PHP高性能框架Libevent的使用详解

PHP高性能I/O框架Libevent的使用详解Libevent是一个用C语言编写的、轻量级的开源高性能I/O框架，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；注册事件优先级。\t"/database/201807/_blank"PHP提供了对应的扩展libevent、Event。libevent扩展很久没有更新了，仅支持PHP5系列，PHP7虽然有网友fork了libevent扩展的\t"/database/201807/_blank"源码进行更新兼容，但是稳定性不好，可能会出现段错误，所以PHP7最好使用Event扩展。与libevent扩展不同的是，Event扩展提供了面向对象的接口，且支持更多特性。libevent扩展\t"/database/201807/_blank"系统需要先安装Libevent库：?1yuminstalllibevent-dev然后安装PHP扩展。PHP5安装：?1peclinstalllibevent-0.1.0PHP7安装（不稳定）：?12345gitclone/expressif/pecl-event-libevent.gitcdpecl-event-libeventphpize./configuremake&&sudomakeinstall注：后面的代码示例均使用的php5.6+libevent-0.1.0环境。基本使用下面的例子实现了一个单进程的TCPserver，基于libevent实现I/O复用，达到高性能。libevent_tcp_server.php?123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115<!--php

$receive=[];$master=[];$buffers=[];

$socket=stream_socket_server("tcp://:9201",$errno,$errstr);if(false===$socket){

echo"$errstr($errno)\n";

exit();}if(!$socket)die($errstr."--".$errno);stream_set_blocking($socket,0);$id=(int)$socket;$master[$id]=$socket;

echo"waitingclient...\n";

//accept事件回调函数，参数分别是$fd,$events,$arg。//也就是event_set函数的$fd,$events,$arg参数。functionev_accept($socket,$flag,$base){

global$receive;

global$master;

global$buffers;

$connection=stream_socket_accept($socket);

stream_set_blocking($connection,0);

$id=(int)$connection;

echo"newClient$id\n";

$event=event_new();

event_set($event,$connection,EV_READ|EV_PERSIST,'ev_read',$id);

event_base_set($event,$base);

event_add($event);

$master[$id]=$connection;

$receive[$id]='';

$buffers[$id]=$event;//event实例一定要存放在一个全局数组里面。如果去掉该行，客户端强制断开再连接，服务端无法正常收到消息}

//read事件回调函数functionev_read($buffer,$flag,$id){

global$receive;

global$master;

global$buffers;

//该方法里的$buffer和$master[$id]指向相同的内容

//var_dump(func_get_args(),$master[$id]);

//循环读取并解析客户端消息

while(1){

$read=@fread($buffer,1024);

//客户端异常断开

if($read===''||$read===false){break;

}

$pos=strpos($read,"\n");

if($pos===false)

{$receive[$id].=$read;//echo"received:".$read.";notallpackage,continuerecpeing\n";

}else{$receive[$id].=trim(substr($read,0,$pos+1));$read=substr($read,$pos+1);

switch($receive[$id]){

case"quit":

echo"clientcloseconn\n";

//fclose($master[$id]);//断开客户端连接

//event_del($buffers[$id]);//删除事件

//下面的写法与上面调用函数效果一样，都是关闭客户端连接

unset($master[$id]);

unset($buffers[$id]);

break;

default:

//echo"allpackage:\n";

echo$receive[$id]."\n";

break;}$receive[$id]='';

}

}}

//创建全局eventbase$base=event_base_new();//创建event$event=event_new();//设置event：其中$events设置为EV_READ|EV_PERSIST；回调事件为ev_accept，参数$base//EV_PERSIST可以让注册的事件在执行完后不被删除,直到调用event_del()删除.event_set($event,$socket,EV_READ|EV_PERSIST,'ev_accept',$base);//全局eventbase添加当前eventevent_base_set($event,$base);event_add($event);echo

"startrun...\n";

//进入事件循环event_base_loop($base);

//下面这句不会被执行echo"Thiscodewillnotbeexecuted.\n";</pre-->我们先运行代码：?123$phplibevent_tcp_server.phpwaitingclient...startrun...客户端使用telnet：?12345$telnet9201Trying...Connectedto.Escapecharacteris'^]'.helloserver!代码里面我加了很多注释，基本上能看明白。需要注意的是：1、event_base是全局的，只需要创建一次，后续都是event的设置和添加。2、event_set的回调函数有三个参数，分别是$fd,$events,$arg。也就是event_set函数的$fd,$events,$arg参数。arg如果需要多个，可以为数组。fd参数实际是保存的客户端连接，是个resource。events参数支持下列这些常量：EV_TIMEOUT:超时。利用事件可以实现定时器EV_READ:只要网络缓冲中还有数据，回调函数就会被触发EV_WRITE:只要塞给网络缓冲的数据被写完，回调函数就会被触发EV_SIGNAL:POSIX信号量EV_PERSIST:不指定这个属性的话，回调函数被触发后事件会被删除EV_ET:Edge-Trigger边缘触发使用event_bufferlibevent还提供了event_buffer_系列函数。手册里的解释是：Libevent在基础的API里提供了一层抽象层，使用bufferedevent，我们无序手动处理I/O。估计是对性能的提升。乐淘棋牌示例：libevent_buffer_tcp_server.php?123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114<!--php

$receive=[];$master=[];$buffers=[];

$socket=stream_socket_server("tcp://:9201",$errno,$errstr);if(false===$socket){

echo"$errstr($errno)\n";

exit();}if(!$socket)die($errstr."--".$errno);stream_set_blocking($socket,0);$id=(int)$socket;$master[$id]=$socket;

echo"waitingclient...\n";

functionev_accept($socket,$flag,$base){

global$receive;

global$master;

global$buffers;

$connection=stream_socket_accept($socket);

stream_set_blocking($connection,0);

$id=(int)$connection;

echo"newClient$id\n";

//#1下面改成了event_buffer事件，与event事件有些不同

//event_buffer_new额外支持写、错误事件

$buffer=event_buffer_new($connection,'ev_read','ev_write','ev_error',$id);

event_buffer_base_set($buffer,$base);

//指定超时时间，单位秒

event_buffer_timeout_set($buffer,30,30);

//设置水位，参考：/nengm1988/p/8203784.html

event_buffer_watermark_set($buffer,EV_READ,0,0xffffff);

//设置优先级

event_buffer_priority_set($buffer,10);

//开启event_buffer

event_buffer_enable($buffer,EV_READ|EV_PERSIST);

$master[$id]=$connection;

$receive[$id]='';

$buffers[$id]=$buffer;}

//#2read回调，由于使用了event_buffer,这里仅接受2个参数，分别是fd和argfunctionev_read($buffer,$id){

//var_dump(func_get_args());

global$receive;

global$master;

global$buffers;

while(1){

//#3使用event_buffer_read，而不是fread

$read=@event_buffer_read($buffer,1024);

if($read===''||$read===false)

{break;

}

$pos=strpos($read,"\n");

if($pos===false)

{$receive[$id].=$read;echo"received:".$read.";notallpackage,continuerecpeing\n";

}else{$receive[$id].=trim(substr($read,0,$pos+1));$read=substr($read,$pos+1);

switch($receive[$id]){

case"quit":

echo"clientcloseconn\n";

unset($master[$id]);

unset($buffers[$id]);

//fclose($master[$id]);

//event_buffer_free($buffers[$id]);

break;

default:

echo"allpackage:\n";

echo$receive[$id]."\n";

break;}$receive[$id]='';

}

}}

functionev_write($buffer,$id){

echo"$id--"."\n";}

functionev_error($buffer,$error,$id){

echo"ev_error-".$error."\n";}

$base=event_base_new();$event=event_new();event_set($event,$socket,EV_READ|EV_PERSIST,'ev_accept',$base);event_base_set($event,$base);event_add($event);echo

"startrun...\n";event_base_loop($base);</pre-->注释我都写了，相比前一个例字，主要有3个地方不同：1、ev_accept里设置read事件全换成了待buffer的函数；2、ev_read回调接收参数为2个；3、ev_read回调里读取消息使用event_buffer_read，而不是fread。另外增加了ev_write，ev_error回调。638棋牌定时器libevent提供了event_timer_*系列函数，实现一次性定时器，精度微秒。libevent_timer.php?123456789101112131415161718192021222324252627282930<!--php

$TIME_INTVAL=1000000;//单位微秒

//回调函数functionev_timer($fd,$events,$args){

//var_dump(func_get_args());//打印结果：参数fd为NULL，参数events固定为EV_TIMEOUT常量

static$c;

$c++;

echotime()."hello\n";

event_timer_add($args[1],$args[0]);//再次添加定时器

if($c-->5){

event_timer_del($args[1]);//删除定时器

}}

$base=event_base_new();$ev_tim