CRITICAL_SECTION //critical_section

落日映苍穹つ 2022-08-20 14:16 162阅读 0赞

/// 关键代码段或是临界区的声明  
CRITICAL\_SECTION g\_cs;  
  
unsigned \_\_stdcall PrintThread1( PVOID pvParm )  
\{  
/// 当前线程号  
volatile static long lTreadNum = 0;  
int iCurThread = InterlockedIncrement( &lTreadNum );  
  
for( int i = 0; i < 20; ++ i)  
\{  
/// 进入临界区  
EnterCriticalSection(&g\_cs);  
/// 对需要保护的资源进行操作  
cout << "线程" << iCurThread << "打印:" << i << endl;  
/// 没此进入临界区后必须调用离开临界区函数  
LeaveCriticalSection(&g\_cs);  
\}  
  
return 0;  
\}  
  
/// 使用TryEnterCriticalSection在获取资源不成功时会立刻返回，这时可以进行一些其它的操作后，再尝试进入  
unsigned \_\_stdcall PrintThread2( PVOID pvParm )  
\{  
volatile static long lTreadNum = 0;  
int iCurThread = InterlockedIncrement( &lTreadNum );  
  
/// 记录尝试进入临界区的次数  
int iTryEnterTimes = 0;  
for( int i = 0; i < 20; ++ i)  
\{  
/// 进入临界区不成功时，尝试次数加1  
while( !TryEnterCriticalSection(&g\_cs) )  
\{  
\++iTryEnterTimes;  
\}  
cout << "线程" << iCurThread << "打印:" << i << " TryTimes:" << iTryEnterTimes << endl;  
iTryEnterTimes = 0;  
LeaveCriticalSection(&g\_cs);  
\}  
  
return 0;  
\}  
  
/// 启动线程并等待线程返回的函数  
void StartThread( unsigned int (\_\_stdcall \* ThreadFuc)( void \*) )  
\{  
HANDLE hThread1 = (HANDLE)\_beginthreadex(NULL, 0, ThreadFuc, NULL, 0, NULL);  
HANDLE hThread2 = (HANDLE)\_beginthreadex(NULL, 0, ThreadFuc, NULL, 0, NULL);  
  
if( hThread1 != NULL )  
\{  
WaitForSingleObject(hThread1, INFINITE);  
CloseHandle(hThread1);  
\}  
  
if( hThread2 != NULL )  
\{  
WaitForSingleObject(hThread2, INFINITE);  
CloseHandle(hThread2);  
\}  
\}  
int \_tmain(int argc, \_TCHAR\* argv\[\])  
\{  
/// 在使用临界区前，必须进行初始化  
InitializeCriticalSection(&g\_cs);  
  
StartThread( PrintThread1 );  
  
cout << endl << endl;  
  
StartThread( PrintThread2 );  
  
/// 使用完后，显示删除以避免资源泄漏  
DeleteCriticalSection(&g\_cs);  
  
cout << endl << endl;  
  
/// 使用旋转锁初始化临界区，可以提高资源使用效率，尽可能使用这种方式进行资源保护  
InitializeCriticalSectionAndSpinCount( &g\_cs, 400);  
StartThread( PrintThread1 );  
DeleteCriticalSection(&g\_cs);  
return 0;  
\}