<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <[email protected]> //
// available at http://getid3.sourceforge.net //
// or http://www.getid3.org //
/////////////////////////////////////////////////////////////////
// //
// 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 = $getID3->analyze('file2.wv');
*
*
* Supported Cache Types
*
* SQL Databases: (use extension.cache.mysql)
*
* cache_type cache_options
* -------------------------------------------------------------------
* mysql host, database, username, password
*
*
* DBM-Style Databases: (this extension)
*
* cache_type cache_options
* -------------------------------------------------------------------
* gdbm dbm_filename, lock_filename
* ndbm dbm_filename, lock_filename
* db2 dbm_filename, lock_filename
* db3 dbm_filename, lock_filename
* db4 dbm_filename, lock_filename (PHP5 required)
*
* PHP must have write access to both dbm_filename and lock_filename.
*
*
* Recommended Cache Types
*
* Infrequent updates, many reads any DBM
* Frequent updates mysql
*/
class getID3_cached_dbm extends getID3
{
// public: constructor - see top of this file for cache type and cache_options
function getID3_cached_dbm($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_writeable($lock_filename)) {
throw new Exception('lock file: '.$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 = $dbm_filename;
// Register destructor
register_shutdown_function(array($this, '__destruct'));
// Check version number and clear cache if changed
if (dba_fetch(getID3::VERSION, $this->dba) != getID3::VERSION) {
$this->clear_cache();
}
parent::getID3();
}
// public: destuctor
function __destruct() {
// Close dbm file
dba_close($this->dba);
// Release exclusive lock
flock($this->lock, LOCK_UN);
// Close lock file
fclose($this->lock);
}
// public: clear cache
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, $this->dba);
// Re-register shutdown function
register_shutdown_function(array($this, '__destruct'));
}
// public: analyze file
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;
}
}
?>
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