MSDN 条件变量使用例子

#include <windows.h>#include <stdlib.h>#include <stdio.h>#define BUFFER_SIZE 10#define PRODUCER_SLEEP_TIME_MS 500#define CONSUMER_SLEEP_TIME_MS 2000LONG Buffer[BUFFER_SIZE];LONG LastItemProduced;ULONG QueueSize;ULONG QueueStartOffset;ULONG TotalItemsProduced;ULONG TotalItemsConsumed;CONDITION_VARIABLE BufferNotEmpty;CONDITION_VARIABLE BufferNotFull;CRITICAL_SECTION   BufferLock;BOOL StopRequested;DWORD WINAPI ProducerThreadProc (PVOID p){    ULONG ProducerId = (ULONG)(ULONG_PTR)p;    while (true)    {        // Produce a new item.        Sleep (rand() % PRODUCER_SLEEP_TIME_MS);        ULONG Item = InterlockedIncrement (&LastItemProduced);        EnterCriticalSection (&BufferLock);        while (QueueSize == BUFFER_SIZE && StopRequested == FALSE)        {            // Buffer is full - sleep so consumers can get items.            SleepConditionVariableCS (&BufferNotFull, &BufferLock, INFINITE);        }        if (StopRequested == TRUE)        {            LeaveCriticalSection (&BufferLock);            break;        }        // Insert the item at the end of the queue and increment size.        Buffer[(QueueStartOffset + QueueSize) % BUFFER_SIZE] = Item;        QueueSize++;        TotalItemsProduced++;        printf ("Producer %u: item %2d, queue size %2u\r\n", ProducerId, Item, QueueSize);        LeaveCriticalSection (&BufferLock);        // If a consumer is waiting, wake it.        WakeConditionVariable (&BufferNotEmpty);    }    printf ("Producer %u exiting\r\n", ProducerId);    return 0;}DWORD WINAPI ConsumerThreadProc (PVOID p){    ULONG ConsumerId = (ULONG)(ULONG_PTR)p;    while (true)    {        EnterCriticalSection (&BufferLock);        while (QueueSize == 0 && StopRequested == FALSE)        {            // Buffer is empty - sleep so producers can create items.            SleepConditionVariableCS (&BufferNotEmpty, &BufferLock, INFINITE);        }        if (StopRequested == TRUE && QueueSize == 0)        {            LeaveCriticalSection (&BufferLock);            break;        }        // Consume the first available item.        LONG Item = Buffer[QueueStartOffset];        QueueSize--;        QueueStartOffset++;        TotalItemsConsumed++;        if (QueueStartOffset == BUFFER_SIZE)        {            QueueStartOffset = 0;        }        printf ("Consumer %u: item %2d, queue size %2u\r\n",             ConsumerId, Item, QueueSize);        LeaveCriticalSection (&BufferLock);        // If a producer is waiting, wake it.        WakeConditionVariable (&BufferNotFull);        // Simulate processing of the item.        Sleep (rand() % CONSUMER_SLEEP_TIME_MS);    }    printf ("Consumer %u exiting\r\n", ConsumerId);    return 0;}int main ( void ){    InitializeConditionVariable (&BufferNotEmpty);    InitializeConditionVariable (&BufferNotFull);    InitializeCriticalSection (&BufferLock);    DWORD id;    HANDLE hProducer1 = CreateThread (NULL, 0, ProducerThreadProc, (PVOID)1, 0, &id);    HANDLE hConsumer1 = CreateThread (NULL, 0, ConsumerThreadProc, (PVOID)1, 0, &id);    HANDLE hConsumer2 = CreateThread (NULL, 0, ConsumerThreadProc, (PVOID)2, 0, &id);    puts ("Press enter to stop...");    getchar();    EnterCriticalSection (&BufferLock);    StopRequested = TRUE;    LeaveCriticalSection (&BufferLock);    WakeAllConditionVariable (&BufferNotFull);    WakeAllConditionVariable (&BufferNotEmpty);    WaitForSingleObject (hProducer1, INFINITE);    WaitForSingleObject (hConsumer1, INFINITE);    WaitForSingleObject (hConsumer2, INFINITE);    printf ("TotalItemsProduced: %u, TotalItemsConsumed: %u\r\n",         TotalItemsProduced, TotalItemsConsumed);    return 0;}