For historical reasons, a few projects of mine look in a number of directories (perhaps 10-15) for object files, and I’ve used an autoload function to handle the code inclusion. Unfortunately at the time, I wasn’t sensible enough to follow e.g. the Zend/PEAR framework’s naming convention which would have allowed me to greatly reduce the number of directory lookups when autoloading. In my mind it made sense to e.g keep Smarty in it’s own separate directory (and not rely on PEAR packages being installed and of the right version) and ditto with ezComponents, Zend Framework and so on with a few bits I wrote.

One approach I could have taken would be to generate a fixed class map – similar to how Propel now behaves (or ezComponents, for that matter), but I’m too lazy to do that – so instead I changed my Autoloader to perform some caching – namely it remembers where it’s found objects with a given name from before. Years ago, I found this Autoloader class, and the other day I thought I’d finally look into using it. Unfortunately (for it) I didn’t think much of it’s code – specifically, I think if a class contains only static functions, then it’s probably designed incorrectly; I also wanted to use APC to cache the class lookup map – rather than  relying on a file on disk (well, one aim is to improve performance, so I might as well try…).

So, without any further ado, here’s some code.

/**
 * Autoloader is a class scanner with caching. i.e. it'll try and discover class files in the
 * given list of directories, and if it finds matche(s) it'll save them in a cache for later use (E.g. APC via Zend_Cache)
 *
 *
 *
 * @see http://anthonybush.com/projects/autoloader/
 * DG re-coded it to not be all static, as that seems stupid.
 *
 *  Sample Usage:
 *  include_once('Autoloader.php');
 *  $autoloader = Autoloader::getInstance();
 *  $autoloader->addClassPath('path/to/classes');
 *  $autoloader->addClassPath(explode(':', ini_get('include_path'));
 *  $autoloader->setCache(Zend_Cache_Frontend $x); // APC?
 *  $autoloader->excludeFolderNamesMatchingRegexp('/^CVS|^\./');
 *  $autoloader->ignoreClassNamesRegexp('/Zend_/'); // use e.g. Zend_Loader instead.
 *  $autoloader->setCacheKey('whatever');
 *  $autoloader->register(); // register with SPL.
 *
 * @author Original: Anthony Bush, Wayne Wight
 * @author David Goodwin
 * @copyright 2006-2008 Academic Superstore. This software is open source protected by the FreeBSD License.
 * @version 2011-04-18
 **/

class Autoloader {
    /* @var Autoloader singleton static thing */
    private static $instance = null;

    /* @var string cache key; should be unique per project using this,
      if multiple projects on the same server. */
    protected $cacheKey = 'autoloader_cache';
    /* @var array */
    protected $classPaths = array();
    /* @var string */
    protected $classFileSuffix = '.php';
    /* @var Zend_Cache instance */
    protected $cacheBackend = null;
    /* @var array list of directories to rummage through */
    protected $cachedPaths = null;
    /* @var string regexp to use to exclude folders we do not wish to search */
    protected $excludeFolderNames = '/^CVS|\..*$/'; // CVS directories and directories starting with a dot (.).
    /* @var string regexp for class names to not even bother looking for - e.g. Zend_ */
    protected $ignoreClassNamesRegexp = '/Zend_/';

   /* explicitly here so you are aware that it doesn't have to be a singleton */
    public function __construct() {
    }

    /**
      * do not consider a file name matching this regexp; e.g. anything with Zend_ - don't bother
      * trying, as we'll always have a 'miss', as we'll use Zend_Loader for them.
      * @param string $regexp
      */
    public function ignoreClassesMatching($regexp) {
        $this->ignoreClassNamesRegexp = $regexp;
    }

    /**
     * Well, if you want, you can use it as a singleton....
     * @return Autoloader $singleton instance
     */
    public static function getInstance() {
        if(self::$instance == null) {
            self::$instance = new Autoloader();
        }
        return self::$instance;
    }

    /**
      * You might need this if running the same code base twice on the same server but
      * under different directories - e.g. dev and live. In which case, specify a local per project key.
      */
    public function setCacheKey($string) {
        $this->cacheKey = $string;
    }

    /**
     * Sets the paths to search in when looking for a class.
     *
     * @param array $paths
     * @return void
     **/
    public  function setClassPaths($paths) {
        $this->classPaths = $paths;
    }

    /**
     * Adds a path to search in when looking for a class.
     *
     * @param string $path
     * @return void
     **/
    public  function addClassPath($path) {
        if(!is_array($path)) {
            $path = array($path);
        }
        foreach($path as $item) {
            $this->classPaths[] = $item;
        }
    }

    /**
     * Set the Zend_Cache instance to use.
     *
     *     
     *     Autoloader->setCache($cache);
     *     
     *
     * @param Zend_Cache_Frontend $cache
     * @return void
     **/
    public function setCache($cache) {
        $this->cacheBackend = $cache;
    }

    /**
     * Return caching backend used; or create new one if none already defined
     * (Zend_Cache_Frontend_Core with APC backend).
     */
    public function getCache() {
        if($this->cacheBackend == null) {
            $this->cacheBackend = Zend_Cache::factory('Core', 'Apc', array('automatic_serialization' => true));
        }
        return $this->cacheBackend;
    }

    /**
     * Sets the suffix to append to a class name in order to get a file name
     * to look for
     *
     * @param string $suffix - $className . $suffix = filename.
     * @return void
     **/
    public static function setClassFileSuffix($suffix) {
        $this->classFileSuffix = $suffix;
    }

    /**
     * When searching the {@link $classPaths} recursively for a matching class
     * file, folder names matching $regex will not be searched.
     *
     * Example:
     *     
     *     Autoloader::excludeFolderNamesMatchingRegex('/^CVS|\..*$/');
     *     
     * @param string $regex - regexp to exclude files/dirs from being selected for possible candidates.
     **/
    public function excludeFolderNamesMatchingRegex($regex) {
        $this->excludeFolderNames = $regex;
    }

    /**
     * Given a map of class names to absolute file paths, try and load the class.
     * If we get to including the file, we ensure that the class_exists after doing
     * so, otherwise we'll return false.
     * Also return false if we don't know where the class ($name) could be.
     * @param string $name the name of the class we wish to load.
     * @param array $list - map of known classnames to absolute file paths.
     */
    protected function tryAndLoadClass($name, $list) {
        if(in_array($name, array_keys($list))) {
            include_once $list[$name];
            if(class_exists($name) || interface_exists($name)) {
                //echo "Successfully loaded $name\n";
                return true;
            }
        }
        return false;
    }

    /**
     * Returns true if the class file was found and included, false if not.
     *
     * @return boolean
     **/
    public function loadClass($className) {
        $cache = $this->getCache();
        $entries = $cache->load($this->cacheKey);
        if($entries == false) {
            $entries = array();
        }
        $status = $this->tryAndLoadClass($className, $entries);
        if($status) {
            // class loaded
            return true;
        }
        if(preg_match($this->ignoreClassNamesRegexp, $className)) {
            return false;
        }

        foreach($this->classPaths as $path) {
            // Scan for file
            $realPath = $this->searchForClassFile($className, $path);
            if($realPath !== false) {
                $entries[$className] = $realPath;
                break;
            }
        }
        $cache->save($entries, $this->cacheKey);
        $status = $this->tryAndLoadClass($className, $entries);
        return $status;
    }

    /**
     * Rummage recursively through all directories found within $directory for a
     * file matching ClassName.$suffix
     * @return string class name if one found; otherwise false.
     */
    protected function searchForClassFile($className, $directory) {
        if(is_dir($directory) && is_readable($directory)) {
            $d = dir($directory);
            while($f = $d->read()) {
                $subPath = realpath($directory . DIRECTORY_SEPARATOR . $f);
                //echo "Looking in $subPath for $className{$this->classFileSuffix}
\n";
                if(is_dir($subPath)) {
                    // Found a subdirectory
                    if(!preg_match($this->excludeFolderNames, $f)) {
                        if($filePath = $this->searchForClassFile($className, $subPath . '/')) {
                            return $filePath;
                        }
                    }
                }
                else { // it's a file... so does the name match ?
                    if($f == $className . $this->classFileSuffix) {
                        return $subPath;
                    }
                }
            }
        }
        return false;
    }

    /**
     * Register this class with SPL as an autoloader.
     * @return void
     */
    public function register() {
        spl_autoload_register(array('Autoloader', 'loadClass'));
    }
}

There are a few ways it could be improved – e.g.

• The ability to pass in a callback or similar which calculates the class name (E.g. appending ‘.class.php’ or strtolower’ing it or whatever);
• The cache key stuff could just be worked out by md5(dirname(__FILE__)) or something… but nevermind.
• I’m not totally sure I like how it recursively trawls the filesystem – this makes it quite expensive to use if the class you are looking for doesn’t exist in the specified hierarchy.
• Finally, it has the obvious problem that Apache needs to be restarted if you change your file/directory structure.

From a performance point of view, one arbitrary page went from taking 180ms to load, to 65ms. That’s a good decrease from my point of view, and does almost seem noticeable.

The only problem is that I’ve seen a few APC Cache slam defence error messages, so I’m not sure if I’ll stick with APC or move to use something else (at least, I can easily inject a different cache into the class, thanks to Zend_Cache), but life is easier if the ‘default’ option works most of the time.

So, perhaps I’ll fix it to not do the recursive thing, and perhaps make the class name lookup part pluggable. Perhaps.

For one customer, we’re currently working on the next iteration of their code base – which incorporates a number of significant changes. When we inherited the code base from the previous developers we spent a long time patching various SQL Injection holes (casting to ints), moving over to use PDO’s prepared statements and trying to keep on top of the customer’s new functionality requests and support issues. There’s still a lot of horrible code to refactor, plenty of security holes (although none public facing) and we know we’re moving in the right direction – hopefully patching and duct tape will soon be a thing of the past as it will develop some form of architecture and look like someone has thought about design and long term maintenance.

I’ve started to properly do Test First Development – at least from a support perspective – as too often we’d find we would patch a bug, only for it to reappear again in a few weeks/months time. This has been especially useful with the SOAP interface the application exposes. The tests run every 5 minutes, and we all get emailed when stuff breaks – it took all of 30 minutes to setup and put in place – then it was just a case of actually writing the unit tests themselves (the tests take minutes to write; finding/fixing any bugs they pin point takes somewhat longer :-/ ). I’ve also abused Simpletest’s web testing ‘stuff’ to also act as an availability checker of the live site (i.e. hit a few remote URLs, and check that we don’t get error messages back and do see expected strings).

The original code base had no ‘model’ like layer (or MVC ‘compliance’) – files containing HTML, CSS, SQL, Javascript and PHP were the norm – we’ve added Propel to the project as the ‘model’ layer – which took a few hours; and then when reverse engineering the database we found a few oddities (tables without primary keys and so on) – anyway, moving the functionality from a handful of legacy objects across into the Propel ones seems to be well underway, and I for one will be glad to see the end of :

$x = new Foo(5);

Accompanied with code that does the equivalent of :

class Foo {

    public function __construct($id = false) {

        if($id != false) {

            // select * from foo where id = 5

            // populate $this; don't bother checking for the edge case where $id isn't valid

       }

       else {

           // insert into foo values ('');

          // populate $this->id; leaving all other fields as empty strings...

     }

     public function setBaz($nv) { // repeat for all table fields

         $this->baz = $nv;

         global $db;

         $db->query('update foo set baz = "' . $nv . '" where id = ' . $this->id);

     }

}

Finally, we have a meaningful directory structure – where some things aren’t exposed in the document root. Hopefully soon a front controller and some decent routing. At the moment a huge amount of code is just sat in the ‘public’ directory due to it’s nature. We hope to fix this in time, and move to using Zend Controller – once we get Smarty integrated with it.

Propel has added some nice new features since we last used it (effectively v1.2); it was a toss up between it and Doctrine (as obviously the ZF is moving in that direction) – but we already had knowledge/experience with Propel and it seemed the easier option.

I’m hoping that with time we’ll be able to get up to at least 60% test coverage of the code base – at that point we should be able to refactor the code far easier and with less fear. At the moment I doubt the unit tests cover more than 5-10% – although maybe it’s time I pointed xdebug or whatever at it to generate some meaningful stats.

My final task is to get some decent performance measurements out of the code base – so we can track any performance regressions. I’m fairly confident that moving to Propel will result in an speedup as duplicate object hydrations will be eliminated thanks to it’s instance pool, however having hard figures and nice graphs to point at would be ideal. So far I’ve knocked up my own script around ‘ab’ which stores some figures to a .csv file and uses ezComponents to generate a graph file. This seems to be a crap solution, but I can’t think or find anything better. Any suggestions dear Internet? Perhaps I should integrate changeset/revision id’s in my benchmarking too. Suggestions here would be exceedingly appreciated.

There, I should have ticked all necessary boxes wrt development practices now. Now to work on finding a contract PHP developer….