EnterCriticalSection 用法

原创于 2023-04-17 15:45:30 发布 · 763 阅读

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该代码示例展示了在Windows环境下如何使用CRITICAL_SECTION进行线程同步，防止多个线程同时访问同一资源。FirstThread和SecondThread两个线程在加锁和解锁机制下安全地对静态变量n_AddValue进行操作，确保数据一致性。

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#include <iostream>
#include "afxmt.h"
using namespace std;

CRITICAL_SECTION cs;//可以理解为锁定一个资源
static int n_AddValue = 0;//定义一个静态的全部变量n_AddValue

DWORD WINAPI FirstThread(LPVOID lParam)
{
EnterCriticalSection(&cs);//加锁接下来的代码处理过程中不允许其他线程进行操作，除非遇到LeaveCriticalSection
for (int i = 0; i < 10; i++) {
n_AddValue++;
cout << "n_AddValue in FirstThread is " << n_AddValue << endl;
}
LeaveCriticalSection(&cs);//解锁到EnterCriticalSection之间代码资源已经释放了，其他线程可以进行操作
return 0;
}

DWORD WINAPI SecondThread(LPVOID lParam)
{
EnterCriticalSection(&cs);//加锁
for (int i = 0; i < 10; i++) {
n_AddValue++;
cout << "n_AddValue in SecondThread is " << n_AddValue << endl;
}
LeaveCriticalSection(&cs);//解锁
return 0;
}

int main()
{
std::cout << "Hello World!\n";

int nRetCode = 0;

InitializeCriticalSection(&cs);//初始化结构CRITICAL_SECTION
HANDLE pFirstThread = CreateThread(NULL, 0, FirstThread, NULL, 0, NULL);
HANDLE pSecondThread = CreateThread(NULL, 0, SecondThread, NULL, 0, NULL);
HANDLE hThreadHandle[2];//
hThreadHandle[0] = pFirstThread;
hThreadHandle[1] = pSecondThread;
//等待线程返回
WaitForMultipleObjects(2, hThreadHandle, TRUE, INFINITE);
DeleteCriticalSection(&cs);//删除临界区
return nRetCode;
}