CMsgThread class
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The CMsgThread class is a worker-thread class that queues requests to the queuing thread for completion asynchronously. To use this class, derive your class from it and override the CMsgThread::ThreadMessageProc member function. The ThreadMessageProc member function carries out each request. Your client functions and the ThreadMessageProc member function must share a common definition of the parameters in the CMsg object.
A negotiated mechanism tells the worker thread to exit. Typically, this will be one value of the CMsg class's uMsg message code.
It is a good idea to send this message from the destructor of your derived class, and call the CMsgThread::WaitForThreadExit member function before completing the destruction of the derived class.
| Protected Data Members | Description |
|---|---|
| m_hSem | Indicates a handle used for signaling. |
| m_Lock | Protects access to lists. |
| m_lWaiting | Indicates waiting for a free thread. |
| m_ThreadQueue | Overrides the CMsgThread::GetThreadMsg member function and blocks on things other than this queue. |
| Member Functions | Description |
| CMsgThread | Constructs a CMsgThread object. |
| CreateThread | Creates a thread. |
| GetThreadHandle | Retrieves the thread handle. |
| GetThreadID | Retrieves the identifier of the thread. |
| GetThreadPriority | Retrieves the current thread priority. |
| PutThreadMsg | Queues a request for execution by the worker thread. |
| ResumeThread | Continues the operation of the worker thread. |
| SetThreadPriority | Sets the priority of the thread to a new value. |
| SuspendThread | Suspends the operation of a running thread. |
| WaitForThreadExit | Blocks until the thread has exited after a call to the CMsgThread::SuspendThread member function. |
| Overridable Member Functions | Description |
| GetThreadMsg | Retrieves a queued CMsg object containing a request. |
| OnThreadInit | Provides initialization on a thread. |
| ThreadMessageProc | Processes requests. This is a pure virtual member function. |