[Chromoting] Add DataChannelManager to manage optional incoming data channels

remoting/protocol/data_channel_manager.h

+// Copyright 2017 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 REMOTING_PROTOCOL_DATA_CHANNEL_MANAGER_H_
+#define REMOTING_PROTOCOL_DATA_CHANNEL_MANAGER_H_
+
+#include <map>

[Sergey Ulanov, 2017/06/05 18:48:29]

not used in this header

[Hzj_jie, 2017/06/06 03:21:52]

Done.

+#include <memory>
+#include <string>
+#include <vector>
+
+#include "base/callback.h"
+
+namespace remoting {
+namespace protocol {
+
+class DataChannelHandler;
+class MessagePipe;
+
+// DataChannelManager helps to manage optional data channels. Each
+// DataChannelHandler implementation registers a factory function to create an
+// instance of itself to handle data from a named data channel. All handles are
+// closed when the associated MessagePipe is closed. Clients can also close a
+// data channel manually by calling DataChannelHandler::Close() function.
+class DataChannelManager final {
+ public:
+  using HandlerFactory = base::Callback<void(

[Sergey Ulanov, 2017/06/05 18:48:29]

"Factory" is usually an interface. Call it CreateHandlerCallback, or make it an
interface.

[Hzj_jie, 2017/06/06 03:21:51]

Done.

+      const std::string& name,
+      std::unique_ptr<MessagePipe> pipe)>;
+
+  DataChannelManager();
+  ~DataChannelManager();
+
+  // Registers a factory function to create a DataChannelHandler to handle a new
+  // incoming data channel with a name matching |regex|. Returns false if the
+  // registration fails, usually it happens when |regex| or |constructor| are
+  // empty.
+  bool RegisterHandlerFactory(const std::string& regex,

[Sergey Ulanov, 2017/06/05 18:48:29]

Is it really worth to pull re2 dependency for this feature? I don't think
regular expressions would make the code more readable. Practically in all cases
we will want to call factory based on the name prefix, so just passing a channel
name prefix should be enough here.
Alternatively we could make HandlerFactory decide if it wants to handle specific
channel or not. The manager would call each factory and then use the handler
from the first factory that can handle the channel.

[Hzj_jie, 2017/06/06 03:21:51]

Done.

+                              HandlerFactory constructor);
+
+  // Creates a DataChannelHandler to handle the new incoming data channel.
+  // Returns true if a handler exists for the new data channel.
+  bool OnIncomingDataChannel(const std::string& name,
+                             std::unique_ptr<MessagePipe> pipe);
+
+ private:
+  std::vector<std::pair<std::string, HandlerFactory>> constructors_;
+};
+
+}  // namespace protocol
+}  // namespace remoting
+
+#endif  // REMOTING_PROTOCOL_DATA_CHANNEL_MANAGER_H_