ipc.h

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#ifndef MOZC_IPC_IPC_H_
#define MOZC_IPC_IPC_H_

#include <cstdint>
#include <memory>
#include <string>

#include "absl/strings/string_view.h"
#include "absl/synchronization/notification.h"
#include "absl/time/time.h"
#include "base/thread.h"

#ifdef __APPLE__
#include <mach/mach.h>  // for mach_port_t
#endif                  // __APPLE__

#ifdef _WIN32
#include <wil/resource.h>
#endif  // _WIN32

namespace mozc {

class IPCPathManager;

inline constexpr size_t IPC_INITIAL_READ_BUFFER_SIZE = 16 * 16384;

// increment this value if protocol has changed.
inline constexpr int IPC_PROTOCOL_VERSION = 3;

enum IPCErrorType {
  IPC_NO_ERROR,
  IPC_NO_CONNECTION,
  IPC_TIMEOUT_ERROR,
  IPC_READ_ERROR,
  IPC_WRITE_ERROR,
  IPC_INVALID_SERVER,
  IPC_UNKNOWN_ERROR,
  IPC_QUIT_EVENT_SIGNALED,
  IPC_MORE_DATA,
  IPC_ERROR_TYPE_SIZE
};

class IPCClientInterface {
 public:
  virtual ~IPCClientInterface() = default;

  virtual bool Connected() const = 0;
  virtual bool Call(const std::string &request, std::string *response,
                    absl::Duration timeout) = 0;

  virtual uint32_t GetServerProtocolVersion() const = 0;
  virtual const std::string &GetServerProductVersion() const = 0;
  virtual uint32_t GetServerProcessId() const = 0;

  // return last error
  virtual IPCErrorType GetLastIPCError() const = 0;
};

#ifdef __APPLE__
class MachPortManagerInterface {
 public:
  virtual ~MachPortManagerInterface() = default;

  // If the mach port can be obtained successfully, set the specified
  // "port" and returns true.  Otherwise port doesn't change and
  // returns false.
  virtual bool GetMachPort(const std::string &name, mach_port_t *port) = 0;

  // Returns true if the connecting server is running, checked via
  // OS-depended way.  This method can be defined differently for testing.
  virtual bool IsServerRunning(const std::string &name) const = 0;
};
#endif  // __APPLE__

// Synchronous, Single-thread IPC Client
// Usage:
//  IPCClient con("name", "/foo/bar/server");
//  string request = "foo";
//  string result;
//  CHECK(con.Connected());
//  // wait for 1000msec
//  CHECK(con.Call(request, &result, absl::Milliseconds(1000));
class IPCClient : public IPCClientInterface {
 public:
  // connect to an IPC server named "name".
  // You can pass an absolute server_path to make sure
  // the client is connecting a valid server.
  // If server_path is empty, no validation is executed.
  // Note: "server_path" will be ignored on Mac (MachIPC).
  IPCClient(absl::string_view name, absl::string_view server_path);

  // old interface
  // same as IPCClient(name, "");
  explicit IPCClient(absl::string_view name);

  ~IPCClient() override;

  // Return true if the connection is available
  bool Connected() const override;

  // Return server protocol version
  uint32_t GetServerProtocolVersion() const override;

  const std::string &GetServerProductVersion() const override;

  uint32_t GetServerProcessId() const override;

  // Synchronous IPC call:
  // Client request is encoded in 'request'.
  // Server response is stored in 'response'.
  // Return true when IPC finishes successfully.
  // When Server doesn't send response within timeout, 'Call' returns false.
  // When timeout (in msec) is set -1, 'Call' waits forever.
  // Note that on Linux and Windows, Call() closes the socket_. This means you
  // cannot call the Call() function more than once.
  bool Call(const std::string &request, std::string *response,
            absl::Duration timeout) override;

  IPCErrorType GetLastIPCError() const override { return last_ipc_error_; }

  // terminate the server process named |name|
  // Do not use it unless version mismatch happens
  static bool TerminateServer(absl::string_view name);

#ifdef __APPLE__
  void SetMachPortManager(MachPortManagerInterface *manager) {
    mach_port_manager_ = manager;
  }
#endif  // __APPLE__

 private:
  void Init(absl::string_view name, absl::string_view server_path);

#ifdef _WIN32
  // Windows
  wil::unique_hfile pipe_handle_;
  wil::unique_event_nothrow pipe_event_;
#elif defined(__APPLE__)
  std::string name_;
  MachPortManagerInterface *mach_port_manager_;
#else   // _WIN32
  int socket_;
#endif  // _WIN32
  bool connected_;
  IPCPathManager *ipc_path_manager_;
  IPCErrorType last_ipc_error_;
};

class IPCClientFactoryInterface {
 public:
  virtual ~IPCClientFactoryInterface() = default;
  virtual std::unique_ptr<IPCClientInterface> NewClient(
      const std::string &name, const std::string &path_name) = 0;

  // old interface for backward compatibility.
  // same as NewClient(name, "");
  virtual std::unique_ptr<IPCClientInterface> NewClient(
      const std::string &name) = 0;
};

// Creates IPCClient object.
class IPCClientFactory : public IPCClientFactoryInterface {
 public:
  // new interface
  std::unique_ptr<IPCClientInterface> NewClient(
      const std::string &name, const std::string &path_name) override;

  // old interface for backward compatibility.
  // same as NewClient(name, "");
  std::unique_ptr<IPCClientInterface> NewClient(
      const std::string &name) override;

  // Return a singleton instance.
  static IPCClientFactory *GetIPCClientFactory();
};

// Synchronous, Single-thread IPC Server
// Usage:
// class MyEchoServer: public IPCServer {
//  public:
//   virtual bool Process(absl::string_view request std::string *response) {
//      implement a logic in Process
//      return true;
//   }
//  };
//  // listen 10 connections, and timeout is 1000msec
//  MyEchoServer server("/tmp/.soket", 10, 1000);
//  CHECK(server.Connected());
//  server.Loop();
class IPCServer {
 public:
  // Make IPCServer instance:
  // name: name of this server
  // num_connections: maximum number of connections per server.
  // timeout: After a client makes a connection, the client needs to
  //          send a request within 'timeout'. If timeout is -1,
  //          IPCServer waits forever. Default setting is -1.
  // TODO(taku): timeout is not implemented properly
  IPCServer(const std::string &name, int32_t num_connections,
            absl::Duration timeout);
  virtual ~IPCServer();

  // Return true if the connection is available
  bool Connected() const;

  // Implement a server algorithm in subclass.
  // If 'Process' return false, server finishes select loop
  virtual bool Process(absl::string_view request, std::string *response) = 0;

  // Start select loop. It goes into infinite loop.
  void Loop();

  // Start select loop and return immediately.
  // It invokes a thread internally.
  void LoopAndReturn();

  // Wait until the thread ends
  void Wait();

  // Terminate select loop from other thread
  // On Win32, we make a control event to terminate
  // main loop gracefully. On Mac/Linux, we simply
  // call TerminateThread()
  void Terminate();

#ifdef __APPLE__
  void SetMachPortManager(MachPortManagerInterface *manager) {
    mach_port_manager_ = manager;
  }
#endif  // __APPLE__

 private:
  bool connected_;
#ifdef _WIN32
  wil::unique_event_nothrow quit_event_;
#else   // _WIN32
  absl::Notification terminate_;
#endif  // !_WIN32
  std::unique_ptr<Thread> server_thread_;

#ifdef _WIN32
  wil::unique_hfile pipe_handle_;
  wil::unique_event_nothrow pipe_event_;
#elif defined(__APPLE__)
  std::string name_;
  MachPortManagerInterface *mach_port_manager_;
#else   // _WIN32
  int socket_;
  std::string server_address_;
#endif  // _WIN32

  absl::Duration timeout_;
};

}  // namespace mozc
#endif  // MOZC_IPC_IPC_H_