C#

Cancel Async Task if not Completed after a Max Time

See more Async Examples

Demonstrates how to wait a maximum amount of time for an asynchronous task to completed. If not completed in the allotted amount of time, the task is cancelled. C#

bool success = false;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

Chilkat.Http http = new Chilkat.Http();

//  Set some timeouts, in seconds:
http.ConnectTimeout = 15;
http.ReadTimeout = 15;

//  Wait a max time of 2 seconds for the task.
//  In this example, it's an unreasonably small amount of time,
//  which means the task will get cancelled.
int waitMaxMs = 2000;

//  We're just going to download for 2 seconds and then cancel.
//  Substitute your own URL with a large enough file for testing..
string downloadUrl = "http://download.mono-project.com/archive/4.6.1/windows-installer/mono-4.6.1.5-gtksharp-2.12.38-win32-0.msi";

Chilkat.Task task = http.DownloadAsync(downloadUrl,"qa_output/mono.msi");
task.Run();

//  Wait a maximum of waitMaxMs for the task (i.e. the HTTP download) to complete.
//  The Wait method returns when the task has been canceled, aborted, or completed, or when the max allotted time has passed.
task.Wait(waitMaxMs);

//  At this point, the download may or may not have completed.  
//  Rather than checking the Task status, we can call task.Cancel because
//  if the Task is no longer running (because it already completed, was canceled or aborted), then the 
//  call to Cancel is a NO-OP (meaning it does nothing and the Task's status is unaffected).
//  Also, task.Cancel returns true if the task was in the "queued" or "running" state and was canceled or aborted. 
//  The method returns false if the task has any other status.
bool wasCanceled = task.Cancel();
if (wasCanceled == true) {
    Debug.WriteLine("The HTTP download took too long and was canceled.");
}
else {
    //  Find out what happened.
    if (task.StatusInt == 7) {
        //  The task completed, which means the background thread's call to Download completed
        //  with success or failure.  Find out which...
        success = task.GetResultBool();
        if (success == true) {
            Debug.WriteLine("Download successful!");
        }
        else {
            Debug.WriteLine("Download failed prior to waitMaxMs...");
            Debug.WriteLine(task.ResultErrorText);
        }

    }
    else {
        //  The task must've been canceled or aborted by some other means..
        Debug.WriteLine("Task did not complete.  Final status: " + task.Status);
    }

}