Question

如果在另一个线程中调用bufferevent_write，则bufferevent_write不会在伙伴上触发EV_READ，这很奇怪。

我准备了一个简化的程序来重现奇怪的结果。超时回调中的bufferevent_write 立即触发伙伴上的EV_READ。但是在另一个线程中运行的bufferevent_write不会立即触发伙伴上的EV_READ。而是在超时事件之前调用do_read。

有人可以帮助解决问题。非常感谢。

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "unistd.h"

#include <event2/bufferevent.h>
#include <event2/event.h>

#define  BUF_BODY   "hello world\n"

void thr_fn( void * pArg )
{
    struct bufferevent *pBufEv = (struct bufferevent *)pArg;
    while (1)
    {
        // write doesn't trigger EV_READ event on the partner.
        bufferevent_write(pBufEv, BUF_BODY, strlen(BUF_BODY) + 1);
        printf("write\n");
        sleep(5);
    }
}

void do_read( struct bufferevent * pBEv, void * pArg )
{
    char buff[1024];
    bufferevent_read(pBEv, buff, 1024);
    puts(buff);
    return;
}

static void
ev_timeout_cb (evutil_socket_t sock_fd, short events, void *ctx)
{
    struct bufferevent * pBufEv = (struct bufferevent * )ctx;
    puts("ev_timeout_cb ...\n");
    // write immediately trigger EV_READ event on the partner.
    //bufferevent_write(pBufEv, BUF_BODY, strlen(BUF_BODY) + 1);
}

int main( void )
{
    struct event_base * pEventBase = NULL;
    struct bufferevent * aPair[2] = {NULL};
    // evthread_use_pthreads();
    pEventBase = event_base_new();
    int nRet = bufferevent_pair_new(pEventBase, 0, aPair);

    bufferevent_setcb(aPair[0], do_read, NULL, NULL, NULL);
    bufferevent_enable(aPair[0], EV_READ);

    pthread_t tid;
    pthread_create(&tid, NULL, thr_fn, aPair[1]);

    struct timeval tv = {10, 0};
    evtimer_add(event_new(pEventBase, -1, EV_PERSIST, ev_timeout_cb, aPair[1]), &tv);

    event_base_dispatch(pEventBase);

    return 0;
}

线程中的bufferevent_write不会在另一个线程中的伙伴上触发EV_READ

0 个答案: