| 1 | <?php |
| 2 | // $Id: cache.inc,v 1.38 2009/07/01 12:47:30 dries Exp $ |
| 3 | |
| 4 | /** |
| 5 | * Get the cache object for a cache bin. |
| 6 | * |
| 7 | * By default, this returns an instance of the DrupalDatabaseCache class. |
| 8 | * Classes implementing DrupalCacheInterface can register themselves both as a |
| 9 | * default implementation and for specific bins. |
| 10 | * |
| 11 | * @see DrupalCacheInterface |
| 12 | * |
| 13 | * @param $bin |
| 14 | * The cache bin for which the cache object should be returned. |
| 15 | */ |
| 16 | function _cache_get_object($bin) { |
| 17 | // We do not use drupal_static() here because we do not want to change the |
| 18 | // storage of a cache bin mid-request. |
| 19 | static $cache_objects, $default_class; |
| 20 | if (!isset($cache_objects[$bin])) { |
| 21 | $class = variable_get($bin, FALSE); |
| 22 | if (empty($class)) { |
| 23 | $class = variable_get('cache_default_class', 'DrupalDatabaseCache'); |
| 24 | } |
| 25 | $cache_objects[$bin] = new $class($bin); |
| 26 | } |
| 27 | return $cache_objects[$bin]; |
| 28 | } |
| 29 | |
| 30 | /** |
| 31 | * Return data from the persistent cache. Data may be stored as either plain |
| 32 | * text or as serialized data. cache_get will automatically return |
| 33 | * unserialized objects and arrays. |
| 34 | * |
| 35 | * @param $cid |
| 36 | * The cache ID of the data to retrieve. |
| 37 | * @param $bin |
| 38 | * The cache bin to store the data in. Valid core values are 'cache_block', |
| 39 | * 'cache_field', 'cache_filter', 'cache_form', 'cache_menu', 'cache_page', |
| 40 | * 'cache_path', 'cache_registry', 'cache_update' or 'cache' for the default |
| 41 | * cache. |
| 42 | * @return The cache or FALSE on failure. |
| 43 | */ |
| 44 | function cache_get($cid, $bin = 'cache') { |
| 45 | return _cache_get_object($bin)->get($cid); |
| 46 | } |
| 47 | |
| 48 | /** |
| 49 | * Return data from the persistent cache when given an array of cache IDs. |
| 50 | * |
| 51 | * @param $cids |
| 52 | * An array of cache IDs for the data to retrieve. This is passed by |
| 53 | * reference, and will have the IDs successfully returned from cache removed. |
| 54 | * @param $bin |
| 55 | * The cache bin where the data is stored. |
| 56 | * @return |
| 57 | * An array of the items successfully returned from cache indexed by cid. |
| 58 | */ |
| 59 | function cache_get_multiple(array &$cids, $bin = 'cache') { |
| 60 | return _cache_get_object($bin)->getMultiple($cids); |
| 61 | } |
| 62 | |
| 63 | /** |
| 64 | * Store data in the persistent cache. |
| 65 | * |
| 66 | * The persistent cache is split up into several cache bins. In the default |
| 67 | * cache implementation, each cache bin corresponds to a database table by the |
| 68 | * same name. Other implementations might want to store several bins in data |
| 69 | * structures that get flushed together. While it is not a problem for most |
| 70 | * cache bins if the entries in them are flushed before their expire time, some |
| 71 | * might break functionality or are extremely expensive to recalculate. These |
| 72 | * will be marked with a (*). The other bins expired automatically by core. |
| 73 | * Contributed modules can add additional bins and get them expired |
| 74 | * automatically by implementing hook_flush_caches(). |
| 75 | * |
| 76 | * - cache: Generic cache storage bin (used for variables, theme registry, |
| 77 | * locale date, list of simpletest tests etc). |
| 78 | * |
| 79 | * - cache_block: Stores the content of various blocks. |
| 80 | * |
| 81 | * - cache field: Stores the field data belonging to a given object. |
| 82 | * |
| 83 | * - cache_filter: Stores filtered pieces of content. |
| 84 | * |
| 85 | * - cache_form(*): Stores multistep forms. Flushing this bin means that some |
| 86 | * forms displayed to users lose their state and the data already submitted |
| 87 | * to them. |
| 88 | * |
| 89 | * - cache_menu: Stores the structure of visible navigation menus per page. |
| 90 | * |
| 91 | * - cache_page: Stores generated pages for anonymous users. It is flushed |
| 92 | * very often, whenever a page changes, at least for every ode and comment |
| 93 | * submission. This is the only bin affected by the page cache setting on |
| 94 | * the administrator panel. |
| 95 | * |
| 96 | * - cache path: Stores the system paths that have an alias. |
| 97 | * |
| 98 | * - cache update(*): Stores available releases. The update server (for |
| 99 | * example, drupal.org) needs to produce the relevant XML for every project |
| 100 | * installed on the current site. As this is different for (almost) every |
| 101 | * site, it's very expensive to recalculate for the update server. |
| 102 | * |
| 103 | * The reasons for having several bins are as follows: |
| 104 | * |
| 105 | * - smaller bins mean smaller database tables and allow for faster selects and |
| 106 | * inserts |
| 107 | * - we try to put fast changing cache items and rather static ones into different |
| 108 | * bins. The effect is that only the fast changing bins will need a lot of |
| 109 | * writes to disk. The more static bins will also be better cacheable with |
| 110 | * MySQL's query cache. |
| 111 | * |
| 112 | * @param $cid |
| 113 | * The cache ID of the data to store. |
| 114 | * @param $data |
| 115 | * The data to store in the cache. Complex data types will be automatically |
| 116 | * serialized before insertion. |
| 117 | * Strings will be stored as plain text and not serialized. |
| 118 | * @param $bin |
| 119 | * The cache bin to store the data in. Valid core values are 'cache_block', |
| 120 | * 'cache_field', 'cache_filter', 'cache_form', 'cache_menu', 'cache_page', |
| 121 | * 'cache_path', 'cache_registry', 'cache_update' or 'cache' for the default |
| 122 | * cache. |
| 123 | * @param $expire |
| 124 | * One of the following values: |
| 125 | * - CACHE_PERMANENT: Indicates that the item should never be removed unless |
| 126 | * explicitly told to using cache_clear_all() with a cache ID. |
| 127 | * - CACHE_TEMPORARY: Indicates that the item should be removed at the next |
| 128 | * general cache wipe. |
| 129 | * - A Unix timestamp: Indicates that the item should be kept at least until |
| 130 | * the given time, after which it behaves like CACHE_TEMPORARY. |
| 131 | * @param $headers |
| 132 | * A string containing HTTP header information for cached pages. |
| 133 | */ |
| 134 | function cache_set($cid, $data, $bin = 'cache', $expire = CACHE_PERMANENT, array $headers = NULL) { |
| 135 | return _cache_get_object($bin)->set($cid, $data, $expire, $headers); |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * Expire data from the cache. |
| 140 | * |
| 141 | * If called without arguments, expirable entries will be cleared from the |
| 142 | * cache_page and cache_block bins. |
| 143 | * |
| 144 | * @param $cid |
| 145 | * If set, the cache ID to delete. Otherwise, all cache entries that can |
| 146 | * expire are deleted. |
| 147 | * |
| 148 | * @param $bin |
| 149 | * If set, the bin $bin to delete from. Mandatory |
| 150 | * argument if $cid is set. |
| 151 | * |
| 152 | * @param $wildcard |
| 153 | * If $wildcard is TRUE, cache IDs starting with $cid are deleted in |
| 154 | * addition to the exact cache ID specified by $cid. If $wildcard is |
| 155 | * TRUE and $cid is '*' then the entire table $table is emptied. |
| 156 | */ |
| 157 | function cache_clear_all($cid = NULL, $bin = NULL, $wildcard = FALSE) { |
| 158 | if (!isset($cid) && !isset($bin)) { |
| 159 | // Clear the block cache first, so stale data will |
| 160 | // not end up in the page cache. |
| 161 | if (module_exists('block')) { |
| 162 | cache_clear_all(NULL, 'cache_block'); |
| 163 | } |
| 164 | cache_clear_all(NULL, 'cache_page'); |
| 165 | return; |
| 166 | } |
| 167 | return _cache_get_object($bin)->clear($cid, $wildcard); |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * Interface for cache implementations. |
| 172 | * |
| 173 | * All cache implementations have to implement this interface. DrupalDatabaseCache |
| 174 | * provides the default implementation, which can be consulted as an example. |
| 175 | * |
| 176 | * To make Drupal use your implementation for a certain cache bin, you have to |
| 177 | * set a variable with the name of the cache bin as its key and the name of your |
| 178 | * class as its value. For example, if your implementation of DrupalCacheInterface |
| 179 | * was called MyCustomCache, the following line would make Drupal use it for the |
| 180 | * 'cache_page' bin: |
| 181 | * @code |
| 182 | * variable_set('cache_page', 'MyCustomCache'); |
| 183 | * @endcode |
| 184 | * |
| 185 | * Additionally, you can register your cache implementation to be used by default |
| 186 | * for all cache bins by setting the variable 'cache_default_class' to the name |
| 187 | * of your implementation of the DrupalCacheInterface, e.g. |
| 188 | * @code |
| 189 | * variable_set('cache_default_class', 'MyCustomCache'); |
| 190 | * @endcode |
| 191 | * |
| 192 | * @see _cache_get_object() |
| 193 | * @see DrupalDatabaseCache |
| 194 | */ |
| 195 | interface DrupalCacheInterface { |
| 196 | /** |
| 197 | * Constructor. |
| 198 | * |
| 199 | * @param $bin |
| 200 | * The cache bin for which the object is created. |
| 201 | */ |
| 202 | function __construct($bin); |
| 203 | |
| 204 | /** |
| 205 | * Return data from the persistent cache. Data may be stored as either plain |
| 206 | * text or as serialized data. cache_get will automatically return |
| 207 | * unserialized objects and arrays. |
| 208 | * |
| 209 | * @param $cid |
| 210 | * The cache ID of the data to retrieve. |
| 211 | * @return The cache or FALSE on failure. |
| 212 | */ |
| 213 | function get($cid); |
| 214 | |
| 215 | /** |
| 216 | * Return data from the persistent cache when given an array of cache IDs. |
| 217 | * |
| 218 | * @param $cids |
| 219 | * An array of cache IDs for the data to retrieve. This is passed by |
| 220 | * reference, and will have the IDs successfully returned from cache |
| 221 | * removed. |
| 222 | * @return |
| 223 | * An array of the items successfully returned from cache indexed by cid. |
| 224 | */ |
| 225 | function getMultiple(&$cids); |
| 226 | |
| 227 | /** |
| 228 | * Store data in the persistent cache. |
| 229 | * |
| 230 | * @param $cid |
| 231 | * The cache ID of the data to store. |
| 232 | * @param $data |
| 233 | * The data to store in the cache. Complex data types will be automatically |
| 234 | * serialized before insertion. |
| 235 | * Strings will be stored as plain text and not serialized. |
| 236 | * @param $expire |
| 237 | * One of the following values: |
| 238 | * - CACHE_PERMANENT: Indicates that the item should never be removed unless |
| 239 | * explicitly told to using cache_clear_all() with a cache ID. |
| 240 | * - CACHE_TEMPORARY: Indicates that the item should be removed at the next |
| 241 | * general cache wipe. |
| 242 | * - A Unix timestamp: Indicates that the item should be kept at least until |
| 243 | * the given time, after which it behaves like CACHE_TEMPORARY. |
| 244 | * @param $headers |
| 245 | * A string containing HTTP header information for cached pages. |
| 246 | */ |
| 247 | function set($cid, $data, $expire = CACHE_PERMANENT, array $headers = NULL); |
| 248 | |
| 249 | |
| 250 | /** |
| 251 | * Expire data from the cache. If called without arguments, expirable |
| 252 | * entries will be cleared from the cache_page and cache_block bins. |
| 253 | * |
| 254 | * @param $cid |
| 255 | * If set, the cache ID to delete. Otherwise, all cache entries that can |
| 256 | * expire are deleted. |
| 257 | * @param $wildcard |
| 258 | * If set to TRUE, the $cid is treated as a substring |
| 259 | * to match rather than a complete ID. The match is a right hand |
| 260 | * match. If '*' is given as $cid, the bin $bin will be emptied. |
| 261 | */ |
| 262 | function clear($cid = NULL, $wildcard = FALSE); |
| 263 | } |
| 264 | |
| 265 | /** |
| 266 | * Default cache implementation. |
| 267 | * |
| 268 | * This is Drupal's default cache implementation. It uses the database to store |
| 269 | * cached data. Each cache bin corresponds to a database table by the same name. |
| 270 | */ |
| 271 | class DrupalDatabaseCache implements DrupalCacheInterface { |
| 272 | protected $bin; |
| 273 | |
| 274 | function __construct($bin) { |
| 275 | $this->bin = $bin; |
| 276 | } |
| 277 | |
| 278 | function get($cid) { |
| 279 | // Garbage collection necessary when enforcing a minimum cache lifetime. |
| 280 | $this->garbageCollection($this->bin); |
| 281 | $cache = db_query("SELECT data, created, headers, expire, serialized FROM {" . $this->bin . "} WHERE cid = :cid", array(':cid' => $cid))->fetchObject(); |
| 282 | |
| 283 | return $this->prepareItem($cache); |
| 284 | } |
| 285 | |
| 286 | function getMultiple(&$cids) { |
| 287 | // Garbage collection necessary when enforcing a minimum cache lifetime. |
| 288 | $this->garbageCollection($this->bin); |
| 289 | $query = db_select($this->bin); |
| 290 | $query->fields($this->bin, array('cid', 'data', 'created', 'headers', 'expire', 'serialized')); |
| 291 | $query->condition($this->bin . '.cid', $cids, 'IN'); |
| 292 | $result = $query->execute(); |
| 293 | $cache = array(); |
| 294 | foreach ($result as $item) { |
| 295 | $item = $this->prepareItem($item); |
| 296 | if ($item) { |
| 297 | $cache[$item->cid] = $item; |
| 298 | } |
| 299 | } |
| 300 | $cids = array_diff($cids, array_keys($cache)); |
| 301 | return $cache; |
| 302 | } |
| 303 | |
| 304 | /** |
| 305 | * Garbage collection for get() and getMultiple(). |
| 306 | * |
| 307 | * @param $bin |
| 308 | * The bin being requested. |
| 309 | */ |
| 310 | protected function garbageCollection() { |
| 311 | global $user; |
| 312 | |
| 313 | // Garbage collection necessary when enforcing a minimum cache lifetime. |
| 314 | $cache_flush = variable_get('cache_flush_' . $this->bin, 0); |
| 315 | if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= REQUEST_TIME)) { |
| 316 | // Reset the variable immediately to prevent a meltdown in heavy load situations. |
| 317 | variable_set('cache_flush_' . $this->bin, 0); |
| 318 | // Time to flush old cache data |
| 319 | db_delete($this->bin) |
| 320 | ->condition('expire', CACHE_PERMANENT, '<>') |
| 321 | ->condition('expire', $cache_flush, '<=') |
| 322 | ->execute(); |
| 323 | } |
| 324 | } |
| 325 | |
| 326 | /** |
| 327 | * Prepare a cached item. |
| 328 | * |
| 329 | * Checks that items are either permanent or did not expire, and unserializes |
| 330 | * data as appropriate. |
| 331 | * |
| 332 | * @param $cache |
| 333 | * An item loaded from cache_get() or cache_get_multiple(). |
| 334 | * @return |
| 335 | * The item with data unserialized as appropriate or FALSE if there is no |
| 336 | * valid item to load. |
| 337 | */ |
| 338 | protected function prepareItem($cache) { |
| 339 | global $user; |
| 340 | |
| 341 | if (!isset($cache->data)) { |
| 342 | return FALSE; |
| 343 | } |
| 344 | // If the data is permanent or we are not enforcing a minimum cache lifetime |
| 345 | // always return the cached data. |
| 346 | if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) { |
| 347 | if ($cache->serialized) { |
| 348 | $cache->data = unserialize($cache->data); |
| 349 | } |
| 350 | } |
| 351 | // If enforcing a minimum cache lifetime, validate that the data is |
| 352 | // currently valid for this user before we return it by making sure the cache |
| 353 | // entry was created before the timestamp in the current session's cache |
| 354 | // timer. The cache variable is loaded into the $user object by _drupal_session_read() |
| 355 | // in session.inc. If the data is permanent or we're not enforcing a minimum |
| 356 | // cache lifetime always return the cached data. |
| 357 | if ($cache->expire != CACHE_PERMANENT && variable_get('cache_lifetime', 0) && $user->cache > $cache->created) { |
| 358 | // This cache data is too old and thus not valid for us, ignore it. |
| 359 | return FALSE; |
| 360 | } |
| 361 | |
| 362 | if (isset($cache->headers)) { |
| 363 | $cache->headers = unserialize($cache->headers); |
| 364 | } |
| 365 | |
| 366 | return $cache; |
| 367 | } |
| 368 | |
| 369 | function set($cid, $data, $expire = CACHE_PERMANENT, array $headers = NULL) { |
| 370 | $fields = array( |
| 371 | 'serialized' => 0, |
| 372 | 'created' => REQUEST_TIME, |
| 373 | 'expire' => $expire, |
| 374 | 'headers' => isset($headers) ? serialize($headers) : NULL, |
| 375 | ); |
| 376 | if (!is_string($data)) { |
| 377 | $fields['data'] = serialize($data); |
| 378 | $fields['serialized'] = 1; |
| 379 | } |
| 380 | else { |
| 381 | $fields['data'] = $data; |
| 382 | $fields['serialized'] = 0; |
| 383 | } |
| 384 | |
| 385 | db_merge($this->bin) |
| 386 | ->key(array('cid' => $cid)) |
| 387 | ->fields($fields) |
| 388 | ->execute(); |
| 389 | } |
| 390 | |
| 391 | function clear($cid = NULL, $wildcard = FALSE) { |
| 392 | global $user; |
| 393 | |
| 394 | if (empty($cid)) { |
| 395 | if (variable_get('cache_lifetime', 0)) { |
| 396 | // We store the time in the current user's $user->cache variable which |
| 397 | // will be saved into the sessions bin by _drupal_session_write(). We then |
| 398 | // simulate that the cache was flushed for this user by not returning |
| 399 | // cached data that was cached before the timestamp. |
| 400 | $user->cache = REQUEST_TIME; |
| 401 | |
| 402 | $cache_flush = variable_get('cache_flush_' . $this->bin, 0); |
| 403 | if ($cache_flush == 0) { |
| 404 | // This is the first request to clear the cache, start a timer. |
| 405 | variable_set('cache_flush_' . $this->bin, REQUEST_TIME); |
| 406 | } |
| 407 | elseif (REQUEST_TIME > ($cache_flush + variable_get('cache_lifetime', 0))) { |
| 408 | // Clear the cache for everyone, cache_lifetime seconds have |
| 409 | // passed since the first request to clear the cache. |
| 410 | db_delete($this->bin) |
| 411 | ->condition('expire', CACHE_PERMANENT, '<>') |
| 412 | ->condition('expire', REQUEST_TIME, '<') |
| 413 | ->execute(); |
| 414 | variable_set('cache_flush_' . $this->bin, 0); |
| 415 | } |
| 416 | } |
| 417 | else { |
| 418 | // No minimum cache lifetime, flush all temporary cache entries now. |
| 419 | db_delete($this->bin) |
| 420 | ->condition('expire', CACHE_PERMANENT, '<>') |
| 421 | ->condition('expire', REQUEST_TIME, '<') |
| 422 | ->execute(); |
| 423 | } |
| 424 | } |
| 425 | else { |
| 426 | if ($wildcard) { |
| 427 | if ($cid == '*') { |
| 428 | db_truncate($this->bin)->execute(); |
| 429 | } |
| 430 | else { |
| 431 | db_delete($this->bin) |
| 432 | ->condition('cid', $cid . '%', 'LIKE') |
| 433 | ->execute(); |
| 434 | } |
| 435 | } |
| 436 | elseif (is_array($cid)) { |
| 437 | // Delete in chunks when a large array is passed. |
| 438 | do { |
| 439 | db_delete($this->bin) |
| 440 | ->condition('cid', array_splice($cid, 0, 1000), 'IN') |
| 441 | ->execute(); |
| 442 | } |
| 443 | while (count($cid)); |
| 444 | } |
| 445 | else { |
| 446 | db_delete($this->bin) |
| 447 | ->condition('cid', $cid) |
| 448 | ->execute(); |
| 449 | } |
| 450 | } |
| 451 | } |
| 452 | } |
| 453 |