ipc/ipc_forwarding_message_filter.h

   1 // Copyright (c) 2012 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 IPC_IPC_FORWARDING_MESSAGE_FILTER_H_
   6 #define IPC_IPC_FORWARDING_MESSAGE_FILTER_H_
   7
   8 #include <map>
   9 #include <set>
  10
  11 #include "base/bind.h"
  12 #include "base/callback_forward.h"
  13 #include "base/synchronization/lock.h"
  14 #include "base/task_runner.h"
  15 #include "ipc/message_filter.h"
  16
  17 namespace IPC {
  18
  19 // This class can be used to intercept routed messages and
  20 // deliver them to a different task runner than they would otherwise
  21 // be sent. Messages are filtered based on type. To route these messages,
  22 // add a MessageRouter to the handler.
  23 //
  24 // The user of this class implements ForwardingMessageFilter::Client,
  25 // which will receive the intercepted messages, on the specified target thread.
  26 class IPC_EXPORT ForwardingMessageFilter : public MessageFilter {
  27  public:
  28
  29   // The handler is invoked on the thread associated with
  30   // |target_task_runner| with messages that were intercepted by this filter.
  31   typedef base::Callback<void(const Message&)> Handler;
  32
  33   // This filter will intercept |message_ids_to_filter| and post
  34   // them to the provided |target_task_runner|, where they will be given
  35   // to |handler|.
  36   //
  37   // The caller must ensure that |handler| outlives the lifetime of the filter.
  38   ForwardingMessageFilter(
  39       const uint32* message_ids_to_filter,
  40       size_t num_message_ids_to_filter,
  41       base::TaskRunner* target_task_runner);
  42
  43   // Define the message routes to be filtered.
  44   void AddRoute(int routing_id, const Handler& handler);
  45   void RemoveRoute(int routing_id);
  46
  47   // MessageFilter methods:
  48   bool OnMessageReceived(const Message& message) override;
  49
  50  private:
  51   ~ForwardingMessageFilter() override;
  52
  53   std::set<int> message_ids_to_filter_;
  54
  55   // The handler_ only gets Run on the thread corresponding to
  56   // target_task_runner_.
  57   scoped_refptr<base::TaskRunner> target_task_runner_;
  58
  59   // Protects access to routes_.
  60   base::Lock handlers_lock_;
  61
  62   // Indicates the routing_ids for which messages should be filtered.
  63   std::map<int, Handler> handlers_;
  64
  65   DISALLOW_COPY_AND_ASSIGN(ForwardingMessageFilter);
  66 };
  67
  68 }  // namespace IPC
  69
  70 #endif  // IPC_IPC_FORWARDING_MESSAGE_FILTER_H_