base/sync_socket.h

   1 // Copyright (c) 2009 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
   8 // A socket abstraction used for sending and receiving plain
   9 // data.  Because they are blocking, they can be used to perform
  10 // rudimentary cross-process synchronization with low latency.
  11
  12 #include "base/basictypes.h"
  13 #if defined(OS_WIN)
  14 #include <windows.h>
  15 #endif
  16 #include <sys/types.h>
  17
  18 namespace base {
  19
  20 class SyncSocket {
  21  public:
  22 #if defined(OS_WIN)
  23   typedef HANDLE Handle;
  24 #else
  25   typedef int Handle;
  26 #endif
  27
  28   // Creates a SyncSocket from a Handle.  Used in transport.
  29   explicit SyncSocket(Handle handle) : handle_(handle) { }
  30   ~SyncSocket() { Close(); }
  31
  32   // Creates an unnamed pair of connected sockets.
  33   // pair is a pointer to an array of two SyncSockets in which connected socket
  34   // descriptors are returned.  Returns true on success, false on failure.
  35   static bool CreatePair(SyncSocket* pair[2]);
  36
  37   // Closes the SyncSocket.  Returns true on success, false on failure.
  38   bool Close();
  39
  40   // Sends the message to the remote peer of the SyncSocket.
  41   // Note it is not safe to send messages from the same socket handle by
  42   // multiple threads simultaneously.
  43   // buffer is a pointer to the data to send.
  44   // length is the length of the data to send (must be non-zero).
  45   // Returns the number of bytes sent, or 0 upon failure.
  46   size_t Send(const void* buffer, size_t length);
  47
  48   // Receives a message from an SyncSocket.
  49   // buffer is a pointer to the buffer to receive data.
  50   // length is the number of bytes of data to receive (must be non-zero).
  51   // Returns the number of bytes received, or 0 upon failure.
  52   size_t Receive(void* buffer, size_t length);
  53
  54   // Returns the number of bytes available. If non-zero, Receive() will not
  55   // not block when called. NOTE: Some implementations cannot reliably
  56   // determine the number of bytes available so avoid using the returned
  57   // size as a promise and simply test against zero.
  58   size_t Peek();
  59
  60   // Extracts the contained handle.  Used for transferring between
  61   // processes.
  62   Handle handle() const { return handle_; }
  63
  64  private:
  65   Handle handle_;
  66
  67   DISALLOW_COPY_AND_ASSIGN(SyncSocket);
  68 };
  69
  70 }  // namespace base
  71
  72 #endif  // BASE_SYNC_SOCKET_H_