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- Bug fixes for general core bugs in 4.3.x will end 7 October 2024 (12 months).
- Bug fixes for security issues in 4.3.x will end 21 April 2025 (18 months).
- PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.2.x is supported too.
/cache/classes/ -> loaders.php (source)
Differences Between: [Versions 310 and 403] [Versions 311 and 403] [Versions 39 and 403] [Versions 400 and 403] [Versions 401 and 403] [Versions 402 and 403]
1 <?php 2 // This file is part of Moodle - http://moodle.org/ 3 // 4 // Moodle is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // Moodle is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU General Public License for more details. 13 // 14 // You should have received a copy of the GNU General Public License 15 // along with Moodle. If not, see <http://www.gnu.org/licenses/>. 16 17 /** 18 * Cache loaders 19 * 20 * This file is part of Moodle's cache API, affectionately called MUC. 21 * It contains the components that are required in order to use caching. 22 * 23 * @package core 24 * @category cache 25 * @copyright 2012 Sam Hemelryk 26 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 27 */ 28 29 defined('MOODLE_INTERNAL') || die(); 30 31 /** 32 * The main cache class. 33 * 34 * This class if the first class that any end developer will interact with. 35 * In order to create an instance of a cache that they can work with they must call one of the static make methods belonging 36 * to this class. 37 * 38 * @package core 39 * @category cache 40 * @copyright 2012 Sam Hemelryk 41 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 42 */ 43 class cache implements cache_loader { 44 45 /** 46 * @var int Constant for cache entries that do not have a version number 47 */ 48 const VERSION_NONE = -1; 49 50 /** 51 * We need a timestamp to use within the cache API. 52 * This stamp needs to be used for all ttl and time based operations to ensure that we don't end up with 53 * timing issues. 54 * @var int 55 */ 56 protected static $now; 57 58 /** 59 * A purge token used to distinguish between multiple cache purges in the same second. 60 * This is in the format <microtime>-<random string>. 61 * 62 * @var string 63 */ 64 protected static $purgetoken; 65 66 /** 67 * The definition used when loading this cache if there was one. 68 * @var cache_definition 69 */ 70 private $definition = false; 71 72 /** 73 * The cache store that this loader will make use of. 74 * @var cache_store 75 */ 76 private $store; 77 78 /** 79 * The next cache loader in the chain if there is one. 80 * If a cache request misses for the store belonging to this loader then the loader 81 * stored here will be checked next. 82 * If there is a loader here then $datasource must be false. 83 * @var cache_loader|false 84 */ 85 private $loader = false; 86 87 /** 88 * The data source to use if we need to load data (because if doesn't exist in the cache store). 89 * If there is a data source here then $loader above must be false. 90 * @var cache_data_source|false 91 */ 92 private $datasource = false; 93 94 /** 95 * Used to quickly check if the store supports key awareness. 96 * This is set when the cache is initialised and is used to speed up processing. 97 * @var bool 98 */ 99 private $supportskeyawareness = null; 100 101 /** 102 * Used to quickly check if the store supports ttl natively. 103 * This is set when the cache is initialised and is used to speed up processing. 104 * @var bool 105 */ 106 private $supportsnativettl = null; 107 108 /** 109 * Gets set to true if the cache is going to be using a static array for acceleration. 110 * The array statically caches items used during the lifetime of the request. This greatly speeds up interaction 111 * with the cache in areas where it will be repetitively hit for the same information such as with strings. 112 * There are several other variables to control how this static acceleration array works. 113 * @var bool 114 */ 115 private $staticacceleration = false; 116 117 /** 118 * The static acceleration array. 119 * Items will be stored in this cache as they were provided. This ensure there is no unnecessary processing taking place. 120 * @var array 121 */ 122 private $staticaccelerationarray = array(); 123 124 /** 125 * The number of items in the static acceleration array. Avoids count calls like you wouldn't believe. 126 * @var int 127 */ 128 private $staticaccelerationcount = 0; 129 130 /** 131 * An array containing just the keys being used in the static acceleration array. 132 * This seems redundant perhaps but is used when managing the size of the static acceleration array. 133 * Items are added to the end of the array and the when we need to reduce the size of the cache we use the 134 * key that is first on this array. 135 * @var array 136 */ 137 private $staticaccelerationkeys = array(); 138 139 /** 140 * The maximum size of the static acceleration array. 141 * 142 * If set to false there is no max size. 143 * Caches that make use of static acceleration should seriously consider setting this to something reasonably small, but 144 * still large enough to offset repetitive calls. 145 * 146 * @var int|false 147 */ 148 private $staticaccelerationsize = false; 149 150 /** 151 * Gets set to true during initialisation if the definition is making use of a ttl. 152 * Used to speed up processing. 153 * @var bool 154 */ 155 private $hasattl = false; 156 157 /** 158 * Gets set to the class name of the store during initialisation. This is used several times in the cache class internally 159 * and having it here helps speed up processing. 160 * @var strubg 161 */ 162 protected $storetype = 'unknown'; 163 164 /** 165 * Gets set to true if we want to collect performance information about the cache API. 166 * @var bool 167 */ 168 protected $perfdebug = false; 169 170 /** 171 * Determines if this loader is a sub loader, not the top of the chain. 172 * @var bool 173 */ 174 protected $subloader = false; 175 176 /** 177 * Gets set to true if the cache writes (set|delete) must have a manual lock created first. 178 * @var bool 179 */ 180 protected $requirelockingbeforewrite = false; 181 182 /** 183 * Gets set to true if the cache's primary store natively supports locking. 184 * If it does then we use that, otherwise we need to instantiate a second store to use for locking. 185 * @var cache_store|null 186 */ 187 protected $nativelocking = null; 188 189 /** 190 * Creates a new cache instance for a pre-defined definition. 191 * 192 * @param string $component The component for the definition 193 * @param string $area The area for the definition 194 * @param array $identifiers Any additional identifiers that should be provided to the definition. 195 * @param string $unused Used to be datasourceaggregate but that was removed and this is now unused. 196 * @return cache_application|cache_session|cache_store 197 */ 198 public static function make($component, $area, array $identifiers = array(), $unused = null) { 199 $factory = cache_factory::instance(); 200 return $factory->create_cache_from_definition($component, $area, $identifiers); 201 } 202 203 /** 204 * Creates a new cache instance based upon the given params. 205 * 206 * @param int $mode One of cache_store::MODE_* 207 * @param string $component The component this cache relates to. 208 * @param string $area The area this cache relates to. 209 * @param array $identifiers Any additional identifiers that should be provided to the definition. 210 * @param array $options An array of options, available options are: 211 * - simplekeys : Set to true if the keys you will use are a-zA-Z0-9_ 212 * - simpledata : Set to true if the type of the data you are going to store is scalar, or an array of scalar vars 213 * - staticacceleration : If set to true the cache will hold onto data passing through it. 214 * - staticaccelerationsize : The max size for the static acceleration array. 215 * @return cache_application|cache_session|cache_request 216 */ 217 public static function make_from_params($mode, $component, $area, array $identifiers = array(), array $options = array()) { 218 $factory = cache_factory::instance(); 219 return $factory->create_cache_from_params($mode, $component, $area, $identifiers, $options); 220 } 221 222 /** 223 * Constructs a new cache instance. 224 * 225 * You should not call this method from your code, instead you should use the cache::make methods. 226 * 227 * This method is public so that the cache_factory is able to instantiate cache instances. 228 * Ideally we would make this method protected and expose its construction to the factory method internally somehow. 229 * The factory class is responsible for this in order to centralise the storage of instances once created. This way if needed 230 * we can force a reset of the cache API (used during unit testing). 231 * 232 * @param cache_definition $definition The definition for the cache instance. 233 * @param cache_store $store The store that cache should use. 234 * @param cache_loader|cache_data_source $loader The next loader in the chain or the data source if there is one and there 235 * are no other cache_loaders in the chain. 236 */ 237 public function __construct(cache_definition $definition, cache_store $store, $loader = null) { 238 global $CFG; 239 $this->definition = $definition; 240 $this->store = $store; 241 $this->storetype = get_class($store); 242 $this->perfdebug = (!empty($CFG->perfdebug) and $CFG->perfdebug > 7); 243 if ($loader instanceof cache_loader) { 244 $this->set_loader($loader); 245 } else if ($loader instanceof cache_data_source) { 246 $this->set_data_source($loader); 247 } 248 $this->definition->generate_definition_hash(); 249 $this->staticacceleration = $this->definition->use_static_acceleration(); 250 if ($this->staticacceleration) { 251 $this->staticaccelerationsize = $this->definition->get_static_acceleration_size(); 252 } 253 $this->hasattl = ($this->definition->get_ttl() > 0); 254 } 255 256 /** 257 * Set the loader for this cache. 258 * 259 * @param cache_loader $loader 260 */ 261 protected function set_loader(cache_loader $loader): void { 262 $this->loader = $loader; 263 264 // Mark the loader as a sub (chained) loader. 265 $this->loader->set_is_sub_loader(true); 266 } 267 268 /** 269 * Set the data source for this cache. 270 * 271 * @param cache_data_source $datasource 272 */ 273 protected function set_data_source(cache_data_source $datasource): void { 274 $this->datasource = $datasource; 275 } 276 277 /** 278 * Used to inform the loader of its state as a sub loader, or as the top of the chain. 279 * 280 * This is important as it ensures that we do not have more than one loader keeping static acceleration data. 281 * Subloaders need to be "pure" loaders in the sense that they are used to store and retrieve information from stores or the 282 * next loader/data source in the chain. 283 * Nothing fancy, nothing flash. 284 * 285 * @param bool $setting 286 */ 287 protected function set_is_sub_loader($setting = true) { 288 if ($setting) { 289 $this->subloader = true; 290 // Subloaders should not keep static acceleration data. 291 $this->staticacceleration = false; 292 $this->staticaccelerationsize = false; 293 } else { 294 $this->subloader = true; 295 $this->staticacceleration = $this->definition->use_static_acceleration(); 296 if ($this->staticacceleration) { 297 $this->staticaccelerationsize = $this->definition->get_static_acceleration_size(); 298 } 299 } 300 } 301 302 /** 303 * Alters the identifiers that have been provided to the definition. 304 * 305 * This is an advanced method and should not be used unless really needed. 306 * It allows the developer to slightly alter the definition without having to re-establish the cache. 307 * It will cause more processing as the definition will need to clear and reprepare some of its properties. 308 * 309 * @param array $identifiers 310 */ 311 public function set_identifiers(array $identifiers) { 312 if ($this->definition->set_identifiers($identifiers)) { 313 // As static acceleration uses input keys and not parsed keys 314 // it much be cleared when the identifier set is changed. 315 $this->staticaccelerationarray = array(); 316 if ($this->staticaccelerationsize !== false) { 317 $this->staticaccelerationkeys = array(); 318 $this->staticaccelerationcount = 0; 319 } 320 } 321 } 322 323 /** 324 * Process any outstanding invalidation events for the cache we are registering, 325 * 326 * Identifiers and event invalidation are not compatible with each other at this time. 327 * As a result the cache does not need to consider identifiers when working out what to invalidate. 328 */ 329 protected function handle_invalidation_events() { 330 if (!$this->definition->has_invalidation_events()) { 331 return; 332 } 333 334 // Each cache stores the current 'lastinvalidation' value within the cache itself. 335 $lastinvalidation = $this->get('lastinvalidation'); 336 if ($lastinvalidation === false) { 337 // There is currently no value for the lastinvalidation token, therefore the token is not set, and there 338 // can be nothing to invalidate. 339 // Set the lastinvalidation value to the current purge token and return early. 340 $this->set('lastinvalidation', self::get_purge_token()); 341 return; 342 } else if ($lastinvalidation == self::get_purge_token()) { 343 // The current purge request has already been fully handled by this cache. 344 return; 345 } 346 347 /* 348 * Now that the whole cache check is complete, we check the meaning of any specific cache invalidation events. 349 * These are stored in the core/eventinvalidation cache as an multi-dimensinoal array in the form: 350 * [ 351 * eventname => [ 352 * keyname => purgetoken, 353 * ] 354 * ] 355 * 356 * The 'keyname' value is used to delete a specific key in the cache. 357 * If the keyname is set to the special value 'purged', then the whole cache is purged instead. 358 * 359 * The 'purgetoken' is the token that this key was last purged. 360 * a) If the purgetoken matches the last invalidation, then the key/cache is not purged. 361 * b) If the purgetoken is newer than the last invalidation, then the key/cache is not purged. 362 * c) If the purge token is older than the last invalidation, or it has a different token component, then the 363 * cache is purged. 364 * 365 * Option b should not happen under normal operation, but may happen in race condition whereby a long-running 366 * request's cache is cleared in another process during that request, and prior to that long-running request 367 * creating the cache. In such a condition, it would be incorrect to clear that cache. 368 */ 369 $cache = self::make('core', 'eventinvalidation'); 370 $events = $cache->get_many($this->definition->get_invalidation_events()); 371 $todelete = array(); 372 $purgeall = false; 373 374 // Iterate the returned data for the events. 375 foreach ($events as $event => $keys) { 376 if ($keys === false) { 377 // No data to be invalidated yet. 378 continue; 379 } 380 381 // Look at each key and check the timestamp. 382 foreach ($keys as $key => $purgetoken) { 383 // If the timestamp of the event is more than or equal to the last invalidation (happened between the last 384 // invalidation and now), then we need to invaliate the key. 385 if (self::compare_purge_tokens($purgetoken, $lastinvalidation) > 0) { 386 if ($key === 'purged') { 387 $purgeall = true; 388 break; 389 } else { 390 $todelete[] = $key; 391 } 392 } 393 } 394 } 395 if ($purgeall) { 396 $this->purge(); 397 } else if (!empty($todelete)) { 398 $todelete = array_unique($todelete); 399 $this->delete_many($todelete); 400 } 401 // Set the time of the last invalidation. 402 if ($purgeall || !empty($todelete)) { 403 $this->set('lastinvalidation', self::get_purge_token(true)); 404 } 405 } 406 407 /** 408 * Retrieves the value for the given key from the cache. 409 * 410 * @param string|int $key The key for the data being requested. 411 * It can be any structure although using a scalar string or int is recommended in the interests of performance. 412 * In advanced cases an array may be useful such as in situations requiring the multi-key functionality. 413 * @param int $strictness One of IGNORE_MISSING | MUST_EXIST 414 * @return mixed|false The data from the cache or false if the key did not exist within the cache. 415 * @throws coding_exception 416 */ 417 public function get($key, $strictness = IGNORE_MISSING) { 418 return $this->get_implementation($key, self::VERSION_NONE, $strictness); 419 } 420 421 /** 422 * Retrieves the value and actual version for the given key, with at least the required version. 423 * 424 * If there is no value for the key, or there is a value but it doesn't have the required 425 * version, then this function will return null (or throw an exception if you set strictness 426 * to MUST_EXIST). 427 * 428 * This function can be used to make it easier to support localisable caches (where the cache 429 * could be stored on a local server as well as a shared cache). Specifying the version means 430 * that it will automatically retrieve the correct version if available, either from the local 431 * server or [if that has an older version] from the shared server. 432 * 433 * If the cached version is newer than specified version, it will be returned regardless. For 434 * example, if you request version 4, but the locally cached version is 5, it will be returned. 435 * If you request version 6, and the locally cached version is 5, then the system will look in 436 * higher-level caches (if any); if there still isn't a version 6 or greater, it will return 437 * null. 438 * 439 * You must use this function if you use set_versioned. 440 * 441 * @param string|int $key The key for the data being requested. 442 * @param int $requiredversion Minimum required version of the data 443 * @param int $strictness One of IGNORE_MISSING or MUST_EXIST. 444 * @param mixed $actualversion If specified, will be set to the actual version number retrieved 445 * @return mixed Data from the cache, or false if the key did not exist or was too old 446 * @throws \coding_exception If you call get_versioned on a non-versioned cache key 447 */ 448 public function get_versioned($key, int $requiredversion, int $strictness = IGNORE_MISSING, &$actualversion = null) { 449 return $this->get_implementation($key, $requiredversion, $strictness, $actualversion); 450 } 451 452 /** 453 * Checks returned data to see if it matches the specified version number. 454 * 455 * For versioned data, this returns the version_wrapper object (or false). For other 456 * data, it returns the actual data (or false). 457 * 458 * @param mixed $result Result data 459 * @param int $requiredversion Required version number or VERSION_NONE if there must be no version 460 * @return bool True if version is current, false if not (or if result is false) 461 * @throws \coding_exception If unexpected type of data (versioned vs non-versioned) is found 462 */ 463 protected static function check_version($result, int $requiredversion): bool { 464 if ($requiredversion === self::VERSION_NONE) { 465 if ($result instanceof \core_cache\version_wrapper) { 466 throw new \coding_exception('Unexpectedly found versioned cache entry'); 467 } else { 468 // No version checks, so version is always correct. 469 return true; 470 } 471 } else { 472 // If there's no result, obviously it doesn't meet the required version. 473 if (!cache_helper::result_found($result)) { 474 return false; 475 } 476 if (!($result instanceof \core_cache\version_wrapper)) { 477 throw new \coding_exception('Unexpectedly found non-versioned cache entry'); 478 } 479 // If the result doesn't match the required version tag, return false. 480 if ($result->version < $requiredversion) { 481 return false; 482 } 483 // The version meets the requirement. 484 return true; 485 } 486 } 487 488 /** 489 * Retrieves the value for the given key from the cache. 490 * 491 * @param string|int $key The key for the data being requested. 492 * It can be any structure although using a scalar string or int is recommended in the interests of performance. 493 * In advanced cases an array may be useful such as in situations requiring the multi-key functionality. 494 * @param int $requiredversion Minimum required version of the data or cache::VERSION_NONE 495 * @param int $strictness One of IGNORE_MISSING | MUST_EXIST 496 * @param mixed $actualversion If specified, will be set to the actual version number retrieved 497 * @return mixed|false The data from the cache or false if the key did not exist within the cache. 498 * @throws coding_exception 499 */ 500 protected function get_implementation($key, int $requiredversion, int $strictness, &$actualversion = null) { 501 // 1. Get it from the static acceleration array if we can (only when it is enabled and it has already been requested/set). 502 $usesstaticacceleration = $this->use_static_acceleration(); 503 504 if ($usesstaticacceleration) { 505 $result = $this->static_acceleration_get($key); 506 if (cache_helper::result_found($result) && self::check_version($result, $requiredversion)) { 507 if ($requiredversion === self::VERSION_NONE) { 508 return $result; 509 } else { 510 $actualversion = $result->version; 511 return $result->data; 512 } 513 } 514 } 515 516 // 2. Parse the key. 517 $parsedkey = $this->parse_key($key); 518 519 // 3. Get it from the store. Obviously wasn't in the static acceleration array. 520 $result = $this->store->get($parsedkey); 521 if (cache_helper::result_found($result)) { 522 // Check the result has at least the required version. 523 try { 524 $validversion = self::check_version($result, $requiredversion); 525 } catch (\coding_exception $e) { 526 // In certain circumstances this could happen before users are taken to the upgrade 527 // screen when upgrading from an earlier Moodle version that didn't use a versioned 528 // cache for this item, so redirect instead of showing error if that's the case. 529 redirect_if_major_upgrade_required(); 530 531 // If we still get an exception because there is incorrect data in the cache (not 532 // versioned when it ought to be), delete it so this exception goes away next time. 533 // The exception should only happen if there is a code bug (which is why we still 534 // throw it) but there are unusual scenarios in development where it might happen 535 // and that would be annoying if it doesn't fix itself. 536 $this->store->delete($parsedkey); 537 throw $e; 538 } 539 540 if (!$validversion) { 541 // If the result was too old, don't use it. 542 $result = false; 543 544 // Also delete it immediately. This improves performance in the 545 // case when the cache item is large and there may be multiple clients simultaneously 546 // requesting it - they won't all have to do a megabyte of IO just in order to find 547 // that it's out of date. 548 $this->store->delete($parsedkey); 549 } 550 } 551 if (cache_helper::result_found($result)) { 552 // Look to see if there's a TTL wrapper. It might be inside a version wrapper. 553 if ($requiredversion !== self::VERSION_NONE) { 554 $ttlconsider = $result->data; 555 } else { 556 $ttlconsider = $result; 557 } 558 if ($ttlconsider instanceof cache_ttl_wrapper) { 559 if ($ttlconsider->has_expired()) { 560 $this->store->delete($parsedkey); 561 $result = false; 562 } else if ($requiredversion === self::VERSION_NONE) { 563 // Use the data inside the TTL wrapper as the result. 564 $result = $ttlconsider->data; 565 } else { 566 // Put the data from the TTL wrapper directly inside the version wrapper. 567 $result->data = $ttlconsider->data; 568 } 569 } 570 if ($usesstaticacceleration) { 571 $this->static_acceleration_set($key, $result); 572 } 573 // Remove version wrapper if necessary. 574 if ($requiredversion !== self::VERSION_NONE) { 575 $actualversion = $result->version; 576 $result = $result->data; 577 } 578 if ($result instanceof cache_cached_object) { 579 $result = $result->restore_object(); 580 } 581 } 582 583 // 4. Load if from the loader/datasource if we don't already have it. 584 $setaftervalidation = false; 585 if (!cache_helper::result_found($result)) { 586 if ($this->perfdebug) { 587 cache_helper::record_cache_miss($this->store, $this->definition); 588 } 589 if ($this->loader !== false) { 590 // We must pass the original (unparsed) key to the next loader in the chain. 591 // The next loader will parse the key as it sees fit. It may be parsed differently 592 // depending upon the capabilities of the store associated with the loader. 593 if ($requiredversion === self::VERSION_NONE) { 594 $result = $this->loader->get($key); 595 } else { 596 $result = $this->loader->get_versioned($key, $requiredversion, IGNORE_MISSING, $actualversion); 597 } 598 } else if ($this->datasource !== false) { 599 if ($requiredversion === self::VERSION_NONE) { 600 $result = $this->datasource->load_for_cache($key); 601 } else { 602 if (!$this->datasource instanceof cache_data_source_versionable) { 603 throw new \coding_exception('Data source is not versionable'); 604 } 605 $result = $this->datasource->load_for_cache_versioned($key, $requiredversion, $actualversion); 606 if ($result && $actualversion < $requiredversion) { 607 throw new \coding_exception('Data source returned outdated version'); 608 } 609 } 610 } 611 $setaftervalidation = (cache_helper::result_found($result)); 612 } else if ($this->perfdebug) { 613 $readbytes = $this->store->get_last_io_bytes(); 614 cache_helper::record_cache_hit($this->store, $this->definition, 1, $readbytes); 615 } 616 // 5. Validate strictness. 617 if ($strictness === MUST_EXIST && !cache_helper::result_found($result)) { 618 throw new coding_exception('Requested key did not exist in any cache stores and could not be loaded.'); 619 } 620 // 6. Set it to the store if we got it from the loader/datasource. Only set to this direct 621 // store; parent method will have set it to all stores if needed. 622 if ($setaftervalidation) { 623 $lock = false; 624 try { 625 // Only try to acquire a lock for this cache if we do not already have one. 626 if (!empty($this->requirelockingbeforewrite) && !$this->check_lock_state($key)) { 627 $this->acquire_lock($key); 628 $lock = true; 629 } 630 if ($requiredversion === self::VERSION_NONE) { 631 $this->set_implementation($key, self::VERSION_NONE, $result, false); 632 } else { 633 $this->set_implementation($key, $actualversion, $result, false); 634 } 635 } finally { 636 if ($lock) { 637 $this->release_lock($key); 638 } 639 } 640 } 641 // 7. Make sure we don't pass back anything that could be a reference. 642 // We don't want people modifying the data in the cache. 643 if (!$this->store->supports_dereferencing_objects() && !is_scalar($result)) { 644 // If data is an object it will be a reference. 645 // If data is an array if may contain references. 646 // We want to break references so that the cache cannot be modified outside of itself. 647 // Call the function to unreference it (in the best way possible). 648 $result = $this->unref($result); 649 } 650 return $result; 651 } 652 653 /** 654 * Retrieves an array of values for an array of keys. 655 * 656 * Using this function comes with potential performance implications. 657 * Not all cache stores will support get_many/set_many operations and in order to replicate this functionality will call 658 * the equivalent singular method for each item provided. 659 * This should not deter you from using this function as there is a performance benefit in situations where the cache store 660 * does support it, but you should be aware of this fact. 661 * 662 * @param array $keys The keys of the data being requested. 663 * Each key can be any structure although using a scalar string or int is recommended in the interests of performance. 664 * In advanced cases an array may be useful such as in situations requiring the multi-key functionality. 665 * @param int $strictness One of IGNORE_MISSING or MUST_EXIST. 666 * @return array An array of key value pairs for the items that could be retrieved from the cache. 667 * If MUST_EXIST was used and not all keys existed within the cache then an exception will be thrown. 668 * Otherwise any key that did not exist will have a data value of false within the results. 669 * @throws coding_exception 670 */ 671 public function get_many(array $keys, $strictness = IGNORE_MISSING) { 672 673 $keysparsed = array(); 674 $parsedkeys = array(); 675 $resultpersist = array(); 676 $resultstore = array(); 677 $keystofind = array(); 678 $readbytes = cache_store::IO_BYTES_NOT_SUPPORTED; 679 680 // First up check the persist cache for each key. 681 $isusingpersist = $this->use_static_acceleration(); 682 foreach ($keys as $key) { 683 $pkey = $this->parse_key($key); 684 if (is_array($pkey)) { 685 $pkey = $pkey['key']; 686 } 687 $keysparsed[$key] = $pkey; 688 $parsedkeys[$pkey] = $key; 689 $keystofind[$pkey] = $key; 690 if ($isusingpersist) { 691 $value = $this->static_acceleration_get($key); 692 if ($value !== false) { 693 $resultpersist[$pkey] = $value; 694 unset($keystofind[$pkey]); 695 } 696 } 697 } 698 699 // Next assuming we didn't find all of the keys in the persist cache try loading them from the store. 700 if (count($keystofind)) { 701 $resultstore = $this->store->get_many(array_keys($keystofind)); 702 if ($this->perfdebug) { 703 $readbytes = $this->store->get_last_io_bytes(); 704 } 705 // Process each item in the result to "unwrap" it. 706 foreach ($resultstore as $key => $value) { 707 if ($value instanceof cache_ttl_wrapper) { 708 if ($value->has_expired()) { 709 $value = false; 710 } else { 711 $value = $value->data; 712 } 713 } 714 if ($value !== false && $this->use_static_acceleration()) { 715 $this->static_acceleration_set($keystofind[$key], $value); 716 } 717 if ($value instanceof cache_cached_object) { 718 $value = $value->restore_object(); 719 } 720 $resultstore[$key] = $value; 721 } 722 } 723 724 // Merge the result from the persis cache with the results from the store load. 725 $result = $resultpersist + $resultstore; 726 unset($resultpersist); 727 unset($resultstore); 728 729 // Next we need to find any missing values and load them from the loader/datasource next in the chain. 730 $usingloader = ($this->loader !== false); 731 $usingsource = (!$usingloader && ($this->datasource !== false)); 732 if ($usingloader || $usingsource) { 733 $missingkeys = array(); 734 foreach ($result as $key => $value) { 735 if ($value === false) { 736 $missingkeys[] = $parsedkeys[$key]; 737 } 738 } 739 if (!empty($missingkeys)) { 740 if ($usingloader) { 741 $resultmissing = $this->loader->get_many($missingkeys); 742 } else { 743 $resultmissing = $this->datasource->load_many_for_cache($missingkeys); 744 } 745 foreach ($resultmissing as $key => $value) { 746 $result[$keysparsed[$key]] = $value; 747 $lock = false; 748 try { 749 if (!empty($this->requirelockingbeforewrite)) { 750 $this->acquire_lock($key); 751 $lock = true; 752 } 753 if ($value !== false) { 754 $this->set($key, $value); 755 } 756 } finally { 757 if ($lock) { 758 $this->release_lock($key); 759 } 760 } 761 } 762 unset($resultmissing); 763 } 764 unset($missingkeys); 765 } 766 767 // Create an array with the original keys and the found values. This will be what we return. 768 $fullresult = array(); 769 foreach ($result as $key => $value) { 770 if (!is_scalar($value)) { 771 // If data is an object it will be a reference. 772 // If data is an array if may contain references. 773 // We want to break references so that the cache cannot be modified outside of itself. 774 // Call the function to unreference it (in the best way possible). 775 $value = $this->unref($value); 776 } 777 $fullresult[$parsedkeys[$key]] = $value; 778 } 779 unset($result); 780 781 // Final step is to check strictness. 782 if ($strictness === MUST_EXIST) { 783 foreach ($keys as $key) { 784 if (!array_key_exists($key, $fullresult)) { 785 throw new coding_exception('Not all the requested keys existed within the cache stores.'); 786 } 787 } 788 } 789 790 if ($this->perfdebug) { 791 $hits = 0; 792 $misses = 0; 793 foreach ($fullresult as $value) { 794 if ($value === false) { 795 $misses++; 796 } else { 797 $hits++; 798 } 799 } 800 cache_helper::record_cache_hit($this->store, $this->definition, $hits, $readbytes); 801 cache_helper::record_cache_miss($this->store, $this->definition, $misses); 802 } 803 804 // Return the result. Phew! 805 return $fullresult; 806 } 807 808 /** 809 * Sends a key => value pair to the cache. 810 * 811 * <code> 812 * // This code will add four entries to the cache, one for each url. 813 * $cache->set('main', 'http://moodle.org'); 814 * $cache->set('docs', 'http://docs.moodle.org'); 815 * $cache->set('tracker', 'http://tracker.moodle.org'); 816 * $cache->set('qa', 'http://qa.moodle.net'); 817 * </code> 818 * 819 * @param string|int $key The key for the data being requested. 820 * It can be any structure although using a scalar string or int is recommended in the interests of performance. 821 * In advanced cases an array may be useful such as in situations requiring the multi-key functionality. 822 * @param mixed $data The data to set against the key. 823 * @return bool True on success, false otherwise. 824 */ 825 public function set($key, $data) { 826 return $this->set_implementation($key, self::VERSION_NONE, $data); 827 } 828 829 /** 830 * Sets the value for the given key with the given version. 831 * 832 * The cache does not store multiple versions - any existing version will be overwritten with 833 * this one. This function should only be used if there is a known 'current version' (e.g. 834 * stored in a database table). It only ensures that the cache does not return outdated data. 835 * 836 * This function can be used to help implement localisable caches (where the cache could be 837 * stored on a local server as well as a shared cache). The version will be recorded alongside 838 * the item and get_versioned will always return the correct version. 839 * 840 * The version number must be an integer that always increases. This could be based on the 841 * current time, or a stored value that increases by 1 each time it changes, etc. 842 * 843 * If you use this function you must use get_versioned to retrieve the data. 844 * 845 * @param string|int $key The key for the data being set. 846 * @param int $version Integer for the version of the data 847 * @param mixed $data The data to set against the key. 848 * @return bool True on success, false otherwise. 849 */ 850 public function set_versioned($key, int $version, $data): bool { 851 return $this->set_implementation($key, $version, $data); 852 } 853 854 /** 855 * Sets the value for the given key, optionally with a version tag. 856 * 857 * @param string|int $key The key for the data being set. 858 * @param int $version Version number for the data or cache::VERSION_NONE if none 859 * @param mixed $data The data to set against the key. 860 * @param bool $setparents If true, sets all parent loaders, otherwise only this one 861 * @return bool True on success, false otherwise. 862 */ 863 protected function set_implementation($key, int $version, $data, bool $setparents = true): bool { 864 if ($this->loader !== false && $setparents) { 865 // We have a loader available set it there as well. 866 // We have to let the loader do its own parsing of data as it may be unique. 867 if ($version === self::VERSION_NONE) { 868 $this->loader->set($key, $data); 869 } else { 870 $this->loader->set_versioned($key, $version, $data); 871 } 872 } 873 $usestaticacceleration = $this->use_static_acceleration(); 874 875 if (is_object($data) && $data instanceof cacheable_object) { 876 $data = new cache_cached_object($data); 877 } else if (!$this->store->supports_dereferencing_objects() && !is_scalar($data)) { 878 // If data is an object it will be a reference. 879 // If data is an array if may contain references. 880 // We want to break references so that the cache cannot be modified outside of itself. 881 // Call the function to unreference it (in the best way possible). 882 $data = $this->unref($data); 883 } 884 885 if ($usestaticacceleration) { 886 // Static acceleration cache should include the cache version wrapper, but not TTL. 887 if ($version === self::VERSION_NONE) { 888 $this->static_acceleration_set($key, $data); 889 } else { 890 $this->static_acceleration_set($key, new \core_cache\version_wrapper($data, $version)); 891 } 892 } 893 894 if ($this->has_a_ttl() && !$this->store_supports_native_ttl()) { 895 $data = new cache_ttl_wrapper($data, $this->definition->get_ttl()); 896 } 897 $parsedkey = $this->parse_key($key); 898 899 if ($version !== self::VERSION_NONE) { 900 $data = new \core_cache\version_wrapper($data, $version); 901 } 902 903 $success = $this->store->set($parsedkey, $data); 904 if ($this->perfdebug) { 905 cache_helper::record_cache_set($this->store, $this->definition, 1, 906 $this->store->get_last_io_bytes()); 907 } 908 return $success; 909 } 910 911 /** 912 * Removes references where required. 913 * 914 * @param stdClass|array $data 915 * @return mixed What ever was put in but without any references. 916 */ 917 protected function unref($data) { 918 if ($this->definition->uses_simple_data()) { 919 return $data; 920 } 921 // Check if it requires serialisation in order to produce a reference free copy. 922 if ($this->requires_serialisation($data)) { 923 // Damn, its going to have to be serialise. 924 $data = serialize($data); 925 // We unserialise immediately so that we don't have to do it every time on get. 926 $data = unserialize($data); 927 } else if (!is_scalar($data)) { 928 // Its safe to clone, lets do it, its going to beat the pants of serialisation. 929 $data = $this->deep_clone($data); 930 } 931 return $data; 932 } 933 934 /** 935 * Checks to see if a var requires serialisation. 936 * 937 * @param mixed $value The value to check. 938 * @param int $depth Used to ensure we don't enter an endless loop (think recursion). 939 * @return bool Returns true if the value is going to require serialisation in order to ensure a reference free copy 940 * or false if its safe to clone. 941 */ 942 protected function requires_serialisation($value, $depth = 1) { 943 if (is_scalar($value)) { 944 return false; 945 } else if (is_array($value) || $value instanceof stdClass || $value instanceof Traversable) { 946 if ($depth > 5) { 947 // Skrew it, mega-deep object, developer you suck, we're just going to serialise. 948 return true; 949 } 950 foreach ($value as $key => $subvalue) { 951 if ($this->requires_serialisation($subvalue, $depth++)) { 952 return true; 953 } 954 } 955 } 956 // Its not scalar, array, or stdClass so we'll need to serialise. 957 return true; 958 } 959 960 /** 961 * Creates a reference free clone of the given value. 962 * 963 * @param mixed $value 964 * @return mixed 965 */ 966 protected function deep_clone($value) { 967 if (is_object($value)) { 968 // Objects must be cloned to begin with. 969 $value = clone $value; 970 } 971 if (is_array($value) || is_object($value)) { 972 foreach ($value as $key => $subvalue) { 973 $value[$key] = $this->deep_clone($subvalue); 974 } 975 } 976 return $value; 977 } 978 979 /** 980 * Sends several key => value pairs to the cache. 981 * 982 * Using this function comes with potential performance implications. 983 * Not all cache stores will support get_many/set_many operations and in order to replicate this functionality will call 984 * the equivalent singular method for each item provided. 985 * This should not deter you from using this function as there is a performance benefit in situations where the cache store 986 * does support it, but you should be aware of this fact. 987 * 988 * <code> 989 * // This code will add four entries to the cache, one for each url. 990 * $cache->set_many(array( 991 * 'main' => 'http://moodle.org', 992 * 'docs' => 'http://docs.moodle.org', 993 * 'tracker' => 'http://tracker.moodle.org', 994 * 'qa' => ''http://qa.moodle.net' 995 * )); 996 * </code> 997 * 998 * @param array $keyvaluearray An array of key => value pairs to send to the cache. 999 * @return int The number of items successfully set. It is up to the developer to check this matches the number of items. 1000 * ... if they care that is. 1001 */ 1002 public function set_many(array $keyvaluearray) { 1003 if ($this->loader !== false) { 1004 // We have a loader available set it there as well. 1005 // We have to let the loader do its own parsing of data as it may be unique. 1006 $this->loader->set_many($keyvaluearray); 1007 } 1008 $data = array(); 1009 $simulatettl = $this->has_a_ttl() && !$this->store_supports_native_ttl(); 1010 $usestaticaccelerationarray = $this->use_static_acceleration(); 1011 $needsdereferencing = !$this->store->supports_dereferencing_objects(); 1012 foreach ($keyvaluearray as $key => $value) { 1013 if (is_object($value) && $value instanceof cacheable_object) { 1014 $value = new cache_cached_object($value); 1015 } else if ($needsdereferencing && !is_scalar($value)) { 1016 // If data is an object it will be a reference. 1017 // If data is an array if may contain references. 1018 // We want to break references so that the cache cannot be modified outside of itself. 1019 // Call the function to unreference it (in the best way possible). 1020 $value = $this->unref($value); 1021 } 1022 if ($usestaticaccelerationarray) { 1023 $this->static_acceleration_set($key, $value); 1024 } 1025 if ($simulatettl) { 1026 $value = new cache_ttl_wrapper($value, $this->definition->get_ttl()); 1027 } 1028 $data[$key] = array( 1029 'key' => $this->parse_key($key), 1030 'value' => $value 1031 ); 1032 } 1033 $successfullyset = $this->store->set_many($data); 1034 if ($this->perfdebug && $successfullyset) { 1035 cache_helper::record_cache_set($this->store, $this->definition, $successfullyset, 1036 $this->store->get_last_io_bytes()); 1037 } 1038 return $successfullyset; 1039 } 1040 1041 /** 1042 * Test is a cache has a key. 1043 * 1044 * The use of the has methods is strongly discouraged. In a high load environment the cache may well change between the 1045 * test and any subsequent action (get, set, delete etc). 1046 * Instead it is recommended to write your code in such a way they it performs the following steps: 1047 * <ol> 1048 * <li>Attempt to retrieve the information.</li> 1049 * <li>Generate the information.</li> 1050 * <li>Attempt to set the information</li> 1051 * </ol> 1052 * 1053 * Its also worth mentioning that not all stores support key tests. 1054 * For stores that don't support key tests this functionality is mimicked by using the equivalent get method. 1055 * Just one more reason you should not use these methods unless you have a very good reason to do so. 1056 * 1057 * @param string|int $key 1058 * @param bool $tryloadifpossible If set to true, the cache doesn't contain the key, and there is another cache loader or 1059 * data source then the code will try load the key value from the next item in the chain. 1060 * @return bool True if the cache has the requested key, false otherwise. 1061 */ 1062 public function has($key, $tryloadifpossible = false) { 1063 if ($this->static_acceleration_has($key)) { 1064 // Hoorah, that was easy. It exists in the static acceleration array so we definitely have it. 1065 return true; 1066 } 1067 $parsedkey = $this->parse_key($key); 1068 1069 if ($this->has_a_ttl() && !$this->store_supports_native_ttl()) { 1070 // The data has a TTL and the store doesn't support it natively. 1071 // We must fetch the data and expect a ttl wrapper. 1072 $data = $this->store->get($parsedkey); 1073 $has = ($data instanceof cache_ttl_wrapper && !$data->has_expired()); 1074 } else if (!$this->store_supports_key_awareness()) { 1075 // The store doesn't support key awareness, get the data and check it manually... puke. 1076 // Either no TTL is set of the store supports its handling natively. 1077 $data = $this->store->get($parsedkey); 1078 $has = ($data !== false); 1079 } else { 1080 // The store supports key awareness, this is easy! 1081 // Either no TTL is set of the store supports its handling natively. 1082 $has = $this->store->has($parsedkey); 1083 } 1084 if (!$has && $tryloadifpossible) { 1085 if ($this->loader !== false) { 1086 $result = $this->loader->get($parsedkey); 1087 } else if ($this->datasource !== null) { 1088 $result = $this->datasource->load_for_cache($key); 1089 } 1090 $has = ($result !== null); 1091 if ($has) { 1092 $this->set($key, $result); 1093 } 1094 } 1095 return $has; 1096 } 1097 1098 /** 1099 * Test is a cache has all of the given keys. 1100 * 1101 * It is strongly recommended to avoid the use of this function if not absolutely required. 1102 * In a high load environment the cache may well change between the test and any subsequent action (get, set, delete etc). 1103 * 1104 * Its also worth mentioning that not all stores support key tests. 1105 * For stores that don't support key tests this functionality is mimicked by using the equivalent get method. 1106 * Just one more reason you should not use these methods unless you have a very good reason to do so. 1107 * 1108 * @param array $keys 1109 * @return bool True if the cache has all of the given keys, false otherwise. 1110 */ 1111 public function has_all(array $keys) { 1112 if (($this->has_a_ttl() && !$this->store_supports_native_ttl()) || !$this->store_supports_key_awareness()) { 1113 foreach ($keys as $key) { 1114 if (!$this->has($key)) { 1115 return false; 1116 } 1117 } 1118 return true; 1119 } 1120 $parsedkeys = array_map(array($this, 'parse_key'), $keys); 1121 return $this->store->has_all($parsedkeys); 1122 } 1123 1124 /** 1125 * Test if a cache has at least one of the given keys. 1126 * 1127 * It is strongly recommended to avoid the use of this function if not absolutely required. 1128 * In a high load environment the cache may well change between the test and any subsequent action (get, set, delete etc). 1129 * 1130 * Its also worth mentioning that not all stores support key tests. 1131 * For stores that don't support key tests this functionality is mimicked by using the equivalent get method. 1132 * Just one more reason you should not use these methods unless you have a very good reason to do so. 1133 * 1134 * @param array $keys 1135 * @return bool True if the cache has at least one of the given keys 1136 */ 1137 public function has_any(array $keys) { 1138 if (($this->has_a_ttl() && !$this->store_supports_native_ttl()) || !$this->store_supports_key_awareness()) { 1139 foreach ($keys as $key) { 1140 if ($this->has($key)) { 1141 return true; 1142 } 1143 } 1144 return false; 1145 } 1146 1147 if ($this->use_static_acceleration()) { 1148 foreach ($keys as $id => $key) { 1149 if ($this->static_acceleration_has($key)) { 1150 return true; 1151 } 1152 } 1153 } 1154 $parsedkeys = array_map(array($this, 'parse_key'), $keys); 1155 return $this->store->has_any($parsedkeys); 1156 } 1157 1158 /** 1159 * Delete the given key from the cache. 1160 * 1161 * @param string|int $key The key to delete. 1162 * @param bool $recurse When set to true the key will also be deleted from all stacked cache loaders and their stores. 1163 * This happens by default and ensure that all the caches are consistent. It is NOT recommended to change this. 1164 * @return bool True of success, false otherwise. 1165 */ 1166 public function delete($key, $recurse = true) { 1167 $this->static_acceleration_delete($key); 1168 if ($recurse && $this->loader !== false) { 1169 // Delete from the bottom of the stack first. 1170 $this->loader->delete($key, $recurse); 1171 } 1172 $parsedkey = $this->parse_key($key); 1173 return $this->store->delete($parsedkey); 1174 } 1175 1176 /** 1177 * Delete all of the given keys from the cache. 1178 * 1179 * @param array $keys The key to delete. 1180 * @param bool $recurse When set to true the key will also be deleted from all stacked cache loaders and their stores. 1181 * This happens by default and ensure that all the caches are consistent. It is NOT recommended to change this. 1182 * @return int The number of items successfully deleted. 1183 */ 1184 public function delete_many(array $keys, $recurse = true) { 1185 if ($this->use_static_acceleration()) { 1186 foreach ($keys as $key) { 1187 $this->static_acceleration_delete($key); 1188 } 1189 } 1190 if ($recurse && $this->loader !== false) { 1191 // Delete from the bottom of the stack first. 1192 $this->loader->delete_many($keys, $recurse); 1193 } 1194 $parsedkeys = array_map(array($this, 'parse_key'), $keys); 1195 return $this->store->delete_many($parsedkeys); 1196 } 1197 1198 /** 1199 * Purges the cache store, and loader if there is one. 1200 * 1201 * @return bool True on success, false otherwise 1202 */ 1203 public function purge() { 1204 // 1. Purge the static acceleration array. 1205 $this->static_acceleration_purge(); 1206 // 2. Purge the store. 1207 $this->store->purge(); 1208 // 3. Optionally pruge any stacked loaders. 1209 if ($this->loader) { 1210 $this->loader->purge(); 1211 } 1212 return true; 1213 } 1214 1215 /** 1216 * Parses the key turning it into a string (or array is required) suitable to be passed to the cache store. 1217 * 1218 * @param string|int $key As passed to get|set|delete etc. 1219 * @return string|array String unless the store supports multi-identifiers in which case an array if returned. 1220 */ 1221 protected function parse_key($key) { 1222 // First up if the store supports multiple keys we'll go with that. 1223 if ($this->store->supports_multiple_identifiers()) { 1224 $result = $this->definition->generate_multi_key_parts(); 1225 $result['key'] = $key; 1226 return $result; 1227 } 1228 // If not we need to generate a hash and to for that we use the cache_helper. 1229 return cache_helper::hash_key($key, $this->definition); 1230 } 1231 1232 /** 1233 * Returns true if the cache is making use of a ttl. 1234 * @return bool 1235 */ 1236 protected function has_a_ttl() { 1237 return $this->hasattl; 1238 } 1239 1240 /** 1241 * Returns true if the cache store supports native ttl. 1242 * @return bool 1243 */ 1244 protected function store_supports_native_ttl() { 1245 if ($this->supportsnativettl === null) { 1246 $this->supportsnativettl = ($this->store->supports_native_ttl()); 1247 } 1248 return $this->supportsnativettl; 1249 } 1250 1251 /** 1252 * Returns the cache definition. 1253 * 1254 * @return cache_definition 1255 */ 1256 protected function get_definition() { 1257 return $this->definition; 1258 } 1259 1260 /** 1261 * Returns the cache store 1262 * 1263 * @return cache_store 1264 */ 1265 protected function get_store() { 1266 return $this->store; 1267 } 1268 1269 /** 1270 * Returns the loader associated with this instance. 1271 * 1272 * @since Moodle 2.4.4 1273 * @return cache|false 1274 */ 1275 protected function get_loader() { 1276 return $this->loader; 1277 } 1278 1279 /** 1280 * Returns the data source associated with this cache. 1281 * 1282 * @since Moodle 2.4.4 1283 * @return cache_data_source|false 1284 */ 1285 protected function get_datasource() { 1286 return $this->datasource; 1287 } 1288 1289 /** 1290 * Returns true if the store supports key awareness. 1291 * 1292 * @return bool 1293 */ 1294 protected function store_supports_key_awareness() { 1295 if ($this->supportskeyawareness === null) { 1296 $this->supportskeyawareness = ($this->store instanceof cache_is_key_aware); 1297 } 1298 return $this->supportskeyawareness; 1299 } 1300 1301 /** 1302 * Returns true if the store natively supports locking. 1303 * 1304 * @return bool 1305 */ 1306 protected function store_supports_native_locking() { 1307 if ($this->nativelocking === null) { 1308 $this->nativelocking = ($this->store instanceof cache_is_lockable); 1309 } 1310 return $this->nativelocking; 1311 } 1312 1313 /** 1314 * @deprecated since 2.6 1315 * @see cache::use_static_acceleration() 1316 */ 1317 protected function is_using_persist_cache() { 1318 throw new coding_exception('cache::is_using_persist_cache() can not be used anymore.' . 1319 ' Please use cache::use_static_acceleration() instead.'); 1320 } 1321 1322 /** 1323 * Returns true if this cache is making use of the static acceleration array. 1324 * 1325 * @return bool 1326 */ 1327 protected function use_static_acceleration() { 1328 return $this->staticacceleration; 1329 } 1330 1331 /** 1332 * @see cache::static_acceleration_has 1333 * @deprecated since 2.6 1334 */ 1335 protected function is_in_persist_cache() { 1336 throw new coding_exception('cache::is_in_persist_cache() can not be used anymore.' . 1337 ' Please use cache::static_acceleration_has() instead.'); 1338 } 1339 1340 /** 1341 * Returns true if the requested key exists within the static acceleration array. 1342 * 1343 * @param string $key The parsed key 1344 * @return bool 1345 */ 1346 protected function static_acceleration_has($key) { 1347 // This could be written as a single line, however it has been split because the ttl check is faster than the instanceof 1348 // and has_expired calls. 1349 if (!$this->staticacceleration || !isset($this->staticaccelerationarray[$key])) { 1350 return false; 1351 } 1352 return true; 1353 } 1354 1355 /** 1356 * @deprecated since 2.6 1357 * @see cache::static_acceleration_get 1358 */ 1359 protected function get_from_persist_cache() { 1360 throw new coding_exception('cache::get_from_persist_cache() can not be used anymore.' . 1361 ' Please use cache::static_acceleration_get() instead.'); 1362 } 1363 1364 /** 1365 * Returns the item from the static acceleration array if it exists there. 1366 * 1367 * @param string $key The parsed key 1368 * @return mixed|false Dereferenced data from the static acceleration array or false if it wasn't there. 1369 */ 1370 protected function static_acceleration_get($key) { 1371 if (!$this->staticacceleration || !isset($this->staticaccelerationarray[$key])) { 1372 $result = false; 1373 } else { 1374 $data = $this->staticaccelerationarray[$key]['data']; 1375 1376 if ($data instanceof cache_cached_object) { 1377 $result = $data->restore_object(); 1378 } else if ($this->staticaccelerationarray[$key]['serialized']) { 1379 $result = unserialize($data); 1380 } else { 1381 $result = $data; 1382 } 1383 } 1384 if (cache_helper::result_found($result)) { 1385 if ($this->perfdebug) { 1386 cache_helper::record_cache_hit(cache_store::STATIC_ACCEL, $this->definition); 1387 } 1388 if ($this->staticaccelerationsize > 1 && $this->staticaccelerationcount > 1) { 1389 // Check to see if this is the last item on the static acceleration keys array. 1390 if (end($this->staticaccelerationkeys) !== $key) { 1391 // It isn't the last item. 1392 // Move the item to the end of the array so that it is last to be removed. 1393 unset($this->staticaccelerationkeys[$key]); 1394 $this->staticaccelerationkeys[$key] = $key; 1395 } 1396 } 1397 return $result; 1398 } else { 1399 if ($this->perfdebug) { 1400 cache_helper::record_cache_miss(cache_store::STATIC_ACCEL, $this->definition); 1401 } 1402 return false; 1403 } 1404 } 1405 1406 /** 1407 * @deprecated since 2.6 1408 * @see cache::static_acceleration_set 1409 */ 1410 protected function set_in_persist_cache() { 1411 throw new coding_exception('cache::set_in_persist_cache() can not be used anymore.' . 1412 ' Please use cache::static_acceleration_set() instead.'); 1413 } 1414 1415 /** 1416 * Sets a key value pair into the static acceleration array. 1417 * 1418 * @param string $key The parsed key 1419 * @param mixed $data 1420 * @return bool 1421 */ 1422 protected function static_acceleration_set($key, $data) { 1423 if ($this->staticaccelerationsize !== false && isset($this->staticaccelerationkeys[$key])) { 1424 $this->staticaccelerationcount--; 1425 unset($this->staticaccelerationkeys[$key]); 1426 } 1427 1428 // We serialize anything that's not; 1429 // 1. A known scalar safe value. 1430 // 2. A definition that says it's simpledata. We trust it that it doesn't contain dangerous references. 1431 // 3. An object that handles dereferencing by itself. 1432 if (is_scalar($data) || $this->definition->uses_simple_data() 1433 || $data instanceof cache_cached_object) { 1434 $this->staticaccelerationarray[$key]['data'] = $data; 1435 $this->staticaccelerationarray[$key]['serialized'] = false; 1436 } else { 1437 $this->staticaccelerationarray[$key]['data'] = serialize($data); 1438 $this->staticaccelerationarray[$key]['serialized'] = true; 1439 } 1440 if ($this->staticaccelerationsize !== false) { 1441 $this->staticaccelerationcount++; 1442 $this->staticaccelerationkeys[$key] = $key; 1443 if ($this->staticaccelerationcount > $this->staticaccelerationsize) { 1444 $dropkey = array_shift($this->staticaccelerationkeys); 1445 unset($this->staticaccelerationarray[$dropkey]); 1446 $this->staticaccelerationcount--; 1447 } 1448 } 1449 return true; 1450 } 1451 1452 /** 1453 * @deprecated since 2.6 1454 * @see cache::static_acceleration_delete() 1455 */ 1456 protected function delete_from_persist_cache() { 1457 throw new coding_exception('cache::delete_from_persist_cache() can not be used anymore.' . 1458 ' Please use cache::static_acceleration_delete() instead.'); 1459 } 1460 1461 /** 1462 * Deletes an item from the static acceleration array. 1463 * 1464 * @param string|int $key As given to get|set|delete 1465 * @return bool True on success, false otherwise. 1466 */ 1467 protected function static_acceleration_delete($key) { 1468 unset($this->staticaccelerationarray[$key]); 1469 if ($this->staticaccelerationsize !== false && isset($this->staticaccelerationkeys[$key])) { 1470 unset($this->staticaccelerationkeys[$key]); 1471 $this->staticaccelerationcount--; 1472 } 1473 return true; 1474 } 1475 1476 /** 1477 * Purge the static acceleration cache. 1478 */ 1479 protected function static_acceleration_purge() { 1480 $this->staticaccelerationarray = array(); 1481 if ($this->staticaccelerationsize !== false) { 1482 $this->staticaccelerationkeys = array(); 1483 $this->staticaccelerationcount = 0; 1484 } 1485 } 1486 1487 /** 1488 * Returns the timestamp from the first request for the time from the cache API. 1489 * 1490 * This stamp needs to be used for all ttl and time based operations to ensure that we don't end up with 1491 * timing issues. 1492 * 1493 * @param bool $float Whether to use floating precision accuracy. 1494 * @return int|float 1495 */ 1496 public static function now($float = false) { 1497 if (self::$now === null) { 1498 self::$now = microtime(true); 1499 } 1500 1501 if ($float) { 1502 return self::$now; 1503 } else { 1504 return (int) self::$now; 1505 } 1506 } 1507 1508 /** 1509 * Get a 'purge' token used for cache invalidation handling. 1510 * 1511 * Note: This function is intended for use from within the Cache API only and not by plugins, or cache stores. 1512 * 1513 * @param bool $reset Whether to reset the token and generate a new one. 1514 * @return string 1515 */ 1516 public static function get_purge_token($reset = false) { 1517 if (self::$purgetoken === null || $reset) { 1518 self::$now = null; 1519 self::$purgetoken = self::now(true) . '-' . uniqid('', true); 1520 } 1521 1522 return self::$purgetoken; 1523 } 1524 1525 /** 1526 * Compare a pair of purge tokens. 1527 * 1528 * If the two tokens are identical, then the return value is 0. 1529 * If the time component of token A is newer than token B, then a positive value is returned. 1530 * If the time component of token B is newer than token A, then a negative value is returned. 1531 * 1532 * Note: This function is intended for use from within the Cache API only and not by plugins, or cache stores. 1533 * 1534 * @param string $tokena 1535 * @param string $tokenb 1536 * @return int 1537 */ 1538 public static function compare_purge_tokens($tokena, $tokenb) { 1539 if ($tokena === $tokenb) { 1540 // There is an exact match. 1541 return 0; 1542 } 1543 1544 // The token for when the cache was last invalidated. 1545 list($atime) = explode('-', "{$tokena}-", 2); 1546 1547 // The token for this cache. 1548 list($btime) = explode('-', "{$tokenb}-", 2); 1549 1550 if ($atime >= $btime) { 1551 // Token A is newer. 1552 return 1; 1553 } else { 1554 // Token A is older. 1555 return -1; 1556 } 1557 } 1558 1559 /** 1560 * Subclasses may support purging cache of all data belonging to the 1561 * current user. 1562 */ 1563 public function purge_current_user() { 1564 } 1565 } 1566 1567 /** 1568 * An application cache. 1569 * 1570 * This class is used for application caches returned by the cache::make methods. 1571 * On top of the standard functionality it also allows locking to be required and or manually operated. 1572 * 1573 * This cache class should never be interacted with directly. Instead you should always use the cache::make methods. 1574 * It is technically possible to call those methods through this class however there is no guarantee that you will get an 1575 * instance of this class back again. 1576 * 1577 * @internal don't use me directly. 1578 * 1579 * @package core 1580 * @category cache 1581 * @copyright 2012 Sam Hemelryk 1582 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1583 */ 1584 class cache_application extends cache implements cache_loader_with_locking { 1585 1586 /** 1587 * Lock identifier. 1588 * This is used to ensure the lock belongs to the cache instance + definition + user. 1589 * @var string 1590 */ 1591 protected $lockidentifier; 1592 1593 /** 1594 * Gets set to true if the cache's primary store natively supports locking. 1595 * If it does then we use that, otherwise we need to instantiate a second store to use for locking. 1596 * @var cache_store 1597 */ 1598 protected $nativelocking = null; 1599 1600 /** 1601 * Gets set to true if the cache is going to be using locking. 1602 * This isn't a requirement, it doesn't need to use locking (most won't) and this bool is used to quickly check things. 1603 * If required then locking will be forced for the get|set|delete operation. 1604 * @var bool 1605 */ 1606 protected $requirelocking = false; 1607 1608 /** 1609 * Gets set to true if the cache writes (set|delete) must have a manual lock created first 1610 * @var bool 1611 */ 1612 protected $requirelockingbeforewrite = false; 1613 1614 /** 1615 * Gets set to a cache_store to use for locking if the caches primary store doesn't support locking natively. 1616 * @var cache_lock_interface 1617 */ 1618 protected $cachelockinstance; 1619 1620 /** 1621 * Store a list of locks acquired by this process. 1622 * @var array 1623 */ 1624 protected $locks; 1625 1626 /** 1627 * Overrides the cache construct method. 1628 * 1629 * You should not call this method from your code, instead you should use the cache::make methods. 1630 * 1631 * @param cache_definition $definition 1632 * @param cache_store $store 1633 * @param cache_loader|cache_data_source $loader 1634 */ 1635 public function __construct(cache_definition $definition, cache_store $store, $loader = null) { 1636 parent::__construct($definition, $store, $loader); 1637 $this->nativelocking = $this->store_supports_native_locking(); 1638 if ($definition->require_locking()) { 1639 $this->requirelocking = true; 1640 $this->requirelockingbeforewrite = $definition->require_locking_before_write(); 1641 } 1642 1643 $this->handle_invalidation_events(); 1644 } 1645 1646 /** 1647 * Returns the identifier to use 1648 * 1649 * @staticvar int $instances Counts the number of instances. Used as part of the lock identifier. 1650 * @return string 1651 */ 1652 public function get_identifier() { 1653 static $instances = 0; 1654 if ($this->lockidentifier === null) { 1655 $this->lockidentifier = md5( 1656 $this->get_definition()->generate_definition_hash() . 1657 sesskey() . 1658 $instances++ . 1659 'cache_application' 1660 ); 1661 } 1662 return $this->lockidentifier; 1663 } 1664 1665 /** 1666 * Fixes the instance up after a clone. 1667 */ 1668 public function __clone() { 1669 // Force a new idenfitier. 1670 $this->lockidentifier = null; 1671 } 1672 1673 /** 1674 * Acquires a lock on the given key. 1675 * 1676 * This is done automatically if the definition requires it. 1677 * It is recommended to use a definition if you want to have locking although it is possible to do locking without having 1678 * it required by the definition. 1679 * The problem with such an approach is that you cannot ensure that code will consistently use locking. You will need to 1680 * rely on the integrators review skills. 1681 * 1682 * @param string|int $key The key as given to get|set|delete 1683 * @return bool Always returns true 1684 * @throws moodle_exception If the lock cannot be obtained 1685 */ 1686 public function acquire_lock($key) { 1687 $releaseparent = false; 1688 try { 1689 if ($this->get_loader() !== false) { 1690 $this->get_loader()->acquire_lock($key); 1691 // We need to release this lock later if the lock is not successful. 1692 $releaseparent = true; 1693 } 1694 $hashedkey = cache_helper::hash_key($key, $this->get_definition()); 1695 $before = microtime(true); 1696 if ($this->nativelocking) { 1697 $lock = $this->get_store()->acquire_lock($hashedkey, $this->get_identifier()); 1698 } else { 1699 $this->ensure_cachelock_available(); 1700 $lock = $this->cachelockinstance->lock($hashedkey, $this->get_identifier()); 1701 } 1702 $after = microtime(true); 1703 if ($lock) { 1704 $this->locks[$hashedkey] = $lock; 1705 if (MDL_PERF || $this->perfdebug) { 1706 \core\lock\timing_wrapper_lock_factory::record_lock_data($after, $before, 1707 $this->get_definition()->get_id(), $hashedkey, $lock, $this->get_identifier() . $hashedkey); 1708 } 1709 $releaseparent = false; 1710 return true; 1711 } else { 1712 throw new moodle_exception('ex_unabletolock', 'cache', '', null, 1713 'store: ' . get_class($this->get_store()) . ', lock: ' . $hashedkey); 1714 } 1715 } finally { 1716 // Release the parent lock if we acquired it, then threw an exception. 1717 if ($releaseparent) { 1718 $this->get_loader()->release_lock($key); 1719 } 1720 } 1721 } 1722 1723 /** 1724 * Checks if this cache has a lock on the given key. 1725 * 1726 * @param string|int $key The key as given to get|set|delete 1727 * @return bool|null Returns true if there is a lock and this cache has it, null if no one has a lock on that key, false if 1728 * someone else has the lock. 1729 */ 1730 public function check_lock_state($key) { 1731 $key = cache_helper::hash_key($key, $this->get_definition()); 1732 if (!empty($this->locks[$key])) { 1733 return true; // Shortcut to save having to make a call to the cache store if the lock is held by this process. 1734 } 1735 if ($this->nativelocking) { 1736 return $this->get_store()->check_lock_state($key, $this->get_identifier()); 1737 } else { 1738 $this->ensure_cachelock_available(); 1739 return $this->cachelockinstance->check_state($key, $this->get_identifier()); 1740 } 1741 } 1742 1743 /** 1744 * Releases the lock this cache has on the given key 1745 * 1746 * @param string|int $key 1747 * @return bool True if the operation succeeded, false otherwise. 1748 */ 1749 public function release_lock($key) { 1750 $loaderkey = $key; 1751 $key = cache_helper::hash_key($key, $this->get_definition()); 1752 if ($this->nativelocking) { 1753 $released = $this->get_store()->release_lock($key, $this->get_identifier()); 1754 } else { 1755 $this->ensure_cachelock_available(); 1756 $released = $this->cachelockinstance->unlock($key, $this->get_identifier()); 1757 } 1758 if ($released && array_key_exists($key, $this->locks)) { 1759 unset($this->locks[$key]); 1760 if (MDL_PERF || $this->perfdebug) { 1761 \core\lock\timing_wrapper_lock_factory::record_lock_released_data($this->get_identifier() . $key); 1762 } 1763 } 1764 if ($this->get_loader() !== false) { 1765 $this->get_loader()->release_lock($loaderkey); 1766 } 1767 return $released; 1768 } 1769 1770 /** 1771 * Ensure that the dedicated lock store is ready to go. 1772 * 1773 * This should only happen if the cache store doesn't natively support it. 1774 */ 1775 protected function ensure_cachelock_available() { 1776 if ($this->cachelockinstance === null) { 1777 $this->cachelockinstance = cache_helper::get_cachelock_for_store($this->get_store()); 1778 } 1779 } 1780 1781 /** 1782 * Sends a key => value pair to the cache. 1783 * 1784 * <code> 1785 * // This code will add four entries to the cache, one for each url. 1786 * $cache->set('main', 'http://moodle.org'); 1787 * $cache->set('docs', 'http://docs.moodle.org'); 1788 * $cache->set('tracker', 'http://tracker.moodle.org'); 1789 * $cache->set('qa', 'http://qa.moodle.net'); 1790 * </code> 1791 * 1792 * @param string|int $key The key for the data being requested. 1793 * @param int $version Version number 1794 * @param mixed $data The data to set against the key. 1795 * @param bool $setparents If true, sets all parent loaders, otherwise only this one 1796 * @return bool True on success, false otherwise. 1797 * @throws coding_exception If a required lock has not beeen acquired 1798 */ 1799 protected function set_implementation($key, int $version, $data, bool $setparents = true): bool { 1800 if ($this->requirelockingbeforewrite && !$this->check_lock_state($key)) { 1801 throw new coding_exception('Attempted to set cache key "' . $key . '" without a lock. ' 1802 . 'Locking before writes is required for ' . $this->get_definition()->get_id()); 1803 } 1804 return parent::set_implementation($key, $version, $data, $setparents); 1805 } 1806 1807 /** 1808 * Sends several key => value pairs to the cache. 1809 * 1810 * Using this function comes with potential performance implications. 1811 * Not all cache stores will support get_many/set_many operations and in order to replicate this functionality will call 1812 * the equivalent singular method for each item provided. 1813 * This should not deter you from using this function as there is a performance benefit in situations where the cache store 1814 * does support it, but you should be aware of this fact. 1815 * 1816 * <code> 1817 * // This code will add four entries to the cache, one for each url. 1818 * $cache->set_many(array( 1819 * 'main' => 'http://moodle.org', 1820 * 'docs' => 'http://docs.moodle.org', 1821 * 'tracker' => 'http://tracker.moodle.org', 1822 * 'qa' => ''http://qa.moodle.net' 1823 * )); 1824 * </code> 1825 * 1826 * @param array $keyvaluearray An array of key => value pairs to send to the cache. 1827 * @return int The number of items successfully set. It is up to the developer to check this matches the number of items. 1828 * ... if they care that is. 1829 * @throws coding_exception If a required lock has not beeen acquired 1830 */ 1831 public function set_many(array $keyvaluearray) { 1832 if ($this->requirelockingbeforewrite) { 1833 foreach ($keyvaluearray as $key => $value) { 1834 if (!$this->check_lock_state($key)) { 1835 throw new coding_exception('Attempted to set cache key "' . $key . '" without a lock. ' 1836 . 'Locking before writes is required for ' . $this->get_definition()->get_id()); 1837 } 1838 } 1839 } 1840 return parent::set_many($keyvaluearray); 1841 } 1842 1843 /** 1844 * Delete the given key from the cache. 1845 * 1846 * @param string|int $key The key to delete. 1847 * @param bool $recurse When set to true the key will also be deleted from all stacked cache loaders and their stores. 1848 * This happens by default and ensure that all the caches are consistent. It is NOT recommended to change this. 1849 * @return bool True of success, false otherwise. 1850 * @throws coding_exception If a required lock has not beeen acquired 1851 */ 1852 public function delete($key, $recurse = true) { 1853 if ($this->requirelockingbeforewrite && !$this->check_lock_state($key)) { 1854 throw new coding_exception('Attempted to delete cache key "' . $key . '" without a lock. ' 1855 . 'Locking before writes is required for ' . $this->get_definition()->get_id()); 1856 } 1857 return parent::delete($key, $recurse); 1858 } 1859 1860 /** 1861 * Delete all of the given keys from the cache. 1862 * 1863 * @param array $keys The key to delete. 1864 * @param bool $recurse When set to true the key will also be deleted from all stacked cache loaders and their stores. 1865 * This happens by default and ensure that all the caches are consistent. It is NOT recommended to change this. 1866 * @return int The number of items successfully deleted. 1867 * @throws coding_exception If a required lock has not beeen acquired 1868 */ 1869 public function delete_many(array $keys, $recurse = true) { 1870 if ($this->requirelockingbeforewrite) { 1871 foreach ($keys as $key) { 1872 if (!$this->check_lock_state($key)) { 1873 throw new coding_exception('Attempted to delete cache key "' . $key . '" without a lock. ' 1874 . 'Locking before writes is required for ' . $this->get_definition()->get_id()); 1875 } 1876 } 1877 } 1878 return parent::delete_many($keys, $recurse); 1879 } 1880 } 1881 1882 /** 1883 * A session cache. 1884 * 1885 * This class is used for session caches returned by the cache::make methods. 1886 * 1887 * It differs from the application loader in a couple of noteable ways: 1888 * 1. Sessions are always expected to exist. 1889 * Because of this we don't ever use the static acceleration array. 1890 * 2. Session data for a loader instance (store + definition) is consolidate into a 1891 * single array for storage within the store. 1892 * Along with this we embed a lastaccessed time with the data. This way we can 1893 * check sessions for a last access time. 1894 * 3. Session stores are required to support key searching and must 1895 * implement cache_is_searchable. This ensures stores used for the cache can be 1896 * targetted for garbage collection of session data. 1897 * 1898 * This cache class should never be interacted with directly. Instead you should always use the cache::make methods. 1899 * It is technically possible to call those methods through this class however there is no guarantee that you will get an 1900 * instance of this class back again. 1901 * 1902 * @todo we should support locking in the session as well. Should be pretty simple to set up. 1903 * 1904 * @internal don't use me directly. 1905 * @method cache_store|cache_is_searchable get_store() Returns the cache store which must implement both cache_is_searchable. 1906 * 1907 * @package core 1908 * @category cache 1909 * @copyright 2012 Sam Hemelryk 1910 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1911 */ 1912 class cache_session extends cache { 1913 /** 1914 * The user the session has been established for. 1915 * @var int 1916 */ 1917 protected static $loadeduserid = null; 1918 1919 /** 1920 * The userid this cache is currently using. 1921 * @var int 1922 */ 1923 protected $currentuserid = null; 1924 1925 /** 1926 * The session id we are currently using. 1927 * @var array 1928 */ 1929 protected $sessionid = null; 1930 1931 /** 1932 * The session data for the above session id. 1933 * @var array 1934 */ 1935 protected $session = null; 1936 1937 /** 1938 * Constant used to prefix keys. 1939 */ 1940 const KEY_PREFIX = 'sess_'; 1941 1942 /** 1943 * This is the key used to track last access. 1944 */ 1945 const LASTACCESS = '__lastaccess__'; 1946 1947 /** 1948 * Override the cache::construct method. 1949 * 1950 * This function gets overriden so that we can process any invalidation events if need be. 1951 * If the definition doesn't have any invalidation events then this occurs exactly as it would for the cache class. 1952 * Otherwise we look at the last invalidation time and then check the invalidation data for events that have occured 1953 * between then now. 1954 * 1955 * You should not call this method from your code, instead you should use the cache::make methods. 1956 * 1957 * @param cache_definition $definition 1958 * @param cache_store $store 1959 * @param cache_loader|cache_data_source $loader 1960 */ 1961 public function __construct(cache_definition $definition, cache_store $store, $loader = null) { 1962 // First up copy the loadeduserid to the current user id. 1963 $this->currentuserid = self::$loadeduserid; 1964 $this->set_session_id(); 1965 parent::__construct($definition, $store, $loader); 1966 1967 // This will trigger check tracked user. If this gets removed a call to that will need to be added here in its place. 1968 $this->set(self::LASTACCESS, cache::now()); 1969 1970 $this->handle_invalidation_events(); 1971 } 1972 1973 /** 1974 * Sets the session id for the loader. 1975 */ 1976 protected function set_session_id() { 1977 $this->sessionid = preg_replace('#[^a-zA-Z0-9_]#', '_', session_id()); 1978 } 1979 1980 /** 1981 * Returns the prefix used for all keys. 1982 * @return string 1983 */ 1984 protected function get_key_prefix() { 1985 return 'u'.$this->currentuserid.'_'.$this->sessionid; 1986 } 1987 1988 /** 1989 * Parses the key turning it into a string (or array is required) suitable to be passed to the cache store. 1990 * 1991 * This function is called for every operation that uses keys. For this reason we use this function to also check 1992 * that the current user is the same as the user who last used this cache. 1993 * 1994 * On top of that if prepends the string 'sess_' to the start of all keys. The _ ensures things are easily identifiable. 1995 * 1996 * @param string|int $key As passed to get|set|delete etc. 1997 * @return string|array String unless the store supports multi-identifiers in which case an array if returned. 1998 */ 1999 protected function parse_key($key) { 2000 $prefix = $this->get_key_prefix(); 2001 if ($key === self::LASTACCESS) { 2002 return $key.$prefix; 2003 } 2004 return $prefix.'_'.parent::parse_key($key); 2005 } 2006 2007 /** 2008 * Check that this cache instance is tracking the current user. 2009 */ 2010 protected function check_tracked_user() { 2011 if (isset($_SESSION['USER']->id) && $_SESSION['USER']->id !== null) { 2012 // Get the id of the current user. 2013 $new = $_SESSION['USER']->id; 2014 } else { 2015 // No user set up yet. 2016 $new = 0; 2017 } 2018 if ($new !== self::$loadeduserid) { 2019 // The current user doesn't match the tracked userid for this request. 2020 if (!is_null(self::$loadeduserid)) { 2021 // Purge the data we have for the old user. 2022 // This way we don't bloat the session. 2023 $this->purge(); 2024 } 2025 self::$loadeduserid = $new; 2026 $this->currentuserid = $new; 2027 } else if ($new !== $this->currentuserid) { 2028 // The current user matches the loaded user but not the user last used by this cache. 2029 $this->purge_current_user(); 2030 $this->currentuserid = $new; 2031 } 2032 } 2033 2034 /** 2035 * Purges the session cache of all data belonging to the current user. 2036 */ 2037 public function purge_current_user() { 2038 $keys = $this->get_store()->find_by_prefix($this->get_key_prefix()); 2039 $this->get_store()->delete_many($keys); 2040 } 2041 2042 /** 2043 * Retrieves the value for the given key from the cache. 2044 * 2045 * @param string|int $key The key for the data being requested. 2046 * It can be any structure although using a scalar string or int is recommended in the interests of performance. 2047 * In advanced cases an array may be useful such as in situations requiring the multi-key functionality. 2048 * @param int $requiredversion Minimum required version of the data or cache::VERSION_NONE 2049 * @param int $strictness One of IGNORE_MISSING | MUST_EXIST 2050 * @param mixed &$actualversion If specified, will be set to the actual version number retrieved 2051 * @return mixed|false The data from the cache or false if the key did not exist within the cache. 2052 * @throws coding_exception 2053 */ 2054 protected function get_implementation($key, int $requiredversion, int $strictness, &$actualversion = null) { 2055 // Check the tracked user. 2056 $this->check_tracked_user(); 2057 2058 // Use parent code. 2059 return parent::get_implementation($key, $requiredversion, $strictness, $actualversion); 2060 } 2061 2062 /** 2063 * Sends a key => value pair to the cache. 2064 * 2065 * <code> 2066 * // This code will add four entries to the cache, one for each url. 2067 * $cache->set('main', 'http://moodle.org'); 2068 * $cache->set('docs', 'http://docs.moodle.org'); 2069 * $cache->set('tracker', 'http://tracker.moodle.org'); 2070 * $cache->set('qa', 'http://qa.moodle.net'); 2071 * </code> 2072 * 2073 * @param string|int $key The key for the data being requested. 2074 * It can be any structure although using a scalar string or int is recommended in the interests of performance. 2075 * In advanced cases an array may be useful such as in situations requiring the multi-key functionality. 2076 * @param mixed $data The data to set against the key. 2077 * @return bool True on success, false otherwise. 2078 */ 2079 public function set($key, $data) { 2080 $this->check_tracked_user(); 2081 $loader = $this->get_loader(); 2082 if ($loader !== false) { 2083 // We have a loader available set it there as well. 2084 // We have to let the loader do its own parsing of data as it may be unique. 2085 $loader->set($key, $data); 2086 } 2087 if (is_object($data) && $data instanceof cacheable_object) { 2088 $data = new cache_cached_object($data); 2089 } else if (!$this->get_store()->supports_dereferencing_objects() && !is_scalar($data)) { 2090 // If data is an object it will be a reference. 2091 // If data is an array if may contain references. 2092 // We want to break references so that the cache cannot be modified outside of itself. 2093 // Call the function to unreference it (in the best way possible). 2094 $data = $this->unref($data); 2095 } 2096 // We dont' support native TTL here as we consolidate data for sessions. 2097 if ($this->has_a_ttl() && !$this->store_supports_native_ttl()) { 2098 $data = new cache_ttl_wrapper($data, $this->get_definition()->get_ttl()); 2099 } 2100 $success = $this->get_store()->set($this->parse_key($key), $data); 2101 if ($this->perfdebug) { 2102 cache_helper::record_cache_set($this->get_store(), $this->get_definition(), 1, 2103 $this->get_store()->get_last_io_bytes()); 2104 } 2105 return $success; 2106 } 2107 2108 /** 2109 * Delete the given key from the cache. 2110 * 2111 * @param string|int $key The key to delete. 2112 * @param bool $recurse When set to true the key will also be deleted from all stacked cache loaders and their stores. 2113 * This happens by default and ensure that all the caches are consistent. It is NOT recommended to change this. 2114 * @return bool True of success, false otherwise. 2115 */ 2116 public function delete($key, $recurse = true) { 2117 $parsedkey = $this->parse_key($key); 2118 if ($recurse && $this->get_loader() !== false) { 2119 // Delete from the bottom of the stack first. 2120 $this->get_loader()->delete($key, $recurse); 2121 } 2122 return $this->get_store()->delete($parsedkey); 2123 } 2124 2125 /** 2126 * Retrieves an array of values for an array of keys. 2127 * 2128 * Using this function comes with potential performance implications. 2129 * Not all cache stores will support get_many/set_many operations and in order to replicate this functionality will call 2130 * the equivalent singular method for each item provided. 2131 * This should not deter you from using this function as there is a performance benefit in situations where the cache store 2132 * does support it, but you should be aware of this fact. 2133 * 2134 * @param array $keys The keys of the data being requested. 2135 * Each key can be any structure although using a scalar string or int is recommended in the interests of performance. 2136 * In advanced cases an array may be useful such as in situations requiring the multi-key functionality. 2137 * @param int $strictness One of IGNORE_MISSING or MUST_EXIST. 2138 * @return array An array of key value pairs for the items that could be retrieved from the cache. 2139 * If MUST_EXIST was used and not all keys existed within the cache then an exception will be thrown. 2140 * Otherwise any key that did not exist will have a data value of false within the results. 2141 * @throws coding_exception 2142 */ 2143 public function get_many(array $keys, $strictness = IGNORE_MISSING) { 2144 $this->check_tracked_user(); 2145 $parsedkeys = array(); 2146 $keymap = array(); 2147 foreach ($keys as $key) { 2148 $parsedkey = $this->parse_key($key); 2149 $parsedkeys[$key] = $parsedkey; 2150 $keymap[$parsedkey] = $key; 2151 } 2152 $result = $this->get_store()->get_many($parsedkeys); 2153 if ($this->perfdebug) { 2154 $readbytes = $this->get_store()->get_last_io_bytes(); 2155 } 2156 $return = array(); 2157 $missingkeys = array(); 2158 $hasmissingkeys = false; 2159 foreach ($result as $parsedkey => $value) { 2160 $key = $keymap[$parsedkey]; 2161 if ($value instanceof cache_ttl_wrapper) { 2162 /* @var cache_ttl_wrapper $value */ 2163 if ($value->has_expired()) { 2164 $this->delete($keymap[$parsedkey]); 2165 $value = false; 2166 } else { 2167 $value = $value->data; 2168 } 2169 } 2170 if ($value instanceof cache_cached_object) { 2171 /* @var cache_cached_object $value */ 2172 $value = $value->restore_object(); 2173 } else if (!$this->get_store()->supports_dereferencing_objects() && !is_scalar($value)) { 2174 // If data is an object it will be a reference. 2175 // If data is an array if may contain references. 2176 // We want to break references so that the cache cannot be modified outside of itself. 2177 // Call the function to unreference it (in the best way possible). 2178 $value = $this->unref($value); 2179 } 2180 $return[$key] = $value; 2181 if ($value === false) { 2182 $hasmissingkeys = true; 2183 $missingkeys[$parsedkey] = $key; 2184 } 2185 } 2186 if ($hasmissingkeys) { 2187 // We've got missing keys - we've got to check any loaders or data sources. 2188 $loader = $this->get_loader(); 2189 $datasource = $this->get_datasource(); 2190 if ($loader !== false) { 2191 foreach ($loader->get_many($missingkeys) as $key => $value) { 2192 if ($value !== false) { 2193 $return[$key] = $value; 2194 unset($missingkeys[$parsedkeys[$key]]); 2195 } 2196 } 2197 } 2198 $hasmissingkeys = count($missingkeys) > 0; 2199 if ($datasource !== false && $hasmissingkeys) { 2200 // We're still missing keys but we've got a datasource. 2201 foreach ($datasource->load_many_for_cache($missingkeys) as $key => $value) { 2202 if ($value !== false) { 2203 $return[$key] = $value; 2204 unset($missingkeys[$parsedkeys[$key]]); 2205 } 2206 } 2207 $hasmissingkeys = count($missingkeys) > 0; 2208 } 2209 } 2210 if ($hasmissingkeys && $strictness === MUST_EXIST) { 2211 throw new coding_exception('Requested key did not exist in any cache stores and could not be loaded.'); 2212 } 2213 if ($this->perfdebug) { 2214 $hits = 0; 2215 $misses = 0; 2216 foreach ($return as $value) { 2217 if ($value === false) { 2218 $misses++; 2219 } else { 2220 $hits++; 2221 } 2222 } 2223 cache_helper::record_cache_hit($this->get_store(), $this->get_definition(), $hits, $readbytes); 2224 cache_helper::record_cache_miss($this->get_store(), $this->get_definition(), $misses); 2225 } 2226 return $return; 2227 2228 } 2229 2230 /** 2231 * Delete all of the given keys from the cache. 2232 * 2233 * @param array $keys The key to delete. 2234 * @param bool $recurse When set to true the key will also be deleted from all stacked cache loaders and their stores. 2235 * This happens by default and ensure that all the caches are consistent. It is NOT recommended to change this. 2236 * @return int The number of items successfully deleted. 2237 */ 2238 public function delete_many(array $keys, $recurse = true) { 2239 $parsedkeys = array_map(array($this, 'parse_key'), $keys); 2240 if ($recurse && $this->get_loader() !== false) { 2241 // Delete from the bottom of the stack first. 2242 $this->get_loader()->delete_many($keys, $recurse); 2243 } 2244 return $this->get_store()->delete_many($parsedkeys); 2245 } 2246 2247 /** 2248 * Sends several key => value pairs to the cache. 2249 * 2250 * Using this function comes with potential performance implications. 2251 * Not all cache stores will support get_many/set_many operations and in order to replicate this functionality will call 2252 * the equivalent singular method for each item provided. 2253 * This should not deter you from using this function as there is a performance benefit in situations where the cache store 2254 * does support it, but you should be aware of this fact. 2255 * 2256 * <code> 2257 * // This code will add four entries to the cache, one for each url. 2258 * $cache->set_many(array( 2259 * 'main' => 'http://moodle.org', 2260 * 'docs' => 'http://docs.moodle.org', 2261 * 'tracker' => 'http://tracker.moodle.org', 2262 * 'qa' => ''http://qa.moodle.net' 2263 * )); 2264 * </code> 2265 * 2266 * @param array $keyvaluearray An array of key => value pairs to send to the cache. 2267 * @return int The number of items successfully set. It is up to the developer to check this matches the number of items. 2268 * ... if they care that is. 2269 */ 2270 public function set_many(array $keyvaluearray) { 2271 $this->check_tracked_user(); 2272 $loader = $this->get_loader(); 2273 if ($loader !== false) { 2274 // We have a loader available set it there as well. 2275 // We have to let the loader do its own parsing of data as it may be unique. 2276 $loader->set_many($keyvaluearray); 2277 } 2278 $data = array(); 2279 $definitionid = $this->get_definition()->get_ttl(); 2280 $simulatettl = $this->has_a_ttl() && !$this->store_supports_native_ttl(); 2281 foreach ($keyvaluearray as $key => $value) { 2282 if (is_object($value) && $value instanceof cacheable_object) { 2283 $value = new cache_cached_object($value); 2284 } else if (!$this->get_store()->supports_dereferencing_objects() && !is_scalar($value)) { 2285 // If data is an object it will be a reference. 2286 // If data is an array if may contain references. 2287 // We want to break references so that the cache cannot be modified outside of itself. 2288 // Call the function to unreference it (in the best way possible). 2289 $value = $this->unref($value); 2290 } 2291 if ($simulatettl) { 2292 $value = new cache_ttl_wrapper($value, $definitionid); 2293 } 2294 $data[$key] = array( 2295 'key' => $this->parse_key($key), 2296 'value' => $value 2297 ); 2298 } 2299 $successfullyset = $this->get_store()->set_many($data); 2300 if ($this->perfdebug && $successfullyset) { 2301 cache_helper::record_cache_set($this->get_store(), $this->get_definition(), $successfullyset, 2302 $this->get_store()->get_last_io_bytes()); 2303 } 2304 return $successfullyset; 2305 } 2306 2307 /** 2308 * Purges the cache store, and loader if there is one. 2309 * 2310 * @return bool True on success, false otherwise 2311 */ 2312 public function purge() { 2313 $this->get_store()->purge(); 2314 if ($this->get_loader()) { 2315 $this->get_loader()->purge(); 2316 } 2317 return true; 2318 } 2319 2320 /** 2321 * Test is a cache has a key. 2322 * 2323 * The use of the has methods is strongly discouraged. In a high load environment the cache may well change between the 2324 * test and any subsequent action (get, set, delete etc). 2325 * Instead it is recommended to write your code in such a way they it performs the following steps: 2326 * <ol> 2327 * <li>Attempt to retrieve the information.</li> 2328 * <li>Generate the information.</li> 2329 * <li>Attempt to set the information</li> 2330 * </ol> 2331 * 2332 * Its also worth mentioning that not all stores support key tests. 2333 * For stores that don't support key tests this functionality is mimicked by using the equivalent get method. 2334 * Just one more reason you should not use these methods unless you have a very good reason to do so. 2335 * 2336 * @param string|int $key 2337 * @param bool $tryloadifpossible If set to true, the cache doesn't contain the key, and there is another cache loader or 2338 * data source then the code will try load the key value from the next item in the chain. 2339 * @return bool True if the cache has the requested key, false otherwise. 2340 */ 2341 public function has($key, $tryloadifpossible = false) { 2342 $this->check_tracked_user(); 2343 $parsedkey = $this->parse_key($key); 2344 $store = $this->get_store(); 2345 if ($this->has_a_ttl() && !$this->store_supports_native_ttl()) { 2346 // The data has a TTL and the store doesn't support it natively. 2347 // We must fetch the data and expect a ttl wrapper. 2348 $data = $store->get($parsedkey); 2349 $has = ($data instanceof cache_ttl_wrapper && !$data->has_expired()); 2350 } else if (!$this->store_supports_key_awareness()) { 2351 // The store doesn't support key awareness, get the data and check it manually... puke. 2352 // Either no TTL is set of the store supports its handling natively. 2353 $data = $store->get($parsedkey); 2354 $has = ($data !== false); 2355 } else { 2356 // The store supports key awareness, this is easy! 2357 // Either no TTL is set of the store supports its handling natively. 2358 /* @var cache_store|cache_is_key_aware $store */ 2359 $has = $store->has($parsedkey); 2360 } 2361 if (!$has && $tryloadifpossible) { 2362 $result = null; 2363 if ($this->get_loader() !== false) { 2364 $result = $this->get_loader()->get($parsedkey); 2365 } else if ($this->get_datasource() !== null) { 2366 $result = $this->get_datasource()->load_for_cache($key); 2367 } 2368 $has = ($result !== null); 2369 if ($has) { 2370 $this->set($key, $result); 2371 } 2372 } 2373 return $has; 2374 } 2375 2376 /** 2377 * Test is a cache has all of the given keys. 2378 * 2379 * It is strongly recommended to avoid the use of this function if not absolutely required. 2380 * In a high load environment the cache may well change between the test and any subsequent action (get, set, delete etc). 2381 * 2382 * Its also worth mentioning that not all stores support key tests. 2383 * For stores that don't support key tests this functionality is mimicked by using the equivalent get method. 2384 * Just one more reason you should not use these methods unless you have a very good reason to do so. 2385 * 2386 * @param array $keys 2387 * @return bool True if the cache has all of the given keys, false otherwise. 2388 */ 2389 public function has_all(array $keys) { 2390 $this->check_tracked_user(); 2391 if (($this->has_a_ttl() && !$this->store_supports_native_ttl()) || !$this->store_supports_key_awareness()) { 2392 foreach ($keys as $key) { 2393 if (!$this->has($key)) { 2394 return false; 2395 } 2396 } 2397 return true; 2398 } 2399 // The cache must be key aware and if support native ttl if it a ttl is set. 2400 /* @var cache_store|cache_is_key_aware $store */ 2401 $store = $this->get_store(); 2402 return $store->has_all(array_map(array($this, 'parse_key'), $keys)); 2403 } 2404 2405 /** 2406 * Test if a cache has at least one of the given keys. 2407 * 2408 * It is strongly recommended to avoid the use of this function if not absolutely required. 2409 * In a high load environment the cache may well change between the test and any subsequent action (get, set, delete etc). 2410 * 2411 * Its also worth mentioning that not all stores support key tests. 2412 * For stores that don't support key tests this functionality is mimicked by using the equivalent get method. 2413 * Just one more reason you should not use these methods unless you have a very good reason to do so. 2414 * 2415 * @param array $keys 2416 * @return bool True if the cache has at least one of the given keys 2417 */ 2418 public function has_any(array $keys) { 2419 if (($this->has_a_ttl() && !$this->store_supports_native_ttl()) || !$this->store_supports_key_awareness()) { 2420 foreach ($keys as $key) { 2421 if ($this->has($key)) { 2422 return true; 2423 } 2424 } 2425 return false; 2426 } 2427 /* @var cache_store|cache_is_key_aware $store */ 2428 $store = $this->get_store(); 2429 return $store->has_any(array_map(array($this, 'parse_key'), $keys)); 2430 } 2431 2432 /** 2433 * The session loader never uses static acceleration. 2434 * Instead it stores things in the static $session variable. Shared between all session loaders. 2435 * 2436 * @return bool 2437 */ 2438 protected function use_static_acceleration() { 2439 return false; 2440 } 2441 } 2442 2443 /** 2444 * An request cache. 2445 * 2446 * This class is used for request caches returned by the cache::make methods. 2447 * 2448 * This cache class should never be interacted with directly. Instead you should always use the cache::make methods. 2449 * It is technically possible to call those methods through this class however there is no guarantee that you will get an 2450 * instance of this class back again. 2451 * 2452 * @internal don't use me directly. 2453 * 2454 * @package core 2455 * @category cache 2456 * @copyright 2012 Sam Hemelryk 2457 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 2458 */ 2459 class cache_request extends cache { 2460 // This comment appeases code pre-checker ;) ! 2461 }
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