RT-Thread 23. 队列中消息大小及数量

1.代码

//mq.c

#include 
#include 
#include "drv_gpio.h"

#define THREAD_PRIORITY   25
#define THREAD_TIMESLICE  10

#define TASK_STACK_MAX    500

/* 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_uint8_t msg_pool[32];
ALIGN(RT_ALIGN_SIZE)
static char thread51_stack[TASK_STACK_MAX];
static struct rt_thread thread51;

/* 线 程 1 入 口 函 数 */
static void thread51_entry(void *parameter)
{
  char buf = 0;
  rt_uint8_t cnt = 0;
  while (1)
  {
    /* 从 消 息 队 列 中 接 收 消 息 */
    if (rt_mq_recv(&mq, &buf, sizeof(buf), RT_WAITING_FOREVER) == RT_EOK)
    {
      rt_kprintf("thread51: recv msg from msg queue, the content:%c\n", buf);
//      if (cnt == 19)
//      {
//        break;
//      }
    }
    /* 延 时 50ms */
    cnt++;
    rt_thread_mdelay(1000);
  }
//  rt_kprintf("thread51: detach mq \n");
//  rt_mq_detach(&mq);
}


void MqKeyScanCallBack(void)
{
  int result;
  static char buf = 'A';
  static rt_uint8_t cnt = 0;
  
//  while (1)
  {
    if (cnt == 8)
    {
      /* 发 送 紧 急 消 息 到 消 息 队 列 中 */
      result = rt_mq_urgent(&mq, &buf, 1);
      if (result == RT_EOK)
      {
        rt_kprintf("thread52: send urgent message - %c\n", buf);
        rt_kprintf("the priority of thread52 is: %s %d\n", rt_thread_self()->name,rt_thread_self()->current_priority);
        buf++;
        cnt++;
      }
      else if(result == -RT_EFULL)
      {
        rt_kprintf("rt_mq_urgent Full\n");
      }
      else
      {
        rt_kprintf("rt_mq_urgent ERR,0x%x\n",result);
      }
    }
    else if (cnt>= 20)/* 发 送 20 次 消 息 之 后 退 出 */
    {
      buf = 'A';
      cnt = 0;
//      rt_kprintf("message queue stop send, thread52 quit\n");
//      break;
    }
    else
    {
      /* 发 送 消 息 到 消 息 队 列 中 */
      result = rt_mq_send(&mq, &buf, 1);
      if (result == RT_EOK)
      {
        rt_kprintf("thread52: send message - %c\n", buf);
        buf++;
        cnt++;
      }
      else if(result == -RT_EFULL)
      {
        rt_kprintf("rt_mq_urgent Full\n");
      }
      else
      {
        rt_kprintf("rt_mq_urgent ERR,0x%x\n",result);
      }
    }
    /* 延 时 5ms */
//    rt_thread_mdelay(5);
  }
}

int MqTaskInit(void)
{
  rt_err_t result;
  /* 初 始 化 消 息 队 列 */
  result = rt_mq_init(&mq,
                      "mqt",
                      &msg_pool[0], /* 内 存 池 指 向 msg_pool */
                      1, /* 每 个 消 息 的 大 小 是 1 字 节 */
                      sizeof(msg_pool), /* 内 存 池 的 大 小 是 msg_pool 的 大 小
                      */
                      RT_IPC_FLAG_FIFO); /* 如 果 有 多 个 线 程 等 待， 按 照 先 来 先 得
                      到 的 方 法 分 配 消 息 */
  if (result != RT_EOK)
  {
    rt_kprintf("init message queue failed.\n");
    return -1;
  }
  rt_thread_init(&thread51,
                "thread51",
                thread51_entry,
                RT_NULL,
                &thread51_stack[0],
                sizeof(thread51_stack), 25, 5);
  rt_thread_startup(&thread51);
  
  return 0;
}

2.分析

static rt_uint8_t msg_pool[32]; 消息池有32字节，每个消息大小为4字节，消息池能放4个消息。查看rt_mq_init()源码

    /* get correct message size */
    mq->msg_size = RT_ALIGN(msg_size, RT_ALIGN_SIZE);
	mq->max_msgs = pool_size / (mq->msg_size + sizeof(struct rt_mq_message));

可以看出，实际的消息大小和消息数量需特别注意是否符合任务需求。

3.输出

list_thread
thread   pri  status      sp     stack size max used left tick  error
-------- ---  ------- ---------- ----------  ------  ---------- ---
usr1       6  suspend 0x00000078 0x0000012c    40%   0x00000014 000
thread51  25  suspend 0x000000a0 0x000001f4    32%   0x00000005 000
thread3    8  suspend 0x00000088 0x000001f4    27%   0x00000005 000
tshell    20  running 0x00000094 0x00001000    12%   0x00000006 000
tidle0    31  ready   0x00000060 0x00000100    37%   0x00000002 000
timer      4  suspend 0x00000064 0x00000200    19%   0x00000009 000
main      10  suspend 0x00000098 0x00000800    13%   0x00000014 000
msh >
msh >

key press val is 1
thread52: send message - A
thread51: recv msg from msg queue, the content:A


key press val is 1
thread52: send message - B


key press val is 1
thread52: send message - C


key press val is 1
thread52: send message - D


key press val is 1
thread52: send message - E


key press val is 1
rt_mq_urgent Full
thread51: recv msg from msg queue, the content:B


key press val is 1
thread52: send message - F


key press val is 1
rt_mq_urgent Full


key press val is 1
rt_mq_urgent Full


thread51: recv msg from msg queue, the content:C


thread51: recv msg from msg queue, the content:D


thread51: recv msg from msg queue, the content:E


thread51: recv msg from msg queue, the content:F


key press val is 1
thread52: send message - G
thread51: recv msg from msg queue, the content:G


key press val is 1
thread52: send message - H
thread51: recv msg from msg queue, the content:H


key press val is 1
thread52: send urgent message - I
the priority of thread52 is: tidle0 31


thread51: recv msg from msg queue, the content:I


key press val is 1
thread52: send message - J
thread51: recv msg from msg queue, the content:J