aboutsummaryrefslogtreecommitdiff
path: root/engine/lib/cache.php
blob: dcbb83ca6b79ac5715a22f7c87e657191ceca430 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
<?php
	/**
	 * Elgg cache
	 * Cache file interface for caching data.
	 * 
	 * @package Elgg
	 * @subpackage API
	 * @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
	 * @author Curverider Ltd <info@elgg.com>
	 * @copyright Curverider Ltd 2008
	 * @link http://elgg.org/
	 */

	/**
	 * ElggCache The elgg cache superclass.
	 * This defines the interface for a cache (wherever that cache is stored).
	 * 
	 * @author Curverider Ltd <info@elgg.com>
	 * @package Elgg
	 * @subpackage API
	 */
	abstract class ElggCache implements
		ArrayAccess // Override for array access
	{
		/**
		 * Variables for the cache object.
		 *
		 * @var array
		 */
		private $variables;
		
		/**
		 * Set the constructor.
		 */
		function __construct() { $this->variables = array(); }
		
		/**
		 * Set a cache variable.
		 *
		 * @param string $variable
		 * @param string $value
		 */
		public function set_variable($variable, $value) 
		{
			if (!is_array($this->variables))
				$this->variables = array();
			
			$this->variables[$variable] = $value;	
		}
		
		/**
		 * Get variables for this cache.
		 *
		 * @param string $variable
		 * @return mixed The variable or null;
		 */
		public function get_variable($variable) 
		{
			if (isset($this->variables[$variable]))
				return $this->variables[$variable];
				
			return null; 
		}
		
		/**
		 * Class member get overloading, returning key using $this->load defaults.
		 *
		 * @param string $key
		 * @return mixed
		 */
		function __get($key) { return $this->load($key); }
		
		/**
		 * Class member set overloading, setting a key using $this->save defaults.
		 *
		 * @param string $key
		 * @param mixed $value
		 * @return mixed
		 */
		function __set($key, $value) { return $this->save($key, $value); }
		
		/**
		 * Supporting isset, using $this->load() with default values.
		 *
		 * @param string $key The name of the attribute or metadata.
		 * @return bool
		 */
		function __isset($key) { if ($this->load($key)!="") return true; else return false; }
		
		/**
		 * Supporting unsetting of magic attributes.
		 *
		 * @param string $key The name of the attribute or metadata.
		 */
		function __unset($key) { return $this->delete($key); }
		
		/**
		 * Save data in a cache.
		 *
		 * @param string $key
		 * @param string $data
		 * @return bool
		 */
		abstract public function save($key, $data);
		
		/**
		 * Load data from the cache using a given key.
		 *
		 * @param string $key
		 * @param int $offset 
		 * @param int $limit
		 * @return mixed The stored data or false.
		 */
		abstract public function load($key, $offset = 0, $limit = null);
		
		/**
		 * Invalidate a key
		 *
		 * @param string $key
		 * @return bool
		 */
		abstract public function delete($key);
		
		/**
		 * Clear out all the contents of the cache.
		 *
		 */
		abstract public function clear();
		
		// ARRAY ACCESS INTERFACE //////////////////////////////////////////////////////////
		function offsetSet($key, $value)
		{
     		$this->save($key, $value);
 		} 
 		
 		function offsetGet($key) 
 		{
   			return $this->load($key);
 		} 
 		
 		function offsetUnset($key) 
 		{
   			if ( isset($this->key) ) {
     			unset($this->key);
   			}
 		} 
 		
 		function offsetExists($offset) 
 		{
   			return isset($this->$offset);
 		} 
	}
	
	/**
	 * ElggStaticVariableCache
	 * Dummy cache which stores values in a static array. Using this makes future replacements to other caching back 
	 * ends (eg memcache) much easier.
	 * 
	 * @author Curverider Ltd <info@elgg.com>
	 * @package Elgg
	 * @subpackage API
	 */
	class ElggStaticVariableCache extends ElggCache
	{
		/**
		 * The cache.
		 *
		 * @var unknown_type
		 */
		private static $__cache;
		
		/**
		 * ID of a cache to use.
		 *
		 * @var unknown_type
		 */
		private $cache_id;
		
		/**
		 * Create the variable cache.
		 * 
		 * This function creates a variable cache in a static variable in memory, optionally with a given namespace (to avoid overlap).
		 *
		 * @param string $cache_id The namespace for this cache to write to - note, namespaces of the same name are shared!
		 */
		function __construct($cache_id = 'default')
		{	
			$this->cache_id = $cache_id;
			$this->clear();
		}
		
		public function save($key, $data) 
		{
			ElggStaticVariableCache::$__cache[$this->cache_id][$key] = $data;
			
			return true;
		}
		
		public function load($key, $offset = 0, $limit = null)
		{
			if (isset(ElggStaticVariableCache::$__cache[$this->cache_id][$key]))
				return ElggStaticVariableCache::$__cache[$this->cache_id][$key];
				
			return false;
		}
		
		public function delete($key) 
		{
			unset(ElggStaticVariableCache::$__cache[$this->cache_id][$key]);
			
			return true;
		}
		
		public function clear()
		{
			if (!isset(ElggStaticVariableCache::$__cache))
				ElggStaticVariableCache::$__cache = array();
				
			if (!isset(ElggStaticVariableCache::$__cache[$this->cache_id]))
				ElggStaticVariableCache::$__cache[$this->cache_id] = array();
		}
	}
	
	/**
	 * ElggFileCache
	 * Store cached data in a file store.
	 * 
	 * @author Curverider Ltd <info@elgg.com>
	 * @package Elgg
	 * @subpackage API
	 */
	class ElggFileCache extends ElggCache
	{
		/**
		 * Set the Elgg cache.
		 *
		 * @param string $cache_path The cache path.
		 * @param int $max_age Maximum age in seconds, 0 if no limit.
		 * @param int $max_size Maximum size of cache in seconds, 0 if no limit.
		 */
		function __construct($cache_path, $max_age = 0, $max_size = 0)
		{
			$this->set_variable("cache_path", $cache_path);
			$this->set_variable("max_age", $max_age);
			$this->set_variable("max_size", $max_size);	

			if ($cache_path=="") throw new ConfigurationException(elgg_echo('ConfigurationException:NoCachePath'));
		}
		
		/**
		 * Create and return a handle to a file.
		 *
		 * @param string $filename
		 * @param string $rw
		 */
		protected function create_file($filename, $rw = "rb")
		{
			// Create a filename matrix
			$matrix = "";
			$depth = strlen($filename);
			if ($depth > 5) $depth = 5;
			 
		//	for ($n = 0; $n < $depth; $n++)
		//		$matrix .= $filename[$n] . "/";	
				
			// Create full path
			$path = $this->get_variable("cache_path") . $matrix;
			
	//		if (!mkdir($path, 0700, true)) throw new IOException("Could not make $path");
			
			// Open the file
			if ((!file_exists($path . $filename)) && ($rw=="rb")) return false;
			
			return fopen($path . $filename, $rw);
		}
		
		/**
		 * Create a sanitised filename for the file.
		 *
		 * @param string $filename
		 */
		protected function sanitise_filename($filename)
		{
			// TODO : Writeme

			return $filename;
		}
		
		/**
		 * Save a key
		 *
		 * @param string $key
		 * @param string $data
		 * @return boolean
		 */
		public function save($key, $data)
		{
			$f = $this->create_file($this->sanitise_filename($key), "wb");
			if ($f)
			{
				$result = fwrite($f, $data);
				fclose($f);
				
				return $result;
			}
			
			return false;
		}
		
		/**
		 * Load a key
		 *
		 * @param string $key
		 * @param int $offset
		 * @param int $limit
		 * @return string
		 */
		public function load($key, $offset = 0, $limit = null)
		{
			$f = $this->create_file($this->sanitise_filename($key));
			if ($f) 
			{
				fseek($f, $offset);
				$data = stream_get_contents($f, $limit, $offset);
				fclose($f);
				
				return $data;
			}
			
			return false;
		}
		
		/**
		 * Invalidate a given key.
		 *
		 * @param string $key
		 * @return bool
		 */
		public function delete($key)
		{
			$dir = $this->get_variable("cache_path");
			
			return unlink($dir.$f);
		}
		
		public function clear()
		{
			// TODO : writeme
		}
		
		public function __destruct()
		{
			// TODO: Check size and age, clean up accordingly
			$size = 0;
			$dir = $this->get_variable("cache_path");
			
			// Short circuit if both size and age are unlimited
			if (($this->get_variable("max_age")==0) && ($this->get_variable("max_size")==0))
				return;
			
			$exclude = array(".","..");
			
			$files = scandir($dir);
			if (!$files) throw new IOException(sprintf(elgg_echo('IOException:NotDirectory'), $dir));
			
			// Perform cleanup
			foreach ($files as $f)
			{
				if (!in_array($f, $exclude))
				{
					$stat = stat($dir.$f);
					
					// Add size
					$size .= $stat['size'];
					
					// Is this older than my maximum date?
					if (($this->get_variable("max_age")>0) && (time() - $stat['mtime'] > $this->get_variable("max_age")))
						unlink($dir.$f);
					
					
					
					// TODO: Size
					
				}
			}
		}
	}
	
	
	/**
	 * A simple function that selects the default caching engine. 
	 * 
	 * This function provides a central way to get a cache for storing local variables.
	 * 
	 * TODO: Do this better & allow plugin overrides.
	 *
	 * @param string $namespace Define which memory space to use.
	 */
	function select_default_memcache($namespace = "default")
	{
		// hook out to the world ? (can't if using as object cache)
		
		// if nothing then use shared memory cache.
		
		// TODO: Use memcache if available?
		
		return new ElggStaticVariableCache($namespace);
		
	}
?>