public int Send(ITftpPacket packet)
{
return(Send(packet.Serialize()));
}
/*
* This method performs the following steps:
* 1) send sendPacket to destinationEP every retryPeriod
* 2) All packets for which receiveFilter returns false are discarded
* This will continue until:
* a) receiveFilter returns true for a received packet - receivedFromEP is set to the
* endpoint from which the packet was received and the packet is returned.
* b) timeout has elapsed - TimeoutException is thrown
* c) cancellationToken has been signalled - OperationCanceledException is thrown
*/
public ITftpPacket SendAndWaitForResponse(
ITftpPacket sendPacket,
IPEndPoint destinationEP,
TimeSpan timeout,
TimeSpan retryPeriod,
Func <ITftpPacket, bool> receiveFilter,
out IPEndPoint receivedFromEP,
CancellationToken cancellationToken)
{
ITftpPacket receivePacket = null;
byte[] sendPacketBytes = sendPacket.Serialize();
// Set up timeout cancellation token and link it with the cancellation token parameter.
var timeoutCts = new CancellationTokenSource(timeout);
var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeoutCts.Token);
// Spin up a task thread to re-send sendPacket every retryPeriod.
Action sendAction = () =>
{
while (true)
{
_udp.Send(sendPacketBytes, destinationEP);
linkedCts.Token.WaitHandle.WaitOne(retryPeriod);
linkedCts.Token.ThrowIfCancellationRequested();
Console.WriteLine("Re-sending packet");
}
};
var sendTask = Task.Factory.StartNew(sendAction, linkedCts.Token);
try
{
receivePacket = Receive(receiveFilter, out receivedFromEP, linkedCts.Token);
}
catch (OperationCanceledException)
{
// Here we need to disambiguate which cancellation token source caused the OperationCanceledException.
// If the cancellation token passed into this method was signalled,
// then we need to let the OperationCanceledException propagate up as-is.
if (cancellationToken.IsCancellationRequested)
{
Console.WriteLine("SendAndWaitForResponse was canceled.");
throw;
}
// Otherwise, the timeout cancellation token caused the OperationCanceledException.
else
{
Console.WriteLine("Receive timed out.");
throw new TimeoutException(string.Format("A response was not received after {0}.", timeout));
}
}
// Cancel and clean up the send task.
linkedCts.Cancel();
try
{
sendTask.Wait();
}
catch (AggregateException ex)
{
ex.Handle(e => e is TaskCanceledException);
}
return(receivePacket);
}
