root/trunk/lib/class.wsdlcache.php

<?php



/**
* caches instances of the wsdl class
* 
* @author   Scott Nichol <snichol@computer.org>
* @author    Ingo Fischer <ingo@apollon.de>
* @version  $Id: class.wsdlcache.php,v 1.5 2005/05/20 17:58:17 snichol Exp $
* @access public 
*/
class wsdlcache {
    /**
     *    @var resource
     *    @access private
     */
    var $fplock;
    /**
     *    @var integer
     *    @access private
     */
    var $cache_lifetime;
    /**
     *    @var string
     *    @access private
     */
    var $cache_dir;
    /**
     *    @var string
     *    @access public
     */
    var $debug_str = '';

    /**
    * constructor
    *
    * @param string $cache_dir directory for cache-files
    * @param integer $cache_lifetime lifetime for caching-files in seconds or 0 for unlimited
    * @access public
    */
    function wsdlcache($cache_dir='.', $cache_lifetime=0) {
        $this->fplock = array();
        $this->cache_dir = $cache_dir != '' ? $cache_dir : '.';
        $this->cache_lifetime = $cache_lifetime;
    }

    /**
    * creates the filename used to cache a wsdl instance
    *
    * @param string $wsdl The URL of the wsdl instance
    * @return string The filename used to cache the instance
    * @access private
    */
    function createFilename($wsdl) {
        return $this->cache_dir.'/wsdlcache-' . md5($wsdl);
    }

    /**
    * adds debug data to the class level debug string
    *
    * @param    string $string debug data
    * @access   private
    */
    function debug($string){
        $this->debug_str .= get_class($this).": $string\n";
    }

    /**
    * gets a wsdl instance from the cache
    *
    * @param string $wsdl The URL of the wsdl instance
    * @return object wsdl The cached wsdl instance, null if the instance is not in the cache
    * @access public
    */
    function get($wsdl) {
        $filename = $this->createFilename($wsdl);
        if ($this->obtainMutex($filename, "r")) {
            // check for expired WSDL that must be removed from the cache
             if ($this->cache_lifetime > 0) {
                if (file_exists($filename) && (time() - filemtime($filename) > $this->cache_lifetime)) {
                    unlink($filename);
                    $this->debug("Expired $wsdl ($filename) from cache");
                    $this->releaseMutex($filename);
                    return null;
                  }
            }
            // see what there is to return
            $fp = @fopen($filename, "r");
            if ($fp) {
                $s = implode("", @file($filename));
                fclose($fp);
                $this->debug("Got $wsdl ($filename) from cache");
            } else {
                $s = null;
                $this->debug("$wsdl ($filename) not in cache");
            }
            $this->releaseMutex($filename);
            return (!is_null($s)) ? unserialize($s) : null;
        } else {
            $this->debug("Unable to obtain mutex for $filename in get");
        }
        return null;
    }

    /**
    * obtains the local mutex
    *
    * @param string $filename The Filename of the Cache to lock
    * @param string $mode The open-mode ("r" or "w") or the file - affects lock-mode
    * @return boolean Lock successfully obtained ?!
    * @access private
    */
    function obtainMutex($filename, $mode) {
        if (isset($this->fplock[md5($filename)])) {
            $this->debug("Lock for $filename already exists");
            return false;
        }
        $this->fplock[md5($filename)] = fopen($filename.".lock", "w");
        if ($mode == "r") {
            return flock($this->fplock[md5($filename)], LOCK_SH);
        } else {
            return flock($this->fplock[md5($filename)], LOCK_EX);
        }
    }

    /**
    * adds a wsdl instance to the cache
    *
    * @param object wsdl $wsdl_instance The wsdl instance to add
    * @return boolean WSDL successfully cached
    * @access public
    */
    function put($wsdl_instance) {
        $filename = $this->createFilename($wsdl_instance->wsdl);
        $s = serialize($wsdl_instance);
        if ($this->obtainMutex($filename, "w")) {
            $fp = fopen($filename, "w");
            fputs($fp, $s);
            fclose($fp);
            $this->debug("Put $wsdl_instance->wsdl ($filename) in cache");
            $this->releaseMutex($filename);
            return true;
        } else {
            $this->debug("Unable to obtain mutex for $filename in put");
        }
        return false;
    }

    /**
    * releases the local mutex
    *
    * @param string $filename The Filename of the Cache to lock
    * @return boolean Lock successfully released
    * @access private
    */
    function releaseMutex($filename) {
        $ret = flock($this->fplock[md5($filename)], LOCK_UN);
        fclose($this->fplock[md5($filename)]);
        unset($this->fplock[md5($filename)]);
        if (! $ret) {
            $this->debug("Not able to release lock for $filename");
        }
        return $ret;
    }

    /**
    * removes a wsdl instance from the cache
    *
    * @param string $wsdl The URL of the wsdl instance
    * @return boolean Whether there was an instance to remove
    * @access public
    */
    function remove($wsdl) {
        $filename = $this->createFilename($wsdl);
        // ignore errors obtaining mutex
        $this->obtainMutex($filename, "w");
        $ret = unlink($filename);
        $this->debug("Removed ($ret) $wsdl ($filename) from cache");
        $this->releaseMutex($filename);
        return $ret;
    }
}
?>