linux 多线程编程之——消费者与生产者

之前 在网上 搜了一堆多线程的经典的例子，其中最简单是消费者与生产者

不过 他们的代码经过测试都有段错误，原因是没有对互斥锁，条件等等初始化。以下是经过修改的代码，可以正常运行。

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <pthread.h>#include <time.h>#include <string.h>#define BUFFER_SIZE 8struct Products{    int buffer[BUFFER_SIZE];    pthread_mutex_t locker;           //保证存取操作的原子性 互斥性    pthread_cond_t notEmpty;          //是否可读           pthread_cond_t notFull;          //是否可写    int posReadFrom;    int posWriteTo;};struct Products products;int BufferIsFull(struct Products* products){    if ((products->posWriteTo + 1) % BUFFER_SIZE == products->posReadFrom)    {        return (1);    }    return (0);}int BufferIsEmpty(struct Products* products){    if (products->posWriteTo == products->posReadFrom)    {        return (1);    }    return (0);}//制造产品。void Produce(struct Products* products, int item){    pthread_mutex_lock(&products->locker); //原子操作            while (BufferIsFull(products))    {        pthread_cond_wait(&products->notFull, &products->locker);    } //无空间可写入            //写入数据    products->buffer[products->posWriteTo] = item;    products->posWriteTo++;            if (products->posWriteTo >= BUFFER_SIZE)    {        products->posWriteTo = 0;    }    pthread_cond_signal(&products->notEmpty);     //发信    pthread_mutex_unlock(&products->locker);    //解锁}int Consume(struct Products* products){    int item;        pthread_mutex_lock(&products->locker);        while (BufferIsEmpty(products))    {        pthread_cond_wait(&products->notEmpty, &products->locker);    } //为空时持续等待,无数据可读        //提取数据    item = products->buffer[products->posReadFrom];    products->posReadFrom++;        if (products->posReadFrom >= BUFFER_SIZE) //如果到末尾,从头读取    {        products->posReadFrom = 0;    }    pthread_cond_signal(&products->notFull);     pthread_mutex_unlock(&products->locker);        return item;}#define END_FLAG (-1)struct Products products;void* ProducerThread(void *arg){    int i;    for (i = 0; i < 16; i++)    {        printf("producer: %d\t", i);        Produce(&products, i);       }    Produce(&products, END_FLAG);    return NULL;}void* ConsumerThread(void *arg){    int item;        while (1)    {        item = Consume(&products);        if (END_FLAG == item)            break;        printf("consumer: %d\t", item);    }        return (NULL);}  void InitProducer(struct Products* products) {    memset(products->buffer,0,BUFFER_SIZE);    pthread_mutex_init(&products->locker, NULL);    products->notEmpty = PTHREAD_COND_INITIALIZER;    products->notFull = PTHREAD_COND_INITIALIZER;    products->posReadFrom = 0;    products->posWriteTo = 0;        }int main(int argc, char* argv[]){                 pthread_t producer;    pthread_t consumer;    void   *result ;    int  ret;            InitProducer(&products);       if ((ret= pthread_create(&producer, NULL, &ProducerThread, NULL)) != 0)    {        printf("producer 创建失败\n");       }    else    {         printf("producer 创建成功\n");      }    if ((ret= pthread_create(&consumer, NULL, &ConsumerThread, NULL) )!= 0)    {        printf("Consumer创建失败\n");       }    else    {         printf("Consumer 创建成功\n");      }              pthread_join(producer, &result);    pthread_join(consumer, &result);    system("pause");    exit(EXIT_SUCCESS);}