base/sync_socket.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_SYNC_SOCKET_H_
   6 #define BASE_SYNC_SOCKET_H_
   7 #pragma once
   8
   9 // A socket abstraction used for sending and receiving plain
  10 // data.  Because they are blocking, they can be used to perform
  11 // rudimentary cross-process synchronization with low latency.
  12
  13 #include "base/basictypes.h"
  14 #if defined(OS_WIN)
  15 #include <windows.h>
  16 #endif
  17 #include <sys/types.h>
  18
  19 #include "base/base_export.h"
  20
  21 namespace base {
  22
  23 class BASE_EXPORT SyncSocket {
  24  public:
  25 #if defined(OS_WIN)
  26   typedef HANDLE Handle;
  27 #else
  28   typedef int Handle;
  29 #endif
  30
  31   // Creates a SyncSocket from a Handle.  Used in transport.
  32   explicit SyncSocket(Handle handle) : handle_(handle) { }
  33   ~SyncSocket() { Close(); }
  34
  35   // Creates an unnamed pair of connected sockets.
  36   // pair is a pointer to an array of two SyncSockets in which connected socket
  37   // descriptors are returned.  Returns true on success, false on failure.
  38   static bool CreatePair(SyncSocket* pair[2]);
  39
  40   // Closes the SyncSocket.  Returns true on success, false on failure.
  41   bool Close();
  42
  43   // Sends the message to the remote peer of the SyncSocket.
  44   // Note it is not safe to send messages from the same socket handle by
  45   // multiple threads simultaneously.
  46   // buffer is a pointer to the data to send.
  47   // length is the length of the data to send (must be non-zero).
  48   // Returns the number of bytes sent, or 0 upon failure.
  49   size_t Send(const void* buffer, size_t length);
  50
  51   // Receives a message from an SyncSocket.
  52   // buffer is a pointer to the buffer to receive data.
  53   // length is the number of bytes of data to receive (must be non-zero).
  54   // Returns the number of bytes received, or 0 upon failure.
  55   size_t Receive(void* buffer, size_t length);
  56
  57   // Returns the number of bytes available. If non-zero, Receive() will not
  58   // not block when called. NOTE: Some implementations cannot reliably
  59   // determine the number of bytes available so avoid using the returned
  60   // size as a promise and simply test against zero.
  61   size_t Peek();
  62
  63   // Extracts the contained handle.  Used for transferring between
  64   // processes.
  65   Handle handle() const { return handle_; }
  66
  67  private:
  68   Handle handle_;
  69
  70   DISALLOW_COPY_AND_ASSIGN(SyncSocket);
  71 };
  72
  73 }  // namespace base
  74
  75 #endif  // BASE_SYNC_SOCKET_H_