NovComet.php

<?php
/**
 * Lazy Comet with PHP (publisher and subscriber)
 *
 * THIS PROGRAM COMES WITH ABSOLUTELY NO WARANTIES !
 * USE IT AT YOUR OWN RISKS !
 *
 * @author Gonzalo Ayuso <gonzalo123@gmail.com>
 * @copyright under GPL 2 licence
 */
class NovComet {
    const COMET_OK = 0;
    const COMET_CHANGED = 1;

    private $_tries;
    private $_var;
    private $_sleep;
    private $_ids = array();
    private $_callback = null;

    public function  __construct($tries = 10, $sleep = 2) 
    {
        $this->_tries = $tries;
        $this->_sleep = $sleep;
    }

    public function setVar($key, $value)
    {
        $this->_vars[$key] = $value;
    }
    
    public function setTries($tries)
    {
        $this->_tries = $tries;
    }
   
    public function setSleepTime($sleep)
    {
        $this->_sleep = $sleep;
    }
    
    public function setCallbackCheck($callback)
    {
        $this->_callback = $callback;
    }
    
    const DEFAULT_COMET_PATH = "/dev/shm/%s.comet";
    
    public function run() {
        if (is_null($this->_callback)) {
            $defaultCometPAth = self::DEFAULT_COMET_PATH;
            $callback = function($id) use ($defaultCometPAth) {
                $cometFile = sprintf($defaultCometPAth, $id);
                return (is_file($cometFile)) ? filemtime($cometFile) : 0;
            };
        } else {
            $callback = $this->_callback;
        }
        $out = array();
        for ($i = 0; $i < $this->_tries; $i++) {
            foreach ($this->_vars as $id => $timestamp) {
                if ((integer) $timestamp == 0) {
                    $timestamp = time();
                }
                $fileTimestamp = $callback($id);
                if ($fileTimestamp > $timestamp) {
                    $out[$id] = $fileTimestamp;
                }
                clearstatcache();
            }
            if (count($out) > 0) {
                return json_encode(array('s' => self::COMET_CHANGED, 'k' => $out));
            }
            sleep($this->_sleep);
        }
        return json_encode(array('s' => self::COMET_OK));
    }
    
    public function publish($id)
    {
        return json_encode(touch(sprintf(self::DEFAULT_COMET_PATH, $id)));
    }
}