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 a listener for a particular message routing ID. 52 // Returns true if succeeded. 53 bool AddRoute(int32 routing_id, IPC::Listener* listener); 54 55 // Called to remove a listener for a particular message routing ID. 56 void RemoveRoute(int32 routing_id); 57 58 private: 59 // A list of all listeners with assigned routing IDs. 60 IDMap<IPC::Listener> routes_; 61 62 DISALLOW_COPY_AND_ASSIGN(MessageRouter); 63 }; 64 65 } // namespace content 66 67 #endif // CONTENT_COMMON_MESSAGE_ROUTER_H_ 68