PHP之高性能I/O框架：Libevent（二）

Event擴展

Event可以認為是替代libevent最好的擴展，因為libevent已經很久不更新了，而Event一直在更新，而且Event支持更多特性，使用起來也比libevent簡單。

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

和libevent一樣，系統需要先安裝 Libevent 庫，因為都是基於 Libevent 庫開發的：

yum install libevent-dev

然后安裝PHP擴展。

PHP7安裝：

pecl install event

Event擴展不支持PHP5。

注：后面的代碼示例均使用的php7.1 + event環境。

基本使用

我們把libevent_tcp_server.php的例子改為Event實現的：

event_tcp_server.php

<?php 
/**
 * Created by PhpStorm.
 * User: 公眾號: 飛鴻影的博客(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); //可選
$id = (int)$socket;
$master[$id] = $socket;

echo "waiting client...\n";


//accept事件回調函數，參數分別是$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);//必須
    $id = (int)$connection;

    echo "new Client $id\n";

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

    $master[$id] = $connection; //根據業務可選
    $receive[$id] = ''; //根據業務可選
    $buffers[$id] = $event; //根據業務可選
}

//read事件回調函數
function ev_read($buffer, $flag, $id)
{
    
    global $receive;
    global $master;
    global $buffers;

    //該方法里的$buffer和$master[$id]指向相同的內容
    // var_dump(func_get_args(), $master[$id] );

    //循環讀取並解析客戶端消息
    while( 1 ) {
        $read = @fread($buffer, 1024);

        //客戶端異常斷開
        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";
                    
                    //關閉客戶端連接
                    unset($master[$id]);//斷開客戶端連接
                    unset($buffers[$id]);//刪除事件
                    break;
                default:
                    // echo "all package:\n";
                    echo $receive[$id]."\n";
                    break;
            }
            $receive[$id]='';
        }
    }
}

//創建全局event base
$base = new EventBase();
//創建並設置 event：其中$events設置為READ | PERSIST ；回調事件為ev_accept，參數 $base
//PERSIST可以讓注冊的事件在執行完后不被刪除,直到調用Event::del()刪除.
$event = new Event($base, $socket, Event::READ | Event::PERSIST, 'ev_accept', $base); 
$event->add();
echo  "start run...\n";

//進入事件循環
$base->loop();

//下面這句不會被執行
echo "This code will not be executed.\n";

可以發現做的改動非常小，而且代碼更簡潔了。運行腳本后，我們使用telnet測試，效果一模一樣。

使用Buffer

直接看例子吧，還是基於上面的例子改的，注釋里寫得很清楚了：

event_buffer_tcp_server.php

<?php 
/**
 * Created by PhpStorm.
 * User: 公眾號: 飛鴻影的博客(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);//可選
$id = (int)$socket;
$master[$id] = $socket;

echo "waiting client...\n";


//accept事件回調函數，參數分別是$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);//可選
    $id = (int)$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; //如果去掉該行，客戶端直接被斷開
    $receive[$id] = ''; //如果去掉該行，服務端無法正常收到消息
    $buffers[$id] = $event; //如果去掉該行，客戶端強制斷開再連接，服務端無法正常收到消息
}

//read事件回調函數，參數分別是EventBufferEvent，arg 
function ev_read($buffer, $id)
{
    
    global $receive;
    global $master;
    global $buffers;

    //該方法里的$buffer和$buffers[$id]指向相同的內容
    // var_dump(func_get_args(), $buffers[$id], $master[$id]);

    //循環讀取並解析客戶端消息
    while( 1 ) {
        $read = $buffer->read(65535);
        // var_dump($read);

        //客戶端異常斷開；這里可能返回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";
                    
                    //關閉客戶端連接
                    unset($master[$id]);//斷開客戶端連接
                    unset($buffers[$id]);//刪除事件
                    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";
}

//創建全局event base
$base = new EventBase();
//創建並設置 event：其中$events設置為READ | PERSIST ；回調事件為ev_accept，參數 $base
//PERSIST可以讓注冊的事件在執行完后不被刪除,直到調用Event::del()刪除.
$event = new Event($base, $socket, Event::READ | Event::PERSIST, 'ev_accept', $base); 
$event->add();
echo  "start run...\n";

//進入事件循環
$base->loop();

//下面這句不會被執行
echo "This code will not be executed.\n";

定時器(Timer)

直接看示例：
event_timer.php

<?php
/**
 * Created by PhpStorm.
 * User: 公眾號: 飛鴻影的博客(fhyblog)
 * Date: 2018/6/23
 */
 
$base  = new  EventBase ();
$n  =  2 ; //sec

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

//添加定時器
$e -> addTimer ( $n ); //sec

$base -> loop ();

運行：

$ php event_timer.php 
 2  seconds elapsed

和libevent擴展一樣，Event::timer也是對Event的封裝：

<?php
/**
 * Created by PhpStorm.
 * User: 公眾號: 飛鴻影的博客(fhyblog)
 * Date: 2018/6/23
 */
 
$base  = new  EventBase ();
$n  =  2 ; //sec

//初始化定時器
$event = new Event($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提供的定時器精度是秒。

信號(Signal)

Event 擴展提供了信號（Signal）操作的函數。

<?php
/**
 * Created by PhpStorm.
 * User: 公眾號: 飛鴻影的博客(fhyblog)
 * Date: 2018/6/23
 */
 
$base  = new  EventBase ();

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

//安裝信號
$e -> addSignal (); //sec

//發送信號
posix_kill(posix_getpid (),  SIGUSR1);

$base -> loop ();

相比pcntl_signal，Event :: signal 高效很多。

總結

Libevent 非常強大，Event實現了其很多的接口供PHP調用，我這里僅是使用了常用的幾個特性。由於Event能參考的資料實在是有限，這章寫起來也相對難一些，例子里還是留了一些待再次理解。

（未完待續）

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