PHP高性能I/O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。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扩展系统需要先安装 Libevent 库:?1yum install libevent-dev然后安装PHP扩展。PHP5安装:?1pecl install libevent-0.1.0PHP7安装(不稳定):?12345git clone https:/github.com/expressif/pecl-event-libevent.gitcd pecl-event-libeventphpize./configuremake && sudo make install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TCP server,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:/0.0.0.0:9201", $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 = $socket; echo "waiting client.n" /accept事件回调函数,参数分别是$fd, $events, $arg。/也就是 event_set 函数的$fd, $events, $arg参数。function ev_accept($socket, $flag, $base) global $receive; global $master; global $buffers; $connection = stream_socket_accept($socket); stream_set_blocking($connection, 0); $id = (int)$connection; echo "new Client $idn" $event = event_new(); event_set($event, $connection, EV_READ | EV_PERSIST, 'ev_read', $id); event_base_set($event, $base); event_add($event); $master$id = $connection; $receive$id = '' $buffers$id = $event; / event实例一定要存放在一个全局数组里面。如果去掉该行,客户端强制断开再连接,服务端无法正常收到消息 /read事件回调函数function ev_read($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."not all package,continue recpeingn" else$receive$id .= trim(substr ($read,0,$pos+1);$read = substr($read,$pos+1); switch ( $receive$id ) case "quit": echo "client close connn" / 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 "all package:n" echo $receive$id."n" break;$receive$id='' /创建全局event base$base = event_base_new();/创建 event$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', $base); / 全局event base添加 当前eventevent_base_set($event, $base);event_add($event);echo "start run.n" /进入事件循环event_base_loop($base); /下面这句不会被执行echo "This code will not be executed.n"</pre->我们先运行代码:?123$ php libevent_tcp_server.phpwaiting client.start run.客户端使用telnet:?12345$ telnet 127.0.0.1 9201Trying 127.0.0.1.Connected to 127.0.0.1.Escape character is ''.hello server!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 buffered event ,我们无序手动处理I/O。估计是对性能的提升。乐淘棋牌http:/www.jiekeqipai.net示例:libevent_buffer_tcp_server.php?123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114<!-php $receive = ;$master = ;$buffers = ; $socket = stream_socket_server ("tc