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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef CHROME_COMMON_IPC_SYNC_SENDER_H__
#define CHROME_COMMON_IPC_SYNC_SENDER_H__
#include <windows.h>
#include <string>
#include <stack>
#include <queue>
#include "base/basictypes.h"
#include "chrome/common/ipc_message.h"
#include "chrome/common/lock.h"
namespace IPC {
// Classes which send synchronous messages need to derive from this.
// This class is called on two threads. The first is the main thread that does
// the message processing (and which may be blocked waiting for a reply to a
// synchronous message). The second is the IPC thread that does the filtering
// of messages before passing it to the (maybe) blocked main thread.
//
// To use this class:
// 1) Your Send() must pass all messages to SendSync()
// 2) You must implement SendPrivate(), which SendSync() will call internally
// 3) You must be able to filter incoming messages on the IPC thread, and
// pass them on to OnFilterMessage().
// 4) You must implement OnDispatchMessage, which is what dispatches
// messages on the main thread.
class SyncSender {
public:
// shutdown_event is an event that can be waited on so that we don't block if
// if the process is shutting down. If it's NULL, then it's not used.
SyncSender(HANDLE shutdown_event);
~SyncSender();
// These are called on the main thread.
// The derived class's Send should just passthrough to SendSync.
bool SendSync(IPC::Message* message);
// SendSync will call your implementation's SendPrivate when it comes
// time to send the message on the channel.
virtual bool SendPrivate(IPC::Message* message) = 0;
// If a message needs to be dispatched immediately because it's blocking our
// reply, this function will be called.
virtual void OnDispatchMessage(const Message& message) = 0;
// This is called on the IPC thread. Returns true if the message has been
// consumed (i.e. don't do any more processing).
bool OnFilterMessage(const Message& message);
private:
// When sending a synchronous message, this structure contains an object that
// knows how to deserialize the response.
struct PendingSyncMsg {
PendingSyncMsg(int id, IPC::MessageReplyDeserializer* d) :
id(id), deserializer(d) { }
int id;
IPC::MessageReplyDeserializer* deserializer;
};
// Set when we got a reply for a synchronous message that we sent.
HANDLE reply_event_;
// Set when we got a synchronous message that we must respond to as the
// sender needs its reply before it can reply to our original synchronous
// message.
HANDLE blocking_event_;
// Copy of shutdown event that we get in constructor.
HANDLE shutdown_event_;
typedef std::stack<PendingSyncMsg> PendingSyncMessageQueue;
PendingSyncMessageQueue deserializers_;
bool reply_deserialize_result_;
// If we're waiting on a reply and the caller sends a synchronous message
// that's blocking the reply, this variable is used to pass the intermediate
// "blocking" message between our two threads. We can store multiple
// messages as a process will want to respond to any synchronous message
// while they're blocked (i.e. because they talk to multiple processes).
typedef std::queue<Message*> BlockingMessageQueue;
BlockingMessageQueue blocking_messages_;
// Above data structure is used on multiple threads, so it need
// synchronization.
Lock blocking_messages_lock_;
DISALLOW_EVIL_CONSTRUCTORS(SyncSender);
};
} // namespace IPC
#endif // CHROME_COMMON_IPC_SYNC_SENDER_H__
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