1 // Copyright 2012 The Chromium Authors 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_MESSAGE_ROUTER_H_ 6 #define IPC_MESSAGE_ROUTER_H_ 7 8 #include <stdint.h> 9 10 #include "base/component_export.h" 11 #include "base/containers/id_map.h" 12 #include "ipc/ipc_listener.h" 13 #include "ipc/ipc_sender.h" 14 15 // The MessageRouter handles all incoming messages sent to it by routing them 16 // to the correct listener. Routing is based on the Message's routing ID. 17 // Since routing IDs are typically assigned asynchronously by the browser 18 // process, the MessageRouter has the notion of pending IDs for listeners that 19 // have not yet been assigned a routing ID. 20 // 21 // When a message arrives, the routing ID is used to index the set of routes to 22 // find a listener. If a listener is found, then the message is passed to it. 23 // Otherwise, the message is ignored if its routing ID is not equal to 24 // MSG_ROUTING_CONTROL. 25 // 26 // The MessageRouter supports the IPC::Sender interface for outgoing messages, 27 // but does not define a meaningful implementation of it. The subclass of 28 // MessageRouter is intended to provide that if appropriate. 29 // 30 // The MessageRouter can be used as a concrete class provided its Send method 31 // is not called and it does not receive any control messages. 32 33 namespace IPC { 34 COMPONENT_EXPORT(IPC)35class COMPONENT_EXPORT(IPC) MessageRouter : public Listener, public Sender { 36 public: 37 MessageRouter(); 38 39 MessageRouter(const MessageRouter&) = delete; 40 MessageRouter& operator=(const MessageRouter&) = delete; 41 42 ~MessageRouter() override; 43 44 // Implemented by subclasses to handle control messages 45 virtual bool OnControlMessageReceived(const Message& msg); 46 47 // Listener implementation: 48 bool OnMessageReceived(const Message& msg) override; 49 50 // Like OnMessageReceived, except it only handles routed messages. Returns 51 // true if the message was dispatched, or false if there was no listener for 52 // that route id. 53 virtual bool RouteMessage(const Message& msg); 54 55 // Sender implementation: 56 bool Send(Message* msg) override; 57 58 // Called to add a listener for a particular message routing ID. 59 // Returns true if succeeded. 60 bool AddRoute(int32_t routing_id, Listener* listener); 61 62 // Called to remove a listener for a particular message routing ID. 63 void RemoveRoute(int32_t routing_id); 64 65 // Returns the Listener associated with |routing_id|. 66 Listener* GetRoute(int32_t routing_id); 67 68 private: 69 // A list of all listeners with assigned routing IDs. 70 base::IDMap<Listener*> routes_; 71 }; 72 73 } // namespace IPC 74 75 #endif // IPC_MESSAGE_ROUTER_H_ 76