生产者消费者——一对一

同步中有一个“生产者消费者”的经典问题，也叫它“有界缓冲区”

生产者生产数据，消费者取数据是消费(取出)数据。”数据多，空间少”才能造成生产者消费者问题
(数据)空的时候不能消费，(空间)满的时候不能生产.

这一篇实现一个生产者对应一个消费者，即一对一的情况

#include<stdio.h>#include<unistd.h>#include<pthread.h>#define MAX_PRODUCER_SIZE 1#define MAX_CONSUMER_SIZE 1#define MAX_COUNT 20#define MAX_BUFFER_SIZE 8struct pcst{    pthread_mutex_t mutex;    pthread_cond_t not_full;    pthread_cond_t not_empty;    int buffer[MAX_BUFFER_SIZE];    int write_pos;    int read_pos;    int nvalue;}shared = {PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER,    PTHREAD_COND_INITIALIZER};//注意not_full/not_empty是一个结构体，系统中它的初始化是PTHREAD_MUTEX_INITIALIZER，这个东西是以宏的形式定义的，所以在这里就对not_full/not_empty进行初始化比较方便，不然后面对它赋值时，相当于给一个结构体赋值，编译会报错。类似结尾给出的一样void init_pcst(){    shared.write_pos = 0;    shared.read_pos = 0;    shared.nvalue = 1;}void put_value(struct pcst *pc, int value){    pthread_mutex_lock(&pc->mutex);    if((pc->write_pos+1)%MAX_BUFFER_SIZE == pc->read_pos)        pthread_cond_wait(&pc->not_full, &pc->mutex);    pc->buffer[pc->write_pos++] = value;    pc->write_pos %= MAX_BUFFER_SIZE;    pthread_cond_signal(&pc->not_empty);    pthread_mutex_unlock(&pc->mutex);}int get_value(struct pcst *pc){    pthread_mutex_lock(&pc->mutex);    if(pc->read_pos == pc->write_pos)        pthread_cond_wait(&pc->not_empty, &pc->mutex);    int data = pc->buffer[pc->read_pos++];    pc->read_pos %= MAX_BUFFER_SIZE;    pthread_cond_signal(&pc->not_full);    pthread_mutex_unlock(&pc->mutex);    return data;}void* producer(void *arg){    for(int i=1; i<=MAX_COUNT; ++i)    {        put_value(&shared, shared.nvalue);        shared.nvalue++;    }}void* consumer(void *arg){    while(1)    {        int value = get_value(&shared);        printf("%d\n", value);        if(value >= MAX_COUNT)            break;       // sleep(1);    }}int main(int argc, char const* argv[]){   // shared.write_pos = shared.read_pos = 0;    //shared.nvalue = 1;    init_pcst();    pthread_t p_id[MAX_PRODUCER_SIZE];    pthread_t c_id[MAX_CONSUMER_SIZE];    for(int i=0; i<MAX_PRODUCER_SIZE; ++i)    {        pthread_create(&p_id[i], NULL, producer, NULL);    }    for(int i=0; i<MAX_CONSUMER_SIZE; ++i)    {        pthread_create(&c_id[i], NULL, consumer, NULL);    }    for(int i=0; i<MAX_PRODUCER_SIZE; ++i)    {        pthread_join(p_id[i], NULL);    }    for(int i=0; i<MAX_CONSUMER_SIZE; ++i)    {        pthread_join(c_id[i], NULL);    }    return 0;}

结果

系统对PTHREAD_COND_INITIALIZER的定义等


对结构体赋值的结果