Chilkat2-Python

Cancel Async Task if not Completed after a Max Time

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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. Chilkat2-Python

import chilkat2

success = False

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

http = chilkat2.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.
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"

# task is a CkTask
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.
wasCanceled = task.Cancel()
if (wasCanceled == True):
    print("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):
            print("Download successful!")
        else:
            print("Download failed prior to waitMaxMs...")
            print(task.ResultErrorText)

    else:
        # The task must've been canceled or aborted by some other means..
        print("Task did not complete.  Final status: " + task.Status)