content/child/child_message_filter.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_CHILD_CROSS_MESSAGE_FILTER_H_
   6 #define CONTENT_CHILD_CROSS_MESSAGE_FILTER_H_
   7
   8 #include "ipc/ipc_channel_proxy.h"
   9
  10 namespace base {
  11 class TaskRunner;
  12 }
  13
  14 namespace content {
  15
  16 class ThreadSafeSender;
  17
  18 // A base class for implementing IPC MessageFilter's that run on a different
  19 // thread or TaskRunner than the main thread.
  20 class ChildMessageFilter
  21     : public base::RefCountedThreadSafe<ChildMessageFilter>,
  22       public IPC::Sender {
  23  public:
  24   // IPC::Sender implementation. Can be called on any threads.
  25   virtual bool Send(IPC::Message* message) OVERRIDE;
  26
  27   // If implementers want to run OnMessageReceived on a different task
  28   // runner it should override this and return the TaskRunner for the message.
  29   // Returning NULL runs OnMessageReceived() on the current IPC thread.
  30   virtual base::TaskRunner* OverrideTaskRunnerForMessage(
  31       const IPC::Message& msg) = 0;
  32
  33   // If OverrideTaskRunnerForMessage is overriden and returns non-null
  34   // this will be called on the returned TaskRunner.
  35   virtual bool OnMessageReceived(const IPC::Message& msg) = 0;
  36
  37   // This method is called when WorkerTaskRunner::PostTask() returned false
  38   // for the target thread.  Note that there's still a little chance that
  39   // PostTask() returns true but OnMessageReceived() is never called on the
  40   // target thread.  By default this does nothing.
  41   virtual void OnStaleMessageReceived(const IPC::Message& msg) {}
  42
  43  protected:
  44   ChildMessageFilter();
  45   virtual ~ChildMessageFilter();
  46
  47  private:
  48   class Internal;
  49   friend class ChildThread;
  50   friend class RenderThreadImpl;
  51   friend class WorkerThread;
  52
  53   friend class base::RefCountedThreadSafe<ChildMessageFilter>;
  54
  55   IPC::ChannelProxy::MessageFilter* GetFilter();
  56
  57   // This implements IPC::ChannelProxy::MessageFilter to hide the actual
  58   // filter methods from child classes.
  59   Internal* internal_;
  60
  61   scoped_refptr<ThreadSafeSender> thread_safe_sender_;
  62
  63   DISALLOW_COPY_AND_ASSIGN(ChildMessageFilter);
  64 };
  65
  66 }  // namespace content
  67
  68 #endif  // CONTENT_CHILD_CROSS_MESSAGE_FILTER_H_