source: trunk/www.guidonia.net/wp/wp-includes/cache.php@ 44

Last change on this file since 44 was 44, checked in by luciano, 15 years ago
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1<?php
2/**
3 * Object Cache API
4 *
5 * @link http://codex.wordpress.org/Function_Reference/WP_Cache
6 *
7 * @package WordPress
8 * @subpackage Cache
9 */
10
11/**
12 * Adds data to the cache, if the cache key doesn't aleady exist.
13 *
14 * @since 2.0.0
15 * @uses $wp_object_cache Object Cache Class
16 * @see WP_Object_Cache::add()
17 *
18 * @param int|string $key The cache ID to use for retrieval later
19 * @param mixed $data The data to add to the cache store
20 * @param string $flag The group to add the cache to
21 * @param int $expire When the cache data should be expired
22 * @return unknown
23 */
24function wp_cache_add($key, $data, $flag = '', $expire = 0) {
25 global $wp_object_cache;
26
27 return $wp_object_cache->add($key, $data, $flag, $expire);
28}
29
30/**
31 * Closes the cache.
32 *
33 * This function has ceased to do anything since WordPress 2.5. The
34 * functionality was removed along with the rest of the persistant cache. This
35 * does not mean that plugins can't implement this function when they need to
36 * make sure that the cache is cleaned up after WordPress no longer needs it.
37 *
38 * @since 2.0.0
39 *
40 * @return bool Always returns True
41 */
42function wp_cache_close() {
43 return true;
44}
45
46/**
47 * Removes the cache contents matching ID and flag.
48 *
49 * @since 2.0.0
50 * @uses $wp_object_cache Object Cache Class
51 * @see WP_Object_Cache::delete()
52 *
53 * @param int|string $id What the contents in the cache are called
54 * @param string $flag Where the cache contents are grouped
55 * @return bool True on successful removal, false on failure
56 */
57function wp_cache_delete($id, $flag = '') {
58 global $wp_object_cache;
59
60 return $wp_object_cache->delete($id, $flag);
61}
62
63/**
64 * Removes all cache items.
65 *
66 * @since 2.0.0
67 * @uses $wp_object_cache Object Cache Class
68 * @see WP_Object_Cache::flush()
69 *
70 * @return bool Always returns true
71 */
72function wp_cache_flush() {
73 global $wp_object_cache;
74
75 return $wp_object_cache->flush();
76}
77
78/**
79 * Retrieves the cache contents from the cache by ID and flag.
80 *
81 * @since 2.0.0
82 * @uses $wp_object_cache Object Cache Class
83 * @see WP_Object_Cache::get()
84 *
85 * @param int|string $id What the contents in the cache are called
86 * @param string $flag Where the cache contents are grouped
87 * @return bool|mixed False on failure to retrieve contents or the cache
88 * contents on success
89 */
90function wp_cache_get($id, $flag = '') {
91 global $wp_object_cache;
92
93 return $wp_object_cache->get($id, $flag);
94}
95
96/**
97 * Sets up Object Cache Global and assigns it.
98 *
99 * @since 2.0.0
100 * @global WP_Object_Cache $wp_object_cache WordPress Object Cache
101 */
102function wp_cache_init() {
103 $GLOBALS['wp_object_cache'] =& new WP_Object_Cache();
104}
105
106/**
107 * Replaces the contents of the cache with new data.
108 *
109 * @since 2.0.0
110 * @uses $wp_object_cache Object Cache Class
111 * @see WP_Object_Cache::replace()
112 *
113 * @param int|string $id What to call the contents in the cache
114 * @param mixed $data The contents to store in the cache
115 * @param string $flag Where to group the cache contents
116 * @param int $expire When to expire the cache contents
117 * @return bool False if cache ID and group already exists, true on success
118 */
119function wp_cache_replace($key, $data, $flag = '', $expire = 0) {
120 global $wp_object_cache;
121
122 return $wp_object_cache->replace($key, $data, $flag, $expire);
123}
124
125/**
126 * Saves the data to the cache.
127 *
128 * @since 2.0
129 * @uses $wp_object_cache Object Cache Class
130 * @see WP_Object_Cache::set()
131 *
132 * @param int|string $id What to call the contents in the cache
133 * @param mixed $data The contents to store in the cache
134 * @param string $flag Where to group the cache contents
135 * @param int $expire When to expire the cache contents
136 * @return bool False if cache ID and group already exists, true on success
137 */
138function wp_cache_set($key, $data, $flag = '', $expire = 0) {
139 global $wp_object_cache;
140
141 return $wp_object_cache->set($key, $data, $flag, $expire);
142}
143
144/**
145 * Adds a group or set of groups to the list of global groups.
146 *
147 * @since 2.6.0
148 *
149 * @param string|array $groups A group or an array of groups to add
150 */
151function wp_cache_add_global_groups( $groups ) {
152 // Default cache doesn't persist so nothing to do here.
153 return;
154}
155
156/**
157 * Adds a group or set of groups to the list of non-persistent groups.
158 *
159 * @since 2.6.0
160 *
161 * @param string|array $groups A group or an array of groups to add
162 */
163function wp_cache_add_non_persistent_groups( $groups ) {
164 // Default cache doesn't persist so nothing to do here.
165 return;
166}
167
168/**
169 * WordPress Object Cache
170 *
171 * The WordPress Object Cache is used to save on trips to the database. The
172 * Object Cache stores all of the cache data to memory and makes the cache
173 * contents available by using a key, which is used to name and later retrieve
174 * the cache contents.
175 *
176 * The Object Cache can be replaced by other caching mechanisms by placing files
177 * in the wp-content folder which is looked at in wp-settings. If that file
178 * exists, then this file will not be included.
179 *
180 * @package WordPress
181 * @subpackage Cache
182 * @since 2.0
183 */
184class WP_Object_Cache {
185
186 /**
187 * Holds the cached objects
188 *
189 * @var array
190 * @access private
191 * @since 2.0.0
192 */
193 var $cache = array ();
194
195 /**
196 * Cache objects that do not exist in the cache
197 *
198 * @var array
199 * @access private
200 * @since 2.0.0
201 */
202 var $non_existant_objects = array ();
203
204 /**
205 * The amount of times the cache data was already stored in the cache.
206 *
207 * @since 2.5.0
208 * @access private
209 * @var int
210 */
211 var $cache_hits = 0;
212
213 /**
214 * Amount of times the cache did not have the request in cache
215 *
216 * @var int
217 * @access public
218 * @since 2.0.0
219 */
220 var $cache_misses = 0;
221
222 /**
223 * Adds data to the cache if it doesn't already exist.
224 *
225 * @uses WP_Object_Cache::get Checks to see if the cache already has data.
226 * @uses WP_Object_Cache::set Sets the data after the checking the cache
227 * contents existance.
228 *
229 * @since 2.0.0
230 *
231 * @param int|string $id What to call the contents in the cache
232 * @param mixed $data The contents to store in the cache
233 * @param string $group Where to group the cache contents
234 * @param int $expire When to expire the cache contents
235 * @return bool False if cache ID and group already exists, true on success
236 */
237 function add($id, $data, $group = 'default', $expire = '') {
238 if (empty ($group))
239 $group = 'default';
240
241 if (false !== $this->get($id, $group, false))
242 return false;
243
244 return $this->set($id, $data, $group, $expire);
245 }
246
247 /**
248 * Remove the contents of the cache ID in the group
249 *
250 * If the cache ID does not exist in the group and $force parameter is set
251 * to false, then nothing will happen. The $force parameter is set to false
252 * by default.
253 *
254 * On success the group and the id will be added to the
255 * $non_existant_objects property in the class.
256 *
257 * @since 2.0.0
258 *
259 * @param int|string $id What the contents in the cache are called
260 * @param string $group Where the cache contents are grouped
261 * @param bool $force Optional. Whether to force the unsetting of the cache
262 * ID in the group
263 * @return bool False if the contents weren't deleted and true on success
264 */
265 function delete($id, $group = 'default', $force = false) {
266 if (empty ($group))
267 $group = 'default';
268
269 if (!$force && false === $this->get($id, $group, false))
270 return false;
271
272 unset ($this->cache[$group][$id]);
273 $this->non_existant_objects[$group][$id] = true;
274 return true;
275 }
276
277 /**
278 * Clears the object cache of all data
279 *
280 * @since 2.0.0
281 *
282 * @return bool Always returns true
283 */
284 function flush() {
285 $this->cache = array ();
286
287 return true;
288 }
289
290 /**
291 * Retrieves the cache contents, if it exists
292 *
293 * The contents will be first attempted to be retrieved by searching by the
294 * ID in the cache group. If the cache is hit (success) then the contents
295 * are returned.
296 *
297 * On failure, the $non_existant_objects property is checked and if the
298 * cache group and ID exist in there the cache misses will not be
299 * incremented. If not in the nonexistant objects property, then the cache
300 * misses will be incremented and the cache group and ID will be added to
301 * the nonexistant objects.
302 *
303 * @since 2.0.0
304 *
305 * @param int|string $id What the contents in the cache are called
306 * @param string $group Where the cache contents are grouped
307 * @return bool|mixed False on failure to retrieve contents or the cache
308 * contents on success
309 */
310 function get($id, $group = 'default') {
311 if (empty ($group))
312 $group = 'default';
313
314 if (isset ($this->cache[$group][$id])) {
315 $this->cache_hits += 1;
316 if ( is_object($this->cache[$group][$id]) )
317 return wp_clone($this->cache[$group][$id]);
318 else
319 return $this->cache[$group][$id];
320 }
321
322 if ( isset ($this->non_existant_objects[$group][$id]) )
323 return false;
324
325 $this->non_existant_objects[$group][$id] = true;
326 $this->cache_misses += 1;
327 return false;
328 }
329
330 /**
331 * Replace the contents in the cache, if contents already exist
332 *
333 * @since 2.0.0
334 * @see WP_Object_Cache::set()
335 *
336 * @param int|string $id What to call the contents in the cache
337 * @param mixed $data The contents to store in the cache
338 * @param string $group Where to group the cache contents
339 * @param int $expire When to expire the cache contents
340 * @return bool False if not exists, true if contents were replaced
341 */
342 function replace($id, $data, $group = 'default', $expire = '') {
343 if (empty ($group))
344 $group = 'default';
345
346 if (false === $this->get($id, $group, false))
347 return false;
348
349 return $this->set($id, $data, $group, $expire);
350 }
351
352 /**
353 * Sets the data contents into the cache
354 *
355 * The cache contents is grouped by the $group parameter followed by the
356 * $id. This allows for duplicate ids in unique groups. Therefore, naming of
357 * the group should be used with care and should follow normal function
358 * naming guidelines outside of core WordPress usage.
359 *
360 * The $expire parameter is not used, because the cache will automatically
361 * expire for each time a page is accessed and PHP finishes. The method is
362 * more for cache plugins which use files.
363 *
364 * @since 2.0.0
365 *
366 * @param int|string $id What to call the contents in the cache
367 * @param mixed $data The contents to store in the cache
368 * @param string $group Where to group the cache contents
369 * @param int $expire Not Used
370 * @return bool Always returns true
371 */
372 function set($id, $data, $group = 'default', $expire = '') {
373 if (empty ($group))
374 $group = 'default';
375
376 if (NULL === $data)
377 $data = '';
378
379 if ( is_object($data) )
380 $data = wp_clone($data);
381
382 $this->cache[$group][$id] = $data;
383
384 if(isset($this->non_existant_objects[$group][$id]))
385 unset ($this->non_existant_objects[$group][$id]);
386
387 return true;
388 }
389
390 /**
391 * Echos the stats of the caching.
392 *
393 * Gives the cache hits, and cache misses. Also prints every cached group,
394 * key and the data.
395 *
396 * @since 2.0.0
397 */
398 function stats() {
399 echo "<p>";
400 echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";
401 echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";
402 echo "</p>";
403
404 foreach ($this->cache as $group => $cache) {
405 echo "<p>";
406 echo "<strong>Group:</strong> $group<br />";
407 echo "<strong>Cache:</strong>";
408 echo "<pre>";
409 print_r($cache);
410 echo "</pre>";
411 }
412 }
413
414 /**
415 * PHP4 constructor; Calls PHP 5 style constructor
416 *
417 * @since 2.0.0
418 *
419 * @return WP_Object_Cache
420 */
421 function WP_Object_Cache() {
422 return $this->__construct();
423 }
424
425 /**
426 * Sets up object properties; PHP 5 style constructor
427 *
428 * @since 2.0.8
429 * @return null|WP_Object_Cache If cache is disabled, returns null.
430 */
431 function __construct() {
432 /**
433 * @todo This should be moved to the PHP4 style constructor, PHP5
434 * already calls __destruct()
435 */
436 register_shutdown_function(array(&$this, "__destruct"));
437 }
438
439 /**
440 * Will save the object cache before object is completely destroyed.
441 *
442 * Called upon object destruction, which should be when PHP ends.
443 *
444 * @since 2.0.8
445 *
446 * @return bool True value. Won't be used by PHP
447 */
448 function __destruct() {
449 return true;
450 }
451}
452?>
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