vendor/james-heinrich/getid3/getid3/extension.cache.dbm.php

   1 <?php
   2 /////////////////////////////////////////////////////////////////
   3 /// getID3() by James Heinrich <info@getid3.org>               //
   4 //  available at http://getid3.sourceforge.net                 //
   5 //            or http://www.getid3.org                         //
   6 //          also https://github.com/JamesHeinrich/getID3       //
   7 /////////////////////////////////////////////////////////////////
   8 //                                                             //
   9 // extension.cache.dbm.php - part of getID3()                  //
  10 // Please see readme.txt for more information                  //
  11 //                                                            ///
  12 /////////////////////////////////////////////////////////////////
  13 //                                                             //
  14 // This extension written by Allan Hansen <ahØartemis*dk>      //
  15 //                                                            ///
  16 /////////////////////////////////////////////////////////////////
  17
  18
  19 /**
  20 * This is a caching extension for getID3(). It works the exact same
  21 * way as the getID3 class, but return cached information very fast
  22 *
  23 * Example:
  24 *
  25 *    Normal getID3 usage (example):
  26 *
  27 *       require_once 'getid3/getid3.php';
  28 *       $getID3 = new getID3;
  29 *       $getID3->encoding = 'UTF-8';
  30 *       $info1 = $getID3->analyze('file1.flac');
  31 *       $info2 = $getID3->analyze('file2.wv');
  32 *
  33 *    getID3_cached usage:
  34 *
  35 *       require_once 'getid3/getid3.php';
  36 *       require_once 'getid3/getid3/extension.cache.dbm.php';
  37 *       $getID3 = new getID3_cached('db3', '/tmp/getid3_cache.dbm',
  38 *                                          '/tmp/getid3_cache.lock');
  39 *       $getID3->encoding = 'UTF-8';
  40 *       $info1 = $getID3->analyze('file1.flac');
  41 *       $info2 = $getID3->analyze('file2.wv');
  42 *
  43 *
  44 * Supported Cache Types
  45 *
  46 *   SQL Databases:          (use extension.cache.mysql)
  47 *
  48 *   cache_type          cache_options
  49 *   -------------------------------------------------------------------
  50 *   mysql               host, database, username, password
  51 *
  52 *
  53 *   DBM-Style Databases:    (this extension)
  54 *
  55 *   cache_type          cache_options
  56 *   -------------------------------------------------------------------
  57 *   gdbm                dbm_filename, lock_filename
  58 *   ndbm                dbm_filename, lock_filename
  59 *   db2                 dbm_filename, lock_filename
  60 *   db3                 dbm_filename, lock_filename
  61 *   db4                 dbm_filename, lock_filename  (PHP5 required)
  62 *
  63 *   PHP must have write access to both dbm_filename and lock_filename.
  64 *
  65 *
  66 * Recommended Cache Types
  67 *
  68 *   Infrequent updates, many reads      any DBM
  69 *   Frequent updates                    mysql
  70 */
  71
  72
  73 class getID3_cached_dbm extends getID3
  74 {
  75
  76         // public: constructor - see top of this file for cache type and cache_options
  77         public function __construct($cache_type, $dbm_filename, $lock_filename) {
  78
  79                 // Check for dba extension
  80                 if (!extension_loaded('dba')) {
  81                         throw new Exception('PHP is not compiled with dba support, required to use DBM style cache.');
  82                 }
  83
  84                 // Check for specific dba driver
  85                 if (!function_exists('dba_handlers') || !in_array($cache_type, dba_handlers())) {
  86                         throw new Exception('PHP is not compiled --with '.$cache_type.' support, required to use DBM style cache.');
  87                 }
  88
  89                 // Create lock file if needed
  90                 if (!file_exists($lock_filename)) {
  91                         if (!touch($lock_filename)) {
  92                                 throw new Exception('failed to create lock file: '.$lock_filename);
  93                         }
  94                 }
  95
  96                 // Open lock file for writing
  97                 if (!is_writeable($lock_filename)) {
  98                         throw new Exception('lock file: '.$lock_filename.' is not writable');
  99                 }
 100                 $this->lock = fopen($lock_filename, 'w');
 101
 102                 // Acquire exclusive write lock to lock file
 103                 flock($this->lock, LOCK_EX);
 104
 105                 // Create dbm-file if needed
 106                 if (!file_exists($dbm_filename)) {
 107                         if (!touch($dbm_filename)) {
 108                                 throw new Exception('failed to create dbm file: '.$dbm_filename);
 109                         }
 110                 }
 111
 112                 // Try to open dbm file for writing
 113                 $this->dba = dba_open($dbm_filename, 'w', $cache_type);
 114                 if (!$this->dba) {
 115
 116                         // Failed - create new dbm file
 117                         $this->dba = dba_open($dbm_filename, 'n', $cache_type);
 118
 119                         if (!$this->dba) {
 120                                 throw new Exception('failed to create dbm file: '.$dbm_filename);
 121                         }
 122
 123                         // Insert getID3 version number
 124                         dba_insert(getID3::VERSION, getID3::VERSION, $this->dba);
 125                 }
 126
 127                 // Init misc values
 128                 $this->cache_type   = $cache_type;
 129                 $this->dbm_filename = $dbm_filename;
 130
 131                 // Register destructor
 132                 register_shutdown_function(array($this, '__destruct'));
 133
 134                 // Check version number and clear cache if changed
 135                 if (dba_fetch(getID3::VERSION, $this->dba) != getID3::VERSION) {
 136                         $this->clear_cache();
 137                 }
 138
 139                 parent::__construct();
 140         }
 141
 142
 143
 144         // public: destructor
 145         public function __destruct() {
 146
 147                 // Close dbm file
 148                 dba_close($this->dba);
 149
 150                 // Release exclusive lock
 151                 flock($this->lock, LOCK_UN);
 152
 153                 // Close lock file
 154                 fclose($this->lock);
 155         }
 156
 157
 158
 159         // public: clear cache
 160         public function clear_cache() {
 161
 162                 // Close dbm file
 163                 dba_close($this->dba);
 164
 165                 // Create new dbm file
 166                 $this->dba = dba_open($this->dbm_filename, 'n', $this->cache_type);
 167
 168                 if (!$this->dba) {
 169                         throw new Exception('failed to clear cache/recreate dbm file: '.$this->dbm_filename);
 170                 }
 171
 172                 // Insert getID3 version number
 173                 dba_insert(getID3::VERSION, getID3::VERSION, $this->dba);
 174
 175                 // Re-register shutdown function
 176                 register_shutdown_function(array($this, '__destruct'));
 177         }
 178
 179
 180
 181         // public: analyze file
 182         public function analyze($filename) {
 183
 184                 if (file_exists($filename)) {
 185
 186                         // Calc key     filename::mod_time::size    - should be unique
 187                         $key = $filename.'::'.filemtime($filename).'::'.filesize($filename);
 188
 189                         // Loopup key
 190                         $result = dba_fetch($key, $this->dba);
 191
 192                         // Hit
 193                         if ($result !== false) {
 194                                 return unserialize($result);
 195                         }
 196                 }
 197
 198                 // Miss
 199                 $result = parent::analyze($filename);
 200
 201                 // Save result
 202                 if (file_exists($filename)) {
 203                         dba_insert($key, serialize($result), $this->dba);
 204                 }
 205
 206                 return $result;
 207         }
 208
 209 }