33edd84811
Required for the SubscribeUniform WebGL extension. BUG=422978 Review URL: https://codereview.chromium.org/634313002 Cr-Commit-Position: refs/heads/master@{#306555}
69 lines
2.5 KiB
C++
69 lines
2.5 KiB
C++
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef CONTENT_COMMON_MESSAGE_ROUTER_H_
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#define CONTENT_COMMON_MESSAGE_ROUTER_H_
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#include "base/id_map.h"
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#include "content/common/content_export.h"
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#include "ipc/ipc_listener.h"
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#include "ipc/ipc_sender.h"
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// The MessageRouter handles all incoming messages sent to it by routing them
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// to the correct listener. Routing is based on the Message's routing ID.
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// Since routing IDs are typically assigned asynchronously by the browser
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// process, the MessageRouter has the notion of pending IDs for listeners that
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// have not yet been assigned a routing ID.
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//
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// When a message arrives, the routing ID is used to index the set of routes to
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// find a listener. If a listener is found, then the message is passed to it.
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// Otherwise, the message is ignored if its routing ID is not equal to
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// MSG_ROUTING_CONTROL.
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//
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// The MessageRouter supports the IPC::Sender interface for outgoing messages,
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// but does not define a meaningful implementation of it. The subclass of
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// MessageRouter is intended to provide that if appropriate.
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//
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// The MessageRouter can be used as a concrete class provided its Send method
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// is not called and it does not receive any control messages.
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namespace content {
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class CONTENT_EXPORT MessageRouter : public IPC::Listener, public IPC::Sender {
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public:
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MessageRouter();
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~MessageRouter() override;
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// Implemented by subclasses to handle control messages
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virtual bool OnControlMessageReceived(const IPC::Message& msg);
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// IPC::Listener implementation:
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bool OnMessageReceived(const IPC::Message& msg) override;
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// Like OnMessageReceived, except it only handles routed messages. Returns
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// true if the message was dispatched, or false if there was no listener for
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// that route id.
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virtual bool RouteMessage(const IPC::Message& msg);
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// IPC::Sender implementation:
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bool Send(IPC::Message* msg) override;
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// Called to add a listener for a particular message routing ID.
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// Returns true if succeeded.
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bool AddRoute(int32 routing_id, IPC::Listener* listener);
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// Called to remove a listener for a particular message routing ID.
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void RemoveRoute(int32 routing_id);
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private:
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// A list of all listeners with assigned routing IDs.
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IDMap<IPC::Listener> routes_;
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DISALLOW_COPY_AND_ASSIGN(MessageRouter);
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};
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} // namespace content
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#endif // CONTENT_COMMON_MESSAGE_ROUTER_H_
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