private async Task Process()
{
try
{
int frameLength;
byte[] payload;
int payloadOffset;
int payloadCount;
while (State == TcpSocketConnectionState.Connected)
{
int receiveCount = await _stream.ReadAsync(_receiveBuffer, 0, _receiveBuffer.Length);
if (receiveCount == 0)
{
break;
}
BufferDeflector.AppendBuffer(_bufferManager, ref _receiveBuffer, receiveCount, ref _sessionBuffer, ref _sessionBufferCount);
while (true)
{
if (_configuration.FrameBuilder.TryDecodeFrame(_sessionBuffer, _sessionBufferCount,
out frameLength, out payload, out payloadOffset, out payloadCount))
{
try
{
await _dispatcher.OnSessionDataReceived(this, payload, payloadOffset, payloadCount);
}
catch (Exception ex)
{
HandleUserSideError(ex);
}
finally
{
BufferDeflector.ShiftBuffer(_bufferManager, frameLength, ref _sessionBuffer, ref _sessionBufferCount);
#if DEBUG
_log.DebugFormat("Session [{0}] buffer length [{1}].", this, _sessionBufferCount);
#endif
}
}
else
{
break;
}
}
}
}
catch (Exception ex) when(!ShouldThrow(ex))
{
}
finally
{
await Close();
}
}
private void ReceiveBuffer(int receiveCount)
{
// TCP guarantees delivery of all packets in the correct order.
// But there is no guarantee that one write operation on the sender-side will result in
// one read event on the receiving side. One call of write(message) by the sender
// can result in multiple messageReceived(session, message) events on the receiver;
// and multiple calls of write(message) can lead to a single messageReceived event.
// In a stream-based transport such as TCP/IP, received data is stored into a socket receive buffer.
// Unfortunately, the buffer of a stream-based transport is not a queue of packets but a queue of bytes.
// It means, even if you sent two messages as two independent packets,
// an operating system will not treat them as two messages but as just a bunch of bytes.
// Therefore, there is no guarantee that what you read is exactly what your remote peer wrote.
// There are three common techniques for splitting the stream of bytes into messages:
// 1. use fixed length messages
// 2. use a fixed length header that indicates the length of the body
// 3. using a delimiter; for example many text-based protocols append
// a newline (or CR LF pair) after every message.
int frameLength;
byte[] payload;
int payloadOffset;
int payloadCount;
BufferDeflector.AppendBuffer(_bufferManager, ref _receiveBuffer, receiveCount, ref _sessionBuffer, ref _sessionBufferCount);
while (true)
{
if (_configuration.FrameBuilder.TryDecodeFrame(_sessionBuffer, _sessionBufferCount,
out frameLength, out payload, out payloadOffset, out payloadCount))
{
try
{
RaiseServerDataReceived(payload, payloadOffset, payloadCount);
}
catch (Exception ex)
{
HandleUserSideError(ex);
}
finally
{
BufferDeflector.ShiftBuffer(_bufferManager, frameLength, ref _sessionBuffer, ref _sessionBufferCount);
#if DEBUG
_log.DebugFormat("Session [{0}] buffer length [{1}].", this, _sessionBufferCount);
#endif
}
}
else
{
break;
}
}
}