private void BtnCancel_Clicked()
{
if (cancellation == null)
{
MessageBox.ErrorQuery("Not Started", "Pipeline execution has not started yet", "Ok");
return;
}
if (cancellation.Token.IsAbortRequested)
{
MessageBox.ErrorQuery("Already Cancelled", "Cancellation already issued", "Ok");
}
else
{
cancellation.Abort();
}
}
private void btnAbortLoad_Click(object sender, EventArgs e)
{
_cancellationTokenSource.Abort();
loadProgressUI1.OnNotify(this, new NotifyEventArgs(ProgressEventType.Warning, "Abort request issued"));
}
/// <summary>
/// Blocking call which runs a set of DataFlowPipelineEngines according to the execution strategy whilst observing the PermissionWindow.
/// Stops the task and returns if the PermissionWindow closes.
/// </summary>
/// <param name="cancellationToken"></param>
/// <param name="cachingEngines"></param>
/// <returns></returns>
private RetrievalResult RunOnce(GracefulCancellationToken cancellationToken, List <IDataFlowPipelineEngine> cachingEngines)
{
// We will be spawning our own task which we want separate control of (to kill if we pass outside the permission window), so need our own cancellation token
var executionCancellationTokenSource = new GracefulCancellationTokenSource();
// We want to be able to stop the engine if we pass outside the permission window, however the execution strategy objects should not know about PermissionWindows
var executionTask = new Task(() =>
_pipelineEngineExecutionStrategy.Execute(cachingEngines, executionCancellationTokenSource.Token, _listener));
// Block waiting on task completion or signalling of the cancellation token
while (!executionTask.IsCompleted)
{
if (executionTask.Status == TaskStatus.Created)
{
executionTask.Start();
}
Task.Delay(1000).Wait();
// We need to handle stop and abort as we have used our own cancellation token with the child task
// If someone above us in the process chain has requested abort or cancel then use our own cancellation token to pass this info on to the child task
if (cancellationToken.IsAbortRequested)
{
// Wait nicely until the child task signals its abort token (by throwing?)
executionCancellationTokenSource.Abort();
_listener.OnNotify(this, new NotifyEventArgs(ProgressEventType.Information, "Have issued Abort request to the Pipeline Execution Task. Waiting for the task to exit..."));
try
{
executionTask.Wait();
}
catch (AggregateException)
{
}
return(RetrievalResult.Aborted);
}
if (cancellationToken.IsStopRequested)
{
// Wait nicely until the child task signals its stop token (by throwing?)
executionCancellationTokenSource.Stop();
_listener.OnNotify(this,
new NotifyEventArgs(ProgressEventType.Information,
"Have issued Stop request to the Pipeline Execution Task, however this may take some to complete as it will attempt to complete the current run through the pipeline."));
executionTask.Wait();
return(RetrievalResult.Stopped);
}
// Now can check to see if we are finished (we have passed outside the permission window)
if (_permissionWindow != null && !_permissionWindow.WithinPermissionWindow())
{
executionCancellationTokenSource.Abort();
_listener.OnNotify(this,
new NotifyEventArgs(ProgressEventType.Information,
"Now outside the PermissionWindow, have issued Abort request to the Pipeline Execution Task."));
executionTask.Wait();
return(RetrievalResult.NotPermitted);
}
}
if (executionTask.IsFaulted)
{
_listener.OnNotify(this, new NotifyEventArgs(ProgressEventType.Error, "Task faulted, information is in the attached exception.", executionTask.Exception));
throw new InvalidOperationException("Task faulted, see inner exception for details.", executionTask.Exception);
}
return(RetrievalResult.Complete);
}