Pony.fm/app/Library/getid3/getid3/extension.cache.dbm.php

<?php

/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <info@getid3.org>               //
//  available at http://getid3.sourceforge.net                 //
//            or http://www.getid3.org                         //
//          also https://github.com/JamesHeinrich/getID3       //
/////////////////////////////////////////////////////////////////
//                                                             //
// extension.cache.dbm.php - part of getID3()                  //
// Please see readme.txt for more information                  //
//                                                            ///
/////////////////////////////////////////////////////////////////
//                                                             //
// This extension written by Allan Hansen <ahØartemis*dk>      //
//                                                            ///
/////////////////////////////////////////////////////////////////

/**
 * This is a caching extension for getID3(). It works the exact same
 * way as the getID3 class, but return cached information very fast.
 *
 * Example:
 *
 *    Normal getID3 usage (example):
 *
 *       require_once 'getid3/getid3.php';
 *       $getID3 = new getID3;
 *       $getID3->encoding = 'UTF-8';
 *       $info1 = $getID3->analyze('file1.flac');
 *       $info2 = $getID3->analyze('file2.wv');
 *
 *    getID3_cached usage:
 *
 *       require_once 'getid3/getid3.php';
 *       require_once 'getid3/getid3/extension.cache.dbm.php';
 *       $getID3 = new getID3_cached('db3', '/tmp/getid3_cache.dbm',
 *                                          '/tmp/getid3_cache.lock');
 *       $getID3->encoding = 'UTF-8';
 *       $info1 = $getID3->analyze('file1.flac');
 *       $info2 = $getID3->analyze('file2.wv');
 *
 *
 * Supported Cache Types
 *
 *   SQL Databases:          (use extension.cache.mysql)
 *
 *   cache_type          cache_options
 *   -------------------------------------------------------------------
 *   mysql               host, database, username, password
 *
 *
 *   DBM-Style Databases:    (this extension)
 *
 *   cache_type          cache_options
 *   -------------------------------------------------------------------
 *   gdbm                dbm_filename, lock_filename
 *   ndbm                dbm_filename, lock_filename
 *   db2                 dbm_filename, lock_filename
 *   db3                 dbm_filename, lock_filename
 *   db4                 dbm_filename, lock_filename  (PHP5 required)
 *
 *   PHP must have write access to both dbm_filename and lock_filename.
 *
 *
 * Recommended Cache Types
 *
 *   Infrequent updates, many reads      any DBM
 *   Frequent updates                    mysql
 */
class getID3_cached_dbm extends getID3
{
    // public: constructor - see top of this file for cache type and cache_options
    public function __construct($cache_type, $dbm_filename, $lock_filename)
    {

        // Check for dba extension
        if (! extension_loaded('dba')) {
            throw new Exception('PHP is not compiled with dba support, required to use DBM style cache.');
        }

        // Check for specific dba driver
        if (! function_exists('dba_handlers') || ! in_array($cache_type, dba_handlers())) {
            throw new Exception('PHP is not compiled --with '.$cache_type.' support, required to use DBM style cache.');
        }

        // Create lock file if needed
        if (! file_exists($lock_filename)) {
            if (! touch($lock_filename)) {
                throw new Exception('failed to create lock file: '.$lock_filename);
            }
        }

        // Open lock file for writing
        if (! is_writable($lock_filename)) {
            throw new Exception('lock file: '.$lock_filename.' is not writable');
        }
        $this->lock = fopen($lock_filename, 'w');

        // Acquire exclusive write lock to lock file
        flock($this->lock, LOCK_EX);

        // Create dbm-file if needed
        if (! file_exists($dbm_filename)) {
            if (! touch($dbm_filename)) {
                throw new Exception('failed to create dbm file: '.$dbm_filename);
            }
        }

        // Try to open dbm file for writing
        $this->dba = dba_open($dbm_filename, 'w', $cache_type);
        if (! $this->dba) {

            // Failed - create new dbm file
            $this->dba = dba_open($dbm_filename, 'n', $cache_type);

            if (! $this->dba) {
                throw new Exception('failed to create dbm file: '.$dbm_filename);
            }

            // Insert getID3 version number
            dba_insert(getID3::VERSION, getID3::VERSION, $this->dba);
        }

        // Init misc values
        $this->cache_type = $cache_type;
        $this->dbm_filename = $dbm_filename;

        // Register destructor
        register_shutdown_function([$this, '__destruct']);

        // Check version number and clear cache if changed
        if (dba_fetch(getID3::VERSION, $this->dba) != getID3::VERSION) {
            $this->clear_cache();
        }

        parent::__construct();
    }

    // public: destructor
    public function __destruct()
    {

        // Close dbm file
        dba_close($this->dba);

        // Release exclusive lock
        flock($this->lock, LOCK_UN);

        // Close lock file
        fclose($this->lock);
    }

    // public: clear cache
    public function clear_cache()
    {

        // Close dbm file
        dba_close($this->dba);

        // Create new dbm file
        $this->dba = dba_open($this->dbm_filename, 'n', $this->cache_type);

        if (! $this->dba) {
            throw new Exception('failed to clear cache/recreate dbm file: '.$this->dbm_filename);
        }

        // Insert getID3 version number
        dba_insert(getID3::VERSION, getID3::VERSION, $this->dba);

        // Re-register shutdown function
        register_shutdown_function([$this, '__destruct']);
    }

    // public: analyze file
    public function analyze($filename)
    {
        if (file_exists($filename)) {

            // Calc key     filename::mod_time::size    - should be unique
            $key = $filename.'::'.filemtime($filename).'::'.filesize($filename);

            // Loopup key
            $result = dba_fetch($key, $this->dba);

            // Hit
            if ($result !== false) {
                return unserialize($result);
            }
        }

        // Miss
        $result = parent::analyze($filename);

        // Save result
        if (file_exists($filename)) {
            dba_insert($key, serialize($result), $this->dba);
        }

        return $result;
    }
}