Unicode 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. Unicode C

#include <C_CkHttpW.h>
#include <C_CkTaskW.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkHttpW http;
    int waitMaxMs;
    const wchar_t *downloadUrl;
    HCkTaskW task;
    BOOL wasCanceled;

    success = FALSE;

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

    http = CkHttpW_Create();

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

    task = CkHttpW_DownloadAsync(http,downloadUrl,L"qa_output/mono.msi");
    CkTaskW_Run(task);

    // 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.
    CkTaskW_Wait(task,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 = CkTaskW_Cancel(task);
    if (wasCanceled == TRUE) {
        wprintf(L"The HTTP download took too long and was canceled.\n");
    }
    else {
        // Find out what happened.
        if (CkTaskW_getStatusInt(task) == 7) {
            // The task completed, which means the background thread's call to Download completed
            // with success or failure.  Find out which...
            success = CkTaskW_GetResultBool(task);
            if (success == TRUE) {
                wprintf(L"Download successful!\n");
            }
            else {
                wprintf(L"Download failed prior to waitMaxMs...\n");
                wprintf(L"%s\n",CkTaskW_resultErrorText(task));
            }

        }
        else {
            // The task must've been canceled or aborted by some other means..
            wprintf(L"Task did not complete.  Final status: %s\n",CkTaskW_status(task));
        }

    }

    CkTaskW_Dispose(task);


    CkHttpW_Dispose(http);

    }