libev如何使用epoll进行事件监听

转载注明出处：http://blog.csdn.net/lengzijian/article/details/8331136

首先来看一个简单的例子(官方文件ev.pod中可以找到)

#include <ev.h>

#include <stdio.h>

ev_io stdin_watcher;

ev_timer timeout_watcher;

static void

stdin_cb(EV_P_ ev_io *w, int revents)

{

puts("stdin ready");

ev_io_stop(EV_A_ w);

ev_break(EV_A_ EVBREAK_ALL);

}

static void

timeout_cb(EV_P_ ev_timer *w, int revents)

{

puts("timeout");

ev_break(EV_A_ EVBREAK_ONE);

}

int main()

{

struct ev_loop *loop = EV_DEFAULT;

ev_io_init(&stdin_watcher, stdin_cb, 0, EV_READ);

ev_io_start(loop, &stdin_watcher);

ev_timer_init(&timeout_watcher, timeout_cb, 5.5, 0. );

ev_timer_start(loop, &timeout_watcher);

ev_run(loop,0);

return 0;

}

我们只关心如下几句：

struct ev_loop *loop = EV_DEFAULT;

ev_io_init(&stdin_watcher, stdin_cb, 0, EV_READ);

ev_io_start(loop, &stdin_watcher);

ev_run(loop, 0);

首先来看ev_io_init中做了些什么操作：

ev.h文件中

#define ev_io_init(ev,cb,fd,events)

do { ev_init ((ev), (cb)); ev_io_set ((ev),(fd),(events)); } while (0)

#define ev_init(ev,cb_) do { \

((ev_watcher *)(void *)(ev))->active = \

((ev_watcher *)(void *)(ev))->pending = 0; \

ev_set_priority ((ev), 0); \

ev_set_cb ((ev), cb_); \

} while (0)

#define ev_io_set(ev,fd_,events_)

do { (ev)->fd = (fd_); (ev)->events = (events_) | EV__IOFDSET; } while (0)

#define ev_set_cb(ev,cb_)

ev_cb (ev) = (cb_)

#define ev_cb(ev)

(ev)->cb /* rw */

通过定义可以看出ev_io_init主要操作时：

&stdin_watcher->active=stdin_watcher->pending=0；

&stdin_watcher->priority=0；

&stdin_watcher->cb=stdin_cb(函数)；

&stdin_watcher->fd；

&stdin_watcher->events=EV_READ|EV__IOFDSET

同样,ev_io_start做了一些赋值操作,这里不过多讲解；

下面通过一张函数调用图来展libev的函数调用：