生产者消费者多线程pthread

1.互斥#include <stdio.h>#include <pthread.h>#define BUFFER_SIZE 4#define OVER (-1)struct producers//定义生产者条件变量结构{int buffer[BUFFER_SIZE]; //定义缓冲区pthread_mutex_t lock; //访问缓冲区的互斥锁int readpos, writepos; //读写的位置pthread_cond_t notempty; //缓冲区有数据时的标记pthread_cond_t notfull; //缓冲区未满的标记};//初始化缓冲区void init(struct producers *b) //参数即为一个结构体，要struct，//定义时不用typedef{pthread_mutex_init(&b->lock,NULL);pthread_cond_init(&b->notempty,NULL);pthread_cond_init(&b->notfull,NULL); //初始化相关量b->readpos=0;b->writepos=0;//开始位置都为0}//在缓冲区存放一个整数void put(struct producers *b, int data) //两个参数，其中一个为数据{pthread_mutex_lock(&b->lock); //在put函数中完成互斥//当缓冲区为满时等待while((b->writepos+1)%BUFFER_SIZE==b->readpos)//满的条件是两个游标相邻{pthread_cond_wait(&b->notfull,&b->lock);}//在返回之前，pthread_con_wait需要参数b.lockb->buffer[b->writepos]=data; //否则在写的位置写入数据b->writepos++;//游标加一if(b->writepos>=BUFFER_SIZE) b->writepos=0; //满时，写位置置0 //发送当前缓冲区中有数据的信号pthread_cond_signal(&b->notempty);//pthread_mutex_unlock(&b->lock);}//从缓冲区读数据并将数据移走int get(struct producers *b){int data;pthread_mutex_lock(&b->lock);while(b->writepos==b->readpos)//此时无数据可读，阻塞{pthread_cond_wait(&b->notempty,&b->lock);}data=b->buffer[b->readpos]; //否则读数据b->readpos++;if(b->readpos>=BUFFER_SIZE) b->readpos=0;pthread_cond_signal(&b->notfull);pthread_mutex_unlock(&b->lock);return data;//返回读的数据}struct producers buffer;//事先要定义这个全局变量void *producer(void *data) //参数应该为void，与上面的data无关{int n;for(n=0;n<10;n++){printf("Producer : %d-->\n",n);put(&buffer,n);}put(&buffer,OVER);return NULL;}void *consumer(void *data){int d;while(1){d=get(&buffer);if(d==OVER) break;printf("Consumer: --> %d\n",d);}return NULL;}int main(){pthread_t tha,thb;void *retval;init(&buffer);pthread_create(&tha,NULL,producer,0);pthread_create(&thb,NULL,consumer,0);pthread_join(tha,&retval);pthread_join(thb,&retval);return 0;}2.用条件变量#include<stdio.h>#include<pthread.h>#define BUFFER_SIZE 8#define OVER (-1)struct producers {//定义生产者条件变量结构int buffer[BUFFER_SIZE]; //缓冲区pthread_mutex_t lock; //互斥LOCKint readpos , writepos; //读写位置pthread_cond_t notempty; //缓冲区非空条件判断pthread_cond_t notfull; //缓冲区未满条件判断};void init(struct producers * b){//初始化缓冲区pthread_mutex_init(&b->lock,NULL);pthread_cond_init(&b->notempty,NULL);pthread_cond_init(&b->notfull,NULL);b->readpos=0;b->writepos=0;}//缓冲区刚开始的情况void put(struct producers * b,int data){//缓冲区中放入一个数据pthread-_mutex_lock(&b->lock);//当缓冲区为满时等待,即写的位置前移一个就是写的位置了if((b->writepos + 1) % BUFFER_SIZE == b->readpos){pthread_cond_wait(&b->notfull, &b->lock) ;//此时已满，要等信号notfull才能写。

所要做的工作是释放mutex互斥锁，并且阻塞条件变量，直到信号被唤醒，在阻塞前自动释放互斥锁，在返回前自动获得它}//在返回之前，需要参数b->lockb->buffer[b->writepos]=data;//向缓冲区写数据，指针前移b->writepos++;if(b->writepos >= BUFFER_SIZE)b->writepos=0;//写满后调头//发送当前缓冲区有数据信号pthread_cond_signal(&b->notempty);//使得关于参数notempty而阻塞的线程退出阻塞状态，并且要在同一个互斥锁的保护下使用；pthread_mutex_unlock(&b->lock);//解锁}//读数据并移走int get(struct prodcons *b){int data;pthread_mutex_lock(&b->lock);//当缓冲区有数据时等待if(b->writepos == b->readpos){pthread_cond _wait(&b->notempty, &b->lock);}data = b->buffer[b->readpos];b->readpos++;//读数据，指针前移if(b->readpos >= BUFFER_SIZE)b->readpos=0;//发送当前缓冲区未满信号pthread_cond_signal(&b->notfull);pthread_mutex_unlock(&b->lock);return data;}struct prodcons buffer;void *producer(void *data){int n;for(n = 0; n < 10000; n++){printf("%d \n", n) ;put(&buffer, n);}put(&buffer, OVER);return NULL;}void *consumer(void * data){int d;while(1){d = get(&buffer);if(d == OVER)break;printf("%d\n", d);}return NULL;}int main(void){pthread_t th_a, th_b;void *retval;init(&buffer);pthread_create(&th_a, NULL, producer, 0); pthread_create(&th_b, NULL, consumer, 0); pthread_join(th_a, &retval);pthread_join(th_b, &retval);return 0;}3.用信号量#include<stdio.h>#include<pthread.h>#include<semaphore.h>#define BUFFER_SIZE 8#define OVER (-1)struct producers {//定义生产者条件变量结构int buffer[BUFFER_SIZE]; //缓冲区sem_t sem_read;sem_t sem_write;int readpos , writepos; //读写位置};void init(struct producers * b){//初始化缓冲区b->readpos=0;b->writepos=0;sem_init(&b->write,0,BUFFER_SIZE-1);sem_init(&b->read,0,0);//初始化一个定位在sem 的匿名信号量。