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C/C++ 信号量,互斥锁使用实例,内含多线程,多进程使用代码(带例子)
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WIN32的使用例子, 下载地址:
http://www.semisecs.com/download/例子.rar
信号量:
单线程情况下,只能获取一次锁,信号量的nCount计数会减一,所以再次获取信号量会导致自锁。
每次使用都必须进行Release进行释放
用到函数
CreateSemaphore
OpenSemaphore
WaitForSingleObject
WaitForMultipleObjects(个数, 指针数组, TRUE等待所有, 时间)
如果并非等待所有事件同时触发,则立即返回
ReleaseSemaphore
CloseHandle
WaitForMultipleObjects 使用问题:
指针数组必须为同一类对象:事件,线程,互斥锁等
// 以下是部分代码,能正常运行
HANDLE handExit = CreateEvent(NULL,TRUE, FALSE, “121X32”);
HANDLE handSemaphore = CreateSemaphore(NULL, 1, 1, “121X3232”);
HANDLE hExit = OpenEvent(EVENT_ALL_ACCESS, FALSE, “121X32”);
HANDLE hSemaphore = OpenSemaphore(SEMAPHORE_ALL_ACCESS, FALSE, “121X3232”);
void Thread(void* da)
{
DWORD rea;
while(true)
{
while(true)
{
rea = ::WaitForSingleObject(hSemaphore, 1000);
if(rea == WAIT_TIMEOUT)
{
if(WAIT_OBJECT_0 == ::WaitForSingleObject(hExit, 0))
{
return;
}
}
else
{
break;
}
}
Sleep(1000);
ReleaseSemaphore(hSemaphore, 1, NULL);
if(WAIT_OBJECT_0 == ::WaitForSingleObject(hExit, 0))
{
return;
}
}
}
void CSemaphoreTestDlg::OnBnClickedButton1()
{
::_beginthread(Thread, 0, this);
::_beginthread(Thread, 0, this);
}
void CSemaphoreTestDlg::OnBnClickedButton3()
{
SetEvent(handExit);
}
void CSemaphoreTestDlg::OnBnClickedButton2()
{
ResetEvent(handExit);
}
互斥锁:
同一线程多次获取互斥信号,不会导致自锁。但是需要执行相对应的Release次数
用到函数
CreateSemaphore
OpenSemaphore
WaitForSingleObject
WaitForMultipleObjects(个数, 指针数组, TRUE等待所有, 时间)
如果并非等待所有事件同时触发,则立即返回
ReleaseSemaphore
CloseHandle
// 以下是部分代码,能正常运行
HANDLE handExit = CreateEvent(NULL,TRUE, FALSE, “121X32”);
HANDLE handMutex = CreateMutex(NULL, FALSE, “121X3232”);
HANDLE hExit = OpenEvent(EVENT_ALL_ACCESS, FALSE, “121X32”);
HANDLE hMutex = OpenMutex(MUTEX_ALL_ACCESS, FALSE, “121X3232”);
void Thread(void* da)
{
DWORD rea;
while(true)
{
while(true)
{
rea = ::WaitForSingleObject(hMutex, 1000);
if(rea == WAIT_TIMEOUT)
{
if(WAIT_OBJECT_0 == ::WaitForSingleObject(hExit, 0))
{
return;
}
}
else
{
break;
}
}
Sleep(1000);
ReleaseMutex(hMutex);
if(WAIT_OBJECT_0 == ::WaitForSingleObject(hExit, 0))
{
return;
}
}
}
void CtestMutexDlg::OnBnClickedButton1()
{
::_beginthread(Thread, 0, this);
::_beginthread(Thread, 0, this);
}
void CtestMutexDlg::OnBnClickedButton2()
{
SetEvent(handExit);
}
void CtestMutexDlg::OnBnClickedButton3()
{
ResetEvent(handExit);
}