace ipc {
 namespace shm {
@@ -16,7 +16,7 @@ class handle::handle_ : public pimpl<handle_> {
     shm::id_t id_ = nullptr;
     void*     m_  = nullptr;
 
-    ipc::string n_;
+    std::string n_;
     std::size_t s_ = 0;
 };
 
diff --git a/src/libipc/sync/condition.cpp b/src/libipc/sync/condition.cpp
index e64e688c..c6afccb9 100644
--- a/src/libipc/sync/condition.cpp
+++ b/src/libipc/sync/condition.cpp
@@ -3,13 +3,13 @@
 
 #include "libipc/utility/pimpl.h"
 #include "libipc/utility/log.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 #include "libipc/platform/detail.h"
-#if defined(IPC_OS_WINDOWS_)
+#if defined(LIBIPC_OS_WIN)
 #include "libipc/platform/win/condition.h"
-#elif defined(IPC_OS_LINUX_)
+#elif defined(LIBIPC_OS_LINUX)
 #include "libipc/platform/linux/condition.h"
-#elif defined(IPC_OS_QNX_)
+#elif defined(LIBIPC_OS_QNX)
 #include "libipc/platform/posix/condition.h"
 #else/*IPC_OS*/
 #   error "Unsupported platform."
diff --git a/src/libipc/sync/mutex.cpp b/src/libipc/sync/mutex.cpp
index c9c59f74..aa7fc083 100644
--- a/src/libipc/sync/mutex.cpp
+++ b/src/libipc/sync/mutex.cpp
@@ -3,13 +3,13 @@
 
 #include "libipc/utility/pimpl.h"
 #include "libipc/utility/log.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 #include "libipc/platform/detail.h"
-#if defined(IPC_OS_WINDOWS_)
+#if defined(LIBIPC_OS_WIN)
 #include "libipc/platform/win/mutex.h"
-#elif defined(IPC_OS_LINUX_)
+#elif defined(LIBIPC_OS_LINUX)
 #include "libipc/platform/linux/mutex.h"
-#elif defined(IPC_OS_QNX_)
+#elif defined(LIBIPC_OS_QNX)
 #include "libipc/platform/posix/mutex.h"
 #else/*IPC_OS*/
 #   error "Unsupported platform."
diff --git a/src/libipc/sync/semaphore.cpp b/src/libipc/sync/semaphore.cpp
index ccb13c47..29665c8f 100644
--- a/src/libipc/sync/semaphore.cpp
+++ b/src/libipc/sync/semaphore.cpp
@@ -3,11 +3,11 @@
 
 #include "libipc/utility/pimpl.h"
 #include "libipc/utility/log.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 #include "libipc/platform/detail.h"
-#if defined(IPC_OS_WINDOWS_)
+#if defined(LIBIPC_OS_WIN)
 #include "libipc/platform/win/semaphore.h"
-#elif defined(IPC_OS_LINUX_) || defined(IPC_OS_QNX_)
+#elif defined(LIBIPC_OS_LINUX) || defined(LIBIPC_OS_QNX)
 #include "libipc/platform/posix/semaphore_impl.h"
 #else/*IPC_OS*/
 #   error "Unsupported platform."
diff --git a/src/libipc/sync/waiter.cpp b/src/libipc/sync/waiter.cpp
index 3a04abfe..cb9f39bc 100644
--- a/src/libipc/sync/waiter.cpp
+++ b/src/libipc/sync/waiter.cpp
@@ -1,11 +1,11 @@
 #include "libipc/waiter.h"
 
 #include "libipc/platform/detail.h"
-#if defined(IPC_OS_WINDOWS_)
+#if defined(LIBIPC_OS_WIN)
 #include "libipc/platform/win/mutex.h"
-#elif defined(IPC_OS_LINUX_)
+#elif defined(LIBIPC_OS_LINUX)
 #include "libipc/platform/linux/mutex.h"
-#elif defined(IPC_OS_QNX_)
+#elif defined(LIBIPC_OS_QNX)
 #include "libipc/platform/posix/mutex.h"
 #else/*IPC_OS*/
 #   error "Unsupported platform."
diff --git a/src/libipc/utility/pimpl.h b/src/libipc/utility/pimpl.h
index ca0edd3c..7151045b 100755
--- a/src/libipc/utility/pimpl.h
+++ b/src/libipc/utility/pimpl.h
@@ -5,7 +5,7 @@
 
 #include "libipc/platform/detail.h"
 #include "libipc/utility/concept.h"
-#include "libipc/pool_alloc.h"
+#include "libipc/mem/new.h"
 
 namespace ipc {
 
@@ -36,12 +36,12 @@ IPC_CONSTEXPR_ auto clear_impl(T* p) -> IsImplComfortable<T, void> {
 
 template <typename T, typename... P>
 IPC_CONSTEXPR_ auto make_impl(P&&... params) -> IsImplUncomfortable<T> {
-    return mem::alloc<T>(std::forward<P>(params)...);
+    return mem::$new<T>(std::forward<P>(params)...);
 }
 
 template <typename T>
 IPC_CONSTEXPR_ auto clear_impl(T* p) -> IsImplUncomfortable<T, void> {
-    mem::free(p);
+    mem::$delete(p);
 }
 
 template <typename T>
diff --git a/src/libipc/utility/utility.h b/src/libipc/utility/utility.h
index 79424d95..f9de13f0 100755
--- a/src/libipc/utility/utility.h
+++ b/src/libipc/utility/utility.h
@@ -27,7 +27,7 @@ constexpr decltype(auto) static_switch(std::size_t i, F&& f, D&& def) {
 
 template <typename F, std::size_t...I>
 IPC_CONSTEXPR_ void static_for(std::index_sequence<I...>, F&& f) {
-    IPC_UNUSED_ auto expand = { (std::forward<F>(f)(std::integral_constant<std::size_t, I>{}), 0)... };
+    LIBIPC_UNUSED auto expand = { (std::forward<F>(f)(std::integral_constant<std::size_t, I>{}), 0)... };
 }
 
 template <std::size_t N, typename F>
@@ -44,18 +44,6 @@ enum {
 // #endif/*__cplusplus < 201703L*/
 };
 
-template <typename T, typename U>
-auto horrible_cast(U rhs) noexcept
-    -> typename std::enable_if<std::is_trivially_copyable<T>::value
-                            && std::is_trivially_copyable<U>::value, T>::type {
-    union {
-        T t;
-        U u;
-    } r = {};
-    r.u = rhs;
-    return r.t;
-}
-
 IPC_CONSTEXPR_ std::size_t make_align(std::size_t align, std::size_t size) {
     // align must be 2^n
     return (size + align - 1) & ~(align - 1);
diff --git a/src/libipc/waiter.h b/src/libipc/waiter.h
index 0892bc12..b2779f62 100644
--- a/src/libipc/waiter.h
+++ b/src/libipc/waiter.h
@@ -63,7 +63,7 @@ class waiter {
 
     template <typename F>
     bool wait_if(F &&pred, std::uint64_t tm = ipc::invalid_value) noexcept {
-        IPC_UNUSED_ std::lock_guard<ipc::sync::mutex> guard {lock_};
+        LIBIPC_UNUSED std::lock_guard<ipc::sync::mutex> guard {lock_};
         while ([this, &pred] {
                     return !quit_.load(std::memory_order_relaxed)
                         && std::forward<F>(pred)();
@@ -75,14 +75,14 @@ class waiter {
 
     bool notify() noexcept {
         {
-            IPC_UNUSED_ std::lock_guard<ipc::sync::mutex> barrier{lock_}; // barrier
+            LIBIPC_UNUSED std::lock_guard<ipc::sync::mutex> barrier{lock_}; // barrier
         }
         return cond_.notify(lock_);
     }
 
     bool broadcast() noexcept {
         {
-            IPC_UNUSED_ std::lock_guard<ipc::sync::mutex> barrier{lock_}; // barrier
+            LIBIPC_UNUSED std::lock_guard<ipc::sync::mutex> barrier{lock_}; // barrier
         }
         return cond_.broadcast(lock_);
     }
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 9398aa30..f87e80df 100755
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -17,6 +17,9 @@ include_directories(
 
 file(GLOB SRC_FILES
     ${LIBIPC_PROJECT_DIR}/test/*.cpp
+    ${LIBIPC_PROJECT_DIR}/test/imp/*.cpp
+    ${LIBIPC_PROJECT_DIR}/test/mem/*.cpp
+    ${LIBIPC_PROJECT_DIR}/test/concur/*.cpp
     # ${LIBIPC_PROJECT_DIR}/test/profiler/*.cpp
     )
 file(GLOB HEAD_FILES ${LIBIPC_PROJECT_DIR}/test/*.h)
diff --git a/test/concur/test_concur_intrusive_stack.cpp b/test/concur/test_concur_intrusive_stack.cpp
new file mode 100644
index 00000000..41ec6ac9
--- /dev/null
+++ b/test/concur/test_concur_intrusive_stack.cpp
@@ -0,0 +1,103 @@
+
+#include "test.h"
+
+#define private public
+#include "libipc/concur/intrusive_stack.h"
+
+using namespace ipc;
+
+TEST(intrusive_stack, construct) {
+  concur::intrusive_stack<int> s;
+  EXPECT_TRUE(s.empty());
+}
+
+TEST(intrusive_stack, construct_node) {
+  concur::intrusive_stack<int>::node n{};
+  EXPECT_TRUE(n.next.load(std::memory_order_relaxed) == nullptr);
+}
+
+TEST(intrusive_stack, copyable) {
+  EXPECT_FALSE(std::is_copy_constructible<concur::intrusive_stack<int>>::value);
+  EXPECT_FALSE(std::is_copy_assignable<concur::intrusive_stack<int>>::value);
+}
+
+TEST(intrusive_stack, moveable) {
+  EXPECT_FALSE(std::is_move_constructible<concur::intrusive_stack<int>>::value);
+  EXPECT_FALSE(std::is_move_assignable<concur::intrusive_stack<int>>::value);
+}
+
+TEST(intrusive_stack, push_one) {
+  concur::intrusive_stack<int> s;
+  concur::intrusive_stack<int>::node n{123};
+  s.push(&n);
+  EXPECT_FALSE(s.empty());
+  EXPECT_TRUE(s.top_.load(std::memory_order_relaxed) == &n);
+  EXPECT_TRUE(n.next.load(std::memory_order_relaxed) == nullptr);
+  EXPECT_EQ(n.value, 123);
+}
+
+TEST(intrusive_stack, push_many) {
+  concur::intrusive_stack<int> s;
+  concur::intrusive_stack<int>::node n1{111111};
+  concur::intrusive_stack<int>::node n2{222222};
+  concur::intrusive_stack<int>::node n3{333333};
+  s.push(&n1);
+  s.push(&n2);
+  s.push(&n3);
+  EXPECT_FALSE(s.empty());
+  EXPECT_TRUE(s.top_.load(std::memory_order_relaxed) == &n3);
+  EXPECT_TRUE(n3.next.load(std::memory_order_relaxed) == &n2);
+  EXPECT_TRUE(n2.next.load(std::memory_order_relaxed) == &n1);
+  EXPECT_TRUE(n1.next.load(std::memory_order_relaxed) == nullptr);
+  EXPECT_EQ(n1.value, 111111);
+  EXPECT_EQ(n2.value, 222222);
+  EXPECT_EQ(n3.value, 333333);
+}
+
+TEST(intrusive_stack, push_same) {
+  concur::intrusive_stack<int> s;
+  concur::intrusive_stack<int>::node n{321};
+  s.push(&n);
+  s.push(&n);
+  EXPECT_FALSE(s.empty());
+  EXPECT_TRUE(s.top_.load(std::memory_order_relaxed) == &n);
+  EXPECT_TRUE(n.next.load(std::memory_order_relaxed) == &n);
+  EXPECT_EQ(n.value, 321);
+}
+
+TEST(intrusive_stack, pop_empty) {
+  concur::intrusive_stack<int> s;
+  EXPECT_TRUE(s.pop() == nullptr);
+}
+
+TEST(intrusive_stack, pop_one) {
+  concur::intrusive_stack<int> s;
+  concur::intrusive_stack<int>::node n{112233};
+  s.push(&n);
+  EXPECT_TRUE(s.pop() == &n);
+  EXPECT_TRUE(s.empty());
+  EXPECT_TRUE(s.top_.load(std::memory_order_relaxed) == nullptr);
+  EXPECT_TRUE(n.next.load(std::memory_order_relaxed) == nullptr);
+  EXPECT_EQ(n.value, 112233);
+}
+
+TEST(intrusive_stack, pop_many) {
+  concur::intrusive_stack<int> s;
+  concur::intrusive_stack<int>::node n1{111111};
+  concur::intrusive_stack<int>::node n2{222222};
+  concur::intrusive_stack<int>::node n3{333333};
+  s.push(&n1);
+  s.push(&n2);
+  s.push(&n3);
+  EXPECT_TRUE(s.pop() == &n3);
+  EXPECT_TRUE(s.pop() == &n2);
+  EXPECT_TRUE(s.pop() == &n1);
+  EXPECT_TRUE(s.empty());
+  EXPECT_TRUE(s.top_.load(std::memory_order_relaxed) == nullptr);
+  EXPECT_TRUE(n3.next.load(std::memory_order_relaxed) == &n2);
+  EXPECT_TRUE(n2.next.load(std::memory_order_relaxed) == &n1);
+  EXPECT_TRUE(n1.next.load(std::memory_order_relaxed) == nullptr);
+  EXPECT_EQ(n1.value, 111111);
+  EXPECT_EQ(n2.value, 222222);
+  EXPECT_EQ(n3.value, 333333);
+}
diff --git a/test/imp/test_imp_byte.cpp b/test/imp/test_imp_byte.cpp
new file mode 100644
index 00000000..92c754f4
--- /dev/null
+++ b/test/imp/test_imp_byte.cpp
@@ -0,0 +1,57 @@
+
+#include "test.h"
+
+#include "libipc/imp/byte.h"
+#include "libipc/imp/span.h"
+#include "libipc/imp/detect_plat.h"
+
+TEST(byte, construct) {
+  {
+    LIBIPC_UNUSED ipc::byte b;
+    SUCCEED();
+  }
+  {
+    ipc::byte b{};
+    EXPECT_EQ(int(b), 0);
+  }
+  {
+    ipc::byte b{123};
+    EXPECT_EQ(int(b), 123);
+  }
+  {
+    ipc::byte b{65535};
+    EXPECT_EQ(int(b), 255);
+    EXPECT_EQ(std::int8_t(b), -1);
+  }
+  {
+    ipc::byte b{65536};
+    EXPECT_EQ(int(b), 0);
+  }
+}
+
+TEST(byte, compare) {
+  {
+    ipc::byte b1{}, b2{};
+    EXPECT_EQ(b1, b2);
+  }
+  {
+    ipc::byte b1{}, b2(321);
+    EXPECT_NE(b1, b2);
+  }
+}
+
+TEST(byte, byte_cast) {
+  int a = 654321;
+  int *pa = &a;
+
+  // int * => byte *
+  ipc::byte *pb = ipc::byte_cast(pa);
+  EXPECT_EQ((std::size_t)pb, (std::size_t)pa);
+
+  // byte * => int32_t *
+  std::int32_t *pc = ipc::byte_cast<std::int32_t>(pb);
+  EXPECT_EQ(*pc, a);
+
+  // byte alignment check
+  EXPECT_EQ(ipc::byte_cast<int>(pb + 1), nullptr);
+}
diff --git a/test/imp/test_imp_codecvt.cpp b/test/imp/test_imp_codecvt.cpp
new file mode 100644
index 00000000..33b9cf74
--- /dev/null
+++ b/test/imp/test_imp_codecvt.cpp
@@ -0,0 +1,40 @@
+
+#include <string>
+#include <cstring>
+
+#include "test.h"
+
+#include "libipc/imp/codecvt.h"
+
+TEST(codecvt, cvt_cstr) {
+  char const utf8[] = "hello world, 你好，こんにちは";
+  wchar_t const utf16[] = L"hello world, 你好，こんにちは";
+  {
+    auto cvt_len = ipc::cvt_cstr(utf8, std::strlen(utf8), (wchar_t *)nullptr, 0);
+    EXPECT_NE(cvt_len, 0);
+    std::wstring wstr(cvt_len, L'\0');
+    EXPECT_EQ(ipc::cvt_cstr(utf8, std::strlen(utf8), &wstr[0], wstr.size()), cvt_len);
+    EXPECT_EQ(wstr, utf16);
+  }
+  {
+    auto cvt_len = ipc::cvt_cstr(utf16, std::wcslen(utf16), (char *)nullptr, 0);
+    EXPECT_NE(cvt_len, 0);
+    std::string str(cvt_len, '\0');
+    EXPECT_EQ(ipc::cvt_cstr(utf16, std::wcslen(utf16), &str[0], str.size()), cvt_len);
+    EXPECT_EQ(str, utf8);
+  }
+  {
+    auto cvt_len = ipc::cvt_cstr(utf8, std::strlen(utf8), (char *)nullptr, 0);
+    EXPECT_EQ(cvt_len, std::strlen(utf8));
+    std::string str(cvt_len, '\0');
+    EXPECT_EQ(ipc::cvt_cstr(utf8, cvt_len, &str[0], str.size()), cvt_len);
+    EXPECT_EQ(str, utf8);
+  }
+  {
+    auto cvt_len = ipc::cvt_cstr(utf16, std::wcslen(utf16), (wchar_t *)nullptr, 0);
+    EXPECT_EQ(cvt_len, std::wcslen(utf16));
+    std::wstring wstr(cvt_len, u'\0');
+    EXPECT_EQ(ipc::cvt_cstr(utf16, cvt_len, &wstr[0], wstr.size()), cvt_len);
+    EXPECT_EQ(wstr, utf16);
+  }
+}
diff --git a/test/imp/test_imp_detect_plat.cpp b/test/imp/test_imp_detect_plat.cpp
new file mode 100644
index 00000000..a74d1bee
--- /dev/null
+++ b/test/imp/test_imp_detect_plat.cpp
@@ -0,0 +1,90 @@
+
+#include "test.h"
+
+#include "libipc/imp/detect_plat.h"
+
+TEST(detect_plat, os) {
+#if defined(LIBIPC_OS_WINCE)
+  std::cout << "LIBIPC_OS_WINCE\n";
+#elif defined(LIBIPC_OS_WIN)
+  std::cout << "LIBIPC_OS_WIN\n";
+#elif defined(LIBIPC_OS_LINUX)
+  std::cout << "LIBIPC_OS_LINUX\n";
+#elif defined(LIBIPC_OS_QNX)
+  std::cout << "LIBIPC_OS_QNX\n";
+#elif defined(LIBIPC_OS_ANDROID)
+  std::cout << "LIBIPC_OS_ANDROID\n";
+#else
+  ASSERT_TRUE(false);
+#endif
+  SUCCEED();
+}
+
+TEST(detect_plat, cc) {
+#if defined(LIBIPC_CC_MSVC)
+  std::cout << "LIBIPC_CC_MSVC\n";
+#elif defined(LIBIPC_CC_GNUC)
+  std::cout << "LIBIPC_CC_GNUC\n";
+#else
+  ASSERT_TRUE(false);
+#endif
+  SUCCEED();
+}
+
+TEST(detect_plat, cpp) {
+#if defined(LIBIPC_CPP_20)
+  std::cout << "LIBIPC_CPP_20\n";
+#elif defined(LIBIPC_CPP_17)
+  std::cout << "LIBIPC_CPP_17\n";
+#elif defined(LIBIPC_CPP_14)
+  std::cout << "LIBIPC_CPP_14\n";
+#else
+  ASSERT_TRUE(false);
+#endif
+  SUCCEED();
+}
+
+TEST(detect_plat, byte_order) {
+  auto is_endian_little = [] {
+    union {
+      std::int32_t a;
+      std::int8_t  b;
+    } c;
+    c.a = 1;
+    return c.b == 1;
+  };
+  EXPECT_EQ(!!LIBIPC_ENDIAN_LIT, is_endian_little());
+  EXPECT_NE(!!LIBIPC_ENDIAN_BIG, is_endian_little());
+}
+
+TEST(detect_plat, fallthrough) {
+  switch (0) {
+  case 0:
+    std::cout << "fallthrough 0\n";
+    LIBIPC_FALLTHROUGH;
+  case 1:
+    std::cout << "fallthrough 1\n";
+    LIBIPC_FALLTHROUGH;
+  default:
+    std::cout << "fallthrough default\n";
+    break;
+  }
+  SUCCEED();
+}
+
+TEST(detect_plat, unused) {
+  LIBIPC_UNUSED int abc;
+  SUCCEED();
+}
+
+TEST(detect_plat, likely_unlikely) {
+  int xx = sizeof(int);
+  if LIBIPC_LIKELY(xx < sizeof(long long)) {
+    std::cout << "sizeof(int) < sizeof(long long)\n";
+  } else if LIBIPC_UNLIKELY(xx < sizeof(char)) {
+    std::cout << "sizeof(int) < sizeof(char)\n";
+  } else {
+    std::cout << "sizeof(int) < whatever\n";
+  }
+  SUCCEED();
+}
diff --git a/test/imp/test_imp_error.cpp b/test/imp/test_imp_error.cpp
new file mode 100644
index 00000000..b8db0e69
--- /dev/null
+++ b/test/imp/test_imp_error.cpp
@@ -0,0 +1,12 @@
+#include <iostream>
+
+#include "test.h"
+
+#include "libipc/imp/error.h"
+#include "libipc/imp/fmt.h"
+
+TEST(error, error_code) {
+  std::error_code ecode;
+  EXPECT_FALSE(ecode);
+  std::cout << ipc::fmt(ecode, '\n');
+}
diff --git a/test/imp/test_imp_expected.cpp b/test/imp/test_imp_expected.cpp
new file mode 100644
index 00000000..cb96e546
--- /dev/null
+++ b/test/imp/test_imp_expected.cpp
@@ -0,0 +1,142 @@
+
+#include "test.h"
+
+#include "libipc/imp/expected.h"
+
+namespace {
+
+class test_val {
+public:
+  int val = 0;
+  int dc_ = 0;
+  int cc_ = 0;
+  int mv_ = 0;
+
+  test_val() {
+    dc_ += 1;
+    std::printf("test_val construct.\n");
+  }
+  test_val(test_val const &o)
+    : val(o.val) {
+    cc_ = o.cc_ + 1;
+    std::printf("test_val copy construct.\n");
+  }
+  test_val(test_val &&o) noexcept
+    : val(std::exchange(o.val, 0)) {
+    mv_ = o.mv_ + 1;
+    std::printf("test_val move construct.\n");
+  }
+  ~test_val() {
+    std::printf("test_val destruct.\n");
+  }
+
+  test_val &operator=(test_val &&o) noexcept {
+    mv_ = o.mv_ + 1;
+    val = std::exchange(o.val, 0);
+    return *this;
+  }
+
+  test_val(int v)
+    : val(v) {
+    std::printf("test_val value initialization.\n");
+  }
+
+  bool operator==(test_val const &rhs) const {
+    return val == rhs.val;
+  }
+};
+
+class test_err {
+public:
+  int dc_ = 0;
+  int cc_ = 0;
+  int mv_ = 0;
+  std::int64_t val = 0;
+
+  test_err() {
+    dc_ += 1;
+    std::printf("test_err construct.\n");
+  }
+  test_err(test_err const &o)
+    : val(o.val) {
+    cc_ = o.cc_ + 1;
+    std::printf("test_err copy construct.\n");
+  }
+  test_err(test_err &&o) noexcept
+    : val(std::exchange(o.val, 0)) {
+    mv_ = o.mv_ + 1;
+    std::printf("test_err move construct.\n");
+  }
+  ~test_err() {
+    std::printf("test_err destruct.\n");
+  }
+
+  test_err &operator=(test_err &&o) noexcept {
+    mv_ = o.mv_ + 1;
+    val = std::exchange(o.val, 0);
+    return *this;
+  }
+
+  test_err(int v)
+    : val(v) {
+    std::printf("test_err value initialization.\n");
+  }
+
+  bool operator==(test_err const &rhs) const {
+    return val == rhs.val;
+  }
+};
+
+} // namespace
+
+TEST(expected, in_place) {
+  ipc::expected<test_val, test_err> e1;
+  EXPECT_TRUE(e1);
+  EXPECT_EQ(e1.value().dc_, 1);
+  EXPECT_EQ(e1.value().val, 0);
+
+  ipc::expected<test_val, test_err> e2 {ipc::in_place, 123};
+  EXPECT_TRUE(e2);
+  EXPECT_EQ(e2.value().dc_, 0);
+  EXPECT_EQ(e2.value().val, 123);
+}
+
+TEST(expected, unexpected) {
+  ipc::expected<test_val, test_err> e1 {ipc::unexpected};
+  EXPECT_FALSE(e1);
+  EXPECT_EQ(e1.error().dc_, 1);
+  EXPECT_EQ(e1.error().val, 0);
+
+  ipc::expected<test_val, test_err> e2 {ipc::unexpected, 321};
+  EXPECT_FALSE(e2);
+  EXPECT_EQ(e2.error().dc_, 0);
+  EXPECT_EQ(e2.error().val, 321);
+}
+
+TEST(expected, copy_and_move) {
+  ipc::expected<test_val, test_err> e1 {ipc::in_place, 123};
+  ipc::expected<test_val, test_err> e2 {e1};
+  EXPECT_TRUE(e1);
+  EXPECT_TRUE(e2);
+  EXPECT_EQ(e1, e2);
+  EXPECT_EQ(e2.value().cc_, 1);
+  EXPECT_EQ(e2.value().val, 123);
+
+  ipc::expected<test_val, test_err> e3 {ipc::unexpected, 333};
+  ipc::expected<test_val, test_err> e4 {e3};
+  EXPECT_FALSE(e3);
+  EXPECT_FALSE(e4);
+  EXPECT_EQ(e3, e4);
+  EXPECT_EQ(e4.error().cc_, 1);
+  EXPECT_EQ(e4.error().val, 333);
+
+  ipc::expected<test_val, test_err> e5;
+  e5 = e1;
+  EXPECT_EQ(e1, e5);
+  EXPECT_EQ(e5.value().val, 123);
+
+  ipc::expected<test_val, test_err> e6;
+  e6 = std::move(e5);
+  EXPECT_EQ(e1, e6);
+  EXPECT_EQ(e5.value().val, 0);
+}
diff --git a/test/imp/test_imp_fmt.cpp b/test/imp/test_imp_fmt.cpp
new file mode 100644
index 00000000..fe480977
--- /dev/null
+++ b/test/imp/test_imp_fmt.cpp
@@ -0,0 +1,193 @@
+#define _CRT_SECURE_NO_WARNINGS
+#include <iostream>
+#include <tuple>
+#include <cstring>
+
+#include "test.h"
+
+#include "libipc/imp/fmt.h"
+#include "libipc/imp/byte.h"
+#include "libipc/imp/span.h"
+#include "libipc/imp/result.h"
+
+TEST(fmt, spec) {
+  EXPECT_STREQ(ipc::spec("hello")(123).fstr.data(), "hello");
+  EXPECT_EQ(ipc::spec("hello")(123).param , 123);
+  EXPECT_STREQ(ipc::spec("hello")("world").fstr.data(), "hello");
+  EXPECT_STREQ(ipc::spec("hello")("world").param , "world");
+}
+
+TEST(fmt, to_string) {
+  std::string joined;
+  ipc::fmt_context ctx(joined);
+
+  auto check = [&](auto &&txt, auto &&...val) {
+    ctx.reset();
+    EXPECT_TRUE(ipc::to_string(ctx, std::forward<decltype(val)>(val)...));
+    ctx.finish();
+    EXPECT_EQ(joined, std::forward<decltype(txt)>(txt));
+  };
+
+  /// \brief string
+  check("", "");
+  check("%what%", "%what%");
+  check("    %what%", "%what%", "10");
+  check("%what%    ", "%what%", "-10");
+
+  /// \brief character
+  check("A", 'A');
+  check("A", L'A');
+  check("A", u'A');
+  check("A", U'A');
+
+  /// \brief numeric
+  check("123"       , (signed char)123      );
+  check("-65"       , (signed char)-321     );
+  check("123"       , (unsigned char)123    );
+  check("65"        , (unsigned char)321    );
+  check("123"       , (short)123            );
+  check("-321"      , (short)-321           );
+  check("123"       , (unsigned short)123   );
+  check("321"       , (unsigned short)321   );
+  check("-7949"     , (short)123123         );
+  check("6359"      , (short)-321321        );
+  check("57587"     , (unsigned short)123123);
+  check("59177"     , (unsigned short)321321);
+  check("123123"    , 123123                );
+  check("-321321"   , -321321               );
+  check("123123"    , 123123u               );
+  check("321321"    , 321321u               );
+  check("123123"    , 123123ll              );
+  check("-321321"   , -321321ll             );
+  check("123123"    , 123123ull             );
+  check("321321"    , 321321ull             );
+  check("1e0f3"     , 123123, "x"           );
+  check("1e0f3"     , 123123u, "x"          );
+  check("1CAAB5C3B3", 123123123123ll, "X"   );
+  check("1CAAB5C3B3", 123123123123ull, "X"  );
+
+  /// \brief floating point
+  check("123.123"     , 123.123f, ".3");
+  check("0123.12300"  , 123.123, "010.5");
+  check("123.123000"  , 123.123l, "010.6");
+  check("1.500000e+00", 1.5, "e");
+  check("1.500000E+00", 1.5, "E");
+  double r = 0.0;
+  ctx.reset(); EXPECT_TRUE(ipc::to_string(ctx, 0.0/r)); ctx.finish();
+  std::cout << joined << "\n";
+  ctx.reset(); EXPECT_TRUE(ipc::to_string(ctx, 1.0/r)); ctx.finish();
+  std::cout << joined << "\n";
+
+  /// \brief pointer
+  check("null", nullptr);
+  int *p = (int *)0x0f013a04;
+  ctx.reset(); EXPECT_TRUE(ipc::to_string(ctx, (void *)p)); ctx.finish();
+  std::cout << joined << "\n";
+
+  /// \brief date and time
+  auto tp = std::chrono::system_clock::now();
+  auto tt = std::chrono::system_clock::to_time_t(tp);
+  auto tm = *std::localtime(&tt);
+  ctx.reset(); EXPECT_TRUE(ipc::to_string(ctx, tm)); ctx.finish();
+  std::cout << joined << "\n";
+  std::string tm_str = joined;
+  ctx.reset(); EXPECT_TRUE(ipc::to_string(ctx, tp)); ctx.finish();
+  EXPECT_EQ(tm_str, joined);
+}
+
+TEST(fmt, fmt) {
+  char const txt[] = "hello world.";
+
+  /// \brief hello world
+  auto s = ipc::fmt("hello", " ", "world", ".");
+  EXPECT_EQ(s, txt);
+
+  /// \brief chrono
+  std::cout << ipc::fmt('[', std::chrono::system_clock::now(), "] ", s) << "\n";
+
+  /// \brief long string
+  s = ipc::fmt(ipc::spec("4096")(txt));
+  std::string test(4096, ' ');
+  std::memcpy(&test[test.size() - sizeof(txt) + 1], txt, sizeof(txt) - 1);
+  EXPECT_EQ(s, test);
+
+  EXPECT_EQ(ipc::fmt("", 1, "", '2', "", 3.0), "123.000000");
+  char const * nc = nullptr;
+  EXPECT_EQ(ipc::fmt(nc, 1, "", '2', "", 3.0), "123.000000");
+  std::string empty;
+  EXPECT_EQ(ipc::fmt(empty, 1, "", '2', "", 3.0), "123.000000");
+}
+
+namespace {
+
+class foo {};
+
+bool tag_invoke(decltype(ipc::fmt_to), ipc::fmt_context &, foo arg) noexcept(false) {
+  throw arg;
+  return {};
+}
+
+} // namespace
+
+TEST(fmt, throw) {
+  EXPECT_THROW(std::ignore = ipc::fmt(foo{}), foo);
+}
+
+TEST(fmt, byte) {
+  {
+    ipc::byte b1{}, b2(31);
+    EXPECT_EQ(ipc::fmt(b1), "00");
+    EXPECT_EQ(ipc::fmt(b2), "1f");
+    EXPECT_EQ(ipc::fmt(ipc::spec("03X")(b2)), "01F");
+  }
+  {
+    ipc::byte bs[] {31, 32, 33, 34, 35, 36, 37, 38};
+    EXPECT_EQ(ipc::fmt(ipc::make_span(bs)), "1f 20 21 22 23 24 25 26");
+  }
+}
+
+TEST(fmt, span) {
+  EXPECT_EQ(ipc::fmt(ipc::span<int>{}), "");
+  EXPECT_EQ(ipc::fmt(ipc::make_span({1, 3, 2, 4, 5, 6, 7})), "1 3 2 4 5 6 7");
+}
+
+TEST(fmt, result) {
+  {
+    ipc::result<std::uint64_t> r1;
+    EXPECT_EQ(ipc::fmt(r1), ipc::fmt("fail, error = ", std::error_code(-1, std::generic_category())));
+    ipc::result<std::uint64_t> r2(65537);
+    EXPECT_EQ(ipc::fmt(r2), "succ, value = 65537");
+    ipc::result<std::uint64_t> r3(0);
+    EXPECT_EQ(ipc::fmt(r3), "succ, value = 0");
+  }
+  {
+    ipc::result<int> r0;
+    EXPECT_EQ(ipc::fmt(r0), ipc::fmt(ipc::result<std::uint64_t>()));
+    ipc::result<int> r1 {std::error_code(-1, std::generic_category())};
+    EXPECT_EQ(ipc::fmt(r1), ipc::fmt("fail, error = ", std::error_code(-1, std::generic_category())));
+
+    ipc::result<void *> r2 {&r1};
+    EXPECT_EQ(ipc::fmt(r2), ipc::fmt("succ, value = ", (void *)&r1));
+
+    int aaa {};
+    ipc::result<int *> r3 {&aaa};
+    EXPECT_EQ(ipc::fmt(r3), ipc::fmt("succ, value = ", (void *)&aaa));
+    ipc::result<int *> r4 {nullptr};
+    EXPECT_EQ(ipc::fmt(r4), ipc::fmt("fail, error = ", std::error_code(-1, std::generic_category())));
+    r4 = std::error_code(1234, std::generic_category());
+    EXPECT_EQ(ipc::fmt(r4), ipc::fmt("fail, error = ", std::error_code(1234, std::generic_category())));
+    ipc::result<int *> r5;
+    EXPECT_EQ(ipc::fmt(r5), ipc::fmt("fail, error = ", std::error_code(-1, std::generic_category())));
+  }
+  {
+    ipc::result<std::int64_t> r1 {-123};
+    EXPECT_EQ(ipc::fmt(r1), ipc::fmt("succ, value = ", -123));
+  }
+  {
+    ipc::result<void> r1;
+    EXPECT_EQ(ipc::fmt(r1), ipc::fmt("fail, error = ", std::error_code(-1, std::generic_category())));
+    r1 = std::error_code{};
+    EXPECT_TRUE(r1);
+    EXPECT_EQ(ipc::fmt(r1), ipc::fmt("succ, error = ", std::error_code()));
+  }
+}
diff --git a/test/imp/test_imp_generic.cpp b/test/imp/test_imp_generic.cpp
new file mode 100644
index 00000000..4d0435dc
--- /dev/null
+++ b/test/imp/test_imp_generic.cpp
@@ -0,0 +1,89 @@
+
+#include "test.h"
+
+#include "libipc/imp/generic.h"
+#include "libipc/imp/detect_plat.h"
+
+TEST(generic, countof) {
+  struct {
+    constexpr int Size() const noexcept { return 3; }
+  } sv;
+  EXPECT_FALSE(ipc::detail_countof::trait_has_size<decltype(sv)>::value);
+  EXPECT_TRUE (ipc::detail_countof::trait_has_Size<decltype(sv)>::value);
+
+  std::vector<int> vec {1, 2, 3, 4, 5};
+  int arr[] {7, 6, 5, 4, 3, 2, 1};
+  auto il = {9, 7, 6, 4, 3, 1, 5};
+  EXPECT_EQ(ipc::countof(sv) , sv.Size());
+  EXPECT_EQ(ipc::countof(vec), vec.size());
+  EXPECT_EQ(ipc::countof(arr), sizeof(arr) / sizeof(arr[0]));
+  EXPECT_EQ(ipc::countof(il) , il.size());
+}
+
+TEST(generic, dataof) {
+  struct {
+    int *Data() const noexcept { return (int *)this; }
+  } sv;
+  EXPECT_FALSE(ipc::detail_dataof::trait_has_data<decltype(sv)>::value);
+  EXPECT_TRUE (ipc::detail_dataof::trait_has_Data<decltype(sv)>::value);
+
+  std::vector<int> vec {1, 2, 3, 4, 5};
+  int arr[] {7, 6, 5, 4, 3, 2, 1};
+  auto il = {9, 7, 6, 4, 3, 1, 5};
+  EXPECT_EQ(ipc::dataof(sv) , sv.Data());
+  EXPECT_EQ(ipc::dataof(vec), vec.data());
+  EXPECT_EQ(ipc::dataof(arr), arr);
+  EXPECT_EQ(ipc::dataof(il) , il.begin());
+}
+
+TEST(generic, horrible_cast) {
+  struct A {
+    int a_;
+  } a {123};
+
+  struct B {
+    char a_[sizeof(int)];
+  } b = ipc::horrible_cast<B>(a);
+
+  EXPECT_EQ(b.a_[1], 0);
+  EXPECT_EQ(b.a_[2], 0);
+#if LIBIPC_ENDIAN_LIT
+  EXPECT_EQ(b.a_[0], 123);
+  EXPECT_EQ(b.a_[3], 0);
+#else
+  EXPECT_EQ(b.a_[3], 123);
+  EXPECT_EQ(b.a_[0], 0);
+#endif
+
+#if LIBIPC_ENDIAN_LIT
+  EXPECT_EQ(ipc::horrible_cast<std::uint32_t>(0xff00'0000'0001ll), 1);
+#else
+  EXPECT_EQ(ipc::horrible_cast<std::uint32_t>(0xff00'0000'0001ll), 0xff00);
+#endif
+}
+
+#if defined(LIBIPC_CPP_17)
+TEST(generic, in_place) {
+  EXPECT_TRUE((std::is_same<std::in_place_t, ipc::in_place_t>::value));
+  [](ipc::in_place_t) {}(std::in_place);
+  [](std::in_place_t) {}(ipc::in_place);
+}
+#endif/*LIBIPC_CPP_17*/
+
+TEST(generic, copy_cvref) {
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int   , long>, long   >()));
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int & , long>, long & >()));
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int &&, long>, long &&>()));
+
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int const   , long>, long const   >()));
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int const & , long>, long const & >()));
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int const &&, long>, long const &&>()));
+
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int volatile   , long>, long volatile   >()));
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int volatile & , long>, long volatile & >()));
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int volatile &&, long>, long volatile &&>()));
+
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int const volatile   , long>, long const volatile   >()));
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int const volatile & , long>, long const volatile & >()));
+  EXPECT_TRUE((std::is_same<ipc::copy_cvref_t<int const volatile &&, long>, long const volatile &&>()));
+}
diff --git a/test/imp/test_imp_log.cpp b/test/imp/test_imp_log.cpp
new file mode 100644
index 00000000..307eb108
--- /dev/null
+++ b/test/imp/test_imp_log.cpp
@@ -0,0 +1,46 @@
+
+#include <iostream>
+#include <string>
+
+#include "test.h"
+
+#include "libipc/imp/log.h"
+
+TEST(log, logger) {
+  {
+    LIBIPC_LOG();
+    log.info("hello");
+  }
+  {
+    LIBIPC_LOG();
+    log.info("hello 2");
+  }
+  {
+    LIBIPC_LOG();
+    log.info("hello ", 3);
+  }
+  SUCCEED();
+}
+
+TEST(log, custom) {
+  struct log {
+    std::string i;
+    std::string e;
+  } ll_data;
+  auto ll = [&ll_data](auto &&ctx) {
+    auto s = ipc::fmt(ctx.params);
+    if (ctx.level == ipc::log::level::error) ll_data.e += s + " ";
+    else
+    if (ctx.level == ipc::log::level::info ) ll_data.i += s + " ";
+  };
+
+  LIBIPC_LOG(ll);
+
+  log.info ("hello", " world");
+  log.error("failed", ":");
+  log.info ("log", '-', "pt");
+  log.error("whatever");
+
+  EXPECT_EQ(ll_data.i, "hello world log-pt ");
+  EXPECT_EQ(ll_data.e, "failed: whatever ");
+}
diff --git a/test/imp/test_imp_result.cpp b/test/imp/test_imp_result.cpp
new file mode 100644
index 00000000..00a19217
--- /dev/null
+++ b/test/imp/test_imp_result.cpp
@@ -0,0 +1,67 @@
+
+#include <sstream>
+#include <cstdint>
+
+#include "test.h"
+
+#include "libipc/imp/result.h"
+
+TEST(result, ok) {
+  ipc::result<std::uint64_t> ret;
+  EXPECT_FALSE(ret);
+  EXPECT_FALSE(ret.ok());
+  EXPECT_EQ(ret.value(), 0);
+
+  ret = {0};
+  EXPECT_TRUE(ret);
+  EXPECT_TRUE(ret.ok());
+  EXPECT_EQ(ret.value(), 0);
+
+  ret = ipc::result<std::uint64_t>(1234);
+  EXPECT_TRUE(ret);
+  EXPECT_TRUE(ret.ok());
+  EXPECT_EQ(ret.value(), 1234);
+
+  ret = std::error_code{9999, std::generic_category()};
+  EXPECT_FALSE(ret);
+  EXPECT_FALSE(ret.ok());
+  EXPECT_EQ(ret.value(), 0);
+
+  ret = 4321;
+  EXPECT_TRUE(ret);
+  EXPECT_TRUE(ret.ok());
+  EXPECT_EQ(ret.value(), 4321);
+
+  ipc::result<void> r1;
+  EXPECT_FALSE(r1);
+  r1 = std::error_code{};
+  EXPECT_TRUE(r1);
+  r1 = {};
+  EXPECT_FALSE(r1);
+  r1 = std::error_code{9999, std::generic_category()};
+  EXPECT_FALSE(r1);
+  EXPECT_EQ(r1.error().value(), 9999);
+
+  ipc::result<int *> r2 {nullptr, std::error_code{4321, std::generic_category()}};
+  EXPECT_NE(r2, nullptr); // ipc::result<int *>{nullptr}
+  EXPECT_EQ(*r2, nullptr);
+  EXPECT_FALSE(r2);
+}
+
+TEST(result, compare) {
+  ipc::result<std::uint64_t> r1, r2;
+  EXPECT_EQ(r1, r2);
+
+  ipc::result<std::uint64_t> r3(0);
+  EXPECT_NE(r1, r3);
+
+  ipc::result<std::uint64_t> r4(222222);
+  EXPECT_NE(r3, r4);
+
+  ipc::result<std::uint64_t> r5(std::error_code{9999, std::generic_category()});
+  EXPECT_NE(r4, r5);
+  EXPECT_NE(r3, r5);
+
+  r3 = r5;
+  EXPECT_EQ(r3, r5);
+}
diff --git a/test/imp/test_imp_span.cpp b/test/imp/test_imp_span.cpp
new file mode 100644
index 00000000..15393b19
--- /dev/null
+++ b/test/imp/test_imp_span.cpp
@@ -0,0 +1,66 @@
+
+#include "test.h"
+
+#include "libipc/imp/span.h"
+#include "libipc/imp/generic.h"
+#include "libipc/imp/byte.h"
+
+TEST(span, to_address) {
+  int *a = new int;
+  EXPECT_EQ(ipc::detail_span::to_address(a), a);
+  std::unique_ptr<int> b {a};
+  EXPECT_EQ(ipc::detail_span::to_address(b), a);
+}
+
+TEST(span, span) {
+  auto test_proc = [](auto &&buf, auto &&sp) {
+    EXPECT_EQ(ipc::countof(buf), sp.size());
+    EXPECT_EQ(sizeof(buf[0]) * ipc::countof(buf), sp.size_bytes());
+    for (std::size_t i = 0; i < sp.size(); ++i) {
+      EXPECT_EQ(buf[i], sp[i]);
+    }
+  };
+  {
+    int buf[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+    auto sp = ipc::make_span(buf);
+    test_proc(buf, sp);
+    test_proc(ipc::make_span({0, 1, 2})   , sp.first(3));
+    test_proc(ipc::make_span({6, 7, 8, 9}), sp.last(4));
+    test_proc(ipc::make_span({3, 4, 5, 6}), sp.subspan(3, 4));
+    test_proc(ipc::make_span({3, 4, 5, 6, 7, 8, 9}), sp.subspan(3));
+  }
+  {
+    std::vector<int> buf = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+    auto sp = ipc::make_span(buf);
+    ipc::span<int> sp2 {buf.begin(), buf.end()};
+    EXPECT_EQ(sp, sp2);
+    test_proc(buf, sp);
+    test_proc(ipc::make_span({0, 1, 2})   , sp.first(3));
+    test_proc(ipc::make_span({6, 7, 8, 9}), sp.last(4));
+    test_proc(ipc::make_span({3, 4, 5, 6}), sp.subspan(3, 4));
+    test_proc(ipc::make_span({3, 4, 5, 6, 7, 8, 9}), sp.subspan(3));
+    test_proc(ipc::make_span((ipc::byte *)sp.data(), sp.size_bytes()), ipc::as_bytes(sp));
+  }
+  {
+    std::string buf = "0123456789";
+    auto sp = ipc::make_span(buf);
+    // if (sp == ipc::make_span({nullptr})) {}
+    test_proc(buf, sp);
+    test_proc(ipc::make_span("012", 3) , sp.first(3));
+    test_proc(ipc::make_span("6789", 4), sp.last(4));
+    test_proc(ipc::make_span("3456", 4), sp.subspan(3, 4));
+    test_proc(ipc::make_span("3456789", 7), sp.subspan(3));
+  }
+}
+
+TEST(span, construct) {
+  struct test_imp_span_construct {
+    /* data */
+    int  size() const noexcept { return sizeof(this); }
+    auto Data() const noexcept { return this; }
+  } d1;
+  ipc::span<test_imp_span_construct const> sp {d1};
+  // ipc::span<int const> spp {d1};
+  EXPECT_EQ(sp.size(), d1.size());
+  EXPECT_EQ(sp.data(), d1.Data());
+}
diff --git a/test/imp/test_imp_system.cpp b/test/imp/test_imp_system.cpp
new file mode 100644
index 00000000..90d57bd9
--- /dev/null
+++ b/test/imp/test_imp_system.cpp
@@ -0,0 +1,10 @@
+
+#include "test.h"
+
+#include "libipc/imp/system.h"
+
+TEST(system, conf) {
+  auto ret = ipc::sys::conf(ipc::sys::info::page_size);
+  EXPECT_TRUE(ret);
+  EXPECT_GE(ret.value(), 4096);
+}
diff --git a/test/imp/test_imp_uninitialized.cpp b/test/imp/test_imp_uninitialized.cpp
new file mode 100644
index 00000000..dcaa8c34
--- /dev/null
+++ b/test/imp/test_imp_uninitialized.cpp
@@ -0,0 +1,46 @@
+
+#include "test.h"
+
+#include "libipc/imp/uninitialized.h"
+
+TEST(uninitialized, construct) {
+  struct Foo {
+    int a_;
+    short b_;
+    char c_;
+  };
+  std::aligned_storage_t<sizeof(Foo)> foo;
+  Foo *pfoo = ipc::construct<Foo>(&foo, 123, short{321}, '1');
+  EXPECT_EQ(pfoo->a_, 123);
+  EXPECT_EQ(pfoo->b_, 321);
+  EXPECT_EQ(pfoo->c_, '1');
+  ipc::destroy(pfoo);
+
+  static int bar_test_flag = 0;
+  struct Bar : Foo {
+    Bar(int a, short b, char c)
+        : Foo{a, b, c} {
+      ++bar_test_flag;
+    }
+    ~Bar() { --bar_test_flag; }
+  };
+  std::aligned_storage_t<sizeof(Bar)> bar;
+  Bar *pbar = ipc::construct<Bar>(&bar, 123, short(321), '1');
+  EXPECT_EQ(pbar->a_, 123);
+  EXPECT_EQ(pbar->b_, 321);
+  EXPECT_EQ(pbar->c_, '1');
+  EXPECT_EQ(bar_test_flag, 1);
+  ipc::destroy(pbar);
+  EXPECT_EQ(bar_test_flag, 0);
+
+  std::aligned_storage_t<sizeof(Bar)> bars[3];
+  for (auto &b : bars) {
+    auto pb = ipc::construct<Bar>(&b, 321, short(123), '3');
+    EXPECT_EQ(pb->a_, 321);
+    EXPECT_EQ(pb->b_, 123);
+    EXPECT_EQ(pb->c_, '3');
+  }
+  //EXPECT_EQ(bar_test_flag, ipc::countof(bars));
+  ipc::destroy(reinterpret_cast<Bar(*)[3]>(&bars));
+  EXPECT_EQ(bar_test_flag, 0);
+}
diff --git a/test/mem/test_mem_block_pool.cpp b/test/mem/test_mem_block_pool.cpp
new file mode 100644
index 00000000..f38662e7
--- /dev/null
+++ b/test/mem/test_mem_block_pool.cpp
@@ -0,0 +1,32 @@
+
+#include "test.h"
+
+#include <utility>
+
+#include "libipc/mem/block_pool.h"
+
+TEST(block_pool, ctor) {
+  ASSERT_TRUE ((std::is_default_constructible<ipc::mem::block_pool<1, 1>>::value));
+  ASSERT_FALSE((std::is_copy_constructible<ipc::mem::block_pool<1, 1>>::value));
+  ASSERT_TRUE ((std::is_move_constructible<ipc::mem::block_pool<1, 1>>::value));
+  ASSERT_FALSE((std::is_copy_assignable<ipc::mem::block_pool<1, 1>>::value));
+  ASSERT_FALSE((std::is_move_assignable<ipc::mem::block_pool<1, 1>>::value));
+}
+
+TEST(block_pool, allocate) {
+  std::vector<void *> v;
+  ipc::mem::block_pool<1, 1> pool;
+  for (int i = 0; i < 100; ++i) {
+    v.push_back(pool.allocate());
+  }
+  for (void *p: v) {
+    ASSERT_FALSE(nullptr == p);
+    pool.deallocate(p);
+  }
+  for (int i = 0; i < 100; ++i) {
+    ASSERT_EQ(v[v.size() - i - 1], pool.allocate());
+  }
+  for (void *p: v) {
+    pool.deallocate(p);
+  }
+}
diff --git a/test/mem/test_mem_bytes_allocator.cpp b/test/mem/test_mem_bytes_allocator.cpp
new file mode 100644
index 00000000..05483f7d
--- /dev/null
+++ b/test/mem/test_mem_bytes_allocator.cpp
@@ -0,0 +1,103 @@
+
+#include <vector>
+#include <utility>
+
+#include "test.h"
+
+#if defined(LIBIPC_CPP_17) && defined(__cpp_lib_memory_resource)
+# include <memory_resource>
+#endif
+
+#include "libipc/mem/bytes_allocator.h"
+#include "libipc/mem/memory_resource.h"
+
+TEST(bytes_allocator, ctor) {
+  ipc::mem::bytes_allocator alc;
+  SUCCEED();
+}
+
+TEST(bytes_allocator, ctor_value_initialization) {
+  ipc::mem::bytes_allocator alc{};
+  auto p = alc.allocate(128);
+  EXPECT_NE(p, nullptr);
+  EXPECT_NO_THROW(alc.deallocate(p, 128));
+}
+
+namespace {
+
+class dummy_resource {
+public:
+  void *allocate(std::size_t, std::size_t = 0) noexcept {
+    return nullptr;
+  }
+  void deallocate(void *, std::size_t, std::size_t = 0) noexcept {
+    return;
+  }
+};
+
+} // namespace
+
+TEST(bytes_allocator, memory_resource_traits) {
+  EXPECT_FALSE(ipc::mem::has_allocate<void>::value);
+  EXPECT_FALSE(ipc::mem::has_allocate<int>::value);
+  EXPECT_FALSE(ipc::mem::has_allocate<std::vector<int>>::value);
+  EXPECT_FALSE(ipc::mem::has_allocate<std::allocator<int>>::value);
+#if defined(LIBIMP_CPP_17) && defined(__cpp_lib_memory_resource)
+  EXPECT_TRUE (ipc::mem::has_allocate<std::ipc::mem::memory_resource>::value);
+  EXPECT_TRUE (ipc::mem::has_allocate<std::ipc::mem::container_allocator<int>>::value);
+#endif
+
+  EXPECT_FALSE(ipc::mem::has_deallocate<void>::value);
+  EXPECT_FALSE(ipc::mem::has_deallocate<int>::value);
+  EXPECT_FALSE(ipc::mem::has_deallocate<std::vector<int>>::value);
+  EXPECT_FALSE(ipc::mem::has_deallocate<std::allocator<int>>::value);
+#if defined(LIBIMP_CPP_17) && defined(__cpp_lib_memory_resource)
+  EXPECT_TRUE (ipc::mem::has_deallocate<std::ipc::mem::memory_resource>::value);
+  EXPECT_FALSE(ipc::mem::has_deallocate<std::ipc::mem::container_allocator<int>>::value);
+#endif
+}
+
+TEST(bytes_allocator, ctor_copy_move) {
+  ipc::mem::new_delete_resource mem_res;
+  dummy_resource dummy_res;
+  ipc::mem::bytes_allocator alc1{&mem_res}, alc2{&dummy_res};
+  auto p = alc1.allocate(128);
+  ASSERT_NE(p, nullptr);
+  ASSERT_NO_THROW(alc1.deallocate(p, 128));
+  ASSERT_EQ(alc2.allocate(128), nullptr);
+
+  ipc::mem::bytes_allocator alc3{alc1}, alc4{alc2}, alc5{std::move(alc1)};
+
+  p = alc3.allocate(128);
+  ASSERT_NE(p, nullptr);
+  ASSERT_NO_THROW(alc3.deallocate(p, 128));
+
+  ASSERT_EQ(alc4.allocate(128), nullptr);
+
+  p = alc5.allocate(128);
+  ASSERT_NE(p, nullptr);
+  ASSERT_NO_THROW(alc5.deallocate(p, 128));
+}
+
+TEST(bytes_allocator, swap) {
+  ipc::mem::new_delete_resource mem_res;
+  dummy_resource dummy_res;
+  ipc::mem::bytes_allocator alc1{&mem_res}, alc2{&dummy_res};
+  alc1.swap(alc2);
+  auto p = alc2.allocate(128);
+  ASSERT_NE(p, nullptr);
+  ASSERT_NO_THROW(alc2.deallocate(p, 128));
+  ASSERT_EQ(alc1.allocate(128), nullptr);
+}
+
+TEST(bytes_allocator, invalid_alloc_free) {
+  ipc::mem::bytes_allocator alc1;
+  EXPECT_EQ(alc1.allocate(0), nullptr);
+  EXPECT_NO_THROW(alc1.deallocate(nullptr, 128));
+  EXPECT_NO_THROW(alc1.deallocate(nullptr, 0));
+  EXPECT_NO_THROW(alc1.deallocate(&alc1, 0));
+}
+
+TEST(bytes_allocator, sizeof) {
+  EXPECT_EQ(sizeof(ipc::mem::bytes_allocator), sizeof(void *) * 2);
+}
diff --git a/test/mem/test_mem_central_cache_allocator.cpp b/test/mem/test_mem_central_cache_allocator.cpp
new file mode 100644
index 00000000..0ab67aac
--- /dev/null
+++ b/test/mem/test_mem_central_cache_allocator.cpp
@@ -0,0 +1,15 @@
+
+#include "test.h"
+
+#include <utility>
+
+#include "libipc/mem/central_cache_allocator.h"
+
+TEST(central_cache_allocator, allocate) {
+  auto &a = ipc::mem::central_cache_allocator();
+  ASSERT_FALSE(nullptr == a.allocate(1));
+  ASSERT_FALSE(nullptr == a.allocate(10));
+  ASSERT_FALSE(nullptr == a.allocate(100));
+  ASSERT_FALSE(nullptr == a.allocate(1000));
+  ASSERT_FALSE(nullptr == a.allocate(10000));
+}
diff --git a/test/mem/test_mem_central_cache_pool.cpp b/test/mem/test_mem_central_cache_pool.cpp
new file mode 100644
index 00000000..4e1ff5af
--- /dev/null
+++ b/test/mem/test_mem_central_cache_pool.cpp
@@ -0,0 +1,44 @@
+
+#include "test.h"
+
+#include <utility>
+
+#include "libipc/mem/central_cache_pool.h"
+
+TEST(central_cache_pool, ctor) {
+  ASSERT_FALSE((std::is_default_constructible<ipc::mem::central_cache_pool<ipc::mem::block<1>, 1>>::value));
+  ASSERT_FALSE((std::is_copy_constructible<ipc::mem::central_cache_pool<ipc::mem::block<1>, 1>>::value));
+  ASSERT_FALSE((std::is_move_constructible<ipc::mem::central_cache_pool<ipc::mem::block<1>, 1>>::value));
+  ASSERT_FALSE((std::is_copy_assignable<ipc::mem::central_cache_pool<ipc::mem::block<1>, 1>>::value));
+  ASSERT_FALSE((std::is_move_assignable<ipc::mem::central_cache_pool<ipc::mem::block<1>, 1>>::value));
+  {
+    auto &pool = ipc::mem::central_cache_pool<ipc::mem::block<1024>, 1>::instance();
+    ipc::mem::block<1024> *b1 = pool.aqueire();
+    ASSERT_FALSE(nullptr == b1);
+    EXPECT_TRUE (nullptr == b1->next);
+    pool.release(b1);
+    ipc::mem::block<1024> *b2 = pool.aqueire();
+    EXPECT_EQ(b1, b2);
+    ipc::mem::block<1024> *b3 = pool.aqueire();
+    ASSERT_FALSE(nullptr == b3);
+    EXPECT_TRUE (nullptr == b3->next);
+    EXPECT_NE(b1, b3);
+  }
+  {
+    auto &pool = ipc::mem::central_cache_pool<ipc::mem::block<1>, 2>::instance();
+    ipc::mem::block<1> *b1 = pool.aqueire();
+    ASSERT_FALSE(nullptr == b1);
+    ASSERT_FALSE(nullptr == b1->next);
+    EXPECT_TRUE (nullptr == b1->next->next);
+    pool.release(b1);
+    ipc::mem::block<1> *b2 = pool.aqueire();
+    EXPECT_EQ(b1, b2);
+    ipc::mem::block<1> *b3 = pool.aqueire();
+    EXPECT_NE(b1, b3);
+    ipc::mem::block<1> *b4 = pool.aqueire();
+    ASSERT_FALSE(nullptr == b4);
+    ASSERT_FALSE(nullptr == b4->next);
+    EXPECT_TRUE (nullptr == b4->next->next);
+    EXPECT_NE(b1, b4);
+  }
+}
diff --git a/test/mem/test_mem_memory_resource.cpp b/test/mem/test_mem_memory_resource.cpp
new file mode 100644
index 00000000..736ed6cf
--- /dev/null
+++ b/test/mem/test_mem_memory_resource.cpp
@@ -0,0 +1,165 @@
+
+#include "test.h"
+
+#include <utility>
+
+#include "libipc/mem/memory_resource.h"
+
+namespace {
+
+template <typename T>
+void *test_mr(T &&mr, std::size_t bytes, std::size_t alignment) {
+  auto p = std::forward<T>(mr).allocate(bytes, alignment);
+  if (alignment == 0) {
+    EXPECT_EQ(p, nullptr);
+  } else if (p != nullptr) {
+    EXPECT_EQ((std::size_t)p % alignment, 0);
+  }
+  std::forward<T>(mr).deallocate(p, bytes, alignment);
+  return p;
+}
+
+} // namespace
+
+TEST(memory_resource, new_delete_resource) {
+  ipc::mem::new_delete_resource mem_res;
+
+  EXPECT_EQ(test_mr(mem_res, 0, 0), nullptr);
+  EXPECT_EQ(test_mr(mem_res, 0, 1), nullptr);
+  EXPECT_EQ(test_mr(mem_res, 0, 2), nullptr);
+  EXPECT_EQ(test_mr(mem_res, 0, 3), nullptr);
+  EXPECT_EQ(test_mr(mem_res, 0, 8), nullptr);
+  EXPECT_EQ(test_mr(mem_res, 0, 64), nullptr);
+
+  EXPECT_EQ(test_mr(mem_res, 1, 0), nullptr);
+  EXPECT_NE(test_mr(mem_res, 1, 1), nullptr);
+  EXPECT_NE(test_mr(mem_res, 1, 2), nullptr);
+  EXPECT_EQ(test_mr(mem_res, 1, 3), nullptr);
+  EXPECT_NE(test_mr(mem_res, 1, 8), nullptr);
+  EXPECT_NE(test_mr(mem_res, 1, 64), nullptr);
+}
+
+TEST(memory_resource, monotonic_buffer_resource_construct) {
+  { ipc::mem::monotonic_buffer_resource tmp; }
+  ipc::mem::monotonic_buffer_resource{};
+  ipc::mem::monotonic_buffer_resource{ipc::mem::bytes_allocator{}};
+  ipc::mem::monotonic_buffer_resource{0};
+  ipc::mem::monotonic_buffer_resource{0, ipc::mem::bytes_allocator{}};
+  ipc::mem::monotonic_buffer_resource{ipc::span<ipc::byte>{}};
+  ipc::mem::monotonic_buffer_resource{ipc::span<ipc::byte>{}, ipc::mem::bytes_allocator{}};
+  SUCCEED();
+}
+
+TEST(memory_resource, monotonic_buffer_resource_no_copy) {
+  EXPECT_FALSE(std::is_copy_constructible<ipc::mem::monotonic_buffer_resource>::value);
+  EXPECT_FALSE(std::is_copy_assignable<ipc::mem::monotonic_buffer_resource>::value);
+  EXPECT_FALSE(std::is_move_constructible<ipc::mem::monotonic_buffer_resource>::value);
+  EXPECT_FALSE(std::is_move_assignable<ipc::mem::monotonic_buffer_resource>::value);
+}
+
+TEST(memory_resource, monotonic_buffer_resource_upstream_resource) {
+  struct dummy_allocator {
+    bool allocated = false;
+    void *allocate(std::size_t, std::size_t) noexcept { allocated = true; return nullptr; }
+    void deallocate(void *, std::size_t, std::size_t) noexcept {}
+  } dummy;
+  ipc::mem::monotonic_buffer_resource tmp{&dummy};
+  ASSERT_EQ(tmp.upstream_resource().allocate(1), nullptr);
+  ASSERT_TRUE(dummy.allocated);
+}
+
+namespace {
+
+struct dummy_allocator {
+  std::size_t allocated = 0;
+  void *allocate(std::size_t size, std::size_t) noexcept {
+    allocated += size;
+    return std::malloc(size);
+  }
+  void deallocate(void *p, std::size_t size, std::size_t) noexcept {
+    allocated -= size;
+    std::free(p);
+  }
+};
+
+} // namespace
+
+TEST(memory_resource, monotonic_buffer_resource_allocate) {
+  dummy_allocator dummy;
+  {
+    ipc::mem::monotonic_buffer_resource tmp{&dummy};
+    ASSERT_EQ(tmp.allocate(0), nullptr);
+    ASSERT_EQ(dummy.allocated, 0);
+  }
+  ASSERT_EQ(dummy.allocated, 0);
+  {
+    ipc::mem::monotonic_buffer_resource tmp{&dummy};
+    std::size_t sz = 0;
+    for (std::size_t i = 1; i < 1024; ++i) {
+      ASSERT_NE(tmp.allocate(i), nullptr);
+      sz += i;
+    }
+    for (std::size_t i = 1; i < 1024; ++i) {
+      ASSERT_NE(tmp.allocate(1024 - i), nullptr);
+      sz += 1024 - i;
+    }
+    ASSERT_GE(dummy.allocated, sz);
+  }
+  ASSERT_EQ(dummy.allocated, 0);
+}
+
+TEST(memory_resource, monotonic_buffer_resource_allocate_by_buffer) {
+  dummy_allocator dummy;
+  std::array<ipc::byte, 4096> buffer;
+  {
+    ipc::mem::monotonic_buffer_resource tmp{buffer, &dummy};
+    for (std::size_t i = 1; i < 64; ++i) {
+      ASSERT_NE(tmp.allocate(i), nullptr);
+    }
+    ASSERT_EQ(dummy.allocated, 0);
+    std::size_t sz = 0;
+    for (std::size_t i = 1; i < 64; ++i) {
+      ASSERT_NE(tmp.allocate(64 - i), nullptr);
+      sz += 64 - i;
+    }
+    ASSERT_GT(dummy.allocated, sz);
+  }
+  ASSERT_EQ(dummy.allocated, 0);
+}
+
+TEST(memory_resource, monotonic_buffer_resource_release) {
+  dummy_allocator dummy;
+  {
+    ipc::mem::monotonic_buffer_resource tmp{&dummy};
+    tmp.release();
+    ASSERT_EQ(dummy.allocated, 0);
+    ASSERT_NE(tmp.allocate(1024), nullptr);
+    ASSERT_GE(dummy.allocated, 1024u);
+    ASSERT_LE(dummy.allocated, 1024u * 1.5);
+    tmp.release();
+    ASSERT_EQ(dummy.allocated, 0);
+    ASSERT_NE(tmp.allocate(1024), nullptr);
+    ASSERT_GE(dummy.allocated, 1024u);
+    ASSERT_LE(dummy.allocated, 1024u * 1.5);
+  }
+  ASSERT_EQ(dummy.allocated, 0);
+  std::array<ipc::byte, 4096> buffer;
+  {
+    ipc::mem::monotonic_buffer_resource tmp{buffer, &dummy};
+    auto *p = tmp.allocate(1024);
+    ASSERT_EQ(p, buffer.data());
+    ASSERT_EQ(dummy.allocated, 0);
+    p = tmp.allocate(10240);
+    ASSERT_NE(p, buffer.data());
+    ASSERT_LE(dummy.allocated, 10240u + 1024u);
+    tmp.release();
+    ASSERT_EQ(dummy.allocated, 0);
+    p = tmp.allocate(1024);
+    ASSERT_EQ(p, buffer.data());
+    ASSERT_EQ(dummy.allocated, 0);
+    p = tmp.allocate(10240);
+    ASSERT_NE(p, buffer.data());
+    ASSERT_LE(dummy.allocated, 10240u + 1024u);
+  }
+  ASSERT_EQ(dummy.allocated, 0);
+}
diff --git a/test/mem/test_mem_new.cpp b/test/mem/test_mem_new.cpp
new file mode 100644
index 00000000..85a79043
--- /dev/null
+++ b/test/mem/test_mem_new.cpp
@@ -0,0 +1,172 @@
+
+#include <limits>
+#include <array>
+#include <cstring>
+#include <cstddef>
+#include <thread>
+
+#include "test.h"
+
+#include "libipc/mem/new.h"
+
+TEST(new, new) {
+  auto p = ipc::mem::$new<int>();
+  ASSERT_NE(p, nullptr);
+  *p = -1;
+  ASSERT_EQ(*p, -1);
+  ipc::mem::$delete(p);
+}
+
+TEST(new, new_value) {
+  auto p = ipc::mem::$new<int>((std::numeric_limits<int>::max)());
+  ASSERT_NE(p, nullptr);
+  ASSERT_EQ(*p, (std::numeric_limits<int>::max)());
+  ipc::mem::$delete(p);
+}
+
+namespace {
+
+template <std::size_t Pts, std::size_t N>
+void test_new$array() {
+  std::array<void *, Pts> pts;
+  using T = std::array<char, N>;
+  for (int i = 0; i < (int)pts.size(); ++i) {
+    auto p = ipc::mem::$new<T>();
+    pts[i] = p;
+    std::memset(p, i, sizeof(T));
+  }
+  for (int i = 0; i < (int)pts.size(); ++i) {
+    T tmp;
+    std::memset(&tmp, i, sizeof(T));
+    ASSERT_EQ(std::memcmp(pts[i], &tmp, sizeof(T)), 0);
+    ipc::mem::$delete(static_cast<T *>(pts[i]));
+  }
+}
+
+} // namespace
+
+TEST(new, new_array) {
+  test_new$array<1000, 10>();
+  test_new$array<1000, 100>();
+  test_new$array<1000, 1000>();
+  test_new$array<1000, 10000>();
+  test_new$array<1000, 100000>();
+  // test_new$array<1000, 1000000>();
+}
+
+namespace {
+
+int construct_count__ = 0;
+
+class Base {
+public:
+  virtual ~Base() = default;
+  virtual int get() const = 0;
+};
+
+class Derived : public Base {
+public:
+  Derived(int value) : value_(value) {
+    construct_count__ = value_;
+  }
+
+  ~Derived() override {
+    construct_count__ = 0;
+  }
+
+  int get() const override { return value_; }
+
+private:
+  int value_;
+};
+
+class Derived64K : public Derived {
+public:
+  using Derived::Derived;
+
+private:
+  std::array<char, 65536> padding_;
+};
+
+} // namespace
+
+TEST(new, delete_poly) {
+  Base *p = ipc::mem::$new<Derived>(-1);
+  ASSERT_NE(p, nullptr);
+  ASSERT_EQ(p->get(), -1);
+  ASSERT_EQ(construct_count__, -1);
+  ipc::mem::$delete(p);
+  ASSERT_EQ(construct_count__, 0);
+
+  ASSERT_EQ(p, ipc::mem::$new<Derived>((std::numeric_limits<int>::max)()));
+  ASSERT_EQ(p->get(), (std::numeric_limits<int>::max)());
+  ASSERT_EQ(construct_count__, (std::numeric_limits<int>::max)());
+  ipc::mem::$delete(p);
+  ASSERT_EQ(construct_count__, 0);
+}
+
+TEST(new, delete_poly64k) {
+  Base *p = ipc::mem::$new<Derived64K>(-1);
+  ASSERT_NE(p, nullptr);
+  ASSERT_EQ(p->get(), -1);
+  ASSERT_EQ(construct_count__, -1);
+  ipc::mem::$delete(p);
+  ASSERT_EQ(construct_count__, 0);
+
+  Base *q = ipc::mem::$new<Derived64K>((std::numeric_limits<int>::max)());
+  ASSERT_EQ(q->get(), (std::numeric_limits<int>::max)());
+  ASSERT_EQ(construct_count__, (std::numeric_limits<int>::max)());
+  ipc::mem::$delete(q);
+  ASSERT_EQ(construct_count__, 0);
+}
+
+TEST(new, delete_null) {
+  Base *p = nullptr;
+  ipc::mem::$delete(p);
+  SUCCEED();
+}
+
+TEST(new, malloc) {
+  void *p = ipc::mem::$new<void>(0);
+  ASSERT_EQ(p, nullptr);
+  ipc::mem::$delete(p);
+  p = ipc::mem::$new<void>(1024);
+  ASSERT_NE(p, nullptr);
+  ipc::mem::$delete(p);
+
+  p = ipc::mem::$new<Derived>(-1);
+  ASSERT_NE(p, nullptr);
+  ASSERT_EQ(((Derived *)p)->get(), -1);
+  ASSERT_EQ(construct_count__, -1);
+  ipc::mem::$delete(p);
+  ASSERT_EQ(construct_count__, 0);
+}
+
+TEST(new, multi_thread) {
+  std::array<std::thread, 16> threads;
+  for (auto &t : threads) {
+    t = std::thread([] {
+      for (int i = 0; i < 10000; ++i) {
+        auto p = ipc::mem::$new<int>();
+        *p = i;
+        ipc::mem::$delete(p);
+      }
+      std::array<void *, 10000> pts;
+      for (int i = 0; i < 10000; ++i) {
+        auto p = ipc::mem::$new<std::array<char, 10>>();
+        pts[i] = p;
+        std::memset(p, i, sizeof(std::array<char, 10>));
+      }
+      for (int i = 0; i < 10000; ++i) {
+        std::array<char, 10> tmp;
+        std::memset(&tmp, i, sizeof(std::array<char, 10>));
+        ASSERT_EQ(std::memcmp(pts[i], &tmp, sizeof(std::array<char, 10>)), 0);
+        ipc::mem::$delete(static_cast<std::array<char, 10> *>(pts[i]));
+      }
+    });
+  }
+  for (auto &t : threads) {
+    t.join();
+  }
+  SUCCEED();
+}
diff --git a/test/test.h b/test/test.h
index db05eed7..7f3ef93f 100755
--- a/test/test.h
+++ b/test/test.h
@@ -15,7 +15,7 @@
 #include "thread_pool.h"
 
 #include "libipc/platform/detail.h"
-#ifdef IPC_OS_LINUX_
+#ifdef LIBIPC_OS_LINUX
 #include <fcntl.h> // ::open
 #endif
 
@@ -88,7 +88,7 @@ inline static thread_pool & reader() {
     return pool;
 }
 
-#ifdef IPC_OS_LINUX_
+#ifdef LIBIPC_OS_LINUX
 inline bool check_exist(char const *name) noexcept {
     int fd = ::open((std::string{"/dev/shm/"} + name).c_str(), O_RDONLY);
     if (fd == -1) {
@@ -100,7 +100,7 @@ inline bool check_exist(char const *name) noexcept {
 #endif
 
 inline bool expect_exist(char const *name, bool expected) noexcept {
-#ifdef IPC_OS_LINUX_
+#ifdef LIBIPC_OS_LINUX
     return ipc_ut::check_exist(name) == expected;
 #else
     return true;
diff --git a/test/test_ipc.cpp b/test/test_ipc.cpp
index 5bd828b4..00dcd276 100755
--- a/test/test_ipc.cpp
+++ b/test/test_ipc.cpp
@@ -4,10 +4,11 @@
 #include <mutex>
 #include <atomic>
 #include <cstring>
+#include <new>
 
 #include "libipc/ipc.h"
 #include "libipc/buffer.h"
-#include "libipc/memory/resource.h"
+#include "libipc/mem/resource.h"
 
 #include "test.h"
 #include "thread_pool.h"
@@ -84,18 +85,19 @@ void test_basic(char const * name) {
 }
 
 class data_set {
-    std::vector<rand_buf> datas_;
+    alignas(rand_buf) char datas_[sizeof(rand_buf[LoopCount])];
+    rand_buf *d_;
 
 public:
     data_set() {
-        datas_.resize(LoopCount);
+        d_ = ::new(datas_) rand_buf[LoopCount];
         for (int i = 0; i < LoopCount; ++i) {
-            datas_[i].set_id(i);
+            d_[i].set_id(i);
         }
     }
 
-    std::vector<rand_buf> const &get() const noexcept {
-        return datas_;
+    rand_buf const *get() const noexcept {
+        return d_;
     }
 } const data_set__;
 
@@ -112,7 +114,7 @@ void test_sr(char const * name, int s_cnt, int r_cnt) {
             Que que { name, ipc::sender };
             ASSERT_TRUE(que.wait_for_recv(r_cnt));
             sw.start();
-            for (int i = 0; i < (int)data_set__.get().size(); ++i) {
+            for (int i = 0; i < LoopCount; ++i) {
                 ASSERT_TRUE(que.send(data_set__.get()[i]));
             }
         };
@@ -128,7 +130,7 @@ void test_sr(char const * name, int s_cnt, int r_cnt) {
                 if (i == -1) {
                     return;
                 }
-                ASSERT_TRUE((i >= 0) && (i < (int)data_set__.get().size()));
+                ASSERT_TRUE((i >= 0) && (i < LoopCount));
                 auto const &data_set = data_set__.get()[i];
                 if (data_set != got) {
                     printf("data_set__.get()[%d] != got, size = %zd/%zd\n", 
@@ -146,7 +148,7 @@ void test_sr(char const * name, int s_cnt, int r_cnt) {
         que.send(rand_buf{msg_head{-1}});
     }
     ipc_ut::reader().wait_for_done();
-    sw.print_elapsed<std::chrono::microseconds>(s_cnt, r_cnt, (int)data_set__.get().size(), name);
+    sw.print_elapsed<std::chrono::microseconds>(s_cnt, r_cnt, LoopCount, name);
 }
 
 } // internal-linkage
diff --git a/test/test_mem.cpp b/test/test_mem.cpp
deleted file mode 100755
index 16a5ad1d..00000000
--- a/test/test_mem.cpp
+++ /dev/null
@@ -1,218 +0,0 @@
-#include <vector>
-#include <array>
-#include <thread>
-#include <atomic>
-#include <cstddef>
-
-#include "capo/random.hpp"
-
-#include "libipc/memory/resource.h"
-#include "libipc/pool_alloc.h"
-
-// #include "gperftools/tcmalloc.h"
-
-#include "test.h"
-#include "thread_pool.h"
-
-namespace {
-
-constexpr int DataMin   = 4;
-constexpr int DataMax   = 256;
-constexpr int LoopCount = 8388608;
-constexpr int ThreadMax = 8;
-
-// constexpr int DataMin   = 256;
-// constexpr int DataMax   = 512;
-// constexpr int LoopCount = 2097152;
-
-std::vector<std::size_t> sizes__;
-std::vector<void*> ptr_cache__[ThreadMax];
-
-template <typename M>
-struct alloc_ix_t {
-    static std::vector<int> ix_;
-    static bool inited_;
-
-    alloc_ix_t() {
-        if (inited_) return;
-        inited_ = true;
-        M::init();
-    }
-
-    template <int ThreadsN>
-    static int index(std::size_t /*pid*/, std::size_t /*k*/, std::size_t n) {
-        return ix_[n];
-    }
-};
-
-template <typename M>
-std::vector<int> alloc_ix_t<M>::ix_(LoopCount);
-template <typename M>
-bool alloc_ix_t<M>::inited_ = false;
-
-struct alloc_FIFO : alloc_ix_t<alloc_FIFO> {
-    static void init() {
-        for (int i = 0; i < LoopCount; ++i) {
-            ix_[static_cast<std::size_t>(i)] = i;
-        }
-    }
-};
-
-struct alloc_LIFO : alloc_ix_t<alloc_LIFO> {
-    static void init() {
-        for (int i = 0; i < LoopCount; ++i) {
-            ix_[static_cast<std::size_t>(i)] = i;
-        }
-    }
-
-    template <int ThreadsN>
-    static int index(std::size_t pid, std::size_t k, std::size_t n) {
-        constexpr static int CacheSize = LoopCount / ThreadsN;
-        if (k) {
-            return ix_[(CacheSize * (2 * pid + 1)) - 1 - n];
-        }
-        else return ix_[n];
-    }
-};
-
-struct alloc_Random : alloc_ix_t<alloc_Random> {
-    static void init() {
-        capo::random<> rdm_index(0, LoopCount - 1);
-        for (int i = 0; i < LoopCount; ++i) {
-            ix_[static_cast<std::size_t>(i)] = rdm_index();
-        }
-    }
-};
-
-struct Init {
-    Init() {
-        capo::random<> rdm{ DataMin, DataMax };
-        for (int i = 0; i < LoopCount; ++i) {
-            sizes__.emplace_back(static_cast<std::size_t>(rdm()));
-        }
-        for (auto& vec : ptr_cache__) {
-            vec.resize(LoopCount, nullptr);
-        }
-    }
-} init__;
-
-template <typename AllocT, int ThreadsN>
-void benchmark_alloc(char const * message) {
-    std::string msg = std::to_string(ThreadsN) + "\t" + message;
-
-    constexpr static int CacheSize = LoopCount / ThreadsN;
-    ipc_ut::sender().start(static_cast<std::size_t>(ThreadsN));
-    ipc_ut::test_stopwatch sw;
-
-    for (int pid = 0; pid < ThreadsN; ++pid) {
-        ipc_ut::sender() << [&, pid] {
-            sw.start();
-            for (int n = (CacheSize * pid); n < (CacheSize * (pid + 1)); ++n) {
-                std::size_t s = sizes__[n];
-                AllocT::free(AllocT::alloc(s), s);
-            }
-        };
-    }
-
-    ipc_ut::sender().wait_for_done();
-    sw.print_elapsed<1>(DataMin, DataMax, LoopCount, msg.c_str());
-}
-
-template <typename AllocT, typename ModeT, int ThreadsN>
-void benchmark_alloc(char const * message) {
-    std::string msg = std::to_string(ThreadsN) + "\t" + message;
-
-    constexpr static int CacheSize = LoopCount / ThreadsN;
-    ModeT mode;
-    ipc_ut::sender().start(static_cast<std::size_t>(ThreadsN));
-    ipc_ut::test_stopwatch sw;
-
-    for (int pid = 0; pid < ThreadsN; ++pid) {
-        ipc_ut::sender() << [&, pid] {
-            auto& vec = ptr_cache__[pid];
-            sw.start();
-            for (std::size_t k = 0; k < 2; ++k)
-            for (int n = (CacheSize * pid); n < (CacheSize * (pid + 1)); ++n) {
-                int    m = mode.template index<ThreadsN>(pid, k, n);
-                void*& p = vec[static_cast<std::size_t>(m)];
-                std::size_t s  = sizes__[static_cast<std::size_t>(m)];
-                if (p == nullptr) {
-                    p = AllocT::alloc(s);
-                }
-                else {
-                    AllocT::free(p, s);
-                    p = nullptr;
-                }
-            }
-        };
-    }
-
-    ipc_ut::sender().wait_for_done();
-    sw.print_elapsed<1>(DataMin, DataMax, LoopCount, msg.c_str());
-}
-
-template <typename AllocT, typename ModeT, int ThreadsN>
-struct test_performance {
-    static void start(char const * message) {
-        test_performance<AllocT, ModeT, ThreadsN / 2>::start(message);
-        benchmark_alloc<AllocT, ModeT, ThreadsN>(message);
-    }
-};
-
-template <typename AllocT, typename ModeT>
-struct test_performance<AllocT, ModeT, 1> {
-    static void start(char const * message) {
-        benchmark_alloc<AllocT, ModeT, 1>(message);
-    }
-};
-
-template <typename AllocT, int ThreadsN>
-struct test_performance<AllocT, void, ThreadsN> {
-    static void start(char const * message) {
-        test_performance<AllocT, void, ThreadsN / 2>::start(message);
-        benchmark_alloc<AllocT, ThreadsN>(message);
-    }
-};
-
-template <typename AllocT>
-struct test_performance<AllocT, void, 1> {
-    static void start(char const * message) {
-        benchmark_alloc<AllocT, 1>(message);
-    }
-};
-
-// class tc_alloc {
-// public:
-//    static void clear() {}
-
-//    static void* alloc(std::size_t size) {
-//        return size ? tc_malloc(size) : nullptr;
-//    }
-
-//    static void free(void* p, std::size_t size) {
-//        tc_free_sized(p, size);
-//    }
-// };
-/*
-TEST(Memory, static_alloc) {
-    test_performance<ipc::mem::static_alloc, void        , ThreadMax>::start("alloc-free");
-    test_performance<ipc::mem::static_alloc, alloc_FIFO  , ThreadMax>::start("alloc-FIFO");
-    test_performance<ipc::mem::static_alloc, alloc_LIFO  , ThreadMax>::start("alloc-LIFO");
-    test_performance<ipc::mem::static_alloc, alloc_Random, ThreadMax>::start("alloc-Rand");
-}
-
-TEST(Memory, pool_alloc) {
-    test_performance<ipc::mem::async_pool_alloc, void        , ThreadMax>::start("alloc-free");
-    test_performance<ipc::mem::async_pool_alloc, alloc_FIFO  , ThreadMax>::start("alloc-FIFO");
-    test_performance<ipc::mem::async_pool_alloc, alloc_LIFO  , ThreadMax>::start("alloc-LIFO");
-    test_performance<ipc::mem::async_pool_alloc, alloc_Random, ThreadMax>::start("alloc-Rand");
-}
-*/
-// TEST(Memory, tc_alloc) {
-//     test_performance<tc_alloc, void       , ThreadMax>::start();
-//     test_performance<tc_alloc, alloc_FIFO  , ThreadMax>::start();
-//     test_performance<tc_alloc, alloc_LIFO  , ThreadMax>::start();
-//     test_performance<tc_alloc, alloc_Random, ThreadMax>::start();
-// }
-
-} // internal-linkage
diff --git a/test/test_platform.cpp b/test/test_platform.cpp
index 65fa5135..d4d893bd 100644
--- a/test/test_platform.cpp
+++ b/test/test_platform.cpp
@@ -17,11 +17,11 @@ TEST(Platform, to_tchar) {
                        "\x81\xab\xe3\x81\xa1\xe3\x81\xaf";
     wchar_t const *utf16 = L"hello world, \u4f60\u597d\uff0c\u3053\u3093\u306b\u3061\u306f";
     {
-        ipc::string str = ipc::detail::to_tchar<char>(utf8);
+        std::string str = ipc::detail::to_tchar<char>(utf8);
         EXPECT_STREQ(str.c_str(), utf8);
     }
     {
-        ipc::wstring wtr = ipc::detail::to_tchar<wchar_t>(utf8);
+        std::wstring wtr = ipc::detail::to_tchar<wchar_t>(utf8);
         EXPECT_STREQ(wtr.c_str(), utf16);
         //std::ofstream out("out.txt", std::ios::binary|std::ios::out);
         //out.write((char const *)wtr.c_str(), wtr.size() * sizeof(wchar_t));
diff --git a/test/test_sync.cpp b/test/test_sync.cpp
index 61d82d16..be4e44e6 100644
--- a/test/test_sync.cpp
+++ b/test/test_sync.cpp
@@ -10,7 +10,7 @@
 #include "test.h"
 
 #include "libipc/platform/detail.h"
-#if defined(IPC_OS_LINUX_)
+#if defined(LIBIPC_OS_LINUX)
 #include <pthread.h>
 #include <time.h>
 
@@ -36,7 +36,7 @@ TEST(PThread, Robust) {
     pthread_mutex_unlock(&mutex);
     pthread_mutex_destroy(&mutex);
 }
-#elif defined(IPC_OS_WINDOWS_)
+#elif defined(LIBIPC_OS_WIN)
 #include <Windows.h>
 #include <tchar.h>