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Unified Diff: ipc/ipc_channel_proxy.h

Issue 155905: Separates ipc code from common (http://crbug.com/16829) (Closed)
Patch Set: Fixes reference to 'common_message_traits' it's actually 'common_param_traits' Created 11 years, 5 months ago
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Index: ipc/ipc_channel_proxy.h
diff --git a/ipc/ipc_channel_proxy.h b/ipc/ipc_channel_proxy.h
new file mode 100644
index 0000000000000000000000000000000000000000..1aed33e6536da6b334857cccc13adbf78842029f
--- /dev/null
+++ b/ipc/ipc_channel_proxy.h
@@ -0,0 +1,209 @@
+// 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 IPC_IPC_CHANNEL_PROXY_H__
+#define IPC_IPC_CHANNEL_PROXY_H__
+
+#include <vector>
+
+#include "base/ref_counted.h"
+#include "ipc/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 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::string& 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.
+ int GetClientFileDescriptor() 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::string& 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::string& 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 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::string& 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::string channel_id_;
+ int peer_pid_;
+ bool channel_connected_called_;
+ };
+
+ Context* context() { return context_; }
+
+ private:
+ void Init(const std::string& 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 // IPC_IPC_CHANNEL_PROXY_H__
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