消息队列例程一些小疑问？

发布于 2023-04-24 15:10:44 浏览：776 订阅该版

这段代码是官方消息队列代码（我自己修改一点）。
在创建消息队列中，我没有使用结构体struct messageequeue，而是使用rt_mq_t。自然我需要为指向对象分配内存，如果我使用malloc运行结果正常,使用rt_malloc没有运行结果。
```c
#include <rtthread.h>
#include <rtdevice.h>
#include <stdlib.h>

#define STACK_SIZE 512
#define PRIORITY 25
#define TICK 20
#define MAXSEM 5

int main(void)
{
    return 0;
}

/* 指向线程控制块的指针 */
static rt_thread_t tid1 = RT_NULL;
static rt_thread_t tid2 = RT_NULL;
static rt_mq_t mq;
static rt_uint8_t msg_pool[2048];

#define THREAD_PRIORITY       10
#define THREAD_STACK_SIZE     512
#define THREAD_TIMESLICE    5

/* 线程 1 入口 */
static void thread1_entry(void *parameter)
{
    char buf = 0;
	  int cnt = 0;
	  while(1){
		   if(rt_mq_recv(mq,&buf,1,RT_WAITING_FOREVER) == RT_EOK)
			 {
			    rt_kprintf("thread1: recv msg from msg queue,the content:%c\n",buf);
				  if(cnt == 19)
						break;
			 }
		   cnt++;
		   rt_thread_mdelay(50);
		}
		rt_kprintf("thread1: detch\n");
		rt_mq_detach(mq);
}

/* 线程 2 入口 */
static void thread2_entry(void *parameter)
{
    int result;
	  char buf = 'a';
	  int cnt = 0;
	  while(1)
		{
		    if(cnt == 8)
				{
				    result = rt_mq_urgent(mq,&buf,1);
					  if(result != RT_EOK){
						  rt_kprintf("ERR\n");
						}else{
						  rt_kprintf("thread2: send urgent message - %c\n",buf);
						}
				}else if(cnt >= 20){
				    rt_kprintf("quit!\n");
				    break;
				}else
				{
				    result = rt_mq_send(mq,&buf,1);
					  if(result != RT_EOK)
						{
						   rt_kprintf("ERR\n");
						}
						rt_kprintf("thread2: send message - %c\n",buf);
				}
				buf++;
				cnt++;
		    rt_thread_mdelay(10);
		}
}
// rt_malloc

int mqt(void)
{  
	  rt_kprintf("mq\n");
	  mq = (rt_mq_t)rt_malloc(sizeof(48));
    rt_err_t result =  rt_mq_init(mq,"mq",msg_pool,1,sizeof(msg_pool),RT_IPC_FLAG_FIFO);
	  //  i 指的是message size 为 1
	  if(result != RT_EOK)   //RT_EOK 为成功
		{
		   rt_kprintf("init message failed\n");
			 return -1;
		}
    /* 创建线程 1 */
    tid1 = rt_thread_create("thread1",
                            thread1_entry,
                            RT_NULL,
                            THREAD_STACK_SIZE,
                            THREAD_PRIORITY, THREAD_TIMESLICE);
    if (tid1 != RT_NULL)
         rt_thread_startup(tid1);

/* 创建线程 2 */
    tid2 = rt_thread_create("thread2",
                            thread2_entry,
                            RT_NULL,
                            THREAD_STACK_SIZE,
                            THREAD_PRIORITY, THREAD_TIMESLICE);
    if (tid2 != RT_NULL)
        rt_thread_startup(tid2);

return 0;
}

/* 导出到 msh 命令列表中 */
MSH_CMD_EXPORT(mqt, prio_inversion sample);
```

![rt_malloc实验现象.png](https://oss-club.rt-thread.org/uploads/20230424/93a40eaddeb1940e6c33041b2db4fbd4.png)