/// <summary>
/// Begins a receive operation on <see cref="Socket"/> using the <typeparamref name="T"/> message handler implementation
/// </summary>
public async Task BeginReceiveAsync <T>(CancellationToken?cancellationToken = null) where T : NetworkMessageHandler
{
try {
if (SerializationHandler == null)
{
// SerializationHandler must be implemented to transform the network message from binary data to T
throw new ArgumentNullException(nameof(SerializationHandler));
}
var messageHandler = Activator.CreateInstance <T>();
while (true)
{
// try receive data from connected socket
int bytesTransferred;
try {
bytesTransferred = await _stream.ReadAsync(messageHandler.Buffer, messageHandler.Offset, messageHandler.Length, cancellationToken ?? _cancellationSource.Token)
.ConfigureAwait(false); // to avoid deadlock, continue the execution on any free thread at the time
} catch (Exception ex) {
if (ex.InnerException is SocketException)
{
var socketEx = ex.InnerException as SocketException;
if (socketEx.SocketErrorCode == SocketError.ConnectionReset ||
socketEx.SocketErrorCode == SocketError.ConnectionAborted)
{
// 'ConnectionReset' will happen when the other party has closed the connection unexpectedly
ClientHandler?.OnConnectionClosedAsync(this);
break;
}
}
// unhandled
throw;
}
if (bytesTransferred == 0)
{
// zero bytes means the connection has been closed
await ClientHandler?.OnConnectionClosedAsync(this);
break;
}
// process the received data in the message handler
var isReceiveCompleted = messageHandler.CompleteReceive(bytesTransferred);
if (isReceiveCompleted == null)
{
// invoke the client handler to process the error in the implementation
ClientHandler?.OnReceiveError(this, new SocketException((int)SocketError.MessageSize));
continue;
}
if ((bool)isReceiveCompleted)
{
// finalize (deobfuscation etc), deserialize to complete message, and process in protocol
await ClientHandler?.OnMessageAsync(this, SerializationHandler.Deserialize(messageHandler.GetFinalized()));
// message has been processed, so handler can be resetted
messageHandler.Reset();
}
}
} catch (Exception ex) {
ClientHandler?.OnReceiveError(this, ex);
}
}
