Go

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. Go

    success := false

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

    http := chilkat.NewHttp()

    // Set some timeouts, in seconds:
    http.SetConnectTimeout(15)
    http.SetReadTimeout(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.
    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..
    downloadUrl := "http://download.mono-project.com/archive/4.6.1/windows-installer/mono-4.6.1.5-gtksharp-2.12.38-win32-0.msi"

    c := make(chan *chilkat.Task)
    go http.DownloadAsync(downloadUrl,"qa_output/mono.msi",c)
    task := <-c

    // 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.
    wasCanceled := task.Cancel()
    if wasCanceled == true {
        fmt.Println("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 {
                fmt.Println("Download successful!")
            } else {
                fmt.Println("Download failed prior to waitMaxMs...")
                fmt.Println(task.ResultErrorText())
            }

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

    }

    task.DisposeTask()

    http.DisposeHttp()
    task.DisposeTask()