Critical Sections
并不是核心对象。因此没有
handle
这样的东西。它和核心对象不同，它存在于进程的内存空间中。你不需要使用想“
Create
”这样的
API
函数获得一个
critical section handle
。你应该做的是将一个类型为
CRITICAL_SECTION
的局部变量初始化，方法是调用
InitializeCriticalSection():
The InitializeCriticalSection function initializes a critical section object.
VOID InitializeCriticalSection(
LPCRITICAL_SECTION lpCriticalSection // address of critical section object
);
Parameters
lpCriticalSection
Points to the critical section object.
Return Values
This function does not return a value.
当你用毕
critical section
时，你必须调用
DeleteCriticalSection()
清除它。这个函数并没有“释放对象”的意义在里头，不要把它和
C++
的
delete
运算符混淆了。
The DeleteCriticalSection function releases all resources used by an unowned critical section object.
VOID DeleteCriticalSection(
LPCRITICAL_SECTION lpCriticalSection // pointer to critical section object
);
Parameters
lpCriticalSection
Points to the critical section object.
Return Values
This function does not return a value.
一旦
critical section
被初始化，每一个线程就可以进入其中——只要他通过了
EnterCriticalSection()
这一关：
The EnterCriticalSection function waits for ownership of the specified critical section object. The function returns when the calling thread is granted ownership.
VOID EnterCriticalSection(
LPCRITICAL_SECTION lpCriticalSection // pointer to critical section object
);
Parameters
lpCriticalSection
Points to the critical section object.
Return Values
This function does not return a value.
当线程准备好离开
critical section
的时候，他必须调用
LeaveCriticalSection():
The LeaveCriticalSection function releases ownership of the specified critical section object.
VOID LeaveCriticalSection(
LPCRITICAL_SECTION lpCriticalSection // address of critical section object
);
Parameters
lpCriticalSection
Points to the critical section object.
Return Values
This function does not return a value.
下面是一个很简单的使用例子，只是为了演示如何使用，没有其它目的：
#include
<stdio.h>
#include
<windows.h>
const
int numThreads = 3;
//¶¨ÒåÒ»¸öcritical section±äÁ¿
CRITICAL_SECTION gCS;
DWORD WINAPI helloFunc(LPVOID pArg)
{
//½øÈëcritical section
EnterCriticalSection(&gCS);
int num = (int) pArg;
printf("Hello Thread %d\n", num);
//Ïß³ÌÓñϣ¬¼ÇµÃµ÷Óô˺¯ÊıÀ뿪critical section¡££¨Enter**ÓëLeave**µÄÊıÁ¿ÒªÅä¶Ô£©
LeaveCriticalSection(&gCS);
return 0;
}
int
main()
{
//³õʼ»¯critical section
InitializeCriticalSection(&gCS);
HANDLE hThread[numThreads];
DWORD begin = GetTickCount();
for (int i = 0; i < numThreads; i++)
{
hThread[i] = CreateThread(NULL, 0, helloFunc, (LPVOID)i, 0, NULL);
}
WaitForMultipleObjects(numThreads, hThread, TRUE, INFINITE);
DWORD elapse = GetTickCount() - begin;
printf("elapse time: %d\n", elapse);
//ËùÓĞÏß³ÌÖ´ĞĞÍê±Ïºó£¬deleteµôcritical section
DeleteCriticalSection(&gCS);
return 0;
}