深入探讨MFC消息循环和消息泵

_tWinMain ->AfxWinMain ->AfxWinInit ->CWinThread::InitApplication ->CWinThread::InitInstance ->CWinThread::Run

//thrdcore.cpp
// main running routine until thread exits
int CWinThread::Run()
{
 ASSERT_VALID(this);

 // for tracking the idle time state
 BOOL bIdle = TRUE;
 LONG lIdleCount = 0;

 // acquire and dispatch messages until a WM_QUIT message is received.
 for (;;)
 {
  // phase1: check to see if we can do idle work
  while (bIdle &&
   !::PeekMessage(&m_msgCur, NULL, NULL, NULL, PM_NOREMOVE))
  {
   // call OnIdle while in bIdle state
   if (!OnIdle(lIdleCount++))
    bIdle = FALSE; // assume "no idle" state
  }

  // phase2: pump messages while available
  do
  {
   // pump message, but quit on WM_QUIT
   if (!PumpMessage())
    return ExitInstance();

   // reset "no idle" state after pumping "normal" message
   if (IsIdleMessage(&m_msgCur))
   {
    bIdle = TRUE;
    lIdleCount = 0;
   }

  } while (::PeekMessage(&m_msgCur, NULL, NULL, NULL, PM_NOREMOVE));
 }    //无限循环，退出条件是收到WM_QUIT消息。

 ASSERT(FALSE);  // not reachable
}