Ruby

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. Ruby

require 'chilkat'

success = false

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

http = Chilkat::CkHttp.new()

# Set some timeouts, in seconds:
http.put_ConnectTimeout(15)
http.put_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." + "\n";
else
    # Find out what happened.
    if (task.get_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!" + "\n";
        else
            print "Download failed prior to waitMaxMs..." + "\n";
            print task.resultErrorText() + "\n";
        end

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

end