为啥我这消息队列收不到消息啊？

发布于 2024-09-14 11:44:20 浏览：231 订阅该版

```c
#include <rtthread.h>
#include <rtdevice.h>

/*消息队列控制块*/
static struct rt_messagequeue mq;
/*消息队列中用到的放置消息的内存池*/
static rt_size_t msg_pool[4096];

struct rt_thread thread1;
struct rt_thread thread2;

static char thread1_stack[1024];
static char thread2_stack[1024];

/*线程一入口函数*/
static void thread1_entry(void *parameter)
{
    char buf = 0;
    rt_uint8_t cnt = 0;

while(1)
    {
        /*从消息队列中接收消息*/
        rt_err_t result = rt_mq_recv(&mq, &buf, sizeof(buf), RT_WAITING_FOREVER);
        if(result == RT_EOK)
        {
            rt_kprintf("thread1 rece message : %c\n", buf);
            if(cnt == 19)
            {
                break;
            }
        }else
        {
            rt_kprintf("thread1 Receive failed: %d\n", result);
            return;
        }
        cnt++;
        rt_thread_mdelay(50);
    }
    rt_kprintf("thread1 detach mq\n");
    rt_mq_delete(&mq);
}

static void thread2_entry(void *parameter)
{
    int result;
    char buf = 'A';
    rt_uint8_t cnt = 0;

while(1)
    {
        if(cnt == 8)
        {
            /*如果count = 8,发送紧急消息到队列中*/
            result = rt_mq_urgent(&mq, &buf, 1);
            if(result != RT_EOK)
            {
                rt_kprintf("rt_mq_urgent is fail!\n");
            }
            else
            {
                rt_kprintf("thread2 send urgent message - %c\n", buf);
            }
        }
        else if(cnt >= 20)
        {
            rt_kprintf("message queue stop send, thread2 quit\n");
            break;
        }
        else
        {
            /*发送消息到队列中*/
            result = rt_mq_send(&mq, &buf, 1);
            if(result != RT_EOK)
            {
                rt_kprintf("rt_mq_urgent is fail!\n");
            }
            else
            {
                rt_kprintf("thread2 send  message - %c\n", buf);
            }
        }
        buf++;
        cnt++;
        rt_thread_mdelay(5);
    }
}

/*消息队列的初始化*/
int msgq_sample()
{
    rt_err_t result;
    int ret = 0;

/*初始化消息队列*/
    result = rt_mq_init(&mq, "mqt", &msg_pool[0], 1, sizeof(msg_pool), RT_IPC_FLAG_FIFO);
    if(result != RT_EOK)
    {
        rt_kprintf("rt_mq_init is fail!\n");
        return -1;
    }

/*初始化两个线程*/
    ret = rt_thread_init(&thread1, "thread1", thread1_entry, RT_NULL, &thread1_stack[0], sizeof(thread1_stack), 11, 5);
    if(ret != RT_EOK)
    {
        rt_kprintf("rt_thread1_init is fail!\n");
        return ret;
    }

ret = rt_thread_init(&thread2, "thread2", thread2_entry, RT_NULL, &thread2_stack[0], sizeof(thread2_stack), 10, 5);
    if(ret != RT_EOK)
    {
        rt_kprintf("rt_thread2_init is fail!\n");
        return ret;
    }

rt_thread_startup(&thread1);
    rt_thread_startup(&thread2);

return 0;
}
```

2 个回答

张世争 2024-09-15

学以致用

问题就是 `rt_mq_recv` 返回值问题，RT-Thread 新版本 `rt_mq_recv` 返回接收到的消息队列的长度，而不是 错误码，修改一下即可

```c
#include <rtthread.h>
#include <rtdevice.h>

/*消息队列控制块*/
static struct rt_messagequeue mq;
/*消息队列中用到的放置消息的内存池*/
static rt_size_t msg_pool[4096];
struct rt_thread thread1;
struct rt_thread thread2;
static char thread1_stack[1024];
static char thread2_stack[1024];

/*线程一入口函数*/
static void thread1_entry(void *parameter)
{
    char buf = 0;
    rt_uint8_t cnt = 0;
    rt_ssize_t recv_len = 0;

while (1)
    {
        /*从消息队列中接收消息*/
        recv_len = rt_mq_recv(&mq, &buf, sizeof(buf), RT_WAITING_FOREVER);
        if (recv_len == sizeof(buf))
        {
            rt_kprintf("thread1 rece message : %c\n", buf);
            if (cnt == 19)
            {
                break;
            }
        }
        else
        {
            rt_kprintf("thread1 Receive failed: %d\n", recv_len);
            return;
        }
        cnt++;
        rt_thread_mdelay(50);
    }
    rt_kprintf("thread1 detach mq\n");
    rt_mq_detach(&mq);
}

static void thread2_entry(void *parameter)
{
    int result;
    char buf = 'A';
    rt_uint8_t cnt = 0;
    while (1)
    {
        if (cnt == 8)
        {
            /*如果count = 8,发送紧急消息到队列中*/
            result = rt_mq_urgent(&mq, &buf, 1);
            if (result != RT_EOK)
            {
                rt_kprintf("rt_mq_urgent is fail!\n");
            }
            else
            {
                rt_kprintf("thread2 send urgent message - %c\n", buf);
            }
        }
        else if (cnt >= 20)
        {
            rt_kprintf("message queue stop send, thread2 quit\n");
            break;
        }
        else
        {
            /*发送消息到队列中*/
            result = rt_mq_send(&mq, &buf, 1);
            if (result != RT_EOK)
            {
                rt_kprintf("rt_mq_urgent is fail!\n");
            }
            else
            {
                rt_kprintf("thread2 send  message - %c\n", buf);
            }
        }
        buf++;
        cnt++;
        rt_thread_mdelay(5);
    }
}

/*消息队列的初始化*/
int msgq_sample(void)
{
    rt_err_t result;
    int ret = 0;
    /*初始化消息队列*/
    result = rt_mq_init(&mq, "mqt", &msg_pool[0], 1, sizeof(msg_pool), RT_IPC_FLAG_FIFO);
    if (result != RT_EOK)
    {
        rt_kprintf("rt_mq_init is fail!\n");
        return -1;
    }
    /*初始化两个线程*/
    ret = rt_thread_init(&thread1, "thread1", thread1_entry, RT_NULL, &thread1_stack[0], sizeof(thread1_stack), 11, 5);
    if (ret != RT_EOK)
    {
        rt_kprintf("rt_thread1_init is fail!\n");
        return ret;
    }
    ret = rt_thread_init(&thread2, "thread2", thread2_entry, RT_NULL, &thread2_stack[0], sizeof(thread2_stack), 10, 5);
    if (ret != RT_EOK)
    {
        rt_kprintf("rt_thread2_init is fail!\n");
        return ret;
    }
    rt_thread_startup(&thread1);
    rt_thread_startup(&thread2);
    return 0;
}

MSH_CMD_EXPORT(msgq_sample, msgq_sample);
```

- 测试效果

```c
msh >msgq_sample
thread2 send  message - A
thread1 rece message : A
msh >thread2 send  message - B
thread2 send  message - C
thread2 send  message - D
thread2 send  message - E
thread2 send  message - F
thread2 send  message - G
thread2 send  message - H
thread1 rece message :thread2 send urgent message - I
ssathread2 send  message - J
thread2 send  message - K
thread2 send  message - L
thread2 send  message - M
thread2 send  message - N
thread2 send  message - O
thread2 send  message - P
thread1 rece message : I
thread2 send  message - Q
thread2 send  message - R
thread2 send  message - S
thread2 send  message - T
message queue stop send, thread2 quit
thread1 rece message : C
thread1 rece message : D
thread1 rece message : E
thread1 rece message : F
thread1 rece message : G
thread1 rece message : H
thread1 rece message : J
thread1 rece message : K
thread1 rece message : L
thread1 rece message : M
thread1 rece message : N
thread1 rece message : O
thread1 rece message : P
thread1 rece message : Q
thread1 rece message : R
thread1 rece message : S
thread1 rece message : T
thread1 detach mq
```