PHP下用Swoole实现Actor并发模型的方法

什么是Actor？

Actor对于PHPer来说，可能会比较陌生，写过Java的同学会比较熟悉，Java一直都有线程的概念（虽然PHP有Pthread,但不普及）,它是一种非共享内存的并发模型，每个Actor内的数据独立存在，Actor之间通过消息传递的形式进行交互调度，且Actor是一种高度抽象化的编程模型，非常适合于游戏、硬件行业。

Swoole协程与信箱

得益于Swoole4.x，我们可以基于Swoole的协程与Channel快速实现一个信箱模式调度。模拟代码如下：

use Swoole\Coroutine\Channel;
go(function (){
  //创建十个信箱通道
  $mailBoxes = [];
  for ($i = 1;$i <= 10;$i++){
    $mailBoxes[$i] = new Channel(16);
  }
  //模拟master 邮局调度,随机像一个信箱投递消息
  go(function ()use($mailBoxes){
    while (1){
      \co::sleep(2);
      $key = rand(1,10);
      ($mailBoxes[$key])->push(time());
    }
  });
  //模拟actor 实体消费
  for ($i = 1;$i <= 10;$i++){
    go(function ()use($mailBoxes,$i){
      while (1){
        $msg = ($mailBoxes[$i])->pop();
        echo "Actor {$i} recv msg : {$msg} \n";
      }
    });
  }
});

以上代码执行输出：

php test.php
Actor 8 recv msg : 1559622691
Actor 10 recv msg : 1559622693
Actor 1 recv msg : 1559622695
Actor 5 recv msg : 1559622697

协程通道每次在POP遇到无数据的时候，都会自动让出执行权（具体可以去看Swoole协程调度）

Actor库

基于上面的原理，我们实行了一个多进程分布的协程Actor库

composer require easyswoole/actor=2.x-dev

我们依赖dev库进行测试，生产可以自己依赖stable版本

进程关系

Easyswoole的Actor模型中，存在两组进程，一组是proxy进程，用来实现Actor对外服务，一组是worker进程，proxy进程与worker进程之间通过unixsock进行通讯，而Actor实例就均匀的分布worker之中。

样例代码

比如在一个聊天室中，我们可以定义一个房间模型。

namespace EasySwoole\Actor\Test;


use EasySwoole\Actor\AbstractActor;
use EasySwoole\Actor\ActorConfig;

class RoomActor extends AbstractActor
{
  public static function configure(ActorConfig $actorConfig)
  {
    $actorConfig->setActorName('Room');
  }
  public function onStart()
  {
    //每当一个RoomActor实体被创建的时候，都会执行该回调
    var_dump('room actor '.$this->actorId().' start');
  }
  public function onMessage($msg)
  {
    //每当一个RoomActor实体收到外部消息的时候，都会执行该回调当
    var_dump('room actor '.$this->actorId().' onmessage: '.$msg);
    return 'reply at '.time();
  }
  public function onExit($arg)
  { 
    //每当一个RoomActor实体退出的时候，都会执行该回调
    var_dump('room actor '.$this->actorId().' exit at arg: '.$arg);
    return 'exit at '.time();
  }
  protected function onException(\Throwable $throwable)
  {
    //每当一个RoomActor出现异常的时候，都会执行该回调
    var_dump($throwable->getMessage());
  }
}

在cli模式下创建一个Actor服务

use EasySwoole\Actor\Actor;
use EasySwoole\Actor\Test\RoomActor;
use EasySwoole\Actor\ProxyProcess;

Actor::getInstance()->register(RoomActor::class);
$list = Actor::getInstance()->generateProcess();

foreach ($list['proxy'] as $proxy){
  /** @var ProxyProcess $proxy */
  $proxy->getProcess()->start();
}
foreach ($list['worker'] as $actors){
  foreach ($actors as $actorProcess){
    /** @var ProxyProcess $actorProcess */
    $actorProcess->getProcess()->start();
  }
}
while($ret = \Swoole\Process::wait()) {
  echo "PID={$ret['pid']}\n";
}

创建一个cli测试脚本

use EasySwoole\Actor\Actor;
use EasySwoole\Actor\Test\RoomActor;
Actor::getInstance()->register(RoomActor::class);

go(function (){
  $actorId = RoomActor::client()->create('create arg1');
  var_dump($actorId);
  \co::sleep(3);
  var_dump(RoomActor::client()->send($actorId,'this is msg'));
  \co::sleep(3);
  var_dump(RoomActor::client()->exit($actorId,'this is exit arg'));
  \co::sleep(3);
  RoomActor::client()->create('create arg2');
  \co::sleep(3);
  RoomActor::client()->create('create arg3');
  \co::sleep(3);
  var_dump(RoomActor::client()->sendAll('sendAll msg'));
  \co::sleep(3);
  var_dump(RoomActor::client()->status());
  \co::sleep(3);
  var_dump(RoomActor::client()->exitAll('sendAll exit'));
});

以上代码执行结果如下：

服务端

php test.php 
string(40) "room actor 00101000000000000000001 start"
string(57) "room actor 00101000000000000000001 onmessage: this is msg"
string(64) "room actor 00101000000000000000001 exit at arg: this is exit arg"
string(40) "room actor 00101000000000000000002 start"
string(40) "room actor 00103000000000000000001 start"
string(57) "room actor 00101000000000000000002 onmessage: sendAll msg"
string(57) "room actor 00103000000000000000001 onmessage: sendAll msg"
string(60) "room actor 00101000000000000000002 exit at arg: sendAll exit"
string(60) "room actor 00103000000000000000001 exit at arg: sendAll exit"

客户端

php test2.php 
string(23) "00101000000000000000001"
string(19) "reply at 1559623925"
string(18) "exit at 1559623928"
bool(true)
array(3) {
 [1]=>
 int(1)
 [2]=>
 int(0)
 [3]=>
 int(1)
}
bool(true)

更多细节可以在EasySwoole项目官网得到文档支持 http://easyswoole.com/

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