修改了下参考文档中的事件集例程，采用RT_IPC_FLAG_FIFO方式，线程1和3等待相同事件集（事件接受设置为不清除），事件集唤醒线程后则打印线程退出；线程2发送事件集。结果显示线程1、3唤醒的顺序与线程挂起的顺序无关，与线程1、3优先级有关，高优先级先执行，低优先级后执行。
注：
1）RTT:V4.0.3, IDE:VSCode , BSP:qemu-express-a9
线程1初始化后延时100ms等待事件集；线程3初始化后直接等待事件集；即等待顺序为线程3在前，线程1在后，Finsh执行list_event看到的等待线程顺序与此一致；
2）测试代码优先级线程1高于线程3，等待顺序为线程3、线程1，线程接收事件集顺序为线程1、线程3，即与先进先出不符，与优先级相符；
3）交换线程1、线程3优先级，则线程接收事件集顺序为线程3、线程1，还是与优先级相符。
请问是不是对FIFO方式理解有误，线程等待顺序与等待线程列表里的顺序不是一回事？理解是否可推广道其它同步方式？
测试代码：
#include <rtthread.h>#include "thread_exp.h"#define THREAD_PRIORITY 9#define THREAD_TIMESLICE 5#define EVENT_FLAG1 (1 << 0)#define EVENT_FLAG2 (1 << 1)#define EVENT_FLAG3 (1 << 2)#define EVENT_FLAG4 (1 << 3)#define EVENT_FLAG5 (1 << 4)#define EVENT_FLAG6 (1 << 5)/* 事件控制块 */static struct rt_event event;ALIGN(RT_ALIGN_SIZE)static char thread1_stack[1024];static struct rt_thread thread1;/* 线程 1 入口函数 */static void thread1_recv_event(void *param){ rt_uint32_t e; /* rt_kprintf("thread1 waitting for 1 and 2.\n"); if (rt_event_recv(&event, (EVENT_FLAG1 | EVENT_FLAG2), RT_EVENT_FLAG_AND | RT_EVENT_FLAG_CLEAR, RT_WAITING_FOREVER, &e) == RT_EOK) { rt_kprintf("thread1: OR recv event 0x%x\n", e); } */ //rt_kprintf("thread1: delay 1s to prepare the second event\n"); rt_thread_mdelay(100); rt_kprintf("thread1 waitting for 4 and 5.\n"); if (rt_event_recv(&event, (EVENT_FLAG4 | EVENT_FLAG5), RT_EVENT_FLAG_AND, RT_WAITING_FOREVER, &e) == RT_EOK) { rt_kprintf("thread1: AND recv event 0x%x\n", e); } rt_kprintf("thread1 leave.\n");}ALIGN(RT_ALIGN_SIZE)static char thread3_stack[1024];static struct rt_thread thread3;/* 线程 1 入口函数 */static void thread3_recv_event(void *param){ rt_uint32_t e; rt_kprintf("thread3 waitting for 4 and 5.\n"); /* 第二次接收事件，事件 3 和事件 5 均发生时才可以触发线程 1，接收完后清除事件标志 */ if (rt_event_recv(&event, (EVENT_FLAG4 | EVENT_FLAG5), RT_EVENT_FLAG_AND, RT_WAITING_FOREVER, &e) == RT_EOK) { rt_kprintf("thread3: AND recv event 0x%x\n", e); } rt_kprintf("thread3 leave.\n");}ALIGN(RT_ALIGN_SIZE)static char thread2_stack[1024];static struct rt_thread thread2;/* 线程 2 入口 */static void thread2_send_event(void *param){ rt_thread_mdelay(2000); rt_kprintf("thread2: send event1\n"); rt_event_send(&event, EVENT_FLAG1); rt_thread_mdelay(200); rt_kprintf("thread2: send event2\n"); rt_event_send(&event, EVENT_FLAG2); rt_thread_mdelay(200); rt_kprintf("thread2: send event3\n"); rt_event_send(&event, EVENT_FLAG3); rt_thread_mdelay(200); rt_kprintf("thread2: send event4\n"); rt_event_send(&event, EVENT_FLAG4); rt_thread_mdelay(200); rt_kprintf("thread2: send event5\n"); rt_event_send(&event, EVENT_FLAG5); rt_kprintf("thread2 leave.\n");}int event_sample(void){ rt_err_t result; //rt_scheduler_sethook(hook_of_scheduler); /* 初始化事件对象 */ result = rt_event_init(&event, "event", RT_IPC_FLAG_FIFO); if (result != RT_EOK) { rt_kprintf("init event failed.\n"); return -1; } rt_thread_init(&thread1, "thread1", thread1_recv_event, RT_NULL, &thread1_stack[0], sizeof(thread1_stack), THREAD_PRIORITY - 2, THREAD_TIMESLICE); rt_thread_startup(&thread1); rt_thread_init(&thread3, "thread3", thread3_recv_event, RT_NULL, &thread3_stack[0], sizeof(thread3_stack), THREAD_PRIORITY-1, THREAD_TIMESLICE); rt_thread_startup(&thread3); rt_thread_init(&thread2, "thread2", thread2_send_event, RT_NULL, &thread2_stack[0], sizeof(thread2_stack), THREAD_PRIORITY, THREAD_TIMESLICE); rt_thread_startup(&thread2); return 0;}
结果如下：
\ | /- RT - Thread Operating System / | \ 4.0.3 build Aug 16 2021 2006 - 2021 Copyright by rt-thread teamlwIP-2.0.2 initialized![32m[I/sal.skt] Socket Abstraction Layer initialize success.[0m[32m[I/SDIO] SD card capacity 65536 KB.[0m[32m[I/SDIO] switching card to high speed failed
我也是这样理解的 但前述的试验结果跟这个不一致
@coolouba 对，看到了，说明你发现了这个bug，官方在 github 上有过这个提醒，最新版也把很多使用 RT_IPC_FLAG_FIFO 的地方修改了。
好的 谢谢