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// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_SYNC_SOCKET_H_
#define BASE_SYNC_SOCKET_H_
#pragma once
// A socket abstraction used for sending and receiving plain
// data. Because they are blocking, they can be used to perform
// rudimentary cross-process synchronization with low latency.
#include "base/basictypes.h"
#if defined(OS_WIN)
#include <windows.h>
#endif
#include <sys/types.h>
namespace base {
class SyncSocket {
public:
#if defined(OS_WIN)
typedef HANDLE Handle;
#else
typedef int Handle;
#endif
// Creates a SyncSocket from a Handle. Used in transport.
explicit SyncSocket(Handle handle) : handle_(handle) { }
~SyncSocket() { Close(); }
// Creates an unnamed pair of connected sockets.
// pair is a pointer to an array of two SyncSockets in which connected socket
// descriptors are returned. Returns true on success, false on failure.
static bool CreatePair(SyncSocket* pair[2]);
// Closes the SyncSocket. Returns true on success, false on failure.
bool Close();
// Sends the message to the remote peer of the SyncSocket.
// Note it is not safe to send messages from the same socket handle by
// multiple threads simultaneously.
// buffer is a pointer to the data to send.
// length is the length of the data to send (must be non-zero).
// Returns the number of bytes sent, or 0 upon failure.
size_t Send(const void* buffer, size_t length);
// Receives a message from an SyncSocket.
// buffer is a pointer to the buffer to receive data.
// length is the number of bytes of data to receive (must be non-zero).
// Returns the number of bytes received, or 0 upon failure.
size_t Receive(void* buffer, size_t length);
// Returns the number of bytes available. If non-zero, Receive() will not
// not block when called. NOTE: Some implementations cannot reliably
// determine the number of bytes available so avoid using the returned
// size as a promise and simply test against zero.
size_t Peek();
// Extracts the contained handle. Used for transferring between
// processes.
Handle handle() const { return handle_; }
private:
Handle handle_;
DISALLOW_COPY_AND_ASSIGN(SyncSocket);
};
} // namespace base
#endif // BASE_SYNC_SOCKET_H_
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