condition variable 和 srwlock的一个例子

Condition Variable

为实现近点的生产者消费者问题。我们可以使用两个CONDITION_VARIABLE：g_full，g_empty来实现。在缓冲区满的时候，生产者线程调用SleepConditionVariableSRW(&g_full, &g_lock, INFINITE, 0)施放获得的锁并等待g_full。缓冲区空的时候，消费者可以调用leepConditionVariableSRW(&g_empty, &g_lock, INFINITE, 0)施放获得的锁并等待g_empty。掉进满足后，可是使用WakeAllConditionVariable唤醒所有等待的线程或者使用WakeConditionVariable唤醒一个等待的线程。

和Condition Variable配置使用的可以使CrticalSection也可以使SRWLock。

BOOL SleepConditionVariableCS(

PCONDITION_VARIABLE pConditionVariable,

PCRITICAL_SECTION pCriticalSection,

DWORD dwMilliseconds);

BOOL SleepConditionVariableSRW(

PCONDITION_VARIABLE pConditionVariable,

PSRWLOCK pSRWLock,

DWORD dwMilliseconds,

ULONG Flags);

参数dwMilliseconds指定等待超时的时间，如果超时方法返回FASLE；INFINITE指定等待不超时。参数Flags指定被唤醒时尝试获得的锁的类型。CONDITION_VARIABLE_LOCKMODE_ SHARED指定获得共享锁或者0指定获得独占锁。

const int MAX_SIZE = 10;

CONDITION_VARIABLE g_full;

CONDITION_VARIABLE g_empty;

SRWLOCK g_lock;

list<Product> products;

unsigned int WINAPI ProduceThreadFunc(void* pvParam)

{

int i(0);

while(true)

{

Sleep(rand() % 100);

AcquireSRWLockExclusive(&g_lock);

if (products.size() >= MAX_SIZE)

{

SleepConditionVariableSRW(&g_full, &g_lock, INFINITE, 0);

}

else

{

cout <<"Produce Product:" <<i <<" by thread " <<GetThreadId(GetCurrentThread()) <<endl;

products.push_back(Product(i++));

}

WakeAllConditionVariable(&g_empty);

ReleaseSRWLockExclusive(&g_lock);

}

return 0;

}

unsigned int WINAPI ConsumeThreadFunc(void* pvParam)

{

while(true)

{

Sleep(rand() % 100);

AcquireSRWLockExclusive(&g_lock);

if(products.size() == 0)

{

SleepConditionVariableSRW(&g_empty, &g_lock, INFINITE, 0);

}

else

{

Product p = products.front();

products.pop_front();

cout <<"Consume Product:" <<p.m_no <<" by thread " <<GetThreadId(GetCurrentThread()) <<endl;

}

WakeAllConditionVariable(&g_full);

ReleaseSRWLockExclusive(&g_lock);

}

return 0;

}

int _tmain(int argc, _TCHAR* argv[])

{

srand((unsigned)time(NULL));

InitializeSRWLock(&g_lock);

unsigned int threadId;

HANDLE thread1 = (HANDLE)_beginthreadex(NULL, 0, ProduceThreadFunc, NULL, 0, &threadId);

HANDLE thread2 = (HANDLE)_beginthreadex(NULL, 0, ConsumeThreadFunc, NULL, 0, &threadId);

HANDLE thread3 = (HANDLE)_beginthreadex(NULL, 0, ConsumeThreadFunc, NULL, 0, &threadId);

WaitForSingleObject(thread1, INFINITE);

WaitForSingleObject(thread2, INFINITE);

WaitForSingleObject(thread3, INFINITE);

system("pause");

return 0;

}