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5 waitqueue等待队列的源码实现为什么是先进后出的？

发布于 2022-06-20 20:36:23 浏览：978 订阅该版

a1012112796 2022-06-21

这家伙很懒，什么也没写！

看懂 rt_list 的数据结构和逻辑，就不难理解这个问题了。 (tip: 注意关注 ``rt_list_insert_before`` 与 `rt_list_insert_after` 的区别)

测试代码及结果:
```c
#include "ipc/waitqueue.h"

static struct rt_wqueue _wait_queue = {0};

void _entry_1(void *p)
{
    rt_kprintf("wait 1\n");
    rt_err_t err = rt_wqueue_wait(&_wait_queue, 0, RT_WAITING_FOREVER);
    rt_kprintf("wait 1 end: %d \n", err);
}

void _entry_2(void *p)
{
    rt_thread_mdelay(50);

rt_kprintf("wait 2\n");
    rt_err_t err = rt_wqueue_wait(&_wait_queue, 0, RT_WAITING_FOREVER);
    rt_kprintf("wait 2 end: %d \n", err);
}

void _entry_end(void *p)
{
    rt_thread_mdelay(100);

rt_kprintf("wackup \n");
    rt_wqueue_wakeup(&_wait_queue, 0);

rt_thread_mdelay(50);

rt_kprintf("wackup 2\n");
    rt_wqueue_wakeup(&_wait_queue, 0);
}

void wqueue_test(void)
{
    rt_wqueue_init(&_wait_queue);

rt_thread_t th = rt_thread_create("t1", _entry_1, RT_NULL, 1024, 10, 10);
    RT_ASSERT(th);
    rt_thread_startup(th);

th = rt_thread_create("t2", _entry_2, RT_NULL, 1024, 10, 10);
    RT_ASSERT(th);
    rt_thread_startup(th);

th = rt_thread_create("t3", _entry_end, RT_NULL, 1024, 10, 10);
    RT_ASSERT(th);
    rt_thread_startup(th);
}
MSH_CMD_EXPORT(wqueue_test, wqueue_test);

```

![屏幕截图 2022-06-21 111536.png](https://oss-club.rt-thread.org/uploads/20220621/43610f23cbc0381de1798efedc498af1.png.webp "屏幕截图 2022-06-21 111536.png")