1<?php
2
3/////////////////////////////////////////////////////////////////
4/// getID3() by James Heinrich <info@getid3.org>               //
5//  available at https://github.com/JamesHeinrich/getID3       //
6//            or https://www.getid3.org                        //
7//            or http://getid3.sourceforge.net                 //
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
73class getID3_cached_dbm extends getID3
74{
75	/**
76	 * @var resource
77	 */
78	private $dba;
79
80	/**
81	 * @var resource|bool
82	 */
83	private $lock;
84
85	/**
86	 * @var string
87	 */
88	private $cache_type;
89
90	/**
91	 * @var string
92	 */
93	private $dbm_filename;
94
95	/**
96	 * constructor - see top of this file for cache type and cache_options
97	 *
98	 * @param string $cache_type
99	 * @param string $dbm_filename
100	 * @param string $lock_filename
101	 *
102	 * @throws Exception
103	 * @throws getid3_exception
104	 */
105	public function __construct($cache_type, $dbm_filename, $lock_filename) {
106
107		// Check for dba extension
108		if (!extension_loaded('dba')) {
109			throw new Exception('PHP is not compiled with dba support, required to use DBM style cache.');
110		}
111
112		// Check for specific dba driver
113		if (!function_exists('dba_handlers') || !in_array($cache_type, dba_handlers())) {
114			throw new Exception('PHP is not compiled --with '.$cache_type.' support, required to use DBM style cache.');
115		}
116
117		// Create lock file if needed
118		if (!file_exists($lock_filename)) {
119			if (!touch($lock_filename)) {
120				throw new Exception('failed to create lock file: '.$lock_filename);
121			}
122		}
123
124		// Open lock file for writing
125		if (!is_writeable($lock_filename)) {
126			throw new Exception('lock file: '.$lock_filename.' is not writable');
127		}
128		$this->lock = fopen($lock_filename, 'w');
129
130		// Acquire exclusive write lock to lock file
131		flock($this->lock, LOCK_EX);
132
133		// Create dbm-file if needed
134		if (!file_exists($dbm_filename)) {
135			if (!touch($dbm_filename)) {
136				throw new Exception('failed to create dbm file: '.$dbm_filename);
137			}
138		}
139
140		// Try to open dbm file for writing
141		$this->dba = dba_open($dbm_filename, 'w', $cache_type);
142		if (!$this->dba) {
143
144			// Failed - create new dbm file
145			$this->dba = dba_open($dbm_filename, 'n', $cache_type);
146
147			if (!$this->dba) {
148				throw new Exception('failed to create dbm file: '.$dbm_filename);
149			}
150
151			// Insert getID3 version number
152			dba_insert(getID3::VERSION, getID3::VERSION, $this->dba);
153		}
154
155		// Init misc values
156		$this->cache_type   = $cache_type;
157		$this->dbm_filename = $dbm_filename;
158
159		// Register destructor
160		register_shutdown_function(array($this, '__destruct'));
161
162		// Check version number and clear cache if changed
163		if (dba_fetch(getID3::VERSION, $this->dba) != getID3::VERSION) {
164			$this->clear_cache();
165		}
166
167		parent::__construct();
168	}
169
170
171
172	/**
173	 * destructor
174	 */
175	public function __destruct() {
176
177		// Close dbm file
178		dba_close($this->dba);
179
180		// Release exclusive lock
181		flock($this->lock, LOCK_UN);
182
183		// Close lock file
184		fclose($this->lock);
185	}
186
187
188
189	/**
190	 * clear cache
191	 *
192	 * @throws Exception
193	 */
194	public function clear_cache() {
195
196		// Close dbm file
197		dba_close($this->dba);
198
199		// Create new dbm file
200		$this->dba = dba_open($this->dbm_filename, 'n', $this->cache_type);
201
202		if (!$this->dba) {
203			throw new Exception('failed to clear cache/recreate dbm file: '.$this->dbm_filename);
204		}
205
206		// Insert getID3 version number
207		dba_insert(getID3::VERSION, getID3::VERSION, $this->dba);
208
209		// Re-register shutdown function
210		register_shutdown_function(array($this, '__destruct'));
211	}
212
213
214
215	/**
216	 * clear cache
217	 *
218	 * @param string   $filename
219	 * @param int      $filesize
220	 * @param string   $original_filename
221	 * @param resource $fp
222	 *
223	 * @return mixed
224	 */
225	public function analyze($filename, $filesize=null, $original_filename='', $fp=null) {
226
227		if (file_exists($filename)) {
228
229			// Calc key     filename::mod_time::size    - should be unique
230			$key = $filename.'::'.filemtime($filename).'::'.filesize($filename);
231
232			// Loopup key
233			$result = dba_fetch($key, $this->dba);
234
235			// Hit
236			if ($result !== false) {
237				return unserialize($result);
238			}
239		}
240
241		// Miss
242		$result = parent::analyze($filename, $filesize, $original_filename, $fp);
243
244		// Save result
245		if (isset($key) && file_exists($filename)) {
246			dba_insert($key, serialize($result), $this->dba);
247		}
248
249		return $result;
250	}
251
252}
253