Promise.php

<?php namespace AMH;

use Exception;
use Jeremeamia\SuperClosure\SerializableClosure;
use Symfony\Component\Process\PhpProcess;

class PromiseValueException extends Exception {}

class Promise
{
    protected $_promises = array();
    protected $_resolvedPromises = array();

    public function __set($key, $callback)
    {
        if ( !is_callable($callback) ) {
            throw new PromiseValueException('You can only set callbacks as promise properties');
        }
        $functionCode = serialize(new SerializableClosure($callback));
        $phpCode = 
        '<?php
            include "../vendor/autoload.php";
            $callback = unserialize("'. str_replace('"', '\\"', $functionCode) .'");
            echo serialize($callback());
        ?>';
        $promise = new PhpProcess($phpCode);
        $promise->start();
        $this->_promises[$key] = $promise;
    }

    public function __get($key)
    {
        if ( !isset($this->_resolvedPromises[$key]) ) {
            $this->_promises[$key]->wait();
            $serializedOutput = $this->_promises[$key]->getOutput();
            if ( !$this->_isSerialized($serializedOutput) ) {
                throw new Exception('Content "'. $serializedOutput .'" returned from Promise could not be unserialized');
            }
            $this->_resolvedPromises[$key] = unserialize($serializedOutput);
            unset($this->_promises[$key]);
        }
        return $this->_resolvedPromises[$key];
    }

    public function _isSerialized($str)
    {
        return ($str == serialize(false) || @unserialize($str) !== false);
    }

    public function __destruct()
    {
        try {
            foreach($this->_promises as $key => $promise) {
                $this->_promises[$key]->stop(0);
            }
        } catch ( Exception $e ) {}
    }
}

include '../vendor/autoload.php';
$time_start = microtime(true);
try {
  $Promise = new AMH\Promise;
  $Promise->test = function() {
      return json_decode(file_get_contents('http://echo.jsontest.com/key/value'));
  };
  $Promise->test;
} catch ( Exception $e ) {
  echo $e->getMessage();
}
$time_end = microtime(true);
$time = $time_end - $time_start;

echo "Did nothing in $time seconds\n";