src/filters/BaseClasses/msgthrd.h

   1 //------------------------------------------------------------------------------
   2 // File: MsgThrd.h
   3 //
   4 // Desc: DirectShow base classes - provides support for a worker thread
   5 //       class to which one can asynchronously post messages.
   6 //
   7 // Copyright (c) 1992-2002 Microsoft Corporation.  All rights reserved.
   8 //------------------------------------------------------------------------------
   9
  10
  11 // Message class - really just a structure.
  12 //
  13 class CMsg {
  14 public:
  15     UINT uMsg;
  16     DWORD dwFlags;
  17     LPVOID lpParam;
  18     CAMEvent *pEvent;
  19
  20     CMsg(UINT u, DWORD dw, LPVOID lp, CAMEvent *pEvnt)
  21         : uMsg(u), dwFlags(dw), lpParam(lp), pEvent(pEvnt) {}
  22
  23     CMsg()
  24         : uMsg(0), dwFlags(0L), lpParam(NULL), pEvent(NULL) {}
  25 };
  26
  27 // This is the actual thread class.  It exports all the usual thread control
  28 // functions.  The created thread is different from a normal WIN32 thread in
  29 // that it is prompted to perform particaular tasks by responding to messages
  30 // posted to its message queue.
  31 //
  32 class AM_NOVTABLE CMsgThread {
  33 private:
  34     static DWORD WINAPI DefaultThreadProc(LPVOID lpParam);
  35     DWORD               m_ThreadId;
  36     HANDLE              m_hThread;
  37
  38 protected:
  39
  40     // if you want to override GetThreadMsg to block on other things
  41     // as well as this queue, you need access to this
  42     CGenericList<CMsg>        m_ThreadQueue;
  43     CCritSec                  m_Lock;
  44     HANDLE                    m_hSem;
  45     LONG                      m_lWaiting;
  46
  47 public:
  48     CMsgThread()
  49         : m_ThreadId(0),
  50         m_hThread(NULL),
  51         m_lWaiting(0),
  52         m_hSem(NULL),
  53         // make a list with a cache of 5 items
  54         m_ThreadQueue(NAME("MsgThread list"), 5)
  55         {
  56         }
  57
  58     ~CMsgThread();
  59     // override this if you want to block on other things as well
  60     // as the message loop
  61     void virtual GetThreadMsg(CMsg *msg);
  62
  63     // override this if you want to do something on thread startup
  64     virtual void OnThreadInit() {
  65     };
  66
  67     BOOL CreateThread();
  68
  69     BOOL WaitForThreadExit(LPDWORD lpdwExitCode) {
  70         if (m_hThread != NULL) {
  71             WaitForSingleObject(m_hThread, INFINITE);
  72             return GetExitCodeThread(m_hThread, lpdwExitCode);
  73         }
  74         return FALSE;
  75     }
  76
  77     DWORD ResumeThread() {
  78         return ::ResumeThread(m_hThread);
  79     }
  80
  81     DWORD SuspendThread() {
  82         return ::SuspendThread(m_hThread);
  83     }
  84
  85     int GetThreadPriority() {
  86         return ::GetThreadPriority(m_hThread);
  87     }
  88
  89     BOOL SetThreadPriority(int nPriority) {
  90         return ::SetThreadPriority(m_hThread, nPriority);
  91     }
  92
  93     HANDLE GetThreadHandle() {
  94         return m_hThread;
  95     }
  96
  97     DWORD GetThreadId() {
  98         return m_ThreadId;
  99     }
 100
 101
 102     void PutThreadMsg(UINT uMsg, DWORD dwMsgFlags,
 103                       LPVOID lpMsgParam, CAMEvent *pEvent = NULL) {
 104         CAutoLock lck(&m_Lock);
 105         CMsg* pMsg = new CMsg(uMsg, dwMsgFlags, lpMsgParam, pEvent);
 106         m_ThreadQueue.AddTail(pMsg);
 107         if (m_lWaiting != 0) {
 108             ReleaseSemaphore(m_hSem, m_lWaiting, 0);
 109             m_lWaiting = 0;
 110         }
 111     }
 112
 113     // This is the function prototype of the function that the client
 114     // supplies.  It is always called on the created thread, never on
 115     // the creator thread.
 116     //
 117     virtual LRESULT ThreadMessageProc(
 118         UINT uMsg, DWORD dwFlags, LPVOID lpParam, CAMEvent *pEvent) = 0;
 119 };
 120