Implement websocket throttling.

net/websockets/websocket_throttle.h

+// Copyright (c) 2009 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 NET_WEBSOCKETS_WEBSOCKET_THROTTLE_H_
+#define NET_WEBSOCKETS_WEBSOCKET_THROTTLE_H_
+
+#include "base/hash_tables.h"
+#include "base/singleton.h"
+#include "net/socket_stream/socket_stream_throttle.h"
+
+namespace net {
+
+// SocketStreamThrottle for WebSocket protocol.
+// Implements the client-side requirements in the spec.
+// http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol
+// 4.1 Handshake
+//   1.   If the user agent already has a Web Socket connection to the
+//        remote host (IP address) identified by /host/, even if known by
+//        another name, wait until that connection has been established or
+//        for that connection to have failed.
+class WebSocketThrottle : public SocketStreamThrottle {
+ public:
+  virtual int OnStartOpenConnection(SocketStream* socket,
+                                    CompletionCallback* callback);
+  virtual int OnRead(SocketStream* socket, const char* data, int len,
+                     CompletionCallback* callback);
+  virtual int OnWrite(SocketStream* socket, const char* data, int len,
+                      CompletionCallback* callback);
+  virtual void OnClose(SocketStream* socket);
+
+  static void Init();
+
+ private:
+  class WebSocketState;
+  typedef std::deque<WebSocketState*> ConnectingQueue;
+  typedef base::hash_map<std::string, ConnectingQueue*> ConnectingAddressMap;
+
+  WebSocketThrottle();
+  virtual ~WebSocketThrottle();
+  friend struct DefaultSingletonTraits<WebSocketThrottle>;
+
+  // Puts |socket| in |queue_| and queues for the destination addresses
+  // of |socket|.  Also sets |state| as UserData of |socket|.
+  // If other socket is using the same destination address, set |state| waiting.
+  void PutInQueue(SocketStream* socket, WebSocketState* state);
+
+  // Removes |socket| from |queue_| and queues for the destination addresses
+  // of |socket|.  Also releases |state| from UserData of |socket|.
+  void RemoveFromQueue(SocketStream* socket, WebSocketState* state);
+
+  // Checks sockets waiting in |queue_| and check the socket is the front of
+  // every queue for the destination addresses of |socket|.
+  // If so, the socket can resume estabilshing connection, so wake up
+  // the socket.
+  void WakeupSocketIfNecessary();
+
+  // Key: string of host's address.  Value: queue of sockets for the address.
+  ConnectingAddressMap addr_map_;
+
+  // Queue of sockets for websockets in opening state.
+  ConnectingQueue queue_;
+};
+
+}  // namespace net
+
+#endif  // NET_WEBSOCKETS_WEBSOCKET_THROTTLE_H_