PHP之高性能I/O框架：Libevent（二）

Event扩展

Event可以认为是替代libevent最好的扩展，因为libevent已经很久不更新了，而Event一直在更新，而且Event支持更多特性，使用起来也比libevent简单。

Event地址: http://pecl.php.net/package/event

Event文档: http://docs.php.net/event

和libevent一样，系统需要先安装 Libevent 库，因为都是基于 Libevent 库开发的：

yum install libevent-dev

然后安装PHP扩展。

PHP7安装：

pecl install event

Event扩展不支持PHP5。

注：后面的代码示例均使用的php7.1 + event环境。

基本使用

我们把libevent_tcp_server.php的例子改为Event实现的：

event_tcp_server.php

<?php
/**
 * Created by PhpStorm.
 * User: 公众号: 飞鸿影的博客(fhyblog)
 * Date: 2018/6/23
 */

$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); //可选
$id = (int)$socket;
$master[$id] = $socket;

echo "waiting client...\n";

//accept事件回调函数，参数分别是$fd, $events, $arg
function ev_accept($socket, $flag, $base){
    global $receive;
    global $master;
    global $buffers;

    $connection = stream_socket_accept($socket);
    stream_set_blocking($connection, 0);//必须
    $id = (int)$connection;

    echo "new Client $id\n";

    $event = new Event($base, $connection, Event::READ | Event::PERSIST, 'ev_read', $id);
    $event->add();

    $master[$id] = $connection; //根据业务可选
    $receive[$id] = ''; //根据业务可选
    $buffers[$id] = $event; //根据业务可选
}

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

            switch ( $receive[$id] ){
                case "quit":
                    echo "client close conn\n";

                    //关闭客户端连接
                    unset($master[$id]);//断开客户端连接
                    unset($buffers[$id]);//删除事件
                    break;
                default:
                    // echo "all package:\n";
                    echo $receive[$id]."\n";
                    break;
            }
            $receive[$id]='';
        }
    }
}

//创建全局event base
$base = new EventBase();
//创建并设置 event：其中$events设置为READ | PERSIST ；回调事件为ev_accept，参数 $base
//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.
$event = new Event($base, $socket, Event::READ | Event::PERSIST, 'ev_accept', $base);
$event->add();
echo  "start run...\n";

//进入事件循环
$base->loop();

//下面这句不会被执行
echo "This code will not be executed.\n";

可以发现做的改动非常小，而且代码更简洁了。运行脚本后，我们使用telnet测试，效果一模一样。

使用Buffer

直接看例子吧，还是基于上面的例子改的，注释里写得很清楚了：

event_buffer_tcp_server.php

<?php
/**
 * Created by PhpStorm.
 * User: 公众号: 飞鸿影的博客(fhyblog)
 * Date: 2018/6/23
 */

$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);//可选
$id = (int)$socket;
$master[$id] = $socket;

echo "waiting client...\n";

//accept事件回调函数，参数分别是$fd, $events, $arg
function ev_accept($socket, $flag, $base){
    global $receive;
    global $master;
    global $buffers;

    $connection = stream_socket_accept($socket);
    //stream_set_blocking($connection, 0);//可选
    $id = (int)$connection;

    echo "new Client $id\n";

    //新建EventBuffer 事件
    $event = new EventBufferEvent($base, $connection, 0, 'ev_read', 'ev_write', 'ev_status', $id);
    $event->setTimeouts(30, 30); //read and write timeout
    $event->setWatermark ( Event::READ, 0, 0xffffff ); //Adjusts read and/or write watermarks
    $event->setPriority(10);
    $event->enable(Event::READ | Event::PERSIST);

    $master[$id] = $connection; //如果去掉该行，客户端直接被断开
    $receive[$id] = ''; //如果去掉该行，服务端无法正常收到消息
    $buffers[$id] = $event; //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，参数分别是EventBufferEvent，arg
function ev_read($buffer, $id)
{

    global $receive;
    global $master;
    global $buffers;

    //该方法里的$buffer和$buffers[$id]指向相同的内容
    // var_dump(func_get_args(), $buffers[$id], $master[$id]);

    //循环读取并解析客户端消息
    while( 1 ) {
        $read = $buffer->read(65535);
        // var_dump($read);

        //客户端异常断开；这里可能返回NULL
        if($read === '' || $read === false || $read === NULL){
            break;
        }

        $pos = strpos($read, "\n");
        if($pos === false)
        {
            $receive[$id] .= $read;
            echo "received:".$read.";not all package,continue recdiveing\n";
        }else{
            $receive[$id] .= trim(substr ($read,0,$pos+1));
            $read = substr($read,$pos+1);

            switch ( $receive[$id] ){
                case "quit":
                    echo "client close conn\n";

                    //关闭客户端连接
                    unset($master[$id]);//断开客户端连接
                    unset($buffers[$id]);//删除事件
                    break;
                default:
                    // echo "all package:\n";
                    echo $receive[$id]."\n";
                    break;
            }
            $receive[$id]='';
        }
    }
}

function ev_write($buffer, $id)
{
    echo "$id -- " ."\n";
}

function ev_status($buffer, $events, $id)
{
    echo "ev_status - ".$events."\n";
}

//创建全局event base
$base = new EventBase();
//创建并设置 event：其中$events设置为READ | PERSIST ；回调事件为ev_accept，参数 $base
//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.
$event = new Event($base, $socket, Event::READ | Event::PERSIST, 'ev_accept', $base);
$event->add();
echo  "start run...\n";

//进入事件循环
$base->loop();

//下面这句不会被执行
echo "This code will not be executed.\n";

定时器(Timer)

直接看示例：

event_timer.php

<?php
/**
 * Created by PhpStorm.
 * User: 公众号: 飞鸿影的博客(fhyblog)
 * Date: 2018/6/23
 */

$base  = new  EventBase ();
$n  =  2 ; //sec

//初始化定时器
$e  =  Event :: timer ( $base , function( $arg ) use (& $e ) {
    echo  " $arg  seconds elapsed\n" ;
     $e -> delTimer ();
},  $n );

//添加定时器
$e -> addTimer ( $n ); //sec

$base -> loop ();

运行：

$ php event_timer.php
 2  seconds elapsed

和libevent扩展一样，Event::timer也是对Event的封装：

<?php
/**
 * Created by PhpStorm.
 * User: 公众号: 飞鸿影的博客(fhyblog)
 * Date: 2018/6/23
 */

$base  = new  EventBase ();
$n  =  2 ; //sec

//初始化定时器
$event = new Event($base, null, Event::TIMEOUT, 'ev_timer',  $n );
$event->add($n);//sec

function ev_timer($fd, $what, $arg){
    echo  " $arg  seconds elapsed\n" ;
    global $event;
    $event->del();
}

$base->loop();

Event提供的定时器精度是秒。

信号(Signal)

Event 扩展提供了信号（Signal）操作的函数。

<?php
/**
 * Created by PhpStorm.
 * User: 公众号: 飞鸿影的博客(fhyblog)
 * Date: 2018/6/23
 */

$base  = new  EventBase ();

//初始化信号事件
$e  =  Event :: signal ( $base , SIGUSR1, function( $signum , $arg ) use (& $e ) {
    echo  " Caught signal $signum\n" ;
    $e->delSignal(); //移除信号
},  '');

//安装信号
$e -> addSignal (); //sec

//发送信号
posix_kill(posix_getpid (),  SIGUSR1);

$base -> loop ();

相比pcntl_signal，Event :: signal 高效很多。

总结

Libevent 非常强大，Event实现了其很多的接口供PHP调用，我这里仅是使用了常用的几个特性。由于Event能参考的资料实在是有限，这章写起来也相对难一些，例子里还是留了一些待再次理解。

（未完待续）

---

推荐

Redis 系列讲座合集

内容概要：Redis 最为目前炙手可热的 Key-Value 数据库，常用做缓存、Session共享中间件，分布式锁等等。

本系列课程包括:

讲师是CSDN 博客专家，多年 Redis 使用经验。感兴趣的朋友可以点击试看！

---