(MFC) Cancel HTTP Get Async Task if not Completed after a Max Time

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.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkHttp.h>
#include <CkTask.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    bool success;
    CkHttp http;

    // Set some timeouts, in seconds:
    http.put_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.
    http.put_ReadTimeout(15);

    const char *url = "https://your-url.com/something";
    CkTask *task = http.QuickGetStrAsync(url);
    task->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.
    int waitMaxMs = 20000;
    task->Wait(waitMaxMs);

    // 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 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.
    bool wasCanceled = task->Cancel();
    if (wasCanceled == true) {
        strOut.append("The HTTP GET took too long and was canceled.");
        strOut.append("\r\n");
    }
    else {
        // Find out what happened.
        if (task->get_StatusInt() == 7) {
            // The task completed, which means the background thread's call to QuickGetStr completed
            // with success or failure.  Find out which...
            if (task->get_TaskSuccess() == true) {
                // Get the string response for the call to QuickGetStr (which happened in Chilkat's background thread).
                const char *responseStr = task->getResultString();
                strOut.append(responseStr);
                strOut.append("\r\n");
                strOut.append("HTTP GET successful!");
                strOut.append("\r\n");
            }
            else {
                strOut.append("HTTP GET failed prior to waitMaxMs...");
                strOut.append("\r\n");
                strOut.append(task->resultErrorText());
                strOut.append("\r\n");
            }

        }
        else {
            // The task must've been canceled or aborted by some other means..
            strOut.append("Task did not complete.  Final status: ");
            strOut.append(task->status());
            strOut.append("\r\n");
        }

    }

    delete task;


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }