Refactor: Simplify WaitableEventWatcher.

ipc/ipc_sync_channel.h

 // 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 IPC_IPC_SYNC_CHANNEL_H_
 #define IPC_IPC_SYNC_CHANNEL_H_
 
 #include <string>
 #include <deque>
 
@@ skipping 40 matching lines @@
 // Significant complexity results from the fact that messages are still coming
 // in while the original thread is blocked. Normal async messages are queued
 // and dispatched after the blocking call is complete. Sync messages must
 // be dispatched in a reentrant manner to avoid deadlock.
 //
 //
 // 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 IPC_EXPORT SyncChannel : public ChannelProxy,
-                               public base::WaitableEventWatcher::Delegate {
+class IPC_EXPORT SyncChannel : public ChannelProxy {
  public:
   enum RestrictDispatchGroup {
     kRestrictDispatchGroup_None = 0,
   };
 
   // Creates and initializes a sync channel. If create_pipe_now is specified,
   // the channel will be initialized synchronously.
   SyncChannel(const IPC::ChannelHandle& channel_handle,
               Channel::Mode mode,
               Listener* listener,
@@ skipping 35 matching lines @@
   // default) will be dispatched in any case.
   void SetRestrictDispatchChannelGroup(int group);
 
  protected:
   class ReceivedSyncMsgQueue;
   friend class ReceivedSyncMsgQueue;
 
   // SyncContext holds the per object data for SyncChannel, so that SyncChannel
   // can be deleted while it's being used in a different thread.  See
   // ChannelProxy::Context for more information.
-  class SyncContext : public Context,
-                      public base::WaitableEventWatcher::Delegate {
+  class SyncContext : public Context {
    public:
     SyncContext(Listener* listener,
                 base::SingleThreadTaskRunner* ipc_task_runner,
                 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(SyncMessage* sync_msg);
 
     // Cleanly remove the top deserializer (and throw it away).  Returns the
@@ skipping 13 matching lines @@
     // Checks if the given message is blocking the listener thread because of a
     // synchronous send.  If it is, the thread is unblocked and true is
     // returned. Otherwise the function returns false.
     bool TryToUnblockListener(const Message* msg);
 
     // Called on the IPC thread when a sync send that runs a nested message loop
     // times out.
     void OnSendTimeout(int message_id);
 
     base::WaitableEvent* shutdown_event() { return shutdown_event_; }
+    base::WaitableEventWatcher::EventCallback
+        shutdown_watcher_callback() const {
+      return shutdown_watcher_callback_;
+    }
 
     ReceivedSyncMsgQueue* received_sync_msgs() {
       return received_sync_msgs_;
     }
 
     void set_restrict_dispatch_group(int group) {
       restrict_dispatch_group_ = group;
     }
 
     int restrict_dispatch_group() const {
       return restrict_dispatch_group_;
     }
 
    private:
     virtual ~SyncContext();
     // ChannelProxy methods that we override.
 
     // Called on the listener thread.
     virtual void Clear() OVERRIDE;
 
     // Called on the IPC thread.
     virtual bool OnMessageReceived(const Message& msg) OVERRIDE;
     virtual void OnChannelError() OVERRIDE;
     virtual void OnChannelOpened() OVERRIDE;
     virtual void OnChannelClosed() OVERRIDE;
 
     // Cancels all pending Send calls.
     void CancelPendingSends();
 
-    // WaitableEventWatcher::Delegate implementation.
-    virtual void OnWaitableEventSignaled(base::WaitableEvent* arg) OVERRIDE;
+    void OnWaitableEventSignaled(base::WaitableEvent* arg);
 
     typedef std::deque<PendingSyncMsg> PendingSyncMessageQueue;
     PendingSyncMessageQueue deserializers_;
     base::Lock deserializers_lock_;
 
     scoped_refptr<ReceivedSyncMsgQueue> received_sync_msgs_;
 
     base::WaitableEvent* shutdown_event_;
     base::WaitableEventWatcher shutdown_watcher_;
+    base::WaitableEventWatcher::EventCallback shutdown_watcher_callback_;

[dmichael (off chromium), 2013/02/01 17:27:18]

Why is this called shutdown_watcher_callback_?

It looks like it's really used to indicate a send finished. Maybe
send_done_watcher_callback?

     int restrict_dispatch_group_;
   };
 
  private:
-  // WaitableEventWatcher::Delegate implementation.
-  virtual void OnWaitableEventSignaled(base::WaitableEvent* arg) OVERRIDE;
+  void OnWaitableEventSignaled(base::WaitableEvent* arg);
 
   SyncContext* sync_context() {
     return reinterpret_cast<SyncContext*>(context());
   }
 
   // Both these functions wait for a reply, timeout or process shutdown.  The
   // latter one also runs a nested message loop in the meantime.
   static void WaitForReply(
       SyncContext* context, base::WaitableEvent* pump_messages_event);
 
   // Runs a nested message loop until a reply arrives, times out, or the process
   // shuts down.
   static void WaitForReplyWithNestedMessageLoop(SyncContext* context);
 
   // Starts the dispatch watcher.
   void StartWatching();
 
   bool sync_messages_with_no_timeout_allowed_;
 
   // Used to signal events between the IPC and listener threads.
   base::WaitableEventWatcher dispatch_watcher_;
+  base::WaitableEventWatcher::EventCallback dispatch_watcher_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncChannel);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_SYNC_CHANNEL_H_