Libevent是一个用C语言编写的、轻量级的开源高性能事件通知库，主要有以下几个亮点：事件驱动( event-driven)，高性能；轻量级，专注于网络。Libevent包括事件管理、缓存管理、DNS、HTTP、缓存事件几大部分。
事件管理包括各种IO(socket)、定时器、信号等事件；缓存管理是指evbuffer功能；DNS是libevent提供的一个异步DNS查询功能；HTTP是libevent的一个轻量级http实现，包括服务器和客户端。
一、 Libevent安装
[root@fedora Workspace]# uname -r 4.17.5-100.fc27.x86_64 [root@fedora Workspace]# dnf list installed | grep libevent libevent.x86_64 2.0.22-6.fc27 @anaconda [root@fedora Workspace]# dnf install libevent-devel
[root@fedora Workspace]# dnf list installed | grep libevent libevent.x86_64 2.0.22-6.fc27 @anaconda libevent-devel.x86_64 2.0.22-6.fc27 @fedora [root@fedora Workspace]# whereis libevent libevent: /usr/lib64/libevent.so [root@fedora Workspace]# ls -al /usr/lib64 | grep libevent lrwxrwxrwx. 1 root root 21 Aug 10 2017 libevent-2.0.so.5 -> libevent-2.0.so.5.1.9 -rwxr-xr-x. 1 root root 303016 Aug 10 2017 libevent-2.0.so.5.1.9 lrwxrwxrwx. 1 root root 26 Aug 10 2017 libevent_core-2.0.so.5 -> libevent_core-2.0.so.5.1.9 -rwxr-xr-x. 1 root root 185952 Aug 10 2017 libevent_core-2.0.so.5.1.9 lrwxrwxrwx 1 root root 26 Aug 10 2017 libevent_core.so -> libevent_core-2.0.so.5.1.9 lrwxrwxrwx. 1 root root 27 Aug 10 2017 libevent_extra-2.0.so.5 -> libevent_extra-2.0.so.5.1.9 -rwxr-xr-x. 1 root root 132328 Aug 10 2017 libevent_extra-2.0.so.5.1.9 lrwxrwxrwx 1 root root 27 Aug 10 2017 libevent_extra.so -> libevent_extra-2.0.so.5.1.9 lrwxrwxrwx. 1 root root 29 Aug 10 2017 libevent_openssl-2.0.so.5 -> libevent_openssl-2.0.so.5.1.9 -rwxr-xr-x. 1 root root 27752 Aug 10 2017 libevent_openssl-2.0.so.5.1.9 lrwxrwxrwx 1 root root 29 Aug 10 2017 libevent_openssl.so -> libevent_openssl-2.0.so.5.1.9 lrwxrwxrwx. 1 root root 30 Aug 10 2017 libevent_pthreads-2.0.so.5 -> libevent_pthreads-2.0.so.5.1.9 -rwxr-xr-x. 1 root root 10944 Aug 10 2017 libevent_pthreads-2.0.so.5.1.9 lrwxrwxrwx 1 root root 30 Aug 10 2017 libevent_pthreads.so -> libevent_pthreads-2.0.so.5.1.9 lrwxrwxrwx 1 root root 21 Aug 10 2017 libevent.so -> libevent-2.0.so.5.1.9
至此，网络库Libevent已经安装完成，下面就看看示例吧。
二、 Libevent示例
#include <stdio.h>
#include <event2/event.h>
int main(void)
{
struct event_base *base;
const char **methods = event_get_supported_methods();
printf("Starting Libevent %s.\n", event_get_version());
printf("Available methods are:\n");
for(int i = 0; methods[i] != NULL; i++)
{
printf("\t%s\n", methods[i]);
}
base = event_base_new();
if(!base)
{
printf("Could not get an event_base!\n");
}
else
{
printf("Using Libevent with backend method is:\n");
printf("\t%s\n", event_base_get_method(base));
}
return 0;
}
运行结果如下：
[ycxie@fedora Workspace]$ gcc -o libevent_method -levent -Wall libevent_method.c [ycxie@fedora Workspace]$ ./libevent_method Starting Libevent 2.0.22-stable. Available methods are: epoll poll select Using Libevent with backend method is: epoll