MFLockSharedWorkQueue function (mfapi.h)
Obtains and locks a shared work queue.
Syntax
HRESULT MFLockSharedWorkQueue(
[in] PCWSTR wszClass,
[in] LONG BasePriority,
[in, out] DWORD *pdwTaskId,
[out] DWORD *pID
);
Parameters
[in] wszClass
The name of the MMCSS task.
[in] BasePriority
The base priority of the work-queue threads.
If the regular-priority queue is being used (wszClass=""), then the value 0 must be passed in.
[in, out] pdwTaskId
The MMCSS task identifier. On input, specify an existing MCCSS task group ID , or use the value zero to create a new task group. If the regular priority queue is being used (wszClass=""), then NULL must be passed in. On output, receives the actual task group ID.
[out] pID
Receives an identifier for the new work queue. Use this identifier when queuing work items.
Return value
If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.
Remarks
A multithreaded work queue uses a thread pool to dispatch work items. Whenever a thread becomes available, it dequeues the next work item from the queue. Work items are dequeued in first-in-first-out order, but work items are not serialized. In other words, the work queue does not wait for a work item to complete before it starts the next work item.
Within a single process, the Microsoft Media Foundation platform creates up to one multithreaded queue for each Multimedia Class Scheduler Service (MMCSS) task. The MFLockSharedWorkQueue function checks whether a matching work queue already exists. If not, the function creates a new work queue and registers the work queue with MMCSS. The function returns the MMCSS task identifier (pdwTaskId) and the work queue identifier (pID). To queue a work item, pass the work queue identifier to any of the following functions:
The MFLockSharedWorkQueue function also locks the queue. Before the process exits, call MFUnlockWorkQueue to unlock the work queue.If the regular priority queue is being used (wszClass=""), then NULL must be passed in to pdwTaskId and the value 0 must be passed into BasePriority.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 8 [desktop apps | UWP apps] |
| Minimum supported server | Windows Server 2012 [desktop apps | UWP apps] |
| Target Platform | Windows |
| Header | mfapi.h |
| Library | Mfplat.lib |
| DLL | Mfplat.dll |