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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef REMOTING_PROTOCOL_MESSAGE_READER_H_
      6 #define REMOTING_PROTOCOL_MESSAGE_READER_H_
      7 
      8 #include "base/bind.h"
      9 #include "base/callback.h"
     10 #include "base/memory/scoped_ptr.h"
     11 #include "base/memory/weak_ptr.h"
     12 #include "base/threading/non_thread_safe.h"
     13 #include "net/base/completion_callback.h"
     14 #include "remoting/base/compound_buffer.h"
     15 #include "remoting/protocol/message_decoder.h"
     16 
     17 namespace net {
     18 class IOBuffer;
     19 class Socket;
     20 }  // namespace net
     21 
     22 namespace remoting {
     23 namespace protocol {
     24 
     25 // MessageReader reads data from the socket asynchronously and calls
     26 // callback for each message it receives. It stops calling the
     27 // callback as soon as the socket is closed, so the socket should
     28 // always be closed before the callback handler is destroyed.
     29 //
     30 // In order to throttle the stream, MessageReader doesn't try to read
     31 // new data from the socket until all previously received messages are
     32 // processed by the receiver (|done_task| is called for each message).
     33 // It is still possible that the MessageReceivedCallback is called
     34 // twice (so that there is more than one outstanding message),
     35 // e.g. when we the sender sends multiple messages in one TCP packet.
     36 class MessageReader : public base::NonThreadSafe {
     37  public:
     38   typedef base::Callback<void(scoped_ptr<CompoundBuffer>, const base::Closure&)>
     39       MessageReceivedCallback;
     40 
     41   MessageReader();
     42   virtual ~MessageReader();
     43 
     44   // Initialize the MessageReader with a socket. If a message is received
     45   // |callback| is called.
     46   void Init(net::Socket* socket, const MessageReceivedCallback& callback);
     47 
     48  private:
     49   void DoRead();
     50   void OnRead(int result);
     51   void HandleReadResult(int result);
     52   void OnDataReceived(net::IOBuffer* data, int data_size);
     53   void RunCallback(scoped_ptr<CompoundBuffer> message);
     54   void OnMessageDone();
     55 
     56   net::Socket* socket_;
     57 
     58   // Set to true, when we have a socket read pending, and expecting
     59   // OnRead() to be called when new data is received.
     60   bool read_pending_;
     61 
     62   // Number of messages that we received, but haven't finished
     63   // processing yet, i.e. |done_task| hasn't been called for these
     64   // messages.
     65   int pending_messages_;
     66 
     67   bool closed_;
     68   scoped_refptr<net::IOBuffer> read_buffer_;
     69 
     70   MessageDecoder message_decoder_;
     71 
     72   // Callback is called when a message is received.
     73   MessageReceivedCallback message_received_callback_;
     74 
     75   base::WeakPtrFactory<MessageReader> weak_factory_;
     76 
     77   DISALLOW_COPY_AND_ASSIGN(MessageReader);
     78 };
     79 
     80 // Version of MessageReader for protocol buffer messages, that parses
     81 // each incoming message.
     82 template <class T>
     83 class ProtobufMessageReader {
     84  public:
     85   // The callback that is called when a new message is received. |done_task|
     86   // must be called by the callback when it's done processing the |message|.
     87   typedef typename base::Callback<void(scoped_ptr<T> message,
     88                                        const base::Closure& done_task)>
     89       MessageReceivedCallback;
     90 
     91   ProtobufMessageReader() { };
     92   ~ProtobufMessageReader() { };
     93 
     94   void Init(net::Socket* socket, const MessageReceivedCallback& callback) {
     95     DCHECK(!callback.is_null());
     96     message_received_callback_ = callback;
     97     message_reader_.reset(new MessageReader());
     98     message_reader_->Init(
     99         socket, base::Bind(&ProtobufMessageReader<T>::OnNewData,
    100                            base::Unretained(this)));
    101   }
    102 
    103  private:
    104   void OnNewData(scoped_ptr<CompoundBuffer> buffer,
    105                  const base::Closure& done_task) {
    106     scoped_ptr<T> message(new T());
    107     CompoundBufferInputStream stream(buffer.get());
    108     bool ret = message->ParseFromZeroCopyStream(&stream);
    109     if (!ret) {
    110       LOG(WARNING) << "Received message that is not a valid protocol buffer.";
    111     } else {
    112       DCHECK_EQ(stream.position(), buffer->total_bytes());
    113       message_received_callback_.Run(message.Pass(), done_task);
    114     }
    115   }
    116 
    117   scoped_ptr<MessageReader> message_reader_;
    118   MessageReceivedCallback message_received_callback_;
    119 };
    120 
    121 }  // namespace protocol
    122 }  // namespace remoting
    123 
    124 #endif  // REMOTING_PROTOCOL_MESSAGE_READER_H_
    125