remoting/protocol/message_reader.h

   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_