Allow synchronous messages to be sent from threads other than the main thread...

ipc/ipc_sync_channel.h

 // Copyright (c) 2006-2008 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 IPC_IPC_SYNC_SENDER_H__
 #define IPC_IPC_SYNC_SENDER_H__
 
 #include <string>
 #include <deque>
 
 #include "base/basictypes.h"
 #include "base/lock.h"
 #include "base/ref_counted.h"
 #include "base/waitable_event_watcher.h"
 #include "ipc/ipc_channel_proxy.h"
+#include "ipc/ipc_sync_message.h"
 
 namespace base {
 class WaitableEvent;
 };
 
 namespace IPC {
 
 class SyncMessage;
 class MessageReplyDeserializer;
 
-// This is similar to IPC::ChannelProxy, with the added feature of supporting
-// sending synchronous messages.
+// This is similar to ChannelProxy, with the added feature of supporting sending
+// synchronous messages.
 // Note that care must be taken that the lifetime of the ipc_thread argument
 // is more than this object.  If the message loop goes away while this object
 // is running and it's used to send a message, then it will use the invalid
 // message loop pointer to proxy it to the ipc thread.
 class SyncChannel : public ChannelProxy,
                     public base::WaitableEventWatcher::Delegate {
  public:
   SyncChannel(const std::string& channel_id, Channel::Mode mode,
               Channel::Listener* listener, MessageFilter* filter,
               MessageLoop* ipc_message_loop, bool create_pipe_now,
@@ skipping 18 matching lines @@
   class SyncContext : public Context,
                       public base::WaitableEventWatcher::Delegate {
    public:
     SyncContext(Channel::Listener* listener,
                 MessageFilter* filter,
                 MessageLoop* ipc_thread,
                 base::WaitableEvent* shutdown_event);
 
     // Adds information about an outgoing sync message to the context so that
     // we know how to deserialize the reply.
-    void Push(IPC::SyncMessage* sync_msg);
+    void Push(SyncMessage* sync_msg);
 
     // Cleanly remove the top deserializer (and throw it away).  Returns the
     // result of the Send call for that message.
     bool Pop();
 
     // Returns an event that's set when the send is complete, timed out or the
     // process shut down.
     base::WaitableEvent* GetSendDoneEvent();
 
     // Returns an event that's set when an incoming message that's not the reply
@@ skipping 12 matching lines @@
     void OnSendTimeout(int message_id);
 
     base::WaitableEvent* shutdown_event() { return shutdown_event_; }
 
     ReceivedSyncMsgQueue* received_sync_msgs() {
       return received_sync_msgs_;
     }
 
    private:
     ~SyncContext();
-    // IPC::ChannelProxy methods that we override.
+    // ChannelProxy methods that we override.
 
     // Called on the listener thread.
     virtual void Clear();
 
     // Called on the IPC thread.
     virtual void OnMessageReceived(const Message& msg);
     virtual void OnChannelError();
     virtual void OnChannelOpened();
     virtual void OnChannelClosed();
 
     // Cancels all pending Send calls.
     void CancelPendingSends();
 
     // WaitableEventWatcher::Delegate implementation.
     virtual void OnWaitableEventSignaled(base::WaitableEvent* arg);
 
-    // 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,
-                     base::WaitableEvent* e) :
-          id(id), deserializer(d), done_event(e), send_result(false) { }
-      int id;
-      IPC::MessageReplyDeserializer* deserializer;
-      base::WaitableEvent* done_event;
-      bool send_result;
-    };
-
     typedef std::deque<PendingSyncMsg> PendingSyncMessageQueue;
     PendingSyncMessageQueue deserializers_;
     Lock deserializers_lock_;
 
     scoped_refptr<ReceivedSyncMsgQueue> received_sync_msgs_;
 
     base::WaitableEvent* shutdown_event_;
     base::WaitableEventWatcher shutdown_watcher_;
   };
 
@@ skipping 18 matching lines @@
 
   // Used to signal events between the IPC and listener threads.
   base::WaitableEventWatcher dispatch_watcher_;
 
   DISALLOW_EVIL_CONSTRUCTORS(SyncChannel);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_SYNC_SENDER_H__