生产者消费者问题

参考地址：http://blog.csdn.net/morewindows/article/details/7577591

生产者消费者问题是一个著名的线程同步问题，该问题描述如下：有一个生产者在生产产品，这些产品将提供给若干个消费者去消费，为了使生产者和消费者能并发执行，在两者之间设置一个具有多个缓冲区的缓冲池，生产者将它生产的产品放入一个缓冲区中，消费者可以从缓冲区中取走产品进行消费，显然生产者和消费者之间必须保持同步，即不允许消费者到一个空的缓冲区中取产品，也不允许生产者向一个已经放入产品的缓冲区中再次投放产品。

代码一：1个生产者，1个消费者，1个缓冲区

#include <iostream>
#include <Windows.h>
#include <process.h>
using namespace std;
/************************************************************************************

                            模拟单个缓冲区的情况

*************************************************************************************/
const int PRODUCT_NUM = 10; //生产产品个数
int g_nBuffer;                //缓冲区
CRITICAL_SECTION g_cs;
HANDLE g_hEventBufferEmpty;
HANDLE g_hEventBufferFull;

//设置控制台文字颜色
BOOL SetConsoleColor(WORD wAttributes)
{
    HANDLE hHandle = GetStdHandle(STD_OUTPUT_HANDLE);
    if (hHandle == INVALID_HANDLE_VALUE)
    {
        cout << "GetStdHandle Error!" << endl;
        return false;
    }
    //SetConsoleTitle(L"生产者消费者问题");
    return SetConsoleTextAttribute(hHandle, wAttributes);
}

unsigned int WINAPI ProducerThreadFunc(PVOID pParam)
{
    for (int i = 1; i <= PRODUCT_NUM; ++i)
    {
        if (i > PRODUCT_NUM)
        {
            return 0;
        }
        WaitForSingleObject(g_hEventBufferEmpty, INFINITE);
        EnterCriticalSection(&g_cs);
        g_nBuffer = i;
        SetConsoleColor(FOREGROUND_BLUE|FOREGROUND_GREEN|FOREGROUND_RED);
        cout << "生产者将数据[" << i << "]放入缓冲区!" << endl;
        LeaveCriticalSection(&g_cs);
        SetEvent(g_hEventBufferFull);
    }
    return 0;
}

unsigned int WINAPI ConsumerThreadFunc(PVOID pParam)
{
    //volatile bool bFlag = true;
    while(true)
    {
        WaitForSingleObject(g_hEventBufferFull, INFINITE);
        EnterCriticalSection(&g_cs);
        SetConsoleColor(FOREGROUND_GREEN);
        cout << "消费者从缓冲区中取出数据[" << g_nBuffer << "]" << endl;
        SetConsoleColor(FOREGROUND_RED|FOREGROUND_BLUE|FOREGROUND_GREEN);
        if (g_nBuffer == PRODUCT_NUM)
        {
            LeaveCriticalSection(&g_cs);
            return 0;
        }
        Sleep(100);
        LeaveCriticalSection(&g_cs);
        SetEvent(g_hEventBufferEmpty);
    }
    return 0;
}

int main()
{
    const int nThreadNum = 2;
    HANDLE hThread[nThreadNum];
    g_hEventBufferEmpty = CreateEvent(NULL, false, true, NULL);
    g_hEventBufferFull = CreateEvent(NULL, false, false, NULL);
    InitializeCriticalSection(&g_cs);

    cout << "\t\t生产者消费者问题：1生产者，1消费者，1缓冲区" << endl;
    hThread[0] = (HANDLE)_beginthreadex(NULL, 0, ProducerThreadFunc, NULL, 0, NULL);
    hThread[1] = (HANDLE)_beginthreadex(NULL, 0, ConsumerThreadFunc, NULL, 0, NULL);
    WaitForMultipleObjects(nThreadNum, hThread, true, INFINITE);
    
    CloseHandle(hThread[0]);
    CloseHandle(hThread[1]);
    CloseHandle(g_hEventBufferFull);
    CloseHandle(g_hEventBufferEmpty);
    DeleteCriticalSection(&g_cs);

    return 0;
}

代码二：1个生成者，2个消费者，4个缓冲区

#include <iostream>
#include <Windows.h>
#include <process.h>
using namespace std;
/************************************************************************************

                        模拟多个缓冲区、多个消费者的情况

*************************************************************************************/
const int PRODUCT_NUM = 10; //生产产品个数
const int BUFFERSIZE = 4;    //缓冲区个数
int g_nBuffer[BUFFERSIZE];
int g_nProduceCnt;    //生产位置
int g_nConsumeCnt;    //消费位置
CRITICAL_SECTION g_cs;
HANDLE g_hSemaphoreEmpty;
HANDLE g_hSemaphoreFull;

//设置控制台文字颜色
BOOL SetConsoleColor(WORD wAttributes)
{
    HANDLE hHandle = GetStdHandle(STD_OUTPUT_HANDLE);
    if (hHandle == INVALID_HANDLE_VALUE)
    {
        cout << "GetStdHandle Error!" << endl;
        return false;
    }
    //SetConsoleTitle(L"生产者消费者问题");
    return SetConsoleTextAttribute(hHandle, wAttributes);
}

unsigned int WINAPI ProducerThreadFunc(PVOID pParam)
{
    for (int i = 1; i <= PRODUCT_NUM; ++i)
    {//生产者与消费者之间本不应该互斥，但是这里考虑到设置控制台颜色的问题，必须互斥，实际情况这里的互斥条件应该去掉
        WaitForSingleObject(g_hSemaphoreEmpty, INFINITE);
        EnterCriticalSection(&g_cs);
        g_nProduceCnt = (i-1)%BUFFERSIZE;
        g_nBuffer[g_nProduceCnt] = i;
        SetConsoleColor(FOREGROUND_BLUE|FOREGROUND_GREEN|FOREGROUND_RED);
        cout << "生产者[" << GetCurrentThreadId() << "]将数据[" << i << "]放入缓冲区位置[" << g_nProduceCnt << "]" << endl;
        LeaveCriticalSection(&g_cs);
        ReleaseSemaphore(g_hSemaphoreFull, 1, NULL);
    }
    return 0;
}

unsigned int WINAPI ConsumerThreadFunc(PVOID pParam)
{
    volatile bool bFlag = true;
    while(bFlag)
    {
        WaitForSingleObject(g_hSemaphoreFull, INFINITE);
        EnterCriticalSection(&g_cs);
        if (!bFlag)
        {
            LeaveCriticalSection(&g_cs);
            return 0;
        }
        SetConsoleColor(FOREGROUND_GREEN);
        cout << "消费者[" << GetCurrentThreadId() << "]从缓冲区中位置[" << g_nConsumeCnt%BUFFERSIZE << "]取出数据[" << 
　　　　　　　　　　　　　　　　g_nBuffer[g_nConsumeCnt%BUFFERSIZE] << "]" << endl;
        ++g_nConsumeCnt;
        SetConsoleColor(FOREGROUND_RED|FOREGROUND_BLUE|FOREGROUND_GREEN);
        if (g_nConsumeCnt == PRODUCT_NUM)
        {
            LeaveCriticalSection(&g_cs);
            bFlag = false;
        }
        Sleep(100);
        LeaveCriticalSection(&g_cs);
        ReleaseSemaphore(g_hSemaphoreEmpty, 1, NULL);
    }
    return 0;
}

int main()
{
    const int nThreadNum = 3;
    HANDLE hThread[nThreadNum];

    g_hSemaphoreEmpty = CreateSemaphore(NULL, 4, BUFFERSIZE, NULL);
    g_hSemaphoreFull = CreateSemaphore(NULL, 0, BUFFERSIZE, NULL);
    InitializeCriticalSection(&g_cs);

    g_nProduceCnt = 0;
    g_nConsumeCnt = 0;
    cout << "\t\t生产者消费者问题：1生产者，2消费者，4缓冲区" << endl;
    hThread[0] = (HANDLE)_beginthreadex(NULL, 0, ProducerThreadFunc, NULL, 0, NULL);
    hThread[1] = (HANDLE)_beginthreadex(NULL, 0, ConsumerThreadFunc, NULL, 0, NULL);
    hThread[2] = (HANDLE)_beginthreadex(NULL, 0, ConsumerThreadFunc, NULL, 0, NULL);
    WaitForMultipleObjects(nThreadNum, hThread, true, INFINITE);
    
    for (int i = 0; i < nThreadNum; ++i)
        CloseHandle(hThread[i]);
    CloseHandle(g_hSemaphoreFull);
    CloseHandle(g_hSemaphoreEmpty);
    DeleteCriticalSection(&g_cs);

    return 0;
}