seastar::socket: Introduce API

This patch adds the seastar::socket class to the API. This class
is responsible for establishing a connection between two endpoints.
It allows for the connection attempt to be canceled.

Signed-off-by: Duarte Nunes <[email protected]>

net/api.hh

@@ -120,6 +120,7 @@ struct tcp_keepalive_params {
 
 /// \cond internal
 class connected_socket_impl;
+class socket_impl;
 class server_socket_impl;
 class udp_channel_impl;
 class get_impl;
@@ -236,6 +237,43 @@ public:
 /// \addtogroup networking-module
 /// @{
 
+namespace seastar {
+
+/// The seastar socket.
+///
+/// A \c socket that allows a connection to be established between
+/// two endpoints.
+class socket {
+    std::unique_ptr<net::socket_impl> _si;
+public:
+    ~socket();
+
+    /// \cond internal
+    explicit socket(std::unique_ptr<net::socket_impl> si);
+    /// \endcond
+    /// Moves a \c seastar::socket object.
+    socket(socket&&) noexcept;
+    /// Move-assigns a \c seastar::socket object.
+    seastar::socket& operator=(seastar::socket&&) noexcept;
+
+    /// Attempts to establish the connection.
+    ///
+    /// \return a \ref connected_socket representing the connection.
+    future<connected_socket> connect(socket_address sa, socket_address local = socket_address(::sockaddr_in{AF_INET, INADDR_ANY, {0}}));
+    /// Stops any in-flight connection attempt.
+    ///
+    /// Cancels the connection attempt if it's still in progress, and
+    /// terminates the connection if it has already been established.
+    void shutdown();
+};
+
+} /* namespace seastar */
+
+/// @}
+
+/// \addtogroup networking-module
+/// @{
+
 /// A listening socket, waiting to accept incoming network connections.
 class server_socket {
     std::unique_ptr<net::server_socket_impl> _ssi;
@@ -274,6 +312,7 @@ public:
     virtual server_socket listen(socket_address sa, listen_options opts) = 0;
     // FIXME: local parameter assumes ipv4 for now, fix when adding other AF
     virtual future<connected_socket> connect(socket_address sa, socket_address local = socket_address(::sockaddr_in{AF_INET, INADDR_ANY, {0}})) = 0;
+    virtual seastar::socket socket() = 0;
     virtual net::udp_channel make_udp_channel(ipv4_addr addr = {}) = 0;
     virtual future<> initialize() {
         return make_ready_future();

net/native-stack.cc

@@ -146,6 +146,9 @@ class native_network_stack : public network_stack {
     explicit native_network_stack(boost::program_options::variables_map opts, std::shared_ptr<device> dev);
     virtual server_socket listen(socket_address sa, listen_options opt) override;
     virtual future<connected_socket> connect(socket_address sa, socket_address local) override;
+    virtual ::seastar::socket socket() override {
+        throw "not implemented";
+    }
     virtual udp_channel make_udp_channel(ipv4_addr addr) override;
     virtual future<> initialize() override;
     static future<std::unique_ptr<network_stack>> create(boost::program_options::variables_map opts) {

net/posix-stack.hh

@@ -95,6 +95,9 @@ public:
     explicit posix_network_stack(boost::program_options::variables_map opts) : _reuseport(engine().posix_reuseport_available()) {}
     virtual server_socket listen(socket_address sa, listen_options opts) override;
     virtual future<connected_socket> connect(socket_address sa, socket_address local) override;
+    virtual ::seastar::socket socket() override {
+        throw "not implemented";
+    }
     virtual net::udp_channel make_udp_channel(ipv4_addr addr) override;
     static future<std::unique_ptr<network_stack>> create(boost::program_options::variables_map opts) {
         return make_ready_future<std::unique_ptr<network_stack>>(std::unique_ptr<network_stack>(new posix_network_stack(opts)));

net/stack.cc

@@ -105,6 +105,25 @@ future<> connected_socket::shutdown_input() {
     return _csi->shutdown_input();
 }
 
+seastar::socket::~socket()
+{}
+
+seastar::socket::socket(
+        std::unique_ptr<net::socket_impl> si)
+        : _si(std::move(si)) {
+}
+
+seastar::socket::socket(seastar::socket&&) noexcept = default;
+seastar::socket& seastar::socket::operator=(seastar::socket&&) noexcept = default;
+
+future<connected_socket> seastar::socket::connect(socket_address sa, socket_address local) {
+    return _si->connect(sa, local);
+}
+
+void seastar::socket::shutdown() {
+    _si->shutdown();
+}
+
 server_socket::server_socket() {
 }
 

net/stack.hh

@@ -41,6 +41,13 @@ public:
     virtual tcp_keepalive_params get_keepalive_parameters() const = 0;
 };
 
+class socket_impl {
+public:
+    virtual ~socket_impl() {}
+    virtual future<connected_socket> connect(socket_address sa, socket_address local) = 0;
+    virtual void shutdown() = 0;
+};
+
 class server_socket_impl {
 public:
     virtual ~server_socket_impl() {}