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 "base/memory/ref_counted.h"
   9 #include "ipc/ipc_sender.h"
  10
  11 namespace base {
  12 class TaskRunner;
  13 }
  14
  15 namespace IPC {
  16 class MessageFilter;
  17 }
  18
  19 namespace content {
  20
  21 class ThreadSafeSender;
  22
  23 // A base class for implementing IPC MessageFilter's that run on a different
  24 // thread or TaskRunner than the main thread.
  25 class ChildMessageFilter
  26     : public base::RefCountedThreadSafe<ChildMessageFilter>,
  27       public IPC::Sender {
  28  public:
  29   // IPC::Sender implementation. Can be called on any threads.
  30   virtual bool Send(IPC::Message* message) OVERRIDE;
  31
  32   // If implementers want to run OnMessageReceived on a different task
  33   // runner it should override this and return the TaskRunner for the message.
  34   // Returning NULL runs OnMessageReceived() on the current IPC thread.
  35   virtual base::TaskRunner* OverrideTaskRunnerForMessage(
  36       const IPC::Message& msg) = 0;
  37
  38   // If OverrideTaskRunnerForMessage is overriden and returns non-null
  39   // this will be called on the returned TaskRunner.
  40   virtual bool OnMessageReceived(const IPC::Message& msg) = 0;
  41
  42   // This method is called when WorkerTaskRunner::PostTask() returned false
  43   // for the target thread.  Note that there's still a little chance that
  44   // PostTask() returns true but OnMessageReceived() is never called on the
  45   // target thread.  By default this does nothing.
  46   virtual void OnStaleMessageReceived(const IPC::Message& msg) {}
  47
  48  protected:
  49   ChildMessageFilter();
  50   virtual ~ChildMessageFilter();
  51
  52  private:
  53   class Internal;
  54   friend class ChildThread;
  55   friend class RenderThreadImpl;
  56   friend class WorkerThread;
  57
  58   friend class base::RefCountedThreadSafe<ChildMessageFilter>;
  59
  60   IPC::MessageFilter* GetFilter();
  61
  62   // This implements IPC::MessageFilter to hide the actual filter methods from
  63   // child classes.
  64   Internal* internal_;
  65
  66   scoped_refptr<ThreadSafeSender> thread_safe_sender_;
  67
  68   DISALLOW_COPY_AND_ASSIGN(ChildMessageFilter);
  69 };
  70
  71 }  // namespace content
  72
  73 #endif  // CONTENT_CHILD_CROSS_MESSAGE_FILTER_H_