libevent简介
一、参考资料
7、libevent源码学习(12):超时管理之common_timeout
二、使用经验
1、创建一个event_base, 即:event_base_new(), 如下:
//创建一个event_base
struct event_base *base = event_base_new();
event_base_new()函数原型及简介:
/**
* Create and return a new event_base to use with the rest of Libevent.
*
* @return a new event_base on success, or NULL on failure.
*
* @see event_base_free(), event_base_new_with_config()
*/
EVENT2_EXPORT_SYMBOL
struct event_base *event_base_new(void);
参考文档: libevent学习篇之一:libevent快速入门
2、创建一个event: 即event_new()
// 创建并绑定一个event
struct event* listen_event; //参数:event_base,监听的对象,需要监听的事件,事件发生后的回调函数,传给回调函数的参数
listen_event = event_new(base, listener, EV_READ | EV_PERSIST, callback_func, (void*)base);
//参数:event,超时时间,NULL表示无超时设置
event_add(listen_event, NULL);
/**
Allocate and asssign a new event structure, ready to be added. The function event_new() returns a new event that can be used in
future calls to event_add() and event_del(). The fd and events
arguments determine which conditions will trigger the event; the
callback and callback_arg arguments tell Libevent what to do when the
event becomes active. If events contains one of EV_READ, EV_WRITE, or EV_READ|EV_WRITE, then
fd is a file descriptor or socket that should get monitored for
readiness to read, readiness to write, or readiness for either operation
(respectively). If events contains EV_SIGNAL, then fd is a signal
number to wait for. If events contains none of those flags, then the
event can be triggered only by a timeout or by manual activation with
event_active(): In this case, fd must be -1. The EV_PERSIST flag can also be passed in the events argument: it makes
event_add() persistent until event_del() is called. The EV_ET flag is compatible with EV_READ and EV_WRITE, and supported
only by certain backends. It tells Libevent to use edge-triggered
events. The EV_TIMEOUT flag has no effect here. It is okay to have multiple events all listening on the same fds; but
they must either all be edge-triggered, or all not be edge triggerd. When the event becomes active, the event loop will run the provided
callbuck function, with three arguments. The first will be the provided
fd value. The second will be a bitfield of the events that triggered:
EV_READ, EV_WRITE, or EV_SIGNAL. Here the EV_TIMEOUT flag indicates
that a timeout occurred, and EV_ET indicates that an edge-triggered
event occurred. The third event will be the callback_arg pointer that
you provide. @param base the event base to which the event should be attached.
@param fd the file descriptor or signal to be monitored, or -1.
@param events desired events to monitor: bitfield of EV_READ, EV_WRITE,
EV_SIGNAL, EV_PERSIST, EV_ET.
@param callback callback function to be invoked when the event occurs
@param callback_arg an argument to be passed to the callback function @return a newly allocated struct event that must later be freed with
event_free().
@see event_free(), event_add(), event_del(), event_assign()
*/
EVENT2_EXPORT_SYMBOL
struct event *event_new(struct event_base *, evutil_socket_t, short, event_callback_fn, void *);
3、把event绑定到event_base中, 即event_add()
/**
Add an event to the set of pending events. The function event_add() schedules the execution of the event 'ev' when the
condition specified by event_assign() or event_new() occurs, or when the time
specified in timeout has elapesed. If atimeout is NULL, no timeout
occurs and the function will only be
called if a matching event occurs. The event in the
ev argument must be already initialized by event_assign() or event_new()
and may not be used
in calls to event_assign() until it is no longer pending. If the event in the ev argument already has a scheduled timeout, calling
event_add() replaces the old timeout with the new one if tv is non-NULL. @param ev an event struct initialized via event_assign() or event_new()
@param timeout the maximum amount of time to wait for the event, or NULL
to wait forever
@return 0 if successful, or -1 if an error occurred
@see event_del(), event_assign(), event_new()
*/
EVENT2_EXPORT_SYMBOL
int event_add(struct event *ev, const struct timeval *timeout);
4、定义回调函数
原型及简介如下:
/**
A callback function for an event. It receives three arguments: @param fd An fd or signal
@param events One or more EV_* flags
@param arg A user-supplied argument. @see event_new()
*/
typedef void (*event_callback_fn)(evutil_socket_t, short, void *);
示例如下:
//tcp客户端读socket数据
struct event *ev_sockfd = event_new(base, sockfd,
EV_READ | EV_PERSIST,
socket_read_cb, NULL); void socket_read_cb(int fd, short events, void *arg)
{
char msg[1024]; //为了简单起见,不考虑读一半数据的情况
int len = read(fd, msg, sizeof(msg)-1);
if( len <= 0 )
{
perror("read fail ");
exit(1);
} msg[len] = '\0'; printf("recv %s from server\n", msg);
}
5、启动event_base的循环,开始处理事件:event_base_dispatch()
原型及简介如下:
/**
Event dispatching loop This loop will run the event base until either there are no more pending or
active, or until something calls event_base_loopbreak() or
event_base_loopexit(). @param base the event_base structure returned by event_base_new() or
event_base_new_with_config()
@return 0 if successful, -1 if an error occurred, or 1 if we exited because
no events were pending or active.
@see event_base_loop()
*/
EVENT2_EXPORT_SYMBOL
int event_base_dispatch(struct event_base *);
6、退出循环:event_base_loopbreak()
/**
Abort the active event_base_loop() immediately. event_base_loop() will abort the loop after the next event is completed;
event_base_loopbreak() is typically invoked from this event's callback.
This behavior is analogous to the "break;" statement. Subsequent invocations of event_base_loop() will proceed normally. @param eb the event_base structure returned by event_init()
@return 0 if successful, or -1 if an error occurred
@see event_base_loopexit()
*/
EVENT2_EXPORT_SYMBOL
int event_base_loopbreak(struct event_base *);
7、删除event及free和close
示例如下:
if (ws->thread.ev) {
event_fd = event_get_fd(ws->thread.ev);
if (event_fd > 0)
close(event_fd); //关闭文件描述符
event_del(ws->thread.ev); //从event_base中删除event
event_free(ws->thread.ev); //释放event
ws->thread.ev = NULL;
}
8、查看libevent参数配置
1)config.h
2)config.log
libevent简介的更多相关文章
- libevent简介 构成
libevent简介 libevent是一个事件驱动的网络库,支持跨平台,如Linux, *BSD, MacOS X, Solaris, Windows.支持I/O多路复用,epoll.poll./d ...
- [转]libevent简介和使用
libevent是一个基于事件触发的网络库,memcached底层也是使用libevent库. 总体来说,libevent有下面一些特点和优势:* 事件驱动,高性能:* 轻量级,专注于网络: * 跨平 ...
- libevent简介和使用【转】
转自:http://www.open-open.com/lib/view/open1386510630330.html libevent是一个基于事件触发的网络库,memcached底层也是使用lib ...
- Libevent教程001: 简介与配置
本文内容大致翻译自 libevent-book, 但不是照本翻译. 成文时, libevent最新的稳定版为 2.1.8 stable. 即本文如无特殊说明, 所有描述均以 2.1.8 stable ...
- 【传智播客】Libevent学习笔记(一):简介和安装
目录 00. 目录 01. libevent简介 02. Libevent的好处 03. Libevent的安装和测试 04. Libevent成功案例 00. 目录 @ 01. libevent简介 ...
- libevent源码深度剖析
原文地址: http://blog.csdn.net/sparkliang/article/details/4957667 第一章 1,前言 Libevent是一个轻量级的开源高性能网络库,使用者众多 ...
- 以libevent网络库为引:网络通信和多线程
1. windows下编译及使用libevent http://www.cnblogs.com/luxiaoxun/p/3603399.html 2. <<libevent学习资料&g ...
- libevent的入门学习-库的安装【转】
转自:https://blog.csdn.net/lookintosky/article/details/61658067 libevent的入门学习-库的安装最近开始接触Linux应用层的东西,发现 ...
- libevent(了解)
1 前言 Libevent是一个轻量级的开源高性能网络库,使用者众多,研究者更甚,相关文章也不少.写这一系列文章的用意在于,一则分享心得:二则对libevent代码和设计思想做系统的.更深层次的分析, ...
随机推荐
- 安装lnmp1.5到最后出现Error: MySQL install failed的解决方法
解决方法: mv /usr/bin/cmake /usr/bin/cmake.backup wget http://www.cmake.org/files/v3.0/cmake-3.0.2.tar.g ...
- MySQL 加密 压缩
许多MySQL加密和压缩函数返回结果可能包含任意字节值的字符串,如果要存储这些结果,请使用VARBINARY或BLOB二进制字符串数据类型.这将避免使用非二进制字符串数据类型(CHAR, VARCHA ...
- 创建用户(adduser和useradd)和删除用户(userdel)及
一 用户创建命令: # adduser 用户名 # useradd 用户名 1) useradd 与 adduser 的区别 在CentOs系统中: useradd与adduser是没有区别的, ...
- POJ 2386 Lake Counting 八方向棋盘搜索
Lake Counting Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 53301 Accepted: 26062 D ...
- NO26 Linux的文件权限--chmod--Linux删除文件说明--suid--sgid
chmod命令改权限: suid: sgid:
- Tornado -- 7 - 查询结果
查询结果 查询结果总结: 条件查询 多表查询
- P1079 延迟的回文数
P1079 延迟的回文数 转跳点:
- jenkins#安装jenkins
1. 访问官网下载地址https://jenkins.io/zh/download/ 2. 选择自己的平台,然后按照文档进行操作: 主要按照文档来,下面是我按照文档按照的一个记录 #访问 https: ...
- 014.Delphi插件之QPlugins,MDI窗口
不知道为什么,这个DEMO编译出来报错,运行不了,在QDAC群里问了一下也没人响应. 效果如下 主程序代码如下 unit Frm_Main; interface uses Winapi.Windows ...
- PHPmyadmin Getshell(10.25 第二十七天)
PHPmyadmin Getshell的方法(1)show global variables like '% secure-file-priv%' 如果该参数设置为空或者指定的文件夹可以利用,然后写木 ...