producer_consumer.c

/*
 * Copyright (c) 2006-2018, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date Author Notes
 * 2018-08-24 yangjie the first version
 */

/*
 * 程序清单：生产者消费者例子
 *
 * 这个例子中将创建两个线程用于实现生产者消费者问题
 *（1）生产者线程将cnt值每次加1并循环存入array数组的5个成员内；
 *（2）消费者线程将生产者中生产的数值打印出来，并累加求和
 */
#include <rtthread.h>

#define THREAD_PRIORITY 6
#define THREAD_STACK_SIZE 512
#define THREAD_TIMESLICE 5

/* 定义最大5个元素能够被产生 */
#define MAXSEM 5

/* 用于放置生产的整数数组 */
rt_uint32_t array[MAXSEM];

/* 指向生产者、消费者在array数组中的读写位置 */
static rt_uint32_t set, get;

/* 指向线程控制块的指针 */
static rt_thread_t producer_tid = RT_NULL;
static rt_thread_t consumer_tid = RT_NULL;

struct rt_semaphore sem_lock;
struct rt_semaphore sem_empty, sem_full;

/* 生产者线程入口 */
void producer_thread_entry(void *parameter)
{
 int cnt = 0;

 /* 运行10次 */
 while (cnt < 10)
 {
 /* 获取一个空位 */
 rt_sem_take(&sem_empty, RT_WAITING_FOREVER);

 /* 修改array内容，上锁 */
 rt_sem_take(&sem_lock, RT_WAITING_FOREVER);
 array[set % MAXSEM] = cnt + 1;
 rt_kprintf("the producer generates a number: %d\n", array[set % MAXSEM]);
 set++;
 rt_sem_release(&sem_lock);

 /* 发布一个满位 */
 rt_sem_release(&sem_full);
 cnt++;

 /* 暂停一段时间 */
 rt_thread_mdelay(20);
 }

 rt_kprintf("the producer exit!\n");
}

/* 消费者线程入口 */
void consumer_thread_entry(void *parameter)
{
 rt_uint32_t sum = 0;

 while (1)
 {
 /* 获取一个满位 */
 rt_sem_take(&sem_full, RT_WAITING_FOREVER);

 /* 临界区，上锁进行操作 */
 rt_sem_take(&sem_lock, RT_WAITING_FOREVER);
 sum += array[get % MAXSEM];
 rt_kprintf("the consumer[%d] get a number: %d\n", (get % MAXSEM), array[get % MAXSEM]);
 get++;
 rt_sem_release(&sem_lock);

 /* 释放一个空位 */
 rt_sem_release(&sem_empty);

 /* 生产者生产到10个数目，停止，消费者线程相应停止 */
 if (get == 10) break;

 /* 暂停一小会时间 */
 rt_thread_mdelay(50);
 }

 rt_kprintf("the consumer sum is: %d\n", sum);
 rt_kprintf("the consumer exit!\n");
}

int producer_consumer(void)
{
 set = 0;
 get = 0;

 /* 初始化3个信号量 */
 rt_sem_init(&sem_lock, "lock", 1, RT_IPC_FLAG_FIFO);
 rt_sem_init(&sem_empty, "empty", MAXSEM, RT_IPC_FLAG_FIFO);
 rt_sem_init(&sem_full, "full", 0, RT_IPC_FLAG_FIFO);

 /* 创建生产者线程 */
 producer_tid = rt_thread_create("producer",
 producer_thread_entry, RT_NULL,
 THREAD_STACK_SIZE,
 THREAD_PRIORITY - 1, THREAD_TIMESLICE);
 if (producer_tid != RT_NULL)
 rt_thread_startup(producer_tid);

 /* 创建消费者线程 */
 consumer_tid = rt_thread_create("consumer",
 consumer_thread_entry, RT_NULL,
 THREAD_STACK_SIZE,
 THREAD_PRIORITY + 1, THREAD_TIMESLICE);
 if (consumer_tid != RT_NULL)
 rt_thread_startup(consumer_tid);

 return 0;
}

/* 导出到 msh 命令列表中 */
MSH_CMD_EXPORT(producer_consumer, producer_consumer sample);