用libevent多线程方式实现echo server

from http://blog.chinaunix.net/uid-756931-id-353296.html
功能： 主线程同时监听定时器事件和IO事件，工作线程简单的监听IO事件。 主线程每隔一秒种向工作线程发送一条字符串信息 工作线程显示该信息并回显给主线程
该示例演示了主线程如何同时监听多个事件。
Makefile

1. eventtest : eventtest.c
2. gcc -Wall -g -levent -lpthread -o eventtest eventtest.c
3. .PHONY : clean
4. clean :
5. rm eventtest -f

    
    #include <stdio.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <pthread.h>

    #include <sys/types.h>
    #include <sys/socket.h>

    #include <event.h>


    struct event_base *workerbase;
    int fd[2];

    static void
    thread_libevent_process(int fd, short which, void *arg)
    {
        int ret;
        char buf[128];

        ret = read(fd, buf, 128);
        if (ret > 0) {
            buf[ret] = '\0';
            printf("thread receive message : %s\n", buf);
        }

        sleep(1);

        write(fd, buf, ret);


        return;
    }

    static void *
    worker_thread(void *arg)
    {
        int fd = *(int *)arg;

        struct event ev;

        event_set(&ev, fd, EV_READ | EV_PERSIST, thread_libevent_process, NULL);
        event_base_set(workerbase, &ev);
        event_add(&ev, 0);

        event_base_loop(workerbase, 0);


        return NULL;
    }

    static void
    main_event_process(int fd, short which, void *arg)
    {
        int ret;
        char buf[128];

        ret = read(fd, buf, 128);
        if (ret > 0) {
            buf[ret]='\0';
            printf("main thread receive echo message : %s\n", buf);
        }


        return;
    }

    static void
    timeout_cb(int fdd, short event, void *arg)
    {
        struct timeval tv;
        struct event *timeout = arg;

        write(fd[0], "Hello world!", sizeof("Hello world!") - 1);

        evutil_timerclear(&tv);
        tv.tv_sec = 1;
        event_add(timeout, &tv);
    }

    int
    main (int argc, char *argv[])
    {
        int ret;

        pthread_t tid;

        struct event ev;
        struct event evtimeout;
        struct timeval tv;

        struct event_base *base;

        base = event_init();
        if (base == NULL) {
            perror("event_init( base )");
            return 1;
        }

        workerbase = event_init();
        if (workerbase == NULL) {
            perror("event_init( workerbase )");
            return 1;
        }



        ret = socketpair(AF_LOCAL, SOCK_STREAM, 0, fd);
        if (ret == -1) {
            perror("socketpair() : ");
            return 1;
        }


        event_set(&ev, fd[0], EV_READ | EV_PERSIST, main_event_process, NULL);
        event_base_set(base, &ev);
        event_add(&ev, 0);

        evtimer_set(&evtimeout, timeout_cb, &evtimeout);
        event_base_set(base, &evtimeout);
        evutil_timerclear(&tv);
        tv.tv_sec = 1;
        event_add(&evtimeout, &tv);

        ret = pthread_create(&tid, NULL, worker_thread, (void *)&fd[1]);
        if (ret != 0) {
            perror("pthread_create()");
            return 1;
        }


        event_base_loop(base, 0);


        return 0;
    }