MFLockSharedWorkQueue function
Obtains and locks a shared work queue.
Syntax
HRESULT MFLockSharedWorkQueue( _In_ PCWSTR wszClass, _In_ LONG BasePriority, _Inout_ DWORD *pdwTaskId, _Out_ DWORD *pID );
Parameters
- wszClass [in]
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The name of the MMCSS task.
- BasePriority [in]
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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.
- pdwTaskId [in, out]
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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.
- pID [out]
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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
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Minimum supported client |
Windows 8 [desktop apps | Windows Store apps] |
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Minimum supported server |
Windows Server 2012 [desktop apps | Windows Store apps] |
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Minimum supported phone |
Windows Phone 8.1 |
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Header |
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Library |
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DLL |
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See also