Lianja

Cancel HTTP Get 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. Lianja

llSuccess = .F.

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

loHttp = createobject("CkHttp")

// Set some timeouts, in seconds:
loHttp.ConnectTimeout = 15
// ReadTimeout specifies the max number of seconds that must elapse when no additional data is received before
// timing out.  For example, if a server sends a 300 byte response at the rate of 1 byte per second, then
// ReadTimeout would never cause a timeout because there is never a 15 second interval when nothing arrives.
loHttp.ReadTimeout = 15

lcUrl = "https://your-url.com/something"
loTask = loHttp.QuickGetStrAsync(lcUrl)
loTask.Run()

// Wait a maximum of waitMaxMs for the task (i.e. the HTTP GET) to complete.
// The Wait method returns when the task has been canceled, aborted, or completed, or when the max allotted time has passed.
lnWaitMaxMs = 20000
loTask.Wait(lnWaitMaxMs)

// At this point, the GET 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 .T. if the task was in the "queued" or "running" state and was canceled or aborted. 
// The method returns .F. if the task has any other status.
llWasCanceled = loTask.Cancel()
if (llWasCanceled = .T.) then
    ? "The HTTP GET took too long and was canceled."
else
    // Find out what happened.
    if (loTask.StatusInt = 7) then
        // The task completed, which means the background thread's call to QuickGetStr completed
        // with success or failure.  Find out which...
        if (loTask.TaskSuccess = .T.) then
            // Get the string response for the call to QuickGetStr (which happened in Chilkat's background thread).
            lcResponseStr = loTask.GetResultString()
            ? lcResponseStr
            ? "HTTP GET successful!"
        else
            ? "HTTP GET failed prior to waitMaxMs..."
            ? loTask.ResultErrorText
        endif

    else
        // The task must've been canceled or aborted by some other means..
        ? "Task did not complete.  Final status: " + loTask.Status
    endif

endif

release loTask


release loHttp