C语言编写一个生产者和消费者程序

在C语言中，生产者和消费者是一种经典的并发编程模型，它通常使用互斥量（mutex）和条件变量（condition variable）来控制两个线程之间的交互。这里是一个简单的例子，假设我们有一个共享缓冲区，生产者负责生产数据放入缓冲区，消费者则从缓冲区中取出数据消费。

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

#define BUFFER_SIZE 10
#define MAX_ITEMS 50

typedef struct {
    int buffer[BUFFER_SIZE];
    int count;
    int max_count;
    pthread_mutex_t mutex; // 互斥锁
    pthread_cond_t cond;   // 条件变量
} producer_consumer;

void* producer(void* arg) {
    producer_consumer* pc = (producer_consumer*)arg;
    for (int i = 0; i < MAX_ITEMS; ++i) {
        pthread_mutex_lock(&pc->mutex);
        while (pc->count == pc->max_count) {
            pthread_cond_wait(&pc->cond, &pc->mutex); // 等待唤醒
        }
        pc->buffer[pc->count++] = i;
        printf("Produced item %d\n", i);
        if (pc->count == pc->max_count) {
            printf("Buffer full, stopping producer.\n");
            break;
        }
        pthread_mutex_unlock(&pc->mutex);
    }
    pthread_exit(NULL);
}

void* consumer(void* arg) {
    producer_consumer* pc = (producer_consumer*)arg;
    for (int i = 0; i < MAX_ITEMS; ++i) {
        pthread_mutex_lock(&pc->mutex);
        while (pc->count == 0) {
            pthread_cond_wait(&pc->cond, &pc->mutex); // 等待唤醒
        }
        pc->count--;
        printf("Consumed item %d\n", pc->buffer[i]);
        if (pc->count == 0) {
            printf("Buffer empty, stopping consumer.\n");
            break;
        }
        pthread_mutex_unlock(&pc->mutex);
    }
    pthread_exit(NULL);
}

int main() {
    producer_consumer pc;
    pthread_t producer_thread, consumer_thread;
    int ret;

    // 初始化互斥锁和条件变量
    pthread_mutex_init(&pc.mutex, NULL);
    pthread_cond_init(&pc.cond, NULL);

    // 设置缓冲区大小和最大元素数
    pc.max_count = BUFFER_SIZE;
    
    // 创建并启动生产者和消费者线程
    ret = pthread_create(&producer_thread, NULL, producer, &pc);
    if (ret != 0) {
        perror("Producer thread creation failed");
        return -1;
    }

    ret = pthread_create(&consumer_thread, NULL, consumer, &pc);
    if (ret != 0) {
        perror("Consumer thread creation failed");
        return -1;
    }

    // 等待线程结束
    pthread_join(producer_thread, NULL);
    pthread_join(consumer_thread, NULL);

    // 清理资源
    pthread_mutex_destroy(&pc.mutex);
    pthread_cond_destroy(&pc.cond);

    return 0;
}