Home | History | Annotate | Download | only in common 
      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 CONTENT_COMMON_MESSAGE_ROUTER_H_
      6 #define CONTENT_COMMON_MESSAGE_ROUTER_H_
      7 
      8 #include "base/id_map.h"
      9 #include "ipc/ipc_listener.h"
     10 #include "ipc/ipc_sender.h"
     11 
     12 // The MessageRouter handles all incoming messages sent to it by routing them
     13 // to the correct listener.  Routing is based on the Message's routing ID.
     14 // Since routing IDs are typically assigned asynchronously by the browser
     15 // process, the MessageRouter has the notion of pending IDs for listeners that
     16 // have not yet been assigned a routing ID.
     17 //
     18 // When a message arrives, the routing ID is used to index the set of routes to
     19 // find a listener.  If a listener is found, then the message is passed to it.
     20 // Otherwise, the message is ignored if its routing ID is not equal to
     21 // MSG_ROUTING_CONTROL.
     22 //
     23 // The MessageRouter supports the IPC::Sender interface for outgoing messages,
     24 // but does not define a meaningful implementation of it.  The subclass of
     25 // MessageRouter is intended to provide that if appropriate.
     26 //
     27 // The MessageRouter can be used as a concrete class provided its Send method
     28 // is not called and it does not receive any control messages.
     29 
     30 namespace content {
     31 
     32 class MessageRouter : public IPC::Listener, public IPC::Sender {
     33  public:
     34   MessageRouter();
     35   virtual ~MessageRouter();
     36 
     37   // Implemented by subclasses to handle control messages
     38   virtual bool OnControlMessageReceived(const IPC::Message& msg);
     39 
     40   // IPC::Listener implementation:
     41   virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
     42 
     43   // Like OnMessageReceived, except it only handles routed messages.  Returns
     44   // true if the message was dispatched, or false if there was no listener for
     45   // that route id.
     46   virtual bool RouteMessage(const IPC::Message& msg);
     47 
     48   // IPC::Sender implementation:
     49   virtual bool Send(IPC::Message* msg) OVERRIDE;
     50 
     51   // Called to add/remove a listener for a particular message routing ID.
     52   void AddRoute(int32 routing_id, IPC::Listener* listener);
     53   void RemoveRoute(int32 routing_id);
     54 
     55  private:
     56   // A list of all listeners with assigned routing IDs.
     57   IDMap<IPC::Listener> routes_;
     58 
     59   DISALLOW_COPY_AND_ASSIGN(MessageRouter);
     60 };
     61 
     62 }  // namespace content
     63 
     64 #endif  // CONTENT_COMMON_MESSAGE_ROUTER_H_
     65