cache/disabledlib.php

   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  * This file contains classes that are used by the Cache API only when it is disabled.
  19  *
  20  * These classes are derivatives of other significant classes used by the Cache API customised specifically
  21  * to only do what is absolutely necessary when initialising and using the Cache API when its been disabled.
  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  * Required as it is needed for cache_config_disabled which extends cache_config_writer.
  33  */
  34 require_once($CFG->dirroot.'/cache/locallib.php');
  35
  36 /**
  37  * The cache loader class used when the Cache has been disabled.
  38  *
  39  * @copyright  2012 Sam Hemelryk
  40  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  41  */
  42 class cache_disabled extends cache implements cache_loader_with_locking {
  43
  44     /**
  45      * Constructs the cache.
  46      *
  47      * @param cache_definition $definition
  48      * @param cache_store $store
  49      * @param null $loader Unused.
  50      */
  51     public function __construct(cache_definition $definition, cache_store $store, $loader = null) {
  52         if ($loader instanceof cache_data_source) {
  53             // Set the data source to allow data sources to work when caching is entirely disabled.
  54             $this->set_data_source($loader);
  55         }
  56
  57         // No other features are handled.
  58     }
  59
  60     /**
  61      * Gets a key from the cache.
  62      *
  63      * @param int|string $key
  64      * @param int $requiredversion Minimum required version of the data or cache::VERSION_NONE
  65      * @param int $strictness Unused.
  66      * @param mixed &$actualversion If specified, will be set to the actual version number retrieved
  67      * @return bool
  68      */
  69     protected function get_implementation($key, int $requiredversion, int $strictness, &$actualversion = null) {
  70         $datasource = $this->get_datasource();
  71         if ($datasource !== false) {
  72             if ($requiredversion === cache::VERSION_NONE) {
  73                 return $datasource->load_for_cache($key);
  74             } else {
  75                 if (!$datasource instanceof cache_data_source_versionable) {
  76                     throw new \coding_exception('Data source is not versionable');
  77                 }
  78                 $result = $datasource->load_for_cache_versioned($key, $requiredversion, $actualversion);
  79                 if ($result && $actualversion < $requiredversion) {
  80                     throw new \coding_exception('Data source returned outdated version');
  81                 }
  82                 return $result;
  83             }
  84         }
  85         return false;
  86     }
  87
  88     /**
  89      * Gets many keys at once from the cache.
  90      *
  91      * @param array $keys
  92      * @param int $strictness Unused.
  93      * @return array
  94      */
  95     public function get_many(array $keys, $strictness = IGNORE_MISSING) {
  96         if ($this->get_datasource() !== false) {
  97             return $this->get_datasource()->load_many_for_cache($keys);
  98         }
  99
 100         return array_combine($keys, array_fill(0, count($keys), false));
 101     }
 102
 103     /**
 104      * Sets a key value pair in the cache.
 105      *
 106      * @param int|string $key Unused.
 107      * @param int $version Unused.
 108      * @param mixed $data Unused.
 109      * @param bool $setparents Unused.
 110      * @return bool
 111      */
 112     protected function set_implementation($key, int $version, $data, bool $setparents = true): bool {
 113         return false;
 114     }
 115
 116     /**
 117      * Sets many key value pairs in the cache at once.
 118      *
 119      * @param array $keyvaluearray Unused.
 120      * @return int
 121      */
 122     public function set_many(array $keyvaluearray) {
 123         return 0;
 124     }
 125
 126     /**
 127      * Deletes an item from the cache.
 128      *
 129      * @param int|string $key Unused.
 130      * @param bool $recurse Unused.
 131      * @return bool
 132      */
 133     public function delete($key, $recurse = true) {
 134         return false;
 135     }
 136
 137     /**
 138      * Deletes many items at once from the cache.
 139      *
 140      * @param array $keys Unused.
 141      * @param bool $recurse Unused.
 142      * @return int
 143      */
 144     public function delete_many(array $keys, $recurse = true) {
 145         return 0;
 146     }
 147
 148     /**
 149      * Checks if the cache has the requested key.
 150      *
 151      * @param int|string $key Unused.
 152      * @param bool $tryloadifpossible Unused.
 153      * @return bool
 154      */
 155     public function has($key, $tryloadifpossible = false) {
 156         $result = $this->get($key);
 157
 158         return $result !== false;
 159     }
 160
 161     /**
 162      * Checks if the cache has all of the requested keys.
 163      * @param array $keys Unused.
 164      * @return bool
 165      */
 166     public function has_all(array $keys) {
 167         if (!$this->get_datasource()) {
 168             return false;
 169         }
 170
 171         foreach ($keys as $key) {
 172             if (!$this->has($key)) {
 173                 return false;
 174             }
 175         }
 176         return true;
 177     }
 178
 179     /**
 180      * Checks if the cache has any of the requested keys.
 181      *
 182      * @param array $keys Unused.
 183      * @return bool
 184      */
 185     public function has_any(array $keys) {
 186         foreach ($keys as $key) {
 187             if ($this->has($key)) {
 188                 return true;
 189             }
 190         }
 191
 192         return false;
 193     }
 194
 195     /**
 196      * Purges all items from the cache.
 197      *
 198      * @return bool
 199      */
 200     public function purge() {
 201         return true;
 202     }
 203
 204     /**
 205      * Pretend that we got a lock to avoid errors.
 206      *
 207      * @param int|string $key
 208      * @return bool
 209      */
 210     public function acquire_lock($key): bool {
 211         return true;
 212     }
 213
 214     /**
 215      * Pretend that we released a lock to avoid errors.
 216      *
 217      * @param int|string $key
 218      * @return bool
 219      */
 220     public function release_lock($key): bool {
 221         return true;
 222     }
 223
 224     /**
 225      * Pretend that we have a lock to avoid errors.
 226      *
 227      * @param int|string $key
 228      * @return bool
 229      */
 230     public function check_lock_state($key): bool {
 231         return true;
 232     }
 233 }
 234
 235 /**
 236  * The cache factory class used when the Cache has been disabled.
 237  *
 238  * @copyright  2012 Sam Hemelryk
 239  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 240  */
 241 class cache_factory_disabled extends cache_factory {
 242     /** @var array Array of temporary caches in use. */
 243     protected static $tempcaches = [];
 244
 245     /**
 246      * Returns an instance of the cache_factor method.
 247      *
 248      * @param bool $forcereload Unused.
 249      * @return cache_factory
 250      * @throws coding_exception
 251      */
 252     public static function instance($forcereload = false) {
 253         throw new coding_exception('You must not call to this cache factory within your code.');
 254     }
 255
 256     /**
 257      * Creates a definition instance or returns the existing one if it has already been created.
 258      *
 259      * @param string $component
 260      * @param string $area
 261      * @param string $unused Used to be datasourceaggregate but that was removed and this is now unused.
 262      * @return cache_definition
 263      */
 264     public function create_definition($component, $area, $unused = null) {
 265         $definition = parent::create_definition($component, $area);
 266         if ($definition->has_data_source()) {
 267             return $definition;
 268         }
 269
 270         return cache_definition::load_adhoc(cache_store::MODE_REQUEST, $component, $area);
 271     }
 272
 273     /**
 274      * Common public method to create a cache instance given a definition.
 275      *
 276      * @param cache_definition $definition
 277      * @return cache_application|cache_session|cache_store
 278      * @throws coding_exception
 279      */
 280     public function create_cache(cache_definition $definition) {
 281         $loader = null;
 282         if ($definition->has_data_source()) {
 283             $loader = $definition->get_data_source();
 284         }
 285         return new cache_disabled($definition, $this->create_dummy_store($definition), $loader);
 286     }
 287
 288     /**
 289      * Creates a cache object given the parameters for a definition.
 290      *
 291      * @param string $component
 292      * @param string $area
 293      * @param array $identifiers
 294      * @param string $unused Used to be datasourceaggregate but that was removed and this is now unused.
 295      * @return cache_application|cache_session|cache_request
 296      */
 297     public function create_cache_from_definition($component, $area, array $identifiers = array(), $unused = null) {
 298         // Temporary in-memory caches are sometimes allowed when caching is disabled.
 299         if (\core_cache\allow_temporary_caches::is_allowed() && !$identifiers) {
 300             $key = $component . '/' . $area;
 301             if (array_key_exists($key, self::$tempcaches)) {
 302                 $cache = self::$tempcaches[$key];
 303             } else {
 304                 $definition = $this->create_definition($component, $area);
 305                 // The cachestore_static class returns true to all three 'SUPPORTS_' checks so it
 306                 // can be used with all definitions.
 307                 $store = new cachestore_static('TEMP:' . $component . '/' . $area);
 308                 $store->initialise($definition);
 309                 // We need to use a cache loader wrapper rather than directly returning the store,
 310                 // or it wouldn't have support for versioning. The cache_application class is used
 311                 // (rather than cache_request which might make more sense logically) because it
 312                 // includes support for locking, which might be necessary for some caches.
 313                 $cache = new cache_application($definition, $store);
 314                 self::$tempcaches[$key] = $cache;
 315             }
 316             return $cache;
 317         }
 318
 319         // Regular cache definitions are cached inside create_definition().  This is not the case for disabledlib.php
 320         // definitions as they use load_adhoc().  They are built as a new object on each call.
 321         // We do not need to clone the definition because we know it's new.
 322         $definition = $this->create_definition($component, $area);
 323         $definition->set_identifiers($identifiers);
 324         $cache = $this->create_cache($definition);
 325         return $cache;
 326     }
 327
 328     /**
 329      * Removes all temporary caches.
 330      *
 331      * Don't call this directly - used by {@see \core_cache\allow_temporary_caches}.
 332      */
 333     public static function clear_temporary_caches(): void {
 334         self::$tempcaches = [];
 335     }
 336
 337     /**
 338      * Creates an ad-hoc cache from the given param.
 339      *
 340      * @param int $mode
 341      * @param string $component
 342      * @param string $area
 343      * @param array $identifiers
 344      * @param array $options An array of options, available options are:
 345      *   - simplekeys : Set to true if the keys you will use are a-zA-Z0-9_
 346      *   - simpledata : Set to true if the type of the data you are going to store is scalar, or an array of scalar vars
 347      *   - staticacceleration : If set to true the cache will hold onto all data passing through it.
 348      *   - staticaccelerationsize : Sets the max size of the static acceleration array.
 349      * @return cache_application|cache_session|cache_request
 350      */
 351     public function create_cache_from_params($mode, $component, $area, array $identifiers = array(), array $options = array()) {
 352         // Regular cache definitions are cached inside create_definition().  This is not the case for disabledlib.php
 353         // definitions as they use load_adhoc().  They are built as a new object on each call.
 354         // We do not need to clone the definition because we know it's new.
 355         $definition = cache_definition::load_adhoc($mode, $component, $area, $options);
 356         $definition->set_identifiers($identifiers);
 357         $cache = $this->create_cache($definition);
 358         return $cache;
 359     }
 360
 361     /**
 362      * Creates a store instance given its name and configuration.
 363      *
 364      * @param string $name Unused.
 365      * @param array $details Unused.
 366      * @param cache_definition $definition
 367      * @return boolean|cache_store
 368      */
 369     public function create_store_from_config($name, array $details, cache_definition $definition) {
 370         return $this->create_dummy_store($definition);
 371     }
 372
 373     /**
 374      * Creates a cache config instance with the ability to write if required.
 375      *
 376      * @param bool $writer Unused.
 377      * @return cache_config_disabled|cache_config_writer
 378      */
 379     public function create_config_instance($writer = false) {
 380         // We are always going to use the cache_config_disabled class for all regular request.
 381         // However if the code has requested the writer then likely something is changing and
 382         // we're going to need to interact with the config.php file.
 383         // In this case we will still use the cache_config_writer.
 384         $class = 'cache_config_disabled';
 385         if ($writer) {
 386             // If the writer was requested then something is changing.
 387             $class = 'cache_config_writer';
 388         }
 389         if (!array_key_exists($class, $this->configs)) {
 390             self::set_state(self::STATE_INITIALISING);
 391             if ($class === 'cache_config_disabled') {
 392                 $configuration = $class::create_default_configuration();
 393                 $this->configs[$class] = new $class;
 394             } else {
 395                 $configuration = false;
 396                 // If we need a writer, we should get the classname from the generic factory.
 397                 // This is so alternative classes can be used if a different writer is required.
 398                 $this->configs[$class] = parent::get_disabled_writer();
 399             }
 400             $this->configs[$class]->load($configuration);
 401         }
 402         self::set_state(self::STATE_READY);
 403
 404         // Return the instance.
 405         return $this->configs[$class];
 406     }
 407
 408     /**
 409      * Returns true if the cache API has been disabled.
 410      *
 411      * @return bool
 412      */
 413     public function is_disabled() {
 414         return true;
 415     }
 416 }
 417
 418 /**
 419  * The cache config class used when the Cache has been disabled.
 420  *
 421  * @copyright  2012 Sam Hemelryk
 422  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 423  */
 424 class cache_config_disabled extends cache_config_writer {
 425
 426     /**
 427      * Returns an instance of the configuration writer.
 428      *
 429      * @return cache_config_disabled
 430      */
 431     public static function instance() {
 432         $factory = cache_factory::instance();
 433         return $factory->create_config_instance(true);
 434     }
 435
 436     /**
 437      * Saves the current configuration.
 438      */
 439     protected function config_save() {
 440         // Nothing to do here.
 441     }
 442
 443     /**
 444      * Generates a configuration array suitable to be written to the config file.
 445      *
 446      * @return array
 447      */
 448     protected function generate_configuration_array() {
 449         $configuration = array();
 450         $configuration['stores'] = $this->configstores;
 451         $configuration['modemappings'] = $this->configmodemappings;
 452         $configuration['definitions'] = $this->configdefinitions;
 453         $configuration['definitionmappings'] = $this->configdefinitionmappings;
 454         $configuration['locks'] = $this->configlocks;
 455         return $configuration;
 456     }
 457
 458     /**
 459      * Adds a plugin instance.
 460      *
 461      * @param string $name Unused.
 462      * @param string $plugin Unused.
 463      * @param array $configuration Unused.
 464      * @return bool
 465      * @throws cache_exception
 466      */
 467     public function add_store_instance($name, $plugin, array $configuration = array()) {
 468         return false;
 469     }
 470
 471     /**
 472      * Sets the mode mappings.
 473      *
 474      * @param array $modemappings Unused.
 475      * @return bool
 476      * @throws cache_exception
 477      */
 478     public function set_mode_mappings(array $modemappings) {
 479         return false;
 480     }
 481
 482     /**
 483      * Edits a give plugin instance.
 484      *
 485      * @param string $name Unused.
 486      * @param string $plugin Unused.
 487      * @param array $configuration Unused.
 488      * @return bool
 489      * @throws cache_exception
 490      */
 491     public function edit_store_instance($name, $plugin, $configuration) {
 492         return false;
 493     }
 494
 495     /**
 496      * Deletes a store instance.
 497      *
 498      * @param string $name Unused.
 499      * @return bool
 500      * @throws cache_exception
 501      */
 502     public function delete_store_instance($name) {
 503         return false;
 504     }
 505
 506     /**
 507      * Creates the default configuration and saves it.
 508      *
 509      * @param bool $forcesave Ignored because we are disabled!
 510      * @return array
 511      */
 512     public static function create_default_configuration($forcesave = false) {
 513         global $CFG;
 514
 515         // HACK ALERT.
 516         // We probably need to come up with a better way to create the default stores, or at least ensure 100% that the
 517         // default store plugins are protected from deletion.
 518         require_once($CFG->dirroot.'/cache/stores/file/lib.php');
 519         require_once($CFG->dirroot.'/cache/stores/session/lib.php');
 520         require_once($CFG->dirroot.'/cache/stores/static/lib.php');
 521
 522         $writer = new self;
 523         $writer->configstores = array(
 524             'default_application' => array(
 525                 'name' => 'default_application',
 526                 'plugin' => 'file',
 527                 'configuration' => array(),
 528                 'features' => cachestore_file::get_supported_features(),
 529                 'modes' => cache_store::MODE_APPLICATION,
 530                 'default' => true,
 531             ),
 532             'default_session' => array(
 533                 'name' => 'default_session',
 534                 'plugin' => 'session',
 535                 'configuration' => array(),
 536                 'features' => cachestore_session::get_supported_features(),
 537                 'modes' => cache_store::MODE_SESSION,
 538                 'default' => true,
 539             ),
 540             'default_request' => array(
 541                 'name' => 'default_request',
 542                 'plugin' => 'static',
 543                 'configuration' => array(),
 544                 'features' => cachestore_static::get_supported_features(),
 545                 'modes' => cache_store::MODE_REQUEST,
 546                 'default' => true,
 547             )
 548         );
 549         $writer->configdefinitions = array();
 550         $writer->configmodemappings = array(
 551             array(
 552                 'mode' => cache_store::MODE_APPLICATION,
 553                 'store' => 'default_application',
 554                 'sort' => -1
 555             ),
 556             array(
 557                 'mode' => cache_store::MODE_SESSION,
 558                 'store' => 'default_session',
 559                 'sort' => -1
 560             ),
 561             array(
 562                 'mode' => cache_store::MODE_REQUEST,
 563                 'store' => 'default_request',
 564                 'sort' => -1
 565             )
 566         );
 567         $writer->configlocks = array(
 568             'default_file_lock' => array(
 569                 'name' => 'cachelock_file_default',
 570                 'type' => 'cachelock_file',
 571                 'dir' => 'filelocks',
 572                 'default' => true
 573             )
 574         );
 575
 576         return $writer->generate_configuration_array();
 577     }
 578
 579     /**
 580      * Updates the definition in the configuration from those found in the cache files.
 581      *
 582      * @param bool $coreonly Unused.
 583      */
 584     public static function update_definitions($coreonly = false) {
 585         // Nothing to do here.
 586     }
 587
 588     /**
 589      * Locates all of the definition files.
 590      *
 591      * @param bool $coreonly Unused.
 592      * @return array
 593      */
 594     protected static function locate_definitions($coreonly = false) {
 595         return array();
 596     }
 597
 598     /**
 599      * Sets the mappings for a given definition.
 600      *
 601      * @param string $definition Unused.
 602      * @param array $mappings Unused.
 603      * @throws coding_exception
 604      */
 605     public function set_definition_mappings($definition, $mappings) {
 606         // Nothing to do here.
 607     }
 608 }