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

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+:ecc8573c3019
+// 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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comparison: ipc/chromium/src/chrome/common/ipc_channel_proxy.h

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