“通过异步程序调用(APC)实现的定时功能”中的疑问
原文链接：http://www.vckbase.com/document/viewdoc/?id=1587
#define _WIN32_WINNT 0x0500#include <windows.h>#include <stdio.h>#define _SECOND 10000000typedef struct _MYDATA { TCHAR *szText; DWORD dwValue;} MYDATA;VOID CALLBACK TimerAPCProc( LPVOID lpArg, // Data value DWORD dwTimerLowValue, // Timer low value DWORD dwTimerHighValue ) // Timer high value{ MYDATA *pMyData = (MYDATA *)lpArg; printf( "Message: %s\nValue: %d\n\n", pMyData->szText, pMyData->dwValue ); MessageBeep(0);}void main( void ) { HANDLE hTimer; BOOL bSuccess; __int64 qwDueTime; LARGE_INTEGER liDueTime; MYDATA MyData; TCHAR szError[255]; MyData.szText = "This is my data."; MyData.dwValue = 100; if ( hTimer = CreateWaitableTimer( NULL, // Default security attributes FALSE, // Create auto-reset timer "MyTimer" ) ) // Name of waitable timer { __try { // Create an integer that will be used to signal the timer // 5 seconds from now. qwDueTime = -5 * _SECOND; // Copy the relative time into a LARGE_INTEGER. liDueTime.LowPart = (DWORD) ( qwDueTime & 0xFFFFFFFF ); liDueTime.HighPart = (LONG) ( qwDueTime >> 32 ); bSuccess = SetWaitableTimer( hTimer, // Handle to the timer object &liDueTime, // When timer will become signaled 2000, // Periodic timer interval of 2 seconds TimerAPCProc, // Completion routine &MyData, // Argument to the completion routine FALSE ); // Do not restore a suspended system if ( bSuccess ) { for ( ; MyData.dwValue < 1000; MyData.dwValue += 100 ) { SleepEx( INFINITE, // Wait forever TRUE ); // Put thread in an alertable state } } else { wsprintf( szError, "SetWaitableTimer failed with Error \ %d.", GetLastError() ); MessageBox( NULL, szError, "Error", MB_ICONEXCLAMATION ); } } __finally { CloseHandle( hTimer ); } } else { wsprintf( szError, "CreateWaitableTimer failed with Error %d.", GetLastError() ); MessageBox( NULL, szError, "Error", MB_ICONEXCLAMATION ); }}