（注意，libev仅支持linux）
从github下载源码 源码
进入源码目录，安装指令三连：
./configure make make install
这样就安装完成了，默认安装在/usr/local/lib
在编写程序时，引用
// a single header file is required #include#include #include // every watcher type has its own typedef'd struct // with the name ev_ ; ev_io stdin_watcher; ev_timer timeout_watcher; // all watcher callbacks have a similar signature // this callback is called when data is readable on stdin static void stdin_cb (EV_P_ struct ev_io *w, int revents) { puts ("stdin ready"); // for one-shot events, one must manually stop the watcher // with its corresponding stop function. ev_io_stop (EV_A_ w); // this causes all nested ev_loop's to stop iterating ev_unloop (EV_A_ EVUNLOOP_ALL); } // another callback, this time for a time-out static void timeout_cb (EV_P_ struct ev_timer *w, int revents) { puts ("timeout"); // this causes the innermost ev_loop to stop iterating ev_unloop (EV_A_ EVUNLOOP_ONE); } int main (void) { // use the default event loop unless you have special needs struct ev_loop *loop = ev_default_loop (0); // initialise an io watcher, then start it // this one will watch for stdin to become readable ev_io_init (&stdin_watcher, stdin_cb, 0, EV_READ); ev_io_start (loop, &stdin_watcher); // initialise a timer watcher, then start it // simple non-repeating 5.5 second timeout ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); ev_timer_start (loop, &timeout_watcher); // now wait for events to arrive ev_loop (loop, 0); // unloop was called, so exit return 0; }
上述代码为官方提供的一段示例程序，从中我们可以一窥使用libev的基本框架
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定义事件监听结构和回调函数
libev提供了多种事件类型，每种事件类型有其相应的事件监听结构，官方称其为watcher
ev_io stdin_watcher; ev_timer timeout_watcher;
代码中先是声明了ev_io 和 ev_timer两种事件监听结构，io即io事件，timer即定时器事件
static void stdin_cb (EV_P_ struct ev_io *w, int revents) { puts ("stdin ready"); // for one-shot events, one must manually stop the watcher // with its corresponding stop function. ev_io_stop (EV_A_ w); // this causes all nested ev_loop's to stop iterating ev_unloop (EV_A_ EVUNLOOP_ALL); } // another callback, this time for a time-out static void timeout_cb (EV_P_ struct ev_timer *w, int revents) { puts ("timeout"); // this causes the innermost ev_loop to stop iterating ev_unloop (EV_A_ EVUNLOOP_ONE); }继而是两种事件的回调函数，即发生事件后调用的函数。
回调函数的结构：
void cb_name(struct ev_loop *loop, xx_watcher *w, int revents);
有三个参数，xx_watcher指的是某种事件监听结构，那种事件的回调就用那种事件的监听结构，比如
void stdin_cb(struct ev_loop *loop, ev_io *w, int revents);
基本io的回调函数，就用ev_io
示例中的EV_P_其实就是 struct ev_loop* 的宏
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初始化事件循环
// use the default event loop unless you have special needs struct ev_loop *loop = ev_default_loop (0);
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初始化事件并绑定回调函数
// initialise an io watcher, then start it // this one will watch for stdin to become readable ev_io_init (&stdin_watcher, stdin_cb, 0, EV_READ); ev_io_start (loop, &stdin_watcher); // initialise a timer watcher, then start it // simple non-repeating 5.5 second timeout ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); ev_timer_start (loop, &timeout_watcher);
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开始事件循环，等待事件
// now wait for events to arrive ev_loop (loop, 0);
所以，总体来看，libev的整体架构就是，将事件和事件回调函数相绑定，然后开启事件循环，等待事件到来，事件到来后调用相应的回调函数，然后继续循环。
这是一个典型的异步非阻塞框架，接下来我们深入源码，分析下libev的实现
