/// <inheritdoc />
public Task <FtpResponse> Execute(IFtpCommandBase handler, FtpCommand command)
{
lock (_syncRoot)
{
if (_handlerTask != null)
{
return(null);
}
_cancellationTokenSource = new CancellationTokenSource();
_handlerTask = handler.Process(command, _cancellationTokenSource.Token);
}
var taskCanceled = _handlerTask
.ContinueWith(
t =>
{
var response = new FtpResponse(426, "Connection closed; transfer aborted.");
Debug.WriteLine($"Background task cancelled with response {response}");
return(response);
},
TaskContinuationOptions.OnlyOnCanceled);
var taskCompleted = _handlerTask
.ContinueWith(
t =>
{
var response = t.Result;
Debug.WriteLine($"{DateTimeOffset.UtcNow} Background task finished successfully with response {response}");
return(response);
},
TaskContinuationOptions.OnlyOnRanToCompletion);
var taskFaulted = _handlerTask
.ContinueWith(
t =>
{
var ex = t.Exception;
_connection.Log?.LogError(ex, "Error while processing background command {0}", command);
var response = new FtpResponse(501, "Syntax error in parameters or arguments.");
Debug.WriteLine($"Background task failed with response {response}");
return(response);
},
TaskContinuationOptions.OnlyOnFaulted);
taskFaulted.ContinueWith(t => { }, TaskContinuationOptions.OnlyOnCanceled);
taskCompleted.ContinueWith(t => { }, TaskContinuationOptions.OnlyOnCanceled);
taskCanceled.ContinueWith(t => { }, TaskContinuationOptions.OnlyOnCanceled);
return(Task.Run(
() =>
{
var tasks = new List <Task <FtpResponse> > {
taskCompleted, taskCanceled, taskFaulted
};
do
{
try
{
var waitTasks = tasks.Where(x => !x.IsCompleted).Cast <Task>().ToArray();
if (waitTasks.Length != 0)
{
Debug.WriteLine($"Waiting for {waitTasks.Length} background tasks");
Task.WaitAll(waitTasks);
}
}
catch (AggregateException ex)
{
ex.Handle(e => e is TaskCanceledException);
}
}while (tasks.Any(t => !t.IsCompleted));
var response = tasks.Single(x => x.Status == TaskStatus.RanToCompletion).Result;
Debug.WriteLine($"{DateTimeOffset.UtcNow} Background task finished with response {response}");
lock (_syncRoot)
{
_handlerTask = null;
}
return response;
}));
}
