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生产者消费者问题
C代码:
#include <windows.h> #include <iostream> const unsigned short SIZE_OF_BUFFER = 2; //缓冲区长度 unsigned short ProductID = 0; //产品号 unsigned short ConsumeID = 0; //将被消耗的产品号 unsigned short in = 0; //产品进缓冲区时的缓冲区下标 unsigned short out = 0; //产品出缓冲区时的缓冲区下标 int buffer[SIZE_OF_BUFFER]; //缓冲区是个循环队列操作系统课程设计指导书 bool p_ccontinue = true; //控制程序结束 HANDLE Mutex; //用于线程间的互斥 HANDLE FullSemaphore; //当缓冲区满时迫使生产者等待 HANDLE EmptySemaphore; //当缓冲区空时迫使消费者等待 DWORD WINAPI Producer(LPVOID); //生产者线程 DWORD WINAPI Consumer(LPVOID); //消费者线程 int main() { //创建各个互斥信号 //注意,互斥信号量和同步信号量的定义方法不同,互斥信号量调用的是 CreateMutex 函数, //调用的是 CreateSemaphore 函数,函数的返回值都是句柄。 Mutex = CreateMutex(NULL,FALSE,NULL); EmptySemaphore = CreateSemaphore(NULL,SIZE_OF_BUFFER,SIZE_OF_BUFFER,NULL); //将上句做如下修改,看看结果会怎样 //EmptySemaphore = CreateSemaphore(NULL,0,SIZE_OF_BUFFER-1,NULL); FullSemaphore = CreateSemaphore(NULL,0,SIZE_OF_BUFFER,NULL); //调整下面的数值,可以发现,当生产者个数多于消费者个数时, //生产速度快,生产者经常等待消费者;反之,消费者经常等待 const unsigned short PRODUCERS_COUNT = 3; //生产者的个数 const unsigned short CONSUMERS_COUNT = 1; //消费者的个数 //总的线程数 const unsigned short THREADS_COUNT = PRODUCERS_COUNT+CONSUMERS_COUNT; HANDLE hThreads[THREADS_COUNT]; //各线程的 handle DWORD producerID[PRODUCERS_COUNT]; //生产者线程的标识符 DWORD consumerID[CONSUMERS_COUNT]; //消费者线程的标识符 //创建生产者线程 for (int i=0;i<PRODUCERS_COUNT;++i){ hThreads[i]=CreateThread(NULL,0,Producer,NULL,0,&producerID[i]); if (hThreads[i]==NULL) return -1; } //创建消费者线程 for (i=0;i<CONSUMERS_COUNT;++i){ hThreads[PRODUCERS_COUNT+i]=CreateThread(NULL,0,Consumer,NULL,0,&consumerID[i]); if (hThreads[i]==NULL) return -1; } while(p_ccontinue){ if(getchar()){ //按回车后终止程序运行操作系统课程设计指导书 p_ccontinue = false; } } return 0; } //生产一个产品。简单模拟了一下,仅输出新产品的 ID 号 void Produce() { std::cout << std::endl<< "Producing " << ++ProductID << " ... "; std::cout << "Succeed" << std::endl; } //把新生产的产品放入缓冲区 void Append() { std::cerr << "Appending a product ... "; buffer[in] = ProductID; in = (in+1)%SIZE_OF_BUFFER; std::cerr << "Succeed" << std::endl; //输出缓冲区当前的状态 for (int i=0;i<SIZE_OF_BUFFER;++i){ std::cout << i <<": " << buffer[i]; if (i==in) std::cout << " <-- 生产"; if (i==out) std::cout << " <-- 消费"; std::cout << std::endl; } } //从缓冲区中取出一个产品 void Take() { std::cerr << "Taking a product ... "; ConsumeID = buffer[out]; buffer[out] = 0; out = (out+1)%SIZE_OF_BUFFER; std::cerr << "Succeed" << std::endl; //输出缓冲区当前的状态 for (int i=0;i<SIZE_OF_BUFFER;++i){ std::cout << i <<": " << buffer[i]; if (i==in) std::cout << " <-- 生产"; if (i==out) std::cout << " <-- 消费"; std::cout << std::endl; } } //消耗一个产品 void Consume() { std::cout << "Consuming " << ConsumeID << " ... "; std::cout << "Succeed" << std::endl; } //生产者 DWORD WINAPI Producer(LPVOID lpPara) { while(p_ccontinue){ WaitForSingleObject(EmptySemaphore,INFINITE); //p(empty); WaitForSingleObject(Mutex,INFINITE); //p(mutex); Produce(); Append(); Sleep(1500); ReleaseMutex(Mutex); //V(mutex); ReleaseSemaphore(FullSemaphore,1,NULL); //V(full); } return 0; } //消费者 DWORD WINAPI Consumer(LPVOID lpPara) { while(p_ccontinue){ WaitForSingleObject(FullSemaphore,INFINITE); //P(full); WaitForSingleObject(Mutex,INFINITE); //P(mutex); Take(); Consume(); Sleep(1500); ReleaseMutex(Mutex); //V(mutex); ReleaseSemaphore(EmptySemaphore,1,NULL); //V(empty); } return 0; }
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