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;
* 跨平台,支持 Windows、Linux、Mac Os等;
* 支持多种 I/O多路复用技术, epoll、poll、dev/poll、select 和kqueue 等;
* 支持 I/O,定时器和信号等事件;
libevent有下面几大部分组成:
* 事件管理包括各种IO(socket)、定时器、信号等事件,也是libevent应用最广的模块;
* 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
一些资料:
* libevent官网:http://libevent.org/
* libevent API:http://www.monkey.org/~provos/libevent/doxygen-2.0.1/index.html
* CSDN上剖析得很赞的文章:http://blog.csdn.net/sparkliang/article/details/4957667
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下面写了2个简单的使用例子,一个是定时器,一个是TCP服务器,都只涉及到libevent的事件管理模块。
一、简单定时器:实现程序每秒输出一个“Game Over!”
event_init() => evtimer_set() => event_add() =>event_dispatch()
09 |
void onTime( int sock, short event, void *arg) |
11 |
cout
<< "Game
Over!" <<
endl; |
17 |
event_add(( struct event*)arg,
&tv); |
27 |
evtimer_set(&evTime,
onTime, &evTime); |
33 |
event_add(&evTime,
&tv); |
编译并执行,编译加 -levent:
1 |
gapp_devnet_1:/data/home/andyawang/code/2013_11/LibeventTest
# mv time.cpp timer.cpp |
2 |
gapp_devnet_1:/data/home/andyawang/code/2013_11/LibeventTest
# g++ -o timer timer.cpp -levent |
3 |
gapp_devnet_1:/data/home/andyawang/code/2013_11/LibeventTest
# ./timer |
二、TCP服务器:实现监听本机8888端口并输出客户端发送过来的信息
event_base_new()=>event_set()=>event_base_set()=>event_add()=>event_base_dispatch()
04 |
#include
<sys/socket.h> |
05 |
#include
<netinet/in.h> |
06 |
#include
<arpa/inet.h> |
13 |
struct event_base*
base; |
16 |
void onRead( int iCliFd, short iEvent, void *arg) |
21 |
iLen
= recv(iCliFd, buf, 1500, 0); |
24 |
cout
<< "Client
Close" <<
endl; |
27 |
struct event
*pEvRead = ( struct event*)arg; |
36 |
cout
<< "Client
Info:" <<
buf << endl; |
40 |
void onAccept( int iSvrFd, short iEvent, void *arg) |
43 |
struct sockaddr_in
sCliAddr; |
45 |
socklen_t
iSinSize = sizeof (sCliAddr); |
46 |
iCliFd
= accept(iSvrFd, ( struct sockaddr*)&sCliAddr,
&iSinSize); |
49 |
struct event
*pEvRead = new event; |
50 |
event_set(pEvRead,
iCliFd, EV_READ|EV_PERSIST, onRead, pEvRead); |
51 |
event_base_set(base,
pEvRead); |
52 |
event_add(pEvRead,
NULL); |
59 |
struct sockaddr_in
sSvrAddr; |
61 |
memset (&sSvrAddr,
0, sizeof (sSvrAddr)); |
62 |
sSvrAddr.sin_family
= AF_INET; |
63 |
sSvrAddr.sin_addr.s_addr
= inet_addr( "127.0.0.1" ); |
64 |
sSvrAddr.sin_port
= htons(8888); |
67 |
iSvrFd
= socket(AF_INET, SOCK_STREAM, 0); |
68 |
bind(iSvrFd,
( struct sockaddr*)&sSvrAddr, sizeof (sSvrAddr)); |
72 |
base
= event_base_new(); |
76 |
event_set(&evListen,
iSvrFd, EV_READ|EV_PERSIST, onAccept, NULL); |
78 |
event_base_set(base,
&evListen); |
80 |
event_add(&evListen,
NULL); |
83 |
event_base_dispatch(base); |