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C++|读者写者问题(一个读者一个写者)

c++多线程操作系统

#include #include #include #include#include using namespace std; struct Storage { //两个条件变量、两个互斥锁 int value; pthread_cond_t rc; pthread_mutex_t rm; int r_wait; pthread_cond_t wc; pthread_mutex_t wm; int w_wait; }; void set_data(Storage *s,int value) { s->value=https://www.it610.com/article/value; }int get_data(Storage *s) { return s->value; }//写者线程执行的线程运行函数 void* set_th(void* arg) { Storage*s=(Storage*)arg; int i=1; for(; i<=100; ++i) { //往Storage中写入数据 set_data(s,i+100); coutr_wait)//判断读者线程是否准备好 { pthread_mutex_unlock(&s->rm); sleep(1); pthread_mutex_lock(&s->rm); } s->r_wait=0; pthread_mutex_unlock(&s->rm); pthread_cond_broadcast(&s->rc); //读者线程已经准备好了，通知(唤醒)读者线程//写者线程等待阻塞 //等待读者线程读取完数据后通知唤醒它 //然后继续写入数据pthread_mutex_lock(&s->wm); s->w_wait=1; //写者线程阻塞，加入阻塞队列wc(条件变量内部是一个的等待队列，存放阻塞的线程) pthread_cond_wait(&s->wc,&s->wm); pthread_mutex_unlock(&s->wm); } return (void*)0; }//读者线程执行的线程运行函数 void* get_th(void* arg) { Storage* s=(Storage*)arg; int i=1; for(; i<=100; ++i) { pthread_mutex_lock(&s->rm); s->r_wait=1; //表示读者线程准备好了 pthread_cond_wait(&s->rc,&s->rm); //读者线程准备好了，将读者线程阻塞 pthread_mutex_unlock(&s->rm); //读者线程被唤醒后从Storage中获取数据 int value= https://www.it610.com/article/get_data(s); coutw_wait) { pthread_mutex_unlock(&s->wm); sleep(1); pthread_mutex_lock(&s->wm); } s->w_wait=0; pthread_mutex_unlock(&s->wm); //去通知写者线程继续写入数据 pthread_cond_broadcast(&s->wc); } return (void*)0; }int main() { int err; pthread_t rth,wth; Storage s; s.r_wait=0; s.w_wait=0; //初始化条件变量和信号量 pthread_cond_init(&s.rc,NULL); pthread_cond_init(&s.wc,NULL); pthread_mutex_init(&s.rm,NULL); pthread_mutex_init(&s.wm,NULL); //创建一个读者线程和一各读者线程 err=pthread_create(&rth,NULL,get_th,(void*)&s); if(err!=0) { perror("create error"); }err=pthread_create(&wth,NULL,set_th,(void*)&s); if(err!=0) { perror("create error"); }pthread_join(rth,NULL); pthread_join(wth,NULL); //销毁互斥量和条件变量 pthread_cond_destroy(&s.rc); pthread_cond_destroy(&s.wc); pthread_mutex_destroy(&s.rm); pthread_mutex_destroy(&s.wm); return 0; }

【C++|读者写者问题(一个读者一个写者)】

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