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Differences Between: [Versions 39 and 310] [Versions 39 and 311] [Versions 39 and 400] [Versions 39 and 401] [Versions 39 and 402] [Versions 39 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   * This file contains the cache factory class.
  19   *
  20   * This file is part of Moodle's cache API, affectionately called MUC.
  21   * It contains the components that are requried 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 cache factory class.
  33   *
  34   * This factory class is important because it stores instances of objects used by the cache API and returns them upon requests.
  35   * This allows us to both reuse objects saving on overhead, and gives us an easy place to "reset" the cache API in situations that
  36   * we need such as unit testing.
  37   *
  38   * @copyright  2012 Sam Hemelryk
  39   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  40   */
  41  class cache_factory {
  42  
  43      /** The cache has not been initialised yet. */
  44      const STATE_UNINITIALISED = 0;
  45      /** The cache is in the process of initialising itself. */
  46      const STATE_INITIALISING = 1;
  47      /** The cache is in the process of saving its configuration file. */
  48      const STATE_SAVING = 2;
  49      /** The cache is ready to use. */
  50      const STATE_READY = 3;
  51      /** The cache is currently updating itself */
  52      const STATE_UPDATING = 4;
  53      /** The cache encountered an error while initialising. */
  54      const STATE_ERROR_INITIALISING = 9;
  55      /** The cache has been disabled. */
  56      const STATE_DISABLED = 10;
  57      /** The cache stores have been disabled */
  58      const STATE_STORES_DISABLED = 11;
  59  
  60      /**
  61       * An instance of the cache_factory class created upon the first request.
  62       * @var cache_factory
  63       */
  64      protected static $instance;
  65  
  66      /**
  67       * An array containing caches created for definitions
  68       * @var array
  69       */
  70      protected $cachesfromdefinitions = array();
  71  
  72      /**
  73       * Array of caches created by parameters, ad-hoc definitions will have been used.
  74       * @var array
  75       */
  76      protected $cachesfromparams = array();
  77  
  78      /**
  79       * An array of stores organised by definitions.
  80       * @var array
  81       */
  82      protected $definitionstores = array();
  83  
  84      /**
  85       * An array of instantiated stores.
  86       * @var array
  87       */
  88      protected $stores = array();
  89  
  90      /**
  91       * An array of configuration instances
  92       * @var array
  93       */
  94      protected $configs = array();
  95  
  96      /**
  97       * An array of initialised definitions
  98       * @var array
  99       */
 100      protected $definitions = array();
 101  
 102      /**
 103       * An array of lock plugins.
 104       * @var array
 105       */
 106      protected $lockplugins = array();
 107  
 108      /**
 109       * The current state of the cache API.
 110       * @var int
 111       */
 112      protected $state = 0;
 113  
 114      /**
 115       * Returns an instance of the cache_factor method.
 116       *
 117       * @param bool $forcereload If set to true a new cache_factory instance will be created and used.
 118       * @return cache_factory
 119       */
 120      public static function instance($forcereload = false) {
 121          global $CFG;
 122          if ($forcereload || self::$instance === null) {
 123              // Initialise a new factory to facilitate our needs.
 124              if (defined('CACHE_DISABLE_ALL') && CACHE_DISABLE_ALL !== false) {
 125                  // The cache has been disabled. Load disabledlib and start using the factory designed to handle this
 126                  // situation. It will use disabled alternatives where available.
 127                  require_once($CFG->dirroot.'/cache/disabledlib.php');
 128                  self::$instance = new cache_factory_disabled();
 129              } else if ((defined('PHPUNIT_TEST') && PHPUNIT_TEST) || defined('BEHAT_SITE_RUNNING')) {
 130                  // We're using the test factory.
 131                  require_once($CFG->dirroot.'/cache/tests/fixtures/lib.php');
 132                  self::$instance = new cache_phpunit_factory();
 133                  if (defined('CACHE_DISABLE_STORES') && CACHE_DISABLE_STORES !== false) {
 134                      // The cache stores have been disabled.
 135                      self::$instance->set_state(self::STATE_STORES_DISABLED);
 136                  }
 137              } else {
 138                  // We're using the regular factory.
 139                  self::$instance = new cache_factory();
 140                  if (defined('CACHE_DISABLE_STORES') && CACHE_DISABLE_STORES !== false) {
 141                      // The cache stores have been disabled.
 142                      self::$instance->set_state(self::STATE_STORES_DISABLED);
 143                  }
 144              }
 145          }
 146          return self::$instance;
 147      }
 148  
 149      /**
 150       * Protected constructor, please use the static instance method.
 151       */
 152      protected function __construct() {
 153          // Nothing to do here.
 154      }
 155  
 156      /**
 157       * Resets the arrays containing instantiated caches, stores, and config instances.
 158       */
 159      public static function reset() {
 160          $factory = self::instance();
 161          $factory->reset_cache_instances();
 162          $factory->configs = array();
 163          $factory->definitions = array();
 164          $factory->definitionstores = array();
 165          $factory->lockplugins = array(); // MUST be null in order to force its regeneration.
 166          // Reset the state to uninitialised.
 167          $factory->state = self::STATE_UNINITIALISED;
 168      }
 169  
 170      /**
 171       * Resets the stores, clearing the array of created stores.
 172       *
 173       * Cache objects still held onto by the code that initialised them will remain as is
 174       * however all future requests for a cache/store will lead to a new instance being re-initialised.
 175       */
 176      public function reset_cache_instances() {
 177          $this->cachesfromdefinitions = array();
 178          $this->cachesfromparams = array();
 179          $this->stores = array();
 180      }
 181  
 182      /**
 183       * Creates a cache object given the parameters for a definition.
 184       *
 185       * If a cache has already been created for the given definition then that cache instance will be returned.
 186       *
 187       * @param string $component
 188       * @param string $area
 189       * @param array $identifiers
 190       * @param string $unused Used to be data source aggregate however that was removed and this is now unused.
 191       * @return cache_application|cache_session|cache_request
 192       */
 193      public function create_cache_from_definition($component, $area, array $identifiers = array(), $unused = null) {
 194          $identifierstring = empty($identifiers) ? '' : '/'.http_build_query($identifiers);
 195          $definitionname = $component.'/'.$area.$identifierstring;
 196          if (isset($this->cachesfromdefinitions[$definitionname])) {
 197              $cache = $this->cachesfromdefinitions[$definitionname];
 198              return $cache;
 199          }
 200          $definition = $this->create_definition($component, $area);
 201          // Identifiers are cached as part of the cache creation, so we store a cloned version of the cache.
 202          $cacheddefinition = clone($definition);
 203          $cacheddefinition->set_identifiers($identifiers);
 204          $cache = $this->create_cache($cacheddefinition);
 205  
 206          // Loaders are always held onto to speed up subsequent requests.
 207          $this->cachesfromdefinitions[$definitionname] = $cache;
 208          return $cache;
 209      }
 210  
 211      /**
 212       * Creates an ad-hoc cache from the given param.
 213       *
 214       * If a cache has already been created using the same params then that cache instance will be returned.
 215       *
 216       * @param int $mode
 217       * @param string $component
 218       * @param string $area
 219       * @param array $identifiers
 220       * @param array $options An array of options, available options are:
 221       *   - simplekeys : Set to true if the keys you will use are a-zA-Z0-9_
 222       *   - simpledata : Set to true if the type of the data you are going to store is scalar, or an array of scalar vars
 223       *   - staticacceleration : If set to true the cache will hold onto data passing through it.
 224       *   - staticaccelerationsize : The maximum number of items to hold onto for acceleration purposes.
 225       * @return cache_application|cache_session|cache_request
 226       */
 227      public function create_cache_from_params($mode, $component, $area, array $identifiers = array(), array $options = array()) {
 228          $identifierstring = empty($identifiers) ? '' : '_'.http_build_query($identifiers);
 229          $key = "{$mode}_{$component}_{$area}{$identifierstring}";
 230          if (isset($this->cachesfromparams[$key])) {
 231              return $this->cachesfromparams[$key];
 232          }
 233          // Regular cache definitions are cached inside create_definition().  This is not the case for Adhoc definitions
 234          // using load_adhoc().  They are built as a new object on each call.
 235          // We do not need to clone the definition because we know it's new.
 236          $definition = cache_definition::load_adhoc($mode, $component, $area, $options);
 237          $definition->set_identifiers($identifiers);
 238          $cache = $this->create_cache($definition);
 239          $this->cachesfromparams[$key] = $cache;
 240          return $cache;
 241      }
 242  
 243      /**
 244       * Common public method to create a cache instance given a definition.
 245       *
 246       * This is used by the static make methods.
 247       *
 248       * @param cache_definition $definition
 249       * @return cache_application|cache_session|cache_store
 250       * @throws coding_exception
 251       */
 252      public function create_cache(cache_definition $definition) {
 253          $class = $definition->get_cache_class();
 254          $stores = cache_helper::get_stores_suitable_for_definition($definition);
 255          foreach ($stores as $key => $store) {
 256              if (!$store::are_requirements_met()) {
 257                  unset($stores[$key]);
 258              }
 259          }
 260          if (count($stores) === 0) {
 261              // Hmm still no stores, better provide a dummy store to mimic functionality. The dev will be none the wiser.
 262              $stores[] = $this->create_dummy_store($definition);
 263          }
 264          $loader = null;
 265          if ($definition->has_data_source()) {
 266              $loader = $definition->get_data_source();
 267          }
 268          while (($store = array_pop($stores)) !== null) {
 269              $loader = new $class($definition, $store, $loader);
 270          }
 271          return $loader;
 272      }
 273  
 274      /**
 275       * Creates a store instance given its name and configuration.
 276       *
 277       * If the store has already been instantiated then the original object will be returned. (reused)
 278       *
 279       * @param string $name The name of the store (must be unique remember)
 280       * @param array $details
 281       * @param cache_definition $definition The definition to instantiate it for.
 282       * @return boolean|cache_store
 283       */
 284      public function create_store_from_config($name, array $details, cache_definition $definition) {
 285          if (!array_key_exists($name, $this->stores)) {
 286              // Properties: name, plugin, configuration, class.
 287              $class = $details['class'];
 288              if (!$class::are_requirements_met()) {
 289                  return false;
 290              }
 291              $store = new $class($details['name'], $details['configuration']);
 292              $this->stores[$name] = $store;
 293          }
 294          /* @var cache_store $store */
 295          $store = $this->stores[$name];
 296          // We check are_requirements_met although we expect is_ready is going to check as well.
 297          if (!$store::are_requirements_met() || !$store->is_ready() || !$store->is_supported_mode($definition->get_mode())) {
 298              return false;
 299          }
 300          // We always create a clone of the original store.
 301          // If we were to clone a store that had already been initialised with a definition then
 302          // we'd run into a myriad of issues.
 303          // We use a method of the store to create a clone rather than just creating it ourselves
 304          // so that if any store out there doesn't handle cloning they can override this method in
 305          // order to address the issues.
 306          $store = $this->stores[$name]->create_clone($details);
 307          $store->initialise($definition);
 308          $definitionid = $definition->get_id();
 309          if (!isset($this->definitionstores[$definitionid])) {
 310              $this->definitionstores[$definitionid] = array();
 311          }
 312          $this->definitionstores[$definitionid][] = $store;
 313          return $store;
 314      }
 315  
 316      /**
 317       * Returns an array of cache stores that have been initialised for use in definitions.
 318       * @param cache_definition $definition
 319       * @return array
 320       */
 321      public function get_store_instances_in_use(cache_definition $definition) {
 322          $id = $definition->get_id();
 323          if (!isset($this->definitionstores[$id])) {
 324              return array();
 325          }
 326          return $this->definitionstores[$id];
 327      }
 328  
 329      /**
 330       * Returns the cache instances that have been used within this request.
 331       * @since Moodle 2.6
 332       * @return array
 333       */
 334      public function get_caches_in_use() {
 335          return $this->cachesfromdefinitions;
 336      }
 337  
 338      /**
 339       * Gets all adhoc caches that have been used within this request.
 340       *
 341       * @return cache_store[] Caches currently in use
 342       */
 343      public function get_adhoc_caches_in_use() {
 344          return $this->cachesfromparams;
 345      }
 346  
 347      /**
 348       * Creates a cache config instance with the ability to write if required.
 349       *
 350       * @param bool $writer If set to true an instance that can update the configuration will be returned.
 351       * @return cache_config|cache_config_writer
 352       */
 353      public function create_config_instance($writer = false) {
 354          global $CFG;
 355  
 356          // The class to use.
 357          $class = 'cache_config';
 358          // Are we running tests of some form?
 359          $testing = (defined('PHPUNIT_TEST') && PHPUNIT_TEST) || defined('BEHAT_SITE_RUNNING');
 360  
 361          // Check if this is a PHPUnit test and redirect to the phpunit config classes if it is.
 362          if ($testing) {
 363              require_once($CFG->dirroot.'/cache/locallib.php');
 364              require_once($CFG->dirroot.'/cache/tests/fixtures/lib.php');
 365              // We have just a single class for PHP unit tests. We don't care enough about its
 366              // performance to do otherwise and having a single method allows us to inject things into it
 367              // while testing.
 368              $class = 'cache_config_testing';
 369          }
 370  
 371          // Check if we need to create a config file with defaults.
 372          $needtocreate = !$class::config_file_exists();
 373  
 374          if ($writer || $needtocreate) {
 375              require_once($CFG->dirroot.'/cache/locallib.php');
 376              if (!$testing) {
 377                  $class .= '_writer';
 378              }
 379          }
 380  
 381          $error = false;
 382          if ($needtocreate) {
 383              // Create the default configuration.
 384              // Update the state, we are now initialising the cache.
 385              self::set_state(self::STATE_INITIALISING);
 386              /** @var cache_config_writer $class */
 387              $configuration = $class::create_default_configuration();
 388              if ($configuration !== true) {
 389                  // Failed to create the default configuration. Disable the cache stores and update the state.
 390                  self::set_state(self::STATE_ERROR_INITIALISING);
 391                  $this->configs[$class] = new $class;
 392                  $this->configs[$class]->load($configuration);
 393                  $error = true;
 394              }
 395          }
 396  
 397          if (!array_key_exists($class, $this->configs)) {
 398              // Create a new instance and call it to load it.
 399              $this->configs[$class] = new $class;
 400              $this->configs[$class]->load();
 401          }
 402  
 403          if (!$error) {
 404              // The cache is now ready to use. Update the state.
 405              self::set_state(self::STATE_READY);
 406          }
 407  
 408          // Return the instance.
 409          return $this->configs[$class];
 410      }
 411  
 412      /**
 413       * Creates a definition instance or returns the existing one if it has already been created.
 414       * @param string $component
 415       * @param string $area
 416       * @param string $unused This used to be data source aggregate - however that functionality has been removed and
 417       *        this argument is now unused.
 418       * @return cache_definition
 419       * @throws coding_exception If the definition cannot be found.
 420       */
 421      public function create_definition($component, $area, $unused = null) {
 422          $id = $component.'/'.$area;
 423          if (!isset($this->definitions[$id])) {
 424              // This is the first time this definition has been requested.
 425              if ($this->is_initialising()) {
 426                  // We're initialising the cache right now. Don't try to create another config instance.
 427                  // We'll just use an ad-hoc cache for the time being.
 428                  $definition = cache_definition::load_adhoc(cache_store::MODE_REQUEST, $component, $area);
 429              } else {
 430                  // Load all the known definitions and find the desired one.
 431                  $instance = $this->create_config_instance();
 432                  $definition = $instance->get_definition_by_id($id);
 433                  if (!$definition) {
 434                      // Oh-oh the definition doesn't exist.
 435                      // There are several things that could be going on here.
 436                      // We may be installing/upgrading a site and have hit a definition that hasn't been used before.
 437                      // Of the developer may be trying to use a newly created definition.
 438                      if ($this->is_updating()) {
 439                          // The cache is presently initialising and the requested cache definition has not been found.
 440                          // This means that the cache initialisation has requested something from a cache (I had recursive nightmares about this).
 441                          // To serve this purpose and avoid errors we are going to make use of an ad-hoc cache rather than
 442                          // search for the definition which would possibly cause an infitite loop trying to initialise the cache.
 443                          $definition = cache_definition::load_adhoc(cache_store::MODE_REQUEST, $component, $area);
 444                      } else {
 445                          // Either a typo of the developer has just created the definition and is using it for the first time.
 446                          $this->reset();
 447                          $instance = $this->create_config_instance(true);
 448                          $instance->update_definitions();
 449                          $definition = $instance->get_definition_by_id($id);
 450                          if (!$definition) {
 451                              throw new coding_exception('The requested cache definition does not exist.'. $id, $id);
 452                          }
 453                          if (!$this->is_disabled()) {
 454                              debugging('Cache definitions reparsed causing cache reset in order to locate definition.
 455                                  You should bump the version number to ensure definitions are reprocessed.', DEBUG_DEVELOPER);
 456                          }
 457                          $definition = cache_definition::load($id, $definition);
 458                      }
 459                  } else {
 460                      $definition = cache_definition::load($id, $definition);
 461                  }
 462              }
 463              $this->definitions[$id] = $definition;
 464          }
 465          return $this->definitions[$id];
 466      }
 467  
 468      /**
 469       * Creates a dummy store object for use when a loader has no potential stores to use.
 470       *
 471       * @param cache_definition $definition
 472       * @return cachestore_dummy
 473       */
 474      protected function create_dummy_store(cache_definition $definition) {
 475          global $CFG;
 476          require_once($CFG->dirroot.'/cache/classes/dummystore.php');
 477          $store = new cachestore_dummy();
 478          $store->initialise($definition);
 479          return $store;
 480      }
 481  
 482      /**
 483       * Returns a lock instance ready for use.
 484       *
 485       * @param array $config
 486       * @return cache_lock_interface
 487       */
 488      public function create_lock_instance(array $config) {
 489          global $CFG;
 490          if (!array_key_exists('name', $config) || !array_key_exists('type', $config)) {
 491              throw new coding_exception('Invalid cache lock instance provided');
 492          }
 493          $name = $config['name'];
 494          $type = $config['type'];
 495          unset($config['name']);
 496          unset($config['type']);
 497  
 498          if (!isset($this->lockplugins[$type])) {
 499              $pluginname = substr($type, 10);
 500              $file = $CFG->dirroot."/cache/locks/{$pluginname}/lib.php";
 501              if (file_exists($file) && is_readable($file)) {
 502                  require_once($file);
 503              }
 504              if (!class_exists($type)) {
 505                  throw new coding_exception('Invalid lock plugin requested.');
 506              }
 507              $this->lockplugins[$type] = $type;
 508          }
 509          if (!array_key_exists($type, $this->lockplugins)) {
 510              throw new coding_exception('Invalid cache lock type.');
 511          }
 512          $class = $this->lockplugins[$type];
 513          return new $class($name, $config);
 514      }
 515  
 516      /**
 517       * Returns the current state of the cache API.
 518       *
 519       * @return int
 520       */
 521      public function get_state() {
 522          return $this->state;
 523      }
 524  
 525      /**
 526       * Updates the state fo the cache API.
 527       *
 528       * @param int $state
 529       * @return bool
 530       */
 531      public function set_state($state) {
 532          if ($state <= $this->state) {
 533              return false;
 534          }
 535          $this->state = $state;
 536          return true;
 537      }
 538  
 539      /**
 540       * Informs the factory that the cache is currently updating itself.
 541       *
 542       * This forces the state to upgrading and can only be called once the cache is ready to use.
 543       * Calling it ensure we don't try to reinstantite things when requesting cache definitions that don't exist yet.
 544       */
 545      public function updating_started() {
 546          if ($this->state !== self::STATE_READY) {
 547              return false;
 548          }
 549          $this->state = self::STATE_UPDATING;
 550          return true;
 551      }
 552  
 553      /**
 554       * Informs the factory that the upgrading has finished.
 555       *
 556       * This forces the state back to ready.
 557       */
 558      public function updating_finished() {
 559          $this->state = self::STATE_READY;
 560      }
 561  
 562      /**
 563       * Returns true if the cache API has been disabled.
 564       *
 565       * @return bool
 566       */
 567      public function is_disabled() {
 568          return $this->state === self::STATE_DISABLED;
 569      }
 570  
 571      /**
 572       * Returns true if the cache is currently initialising itself.
 573       *
 574       * This includes both initialisation and saving the cache config file as part of that initialisation.
 575       *
 576       * @return bool
 577       */
 578      public function is_initialising() {
 579          return $this->state === self::STATE_INITIALISING || $this->state === self::STATE_SAVING;
 580      }
 581  
 582      /**
 583       * Returns true if the cache is currently updating itself.
 584       *
 585       * @return bool
 586       */
 587      public function is_updating() {
 588          return $this->state === self::STATE_UPDATING;
 589      }
 590  
 591      /**
 592       * Disables as much of the cache API as possible.
 593       *
 594       * All of the magic associated with the disabled cache is wrapped into this function.
 595       * In switching out the factory for the disabled factory it gains full control over the initialisation of objects
 596       * and can use all of the disabled alternatives.
 597       * Simple!
 598       *
 599       * This function has been marked as protected so that it cannot be abused through the public API presently.
 600       * Perhaps in the future we will allow this, however as per the build up to the first release containing
 601       * MUC it was decided that this was just to risky and abusable.
 602       */
 603      protected static function disable() {
 604          global $CFG;
 605          require_once($CFG->dirroot.'/cache/disabledlib.php');
 606          self::$instance = new cache_factory_disabled();
 607      }
 608  
 609      /**
 610       * Returns true if the cache stores have been disabled.
 611       *
 612       * @return bool
 613       */
 614      public function stores_disabled() {
 615          return $this->state === self::STATE_STORES_DISABLED || $this->is_disabled();
 616      }
 617  
 618      /**
 619       * Disables cache stores.
 620       *
 621       * The cache API will continue to function however none of the actual stores will be used.
 622       * Instead the dummy store will be provided for all cache requests.
 623       * This is useful in situations where you cannot be sure any stores are working.
 624       *
 625       * In order to re-enable the cache you must call the cache factories static reset method:
 626       * <code>
 627       * // Disable the cache factory.
 628       * cache_factory::disable_stores();
 629       * // Re-enable the cache factory by resetting it.
 630       * cache_factory::reset();
 631       * </code>
 632       */
 633      public static function disable_stores() {
 634          // First reset to clear any static acceleration array.
 635          $factory = self::instance();
 636          $factory->reset_cache_instances();
 637          $factory->set_state(self::STATE_STORES_DISABLED);
 638      }
 639  }