php基于协程实现异步的方法分析

本文实例讲述了php基于协程实现异步的方法。分享给大家供大家参考，具体如下：

github上php的协程大部分是根据这篇文章实现的：http://nikic.github.io/2012/12/22/Cooperative-multitasking-using-coroutines-in-PHP.html。

它们最终的结果都是把回调变成了优雅的顺序执行的代码，但还是阻塞的，不是真正的异步。

比如最热门的：https://github.com/recoilphp/recoil

先安装：

composer require recoil/recoil

执行：

<?php
//recoil.php
include __DIR__ . '/vendor/autoload.php';
use Recoil\React\ReactKernel;
$i = 100000;
ReactKernel::start(task1());
ReactKernel::start(task2());
function task1(){
  global $i;
  echo "wait start" . PHP_EOL;
  while ($i-- > 0) {
    yield;
  }
  echo "wait end" . PHP_EOL;
};
function task2(){
  echo "Hello " . PHP_EOL;
  yield;
  echo "world!" . PHP_EOL;
}

结果：

wait start
//等待若干秒
wait end
Hello
world!

我本来是想让两个任务并行，结果两个任务变成了串行，中间等待的时间什么事情都干不了。React响应式的编程是严格禁止这种等待的，所以我就参照unity3d的协程自己写了个php版本的。上代码：

<?php
//Coroutine.php
//依赖swoole实现的定时器，也可以用其它方法实现定时器
class Coroutine
{
  //可以根据需要更改定时器间隔，单位ms
  const TICK_INTERVAL = 1;
  private $routineList;
  private $tickId = -1;
  public function __construct()
  {
    $this->routineList = [];
  }
  public function start(Generator $routine)
  {
    $task = new Task($routine);
    $this->routineList[] = $task;
    $this->startTick();
  }
  public function stop(Generator $routine)
  {
    foreach ($this->routineList as $k => $task) {
      if($task->getRoutine() == $routine){
        unset($this->routineList[$k]);
      }
    }
  }
  private function startTick()
  {
    swoole_timer_tick(self::TICK_INTERVAL, function($timerId){
      $this->tickId = $timerId;
      $this->run();
    });
  }
  private function stopTick()
  {
    if($this->tickId >= 0) {
      swoole_timer_clear($this->tickId);
    }
  }
  private function run()
  {
    if(empty($this->routineList)){
      $this->stopTick();
      return;
    }
    foreach ($this->routineList as $k => $task) {
      $task->run();
      if($task->isFinished()){
        unset($this->routineList[$k]);
      }
    }
  }

}
class Task
{
  protected $stack;
  protected $routine;
  public function __construct(Generator $routine)
  {
    $this->routine = $routine;
    $this->stack = new SplStack();
  }
  /**
   * [run 协程调度]
   * @return [type]     [description]
   */
  public function run()
  {
    $routine = &$this->routine;
    try {
      if(!$routine){
        return;
      }
      $value = $routine->current();
      //嵌套的协程
      if ($value instanceof Generator) {
        $this->stack->push($routine);
        $routine = $value;
        return;
      }
      //嵌套的协程返回
      if(!$routine->valid() && !$this->stack->isEmpty()) {
        $routine = $this->stack->pop();
      }
      $routine->next();
    } catch (Exception $e) {
      if ($this->stack->isEmpty()) {
        /*
          throw the exception
        */
        return;
      }
    }
  }
  /**
   * [isFinished 判断该task是否完成]
   * @return boolean [description]
   */
  public function isFinished()
  {
    return $this->stack->isEmpty() && !$this->routine->valid();
  }
  public function getRoutine()
  {
    return $this->routine;
  }
}

测试代码：

<?php
//test.php
 require 'Coroutine.php';
$i = 10000;
$c = new Coroutine();
$c->start(task1());
$c->start(task2());
function task1(){
  global $i;
  echo "wait start" . PHP_EOL;
  while ($i-- > 0) {
    yield;
  }
  echo "wait end" . PHP_EOL;
};
function task2(){
  echo "Hello " . PHP_EOL;
  yield;
  echo "world!" . PHP_EOL;
}

结果：

wait start
Hello
world!
//等待几秒，但不阻塞
wait end

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