Win32_2-线程控制--临界区&互斥体

Myth丶恋晨 2022-05-13 18:04 188阅读 0赞

## 临界区 ##

typedef struct _RTL_CRITICAL_SECTION {
        PRTL_CRITICAL_SECTION_DEBUG DebugInfo;
        //
        //  The following three fields control entering and exiting the critical
        //  section for the resource
        //
    
        LONG LockCount;             //初始化为数值-1，此数值等于或者大于0时，表示此临界区被占用
        							//等待获得临界区的线程数:LockCount-(RecursionCount-1)
        LONG RecursionCount;        //此字段包含所有线程已经获得该临界区的次数
        HANDLE OwningThread;        //占用此临界区的线程的线程标识符，此线程ID与GetCurrentThreadId所返回的ID相同
        HANDLE LockSemaphore;
        ULONG_PTR SpinCount;        // force size on 64-bit systems when packed
    } RTL_CRITICAL_SECTION, *PRTL_CRITICAL_SECTION;

typedef RTL_CRITICAL_SECTION CRITICAL_SECTION;//简化的宏定义

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使用以下代码创建临界区，并且初始化：

CRITICAL_SECTION cs;                   //创建临界区
    InitializeCriticalSection(&cs);        // 初始化临界区

进入临界区和离开

EnterCriticalSection(&cs);
    LeaveCriticalSection(&g_cs);

释放临界区

VOID DeleteCriticalSection(PCRITICAL_SECTION pcs);

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM1NDI1MjQz_size_27_color_FFFFFF_t_70 1]一个简单使用临界区的例子

#include <iostream>
    #include <windows.h>
    CRITICAL_SECTION cs;
    int a = 0;
    HANDLE ht1; HANDLE ht2;
    DWORD WINAPI ThreadPorc1(LPVOID  lpParameter)
    {
    	for (int i = 0; i < 100; i++)
    	{
    		EnterCriticalSection(&cs);
    		a++;
    		printf("线程1对a进行读写--%d\n", a);
    		LeaveCriticalSection(&cs);
    		Sleep(100);
    	}
    	
    	return 0;
    }
    
    DWORD WINAPI ThreadPorc2(LPVOID  lpParameter)
    {
    	for (int i = 0; i < 100; i++)
    	{
    		EnterCriticalSection(&cs);
    		a++;
    		printf("线程2对a进行读写--%d\n", a);
    		LeaveCriticalSection(&cs);
    		Sleep(100);
    	}
    	return 0;
    }
    int main()
    {
    	InitializeCriticalSection(&cs);
    	HANDLE ht1 = ::CreateThread(NULL, 0, ThreadPorc1, NULL, 0, NULL);
    	HANDLE ht2 = ::CreateThread(NULL, 0, ThreadPorc2, NULL, 0, NULL);
    	::WaitForSingleObject(ht1, INFINITE); ::CloseHandle(ht1);
    	::WaitForSingleObject(ht2, INFINITE); ::CloseHandle(ht2);
    	
    	return 0;
    }

--------------------

## 等待内核对象 ##

DWORD WaitForSingleObject(
    	HANDLE hHandle,        // 内核对象句柄，可以是进程也可以是线程.
    	DWORD dwMilliseconds   // 等待时间，单位是毫秒  INFINITE(-1)一直等待		
    );

等待函数可使线程自愿进入等待状态，直到一个特定的内核对象变为已通知状态为止.

1、内核对象中的每种对象都可以说是处于已通知或未通知的状态之中

2、这种状态的切换是由Microsoft为每个对象建立的一套规则来决定的

3、当线程正在运行的时候，线程内核对象处于未通知状态

4、当线程终止运行的时候，它就变为已通知状态

5、在内核中就是个BOOL值，运行时FALSE 结束TRUE

//创建一个新的线程				
    HANDLE hThread1 = ::CreateThread(NULL, 0, ThreadProc1,NULL, 0, NULL);
    ::WaitForSingleObject(hThread1, INFINITE); //当线程 hThread1  执行完毕以后
    ->执行代码

--------------------

DWORD WaitForMultipleObjects(
    	DWORD nCount,             //要查看内核对象的数量
    	CONST HANDLE *lpHandles,  //内核对象数组	
    	BOOL bWaitAll,            //等到类型  TRUE 等到所有变为已通知  FALSE 只要有一个变为已通知				
    	DWORD dwMilliseconds      // 等待时间，单位是毫秒  INFINITE(-1)一直等待						
    );

HANDLE hArray[2];			
    HANDLE hArray[0]= ::CreateThread(NULL, 0, ThreadProc1,NULL, 0, NULL);
    HANDLE hArray[1]= ::CreateThread(NULL, 0, ThreadProc2,NULL, 0, NULL);
    DWORD dwCode = ::WaitForMultipleObjects(2, hArray, FALSE, INFINITE);
    ->执行代码

## 互斥体 ##

HANDLE CreateMutexA(  				           //跨进程
      LPSECURITY_ATTRIBUTES lpMutexAttributes,     //使用互斥的权限，只读等待
      BOOL                  bInitialOwner,		   //是否可继承
      LPCSTR                lpName                 //标识符号名字
    );

创建互斥体

HANDLE g_hMutex = CreateMutex(NULL,FALSE, "XYZ");

HANDLE g_hMutex = OpenMutex(MUTEX_ALL_ACCESS, FALSE, "XYZ");
    
    WaitForSingleObject(g_hMutex, INFINITE);
    
    //逻辑代码1
    
    ReleaseMutex(g_hMutex);
    
    HANDLE g_hMutex = OpenMutex(MUTEX_ALL_ACCESS, FALSE, "XYZ");
    
    WaitForSingleObject(g_hMutex, INFINITE);
    
    //逻辑代码2
    
    ReleaseMutex(g_hMutex);

#include <iostream>
    #include <windows.h>
    HANDLE g_hMutex = CreateMutex(NULL, FALSE, L"XYZ");
    int a = 0;
    HANDLE hArray[2];
    DWORD WINAPI ThreadPorc1(LPVOID  lpParameter)
    {
    	for (int i = 0; i < 100; i++)
    	{
    		HANDLE g_hMutex = OpenMutex(MUTEX_ALL_ACCESS, FALSE, L"XYZ");
    		WaitForSingleObject(g_hMutex, INFINITE);
    		a++;
    		printf("线程1对a进行读写--%d\n", a);
    		ReleaseMutex(g_hMutex);
    		Sleep(100);
    	}
    	
    	return 0;
    }
    
    DWORD WINAPI ThreadPorc2(LPVOID  lpParameter)
    {
    	for (int i = 0; i < 100; i++)
    	{
    		HANDLE g_hMutex = OpenMutex(MUTEX_ALL_ACCESS, FALSE, L"XYZ");
    		WaitForSingleObject(g_hMutex, INFINITE);
    		a++;
    		printf("线程2对a进行读写--%d\n", a);
    		ReleaseMutex(g_hMutex);
    		Sleep(100);
    	}
    	return 0;
    }
    int main()
    {
    	hArray[0] = ::CreateThread(NULL, 0, ThreadPorc1, NULL, 0, NULL);
    	hArray[1] = ::CreateThread(NULL, 0, ThreadPorc2, NULL, 0, NULL);
    	DWORD dwCode = ::WaitForMultipleObjects(2, hArray, FALSE, INFINITE);
    	return 0;
    }

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