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_api.h" 20 21 namespace base { 22 23 class BASE_API 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_ 76
