XTaskQueueCreateComposite

Creates a task queue composed of ports of other task queues.

Syntax

HRESULT XTaskQueueCreateComposite(  
         XTaskQueuePortHandle workPort,  
         XTaskQueuePortHandle completionPort,  
         XTaskQueueHandle* queue  
)  

Parameters

workPort   _In_
Type: XTaskQueuePortHandle

The port to use for queuing work callbacks.

completionPort   _In_
Type: XTaskQueuePortHandle

The port to use for queuing completion callbacks.

queue   _Out_
Type: XTaskQueueHandle*

The newly created queue.

Return value

Type: HRESULT

HRESULT success or error code.

Remarks

Task queues are reference counted objects. Release the reference by calling XTaskQueueCloseHandle.

A task queue has work and completion ports and tasks can be queued to either port. Each port can be configured with its own dispatch mode.

For most scenarios, you create a task queue with the XTaskQueueCreate API. If you are chaining multiple asynchronous calls together, however, sometimes it is useful to create a composite queue via XTaskQueueCreateComposite. Consider an API whose implementation needs to invoke another API that uses a task queue. You may want to redirect the completion callback of the API so it doesn't tie up the completion thread of the caller. In this case, you can create a composite task queue whose work and completion ports are built from the work port of another queue.

The following example creates a composite task queue.

void CreatingCompositeQueue()
{
    XTaskQueueHandle queue;

    HRESULT hr = XTaskQueueCreate(
        XTaskQueueDispatchMode::ThreadPool, 
        XTaskQueueDispatchMode::Manual, 
        &queue);

    if (FAILED(hr))
    {
        printf("failed to create task queue: 0x%x\r\n", hr);
        return;
    }

    XTaskQueuePortHandle workPort;

    // Create a composite queue that uses the work port from
    // another queue for both work and completion ports.

    hr = XTaskQueueGetPort(queue, XTaskQueuePort::Work, &workPort);
    if (FAILED(hr))
    {
        printf("failed to get work port 0x%x\r\n", hr);
        XTaskQueueCloseHandle(queue);
        return;
    }

    XTaskQueueHandle compositeQueue;
    hr = XTaskQueueCreateComposite(workPort, workPort, &compositeQueue);
    if (FAILED(hr))
    {
        printf("failed to create composiute queue 0x%x\r\n", hr);
        XTaskQueueCloseHandle(queue);
        return;
    }

    // Use the queue as needed
    SubmitCallbacks(compositeQueue);

    // Wait a while for the callbacks to run
    Sleep(1000);

    XTaskQueueCloseHandle(compositeQueue);
    XTaskQueueCloseHandle(queue);
}

Requirements

Header: XTaskQueue.h

Library: xgameruntime.lib

Supported platforms: Windows, Xbox One family consoles and Xbox Series consoles

See also

XTaskQueue members
Asynchronous Programming Model
Async Task Queue Design