The Tor Browser: ipc/chromium/src/chrome/common/ipc_channel

ipc/chromium/src/chrome/common/ipc_channel_proxy.h@6474c204b198 (annotated)

ipc/chromium/src/chrome/common/ipc_channel_proxy.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 #ifndef CHROME_COMMON_IPC_CHANNEL_PROXY_H__
 #define CHROME_COMMON_IPC_CHANNEL_PROXY_H__
 #include <vector>
 #include "base/lock.h"
 #include "base/ref_counted.h"
 #include "chrome/common/ipc_channel.h"
 class MessageLoop;
 namespace IPC {
 //-----------------------------------------------------------------------------
 // IPC::ChannelProxy
 //
 // This class is a helper class that is useful when you wish to run an IPC
 // channel on a background thread.  It provides you with the option of either
 // handling IPC messages on that background thread or having them dispatched to
 // your main thread (the thread on which the IPC::ChannelProxy is created).
 //
 // The API for an IPC::ChannelProxy is very similar to that of an IPC::Channel.
 // When you send a message to an IPC::ChannelProxy, the message is routed to
 // the background thread, where it is then passed to the IPC::Channel's Send
 // method.  This means that you can send a message from your thread and your
 // message will be sent over the IPC channel when possible instead of being
 // delayed until your thread returns to its message loop.  (Often IPC messages
 // will queue up on the IPC::Channel when there is a lot of traffic, and the
 // channel will not get cycles to flush its message queue until the thread, on
 // which it is running, returns to its message loop.)
 //
 // An IPC::ChannelProxy can have a MessageFilter associated with it, which will
 // be notified of incoming messages on the IPC::Channel's thread.  This gives
 // the consumer of IPC::ChannelProxy the ability to respond to incoming
 // messages on this background thread instead of on their own thread, which may
 // be bogged down with other processing.  The result can be greatly improved
 // latency for messages that can be handled on a background thread.
 //
 // The consumer of IPC::ChannelProxy is responsible for allocating the Thread
 // instance where the IPC::Channel will be created and operated.
 //
 class ChannelProxy : public Message::Sender {
  public:
   // A class that receives messages on the thread where the IPC channel is
   // running.  It can choose to prevent the default action for an IPC message.
   class MessageFilter : public base::RefCountedThreadSafe<MessageFilter> {
    public:
     virtual ~MessageFilter() {}
     // Called on the background thread to provide the filter with access to the
     // channel.  Called when the IPC channel is initialized or when AddFilter
     // is called if the channel is already initialized.
     virtual void OnFilterAdded(Channel* channel) {}
     // Called on the background thread when the filter has been removed from
     // the ChannelProxy and when the Channel is closing.  After a filter is
     // removed, it will not be called again.
     virtual void OnFilterRemoved() {}
     // Called to inform the filter that the IPC channel is connected and we
     // have received the internal Hello message from the peer.
     virtual void OnChannelConnected(int32_t peer_pid) {}
     // Called when there is an error on the channel, typically that the channel
     // has been closed.
     virtual void OnChannelError() {}
     // Called to inform the filter that the IPC channel will be destroyed.
     // OnFilterRemoved is called immediately after this.
     virtual void OnChannelClosing() {}
     // Return true to indicate that the message was handled, or false to let
     // the message be handled in the default way.
     virtual bool OnMessageReceived(const Message& message) {
       return false;
     }
   };
   // Initializes a channel proxy.  The channel_id and mode parameters are
   // passed directly to the underlying IPC::Channel.  The listener is called on
   // the thread that creates the ChannelProxy.  The filter's OnMessageReceived
   // method is called on the thread where the IPC::Channel is running.  The
   // filter may be null if the consumer is not interested in handling messages
   // on the background thread.  Any message not handled by the filter will be
   // dispatched to the listener.  The given message loop indicates where the
   // IPC::Channel should be created.
   ChannelProxy(const std::wstring& channel_id, Channel::Mode mode,
                Channel::Listener* listener, MessageFilter* filter,
                MessageLoop* ipc_thread_loop);
   ~ChannelProxy() {
     Close();
   }
   // Close the IPC::Channel.  This operation completes asynchronously, once the
   // background thread processes the command to close the channel.  It is ok to
   // call this method multiple times.  Redundant calls are ignored.
   //
   // WARNING: The MessageFilter object held by the ChannelProxy is also
   // released asynchronously, and it may in fact have its final reference
   // released on the background thread.  The caller should be careful to deal
   // with / allow for this possibility.
   void Close();
   // Send a message asynchronously.  The message is routed to the background
   // thread where it is passed to the IPC::Channel's Send method.
   virtual bool Send(Message* message);
   // Used to intercept messages as they are received on the background thread.
   //
   // Ordinarily, messages sent to the ChannelProxy are routed to the matching
   // listener on the worker thread.  This API allows code to intercept messages
   // before they are sent to the worker thread.
   void AddFilter(MessageFilter* filter);
   void RemoveFilter(MessageFilter* filter);
 #if defined(OS_POSIX)
   // Calls through to the underlying channel's methods.
   // TODO(playmobil): For now this is only implemented in the case of
   // create_pipe_now = true, we need to figure this out for the latter case.
   void GetClientFileDescriptorMapping(int *src_fd, int *dest_fd) const;
 #endif  // defined(OS_POSIX)
  protected:
   class Context;
   // A subclass uses this constructor if it needs to add more information
   // to the internal state.  If create_pipe_now is true, the pipe is created
   // immediately.  Otherwise it's created on the IO thread.
   ChannelProxy(const std::wstring& channel_id, Channel::Mode mode,
                MessageLoop* ipc_thread_loop, Context* context,
                bool create_pipe_now);
   // Used internally to hold state that is referenced on the IPC thread.
   class Context : public base::RefCountedThreadSafe<Context>,
                   public Channel::Listener {
    public:
     Context(Channel::Listener* listener, MessageFilter* filter,
             MessageLoop* ipc_thread);
     virtual ~Context() { }
     MessageLoop* ipc_message_loop() const { return ipc_message_loop_; }
     const std::wstring& channel_id() const { return channel_id_; }
     // Dispatches a message on the listener thread.
     void OnDispatchMessage(const Message& message);
    protected:
     // IPC::Channel::Listener methods:
     virtual void OnMessageReceived(const Message& message);
     virtual void OnChannelConnected(int32_t peer_pid);
     virtual void OnChannelError();
     // Like OnMessageReceived but doesn't try the filters.
     void OnMessageReceivedNoFilter(const Message& message);
     // Gives the filters a chance at processing |message|.
     // Returns true if the message was processed, false otherwise.
     bool TryFilters(const Message& message);
     // Like Open and Close, but called on the IPC thread.
     virtual void OnChannelOpened();
     virtual void OnChannelClosed();
     // Called on the consumers thread when the ChannelProxy is closed.  At that
     // point the consumer is telling us that they don't want to receive any
     // more messages, so we honor that wish by forgetting them!
     virtual void Clear() { listener_ = NULL; }
    private:
     friend class ChannelProxy;
     // Create the Channel
     void CreateChannel(const std::wstring& id, const Channel::Mode& mode);
     // Methods called via InvokeLater:
     void OnSendMessage(Message* message_ptr);
     void OnAddFilter(MessageFilter* filter);
     void OnRemoveFilter(MessageFilter* filter);
     void OnDispatchConnected();
     void OnDispatchError();
     MessageLoop* listener_message_loop_;
     Channel::Listener* listener_;
     // List of filters.  This is only accessed on the IPC thread.
     std::vector<scoped_refptr<MessageFilter> > filters_;
     MessageLoop* ipc_message_loop_;
     Channel* channel_;
     std::wstring channel_id_;
     int peer_pid_;
     bool channel_connected_called_;
   };
   Context* context() { return context_; }
  private:
   void Init(const std::wstring& channel_id, Channel::Mode mode,
             MessageLoop* ipc_thread_loop, bool create_pipe_now);
   // By maintaining this indirection (ref-counted) to our internal state, we
   // can safely be destroyed while the background thread continues to do stuff
   // that involves this data.
   scoped_refptr<Context> context_;
 };
 }  // namespace IPC
 #endif  // CHROME_COMMON_IPC_CHANNEL_PROXY_H__

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ipc/chromium/src/chrome/common/ipc_channel_proxy.h@6474c204b198 (annotated)

ipc/chromium/src/chrome/common/ipc_channel_proxy.h