131 lines
4.6 KiB
C++
131 lines
4.6 KiB
C++
// Copyright (c) 2012 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_
|
|
|
|
// A socket abstraction used for sending and receiving plain
|
|
// data. Because the receiving is 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>
|
|
|
|
#include "base/base_export.h"
|
|
#include "base/compiler_specific.h"
|
|
#include "base/synchronization/waitable_event.h"
|
|
|
|
namespace base {
|
|
|
|
class BASE_EXPORT SyncSocket {
|
|
public:
|
|
#if defined(OS_WIN)
|
|
typedef HANDLE Handle;
|
|
#else
|
|
typedef int Handle;
|
|
#endif
|
|
static const Handle kInvalidHandle;
|
|
|
|
SyncSocket();
|
|
|
|
// Creates a SyncSocket from a Handle. Used in transport.
|
|
explicit SyncSocket(Handle handle) : handle_(handle) {}
|
|
virtual ~SyncSocket();
|
|
|
|
// Initializes and connects a pair of sockets.
|
|
// |socket_a| and |socket_b| must not hold a valid handle. Upon successful
|
|
// return, the sockets will both be valid and connected.
|
|
static bool CreatePair(SyncSocket* socket_a, SyncSocket* socket_b);
|
|
|
|
// Closes the SyncSocket. Returns true on success, false on failure.
|
|
virtual 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.
|
|
virtual 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.
|
|
virtual 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_; }
|
|
|
|
protected:
|
|
Handle handle_;
|
|
|
|
private:
|
|
DISALLOW_COPY_AND_ASSIGN(SyncSocket);
|
|
};
|
|
|
|
// Derives from SyncSocket and adds support for shutting down the socket from
|
|
// another thread while a blocking Receive or Send is being done from the
|
|
// thread that owns the socket.
|
|
class BASE_EXPORT CancelableSyncSocket : public SyncSocket {
|
|
public:
|
|
CancelableSyncSocket();
|
|
explicit CancelableSyncSocket(Handle handle);
|
|
virtual ~CancelableSyncSocket() {}
|
|
|
|
// Initializes a pair of cancelable sockets. See documentation for
|
|
// SyncSocket::CreatePair for more details.
|
|
static bool CreatePair(CancelableSyncSocket* socket_a,
|
|
CancelableSyncSocket* socket_b);
|
|
|
|
// A way to shut down a socket even if another thread is currently performing
|
|
// a blocking Receive or Send.
|
|
bool Shutdown();
|
|
|
|
#if defined(OS_WIN)
|
|
// Since the Linux and Mac implementations actually use a socket, shutting
|
|
// them down from another thread is pretty simple - we can just call
|
|
// shutdown(). However, the Windows implementation relies on named pipes
|
|
// and there isn't a way to cancel a blocking synchronous Read that is
|
|
// supported on <Vista. So, for Windows only, we override these
|
|
// SyncSocket methods in order to support shutting down the 'socket'.
|
|
virtual bool Close() OVERRIDE;
|
|
virtual size_t Receive(void* buffer, size_t length) OVERRIDE;
|
|
#endif
|
|
|
|
// Send() is overridden to catch cases where the remote end is not responding
|
|
// and we fill the local socket buffer. When the buffer is full, this
|
|
// implementation of Send() will not block indefinitely as
|
|
// SyncSocket::Send will, but instead return 0, as no bytes could be sent.
|
|
// Note that the socket will not be closed in this case.
|
|
virtual size_t Send(const void* buffer, size_t length) OVERRIDE;
|
|
|
|
private:
|
|
#if defined(OS_WIN)
|
|
WaitableEvent shutdown_event_;
|
|
WaitableEvent file_operation_;
|
|
#endif
|
|
DISALLOW_COPY_AND_ASSIGN(CancelableSyncSocket);
|
|
};
|
|
|
|
#if defined(OS_WIN) && !defined(COMPONENT_BUILD)
|
|
// TODO(cpu): remove this once chrome is split in two dlls.
|
|
__declspec(selectany)
|
|
const SyncSocket::Handle SyncSocket::kInvalidHandle = INVALID_HANDLE_VALUE;
|
|
#endif
|
|
|
|
} // namespace base
|
|
|
|
#endif // BASE_SYNC_SOCKET_H_
|