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锁定老帖子 主题：libev简单使用介绍
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发表时间：2008-12-30
更详细的用法请看他的文档：
http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod struct ev_loop *ev_default_loop (unsigned int flags) struct ev_loop *ev_loop_new (unsigned int flags) 这两个函数都是默认初始化一个loop，区别是第一个不是线程安全的，第二个不能捕捉信号和子进程的watcher。 参数flags可以为下面几种类型： 引用 #define EVFLAG_AUTO 0x00000000U /* not quite a mask */
/* flag bits */ #define EVFLAG_NOENV 0x01000000U /* do NOT consult environment */ #define EVFLAG_FORKCHECK 0x02000000U /* check for a fork in each iteration */ /* method bits to be ored together */ #define EVBACKEND_SELECT 0x00000001U /* about anywhere */ #define EVBACKEND_POLL 0x00000002U /* !win */ #define EVBACKEND_EPOLL 0x00000004U /* linux */ #define EVBACKEND_KQUEUE 0x00000008U /* bsd */ #define EVBACKEND_DEVPOLL 0x00000010U /* solaris 8 */ /* NYI */ #define EVBACKEND_PORT 0x00000020U /* solaris 10 */ ev_default_fork () ev_loop_fork (loop) 这两个函数就是当你在子进程里需要使用libev的函数的之前必须要调用。他们的区别是第二个函数是当使用ev_loop_new创建的loop时，才用第二个函数,也就是说重用父进程创建的loop。 ev_loop (loop, int flags) 开始事件循环。 ev_TYPE_init (ev_TYPE *watcher, callback, [args]) 初始化一个watcher。TYPE也就是libev支持的事件类型，比如io，比如time等等。。 第一个参数为一个watcher,第二个回调函数，第三个句柄，第四个事件类型。包含下面几种： 引用 #define EV_UNDEF -1 /* guaranteed to be invalid */
#define EV_NONE 0x00 /* no events */ #define EV_READ 0x01 /* ev_io detected read will not block */ #define EV_WRITE 0x02 /* ev_io detected write will not block */ #define EV_IOFDSET 0x80 /* internal use only */ #define EV_TIMEOUT 0x00000100 /* timer timed out */ #define EV_PERIODIC 0x00000200 /* periodic timer timed out */ #define EV_SIGNAL 0x00000400 /* signal was received */ #define EV_CHILD 0x00000800 /* child/pid had status change */ #define EV_STAT 0x00001000 /* stat data changed */ #define EV_IDLE 0x00002000 /* event loop is idling */ #define EV_PREPARE 0x00004000 /* event loop about to poll */ #define EV_CHECK 0x00008000 /* event loop finished poll */ #define EV_EMBED 0x00010000 /* embedded event loop needs sweep */ #define EV_FORK 0x00020000 /* event loop resumed in child */ #define EV_ASYNC 0x00040000 /* async intra-loop signal */ #define EV_ERROR 0x80000000 /* sent when an error occurs */ 引用 ev_TYPE_start (loop *, ev_TYPE *watcher)
启动一个watcher。 例子： #include <ev.h>
#include <stdio.h>
//不同的watcher
ev_io stdin_watcher;
ev_timer timeout_watcher;
ev_timer timeout_watcher_child;
//标准输入的回调函数
static void
stdin_cb (EV_P_ ev_io *w, int revents)
{
puts ("stdin ready");
ev_io_stop (EV_A_ w);
ev_unloop (EV_A_ EVUNLOOP_ALL);
}
//父进程的定时器回调函数
static void
timeout_cb (EV_P_ ev_timer *w, int revents)
{
puts ("timeout");
ev_unloop (EV_A_ EVUNLOOP_ONE);
}
//子进程的定时器回调函数
static void
timeout_cb_child (EV_P_ ev_timer *w, int revents)
{
puts ("child timeout");
ev_unloop (EV_A_ EVUNLOOP_ONE);
}
int
main (void)
{
//创建一个backend为select的loop
struct ev_loop *loop = ev_loop_new(EVBACKEND_SELECT);
//初始化并启动父进程的watcher
ev_timer_init(&timeout_watcher, timeout_cb, 10, 0.);
ev_timer_start(loop, &timeout_watcher);
switch (fork()) {
case -1:
return -1;
case 0:
//使用父进程loop。
ev_loop_fork(loop);
//子进程的loop
struct ev_loop *loop_child = ev_loop_new (EVBACKEND_SELECT);
ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
ev_io_start (loop, &stdin_watcher);
ev_timer_init(&timeout_watcher_child, timeout_cb_child, 5.5, 0.);
ev_timer_start(loop_child, &timeout_watcher_child);
ev_loop(loop_child,0);
}
//等待事件
ev_loop (loop, 0);
return 0;
}
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