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Long Term Support Release

  • Bug fixes for general core bugs in 3.1.x ended 8 May 2017 (12 months).
  • Bug fixes for security issues in 3.1.x ended 13 May 2019 (36 months).
  • minimum PHP 5.4.4 (always use latest PHP 5.4.x , 5.5.x or 5.6.x on Windows - http://windows.php.net/download/). PHP 7.0.x is supported but has some engine limitations. PHP 7.1.x is not supported.
  • /cache/ -> locallib.php (source)

    Differences Between: [Versions 29 and 31] [Versions 30 and 31] [Versions 31 and 32] [Versions 31 and 33] [Versions 31 and 34] [Versions 31 and 35] [Versions 31 and 36] [Versions 31 and 37] [Versions 31 and 38]

       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   * The supplementary cache API.
      19   *
      20   * This file is part of Moodle's cache API, affectionately called MUC.
      21   * It contains elements of the API that are not required in order to use caching.
      22   * Things in here are more in line with administration and management of the cache setup and configuration.
      23   *
      24   * @package    core
      25   * @category   cache
      26   * @copyright  2012 Sam Hemelryk
      27   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
      28   */
      29  
      30  defined('MOODLE_INTERNAL') || die();
      31  
      32  /**
      33   * Cache configuration writer.
      34   *
      35   * This class should only be used when you need to write to the config, all read operations exist within the cache_config.
      36   *
      37   * @package    core
      38   * @category   cache
      39   * @copyright  2012 Sam Hemelryk
      40   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
      41   */
      42  class cache_config_writer extends cache_config {
      43  
      44      /**
      45       * Switch that gets set to true when ever a cache_config_writer instance is saving the cache configuration file.
      46       * If this is set to true when save is next called we must avoid the trying to save and instead return the
      47       * generated config so that is may be used instead of the file.
      48       * @var bool
      49       */
      50      protected static $creatingconfig = false;
      51  
      52      /**
      53       * Returns an instance of the configuration writer.
      54       *
      55       * @return cache_config_writer
      56       */
      57      public static function instance() {
      58          $factory = cache_factory::instance();
      59          return $factory->create_config_instance(true);
      60      }
      61  
      62      /**
      63       * Saves the current configuration.
      64       *
      65       * Exceptions within this function are tolerated but must be of type cache_exception.
      66       * They are caught during initialisation and written to the error log. This is required in order to avoid
      67       * infinite loop situations caused by the cache throwing exceptions during its initialisation.
      68       */
      69      protected function config_save() {
      70          global $CFG;
      71          $cachefile = static::get_config_file_path();
      72          $directory = dirname($cachefile);
      73          if ($directory !== $CFG->dataroot && !file_exists($directory)) {
      74              $result = make_writable_directory($directory, false);
      75              if (!$result) {
      76                  throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Cannot create config directory. Check the permissions on your moodledata directory.');
      77              }
      78          }
      79          if (!file_exists($directory) || !is_writable($directory)) {
      80              throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Config directory is not writable. Check the permissions on the moodledata/muc directory.');
      81          }
      82  
      83          // Prepare a configuration array to store.
      84          $configuration = $this->generate_configuration_array();
      85  
      86          // Prepare the file content.
      87          $content = "<?php defined('MOODLE_INTERNAL') || die();\n \$configuration = ".var_export($configuration, true).";";
      88  
      89          // We need to create a temporary cache lock instance for use here. Remember we are generating the config file
      90          // it doesn't exist and thus we can't use the normal API for this (it'll just try to use config).
      91          $lockconf = reset($this->configlocks);
      92          if ($lockconf === false) {
      93              debugging('Your cache configuration file is out of date and needs to be refreshed.', DEBUG_DEVELOPER);
      94              // Use the default
      95              $lockconf = array(
      96                  'name' => 'cachelock_file_default',
      97                  'type' => 'cachelock_file',
      98                  'dir' => 'filelocks',
      99                  'default' => true
     100              );
     101          }
     102          $factory = cache_factory::instance();
     103          $locking = $factory->create_lock_instance($lockconf);
     104          if ($locking->lock('configwrite', 'config', true)) {
     105              // Its safe to use w mode here because we have already acquired the lock.
     106              $handle = fopen($cachefile, 'w');
     107              fwrite($handle, $content);
     108              fflush($handle);
     109              fclose($handle);
     110              $locking->unlock('configwrite', 'config');
     111              @chmod($cachefile, $CFG->filepermissions);
     112              // Tell PHP to recompile the script.
     113              core_component::invalidate_opcode_php_cache($cachefile);
     114          } else {
     115              throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Unable to open the cache config file.');
     116          }
     117      }
     118  
     119      /**
     120       * Generates a configuration array suitable to be written to the config file.
     121       * @return array
     122       */
     123      protected function generate_configuration_array() {
     124          $configuration = array();
     125          $configuration['siteidentifier'] = $this->siteidentifier;
     126          $configuration['stores'] = $this->configstores;
     127          $configuration['modemappings'] = $this->configmodemappings;
     128          $configuration['definitions'] = $this->configdefinitions;
     129          $configuration['definitionmappings'] = $this->configdefinitionmappings;
     130          $configuration['locks'] = $this->configlocks;
     131          return $configuration;
     132      }
     133  
     134      /**
     135       * Adds a plugin instance.
     136       *
     137       * This function also calls save so you should redirect immediately, or at least very shortly after
     138       * calling this method.
     139       *
     140       * @param string $name The name for the instance (must be unique)
     141       * @param string $plugin The name of the plugin.
     142       * @param array $configuration The configuration data for the plugin instance.
     143       * @return bool
     144       * @throws cache_exception
     145       */
     146      public function add_store_instance($name, $plugin, array $configuration = array()) {
     147          if (array_key_exists($name, $this->configstores)) {
     148              throw new cache_exception('Duplicate name specificed for cache plugin instance. You must provide a unique name.');
     149          }
     150          $class = 'cachestore_'.$plugin;
     151          if (!class_exists($class)) {
     152              $plugins = core_component::get_plugin_list_with_file('cachestore', 'lib.php');
     153              if (!array_key_exists($plugin, $plugins)) {
     154                  throw new cache_exception('Invalid plugin name specified. The plugin does not exist or is not valid.');
     155              }
     156              $file = $plugins[$plugin];
     157              if (file_exists($file)) {
     158                  require_once($file);
     159              }
     160              if (!class_exists($class)) {
     161                  throw new cache_exception('Invalid cache plugin specified. The plugin does not contain the required class.');
     162              }
     163          }
     164          $reflection = new ReflectionClass($class);
     165          if (!$reflection->isSubclassOf('cache_store')) {
     166              throw new cache_exception('Invalid cache plugin specified. The plugin does not extend the required class.');
     167          }
     168          if (!$class::are_requirements_met()) {
     169              throw new cache_exception('Unable to add new cache plugin instance. The requested plugin type is not supported.');
     170          }
     171          $this->configstores[$name] = array(
     172              'name' => $name,
     173              'plugin' => $plugin,
     174              'configuration' => $configuration,
     175              'features' => $class::get_supported_features($configuration),
     176              'modes' => $class::get_supported_modes($configuration),
     177              'mappingsonly' => !empty($configuration['mappingsonly']),
     178              'class' => $class,
     179              'default' => false
     180          );
     181          if (array_key_exists('lock', $configuration)) {
     182              $this->configstores[$name]['lock'] = $configuration['lock'];
     183              unset($this->configstores[$name]['configuration']['lock']);
     184          }
     185          // Call instance_created()
     186          $store = new $class($name, $this->configstores[$name]['configuration']);
     187          $store->instance_created();
     188  
     189          $this->config_save();
     190          return true;
     191      }
     192  
     193      /**
     194       * Adds a new lock instance to the config file.
     195       *
     196       * @param string $name The name the user gave the instance. PARAM_ALHPANUMEXT
     197       * @param string $plugin The plugin we are creating an instance of.
     198       * @param string $configuration Configuration data from the config instance.
     199       * @throws cache_exception
     200       */
     201      public function add_lock_instance($name, $plugin, $configuration = array()) {
     202          if (array_key_exists($name, $this->configlocks)) {
     203              throw new cache_exception('Duplicate name specificed for cache lock instance. You must provide a unique name.');
     204          }
     205          $class = 'cachelock_'.$plugin;
     206          if (!class_exists($class)) {
     207              $plugins = core_component::get_plugin_list_with_file('cachelock', 'lib.php');
     208              if (!array_key_exists($plugin, $plugins)) {
     209                  throw new cache_exception('Invalid lock name specified. The plugin does not exist or is not valid.');
     210              }
     211              $file = $plugins[$plugin];
     212              if (file_exists($file)) {
     213                  require_once($file);
     214              }
     215              if (!class_exists($class)) {
     216                  throw new cache_exception('Invalid lock plugin specified. The plugin does not contain the required class.');
     217              }
     218          }
     219          $reflection = new ReflectionClass($class);
     220          if (!$reflection->implementsInterface('cache_lock_interface')) {
     221              throw new cache_exception('Invalid lock plugin specified. The plugin does not implement the required interface.');
     222          }
     223          $this->configlocks[$name] = array_merge($configuration, array(
     224              'name' => $name,
     225              'type' => 'cachelock_'.$plugin,
     226              'default' => false
     227          ));
     228          $this->config_save();
     229      }
     230  
     231      /**
     232       * Deletes a lock instance given its name.
     233       *
     234       * @param string $name The name of the plugin, PARAM_ALPHANUMEXT.
     235       * @return bool
     236       * @throws cache_exception
     237       */
     238      public function delete_lock_instance($name) {
     239          if (!array_key_exists($name, $this->configlocks)) {
     240              throw new cache_exception('The requested store does not exist.');
     241          }
     242          if ($this->configlocks[$name]['default']) {
     243              throw new cache_exception('You can not delete the default lock.');
     244          }
     245          foreach ($this->configstores as $store) {
     246              if (isset($store['lock']) && $store['lock'] === $name) {
     247                  throw new cache_exception('You cannot delete a cache lock that is being used by a store.');
     248              }
     249          }
     250          unset($this->configlocks[$name]);
     251          $this->config_save();
     252          return true;
     253      }
     254  
     255      /**
     256       * Sets the mode mappings.
     257       *
     258       * These determine the default caches for the different modes.
     259       * This function also calls save so you should redirect immediately, or at least very shortly after
     260       * calling this method.
     261       *
     262       * @param array $modemappings
     263       * @return bool
     264       * @throws cache_exception
     265       */
     266      public function set_mode_mappings(array $modemappings) {
     267          $mappings = array(
     268              cache_store::MODE_APPLICATION => array(),
     269              cache_store::MODE_SESSION => array(),
     270              cache_store::MODE_REQUEST => array(),
     271          );
     272          foreach ($modemappings as $mode => $stores) {
     273              if (!array_key_exists($mode, $mappings)) {
     274                  throw new cache_exception('The cache mode for the new mapping does not exist');
     275              }
     276              $sort = 0;
     277              foreach ($stores as $store) {
     278                  if (!array_key_exists($store, $this->configstores)) {
     279                      throw new cache_exception('The instance name for the new mapping does not exist');
     280                  }
     281                  if (array_key_exists($store, $mappings[$mode])) {
     282                      throw new cache_exception('This cache mapping already exists');
     283                  }
     284                  $mappings[$mode][] = array(
     285                      'store' => $store,
     286                      'mode' => $mode,
     287                      'sort' => $sort++
     288                  );
     289              }
     290          }
     291          $this->configmodemappings = array_merge(
     292              $mappings[cache_store::MODE_APPLICATION],
     293              $mappings[cache_store::MODE_SESSION],
     294              $mappings[cache_store::MODE_REQUEST]
     295          );
     296  
     297          $this->config_save();
     298          return true;
     299      }
     300  
     301      /**
     302       * Edits a give plugin instance.
     303       *
     304       * The plugin instance is determined by its name, hence you cannot rename plugins.
     305       * This function also calls save so you should redirect immediately, or at least very shortly after
     306       * calling this method.
     307       *
     308       * @param string $name
     309       * @param string $plugin
     310       * @param array $configuration
     311       * @return bool
     312       * @throws cache_exception
     313       */
     314      public function edit_store_instance($name, $plugin, $configuration) {
     315          if (!array_key_exists($name, $this->configstores)) {
     316              throw new cache_exception('The requested instance does not exist.');
     317          }
     318          $plugins = core_component::get_plugin_list_with_file('cachestore', 'lib.php');
     319          if (!array_key_exists($plugin, $plugins)) {
     320              throw new cache_exception('Invalid plugin name specified. The plugin either does not exist or is not valid.');
     321          }
     322          $class = 'cachestore_'.$plugin;
     323          $file = $plugins[$plugin];
     324          if (!class_exists($class)) {
     325              if (file_exists($file)) {
     326                  require_once($file);
     327              }
     328              if (!class_exists($class)) {
     329                  throw new cache_exception('Invalid cache plugin specified. The plugin does not contain the required class.'.$class);
     330              }
     331          }
     332          $this->configstores[$name] = array(
     333              'name' => $name,
     334              'plugin' => $plugin,
     335              'configuration' => $configuration,
     336              'features' => $class::get_supported_features($configuration),
     337              'modes' => $class::get_supported_modes($configuration),
     338              'mappingsonly' => !empty($configuration['mappingsonly']),
     339              'class' => $class,
     340              'default' => $this->configstores[$name]['default'] // Can't change the default.
     341          );
     342          if (array_key_exists('lock', $configuration)) {
     343              $this->configstores[$name]['lock'] = $configuration['lock'];
     344              unset($this->configstores[$name]['configuration']['lock']);
     345          }
     346          $this->config_save();
     347          return true;
     348      }
     349  
     350      /**
     351       * Deletes a store instance.
     352       *
     353       * This function also calls save so you should redirect immediately, or at least very shortly after
     354       * calling this method.
     355       *
     356       * @param string $name The name of the instance to delete.
     357       * @return bool
     358       * @throws cache_exception
     359       */
     360      public function delete_store_instance($name) {
     361          if (!array_key_exists($name, $this->configstores)) {
     362              throw new cache_exception('The requested store does not exist.');
     363          }
     364          if ($this->configstores[$name]['default']) {
     365              throw new cache_exception('The can not delete the default stores.');
     366          }
     367          foreach ($this->configmodemappings as $mapping) {
     368              if ($mapping['store'] === $name) {
     369                  throw new cache_exception('You cannot delete a cache store that has mode mappings.');
     370              }
     371          }
     372          foreach ($this->configdefinitionmappings as $mapping) {
     373              if ($mapping['store'] === $name) {
     374                  throw new cache_exception('You cannot delete a cache store that has definition mappings.');
     375              }
     376          }
     377  
     378          // Call instance_deleted()
     379          $class = 'cachestore_'.$this->configstores[$name]['plugin'];
     380          $store = new $class($name, $this->configstores[$name]['configuration']);
     381          $store->instance_deleted();
     382  
     383          unset($this->configstores[$name]);
     384          $this->config_save();
     385          return true;
     386      }
     387  
     388      /**
     389       * Creates the default configuration and saves it.
     390       *
     391       * This function calls config_save, however it is safe to continue using it afterwards as this function should only ever
     392       * be called when there is no configuration file already.
     393       *
     394       * @param bool $forcesave If set to true then we will forcefully save the default configuration file.
     395       * @return true|array Returns true if the default configuration was successfully created.
     396       *     Returns a configuration array if it could not be saved. This is a bad situation. Check your error logs.
     397       */
     398      public static function create_default_configuration($forcesave = false) {
     399          // HACK ALERT.
     400          // We probably need to come up with a better way to create the default stores, or at least ensure 100% that the
     401          // default store plugins are protected from deletion.
     402          $writer = new self;
     403          $writer->configstores = self::get_default_stores();
     404          $writer->configdefinitions = self::locate_definitions();
     405          $writer->configmodemappings = array(
     406              array(
     407                  'mode' => cache_store::MODE_APPLICATION,
     408                  'store' => 'default_application',
     409                  'sort' => -1
     410              ),
     411              array(
     412                  'mode' => cache_store::MODE_SESSION,
     413                  'store' => 'default_session',
     414                  'sort' => -1
     415              ),
     416              array(
     417                  'mode' => cache_store::MODE_REQUEST,
     418                  'store' => 'default_request',
     419                  'sort' => -1
     420              )
     421          );
     422          $writer->configlocks = array(
     423              'default_file_lock' => array(
     424                  'name' => 'cachelock_file_default',
     425                  'type' => 'cachelock_file',
     426                  'dir' => 'filelocks',
     427                  'default' => true
     428              )
     429          );
     430  
     431          $factory = cache_factory::instance();
     432          // We expect the cache to be initialising presently. If its not then something has gone wrong and likely
     433          // we are now in a loop.
     434          if (!$forcesave && $factory->get_state() !== cache_factory::STATE_INITIALISING) {
     435              return $writer->generate_configuration_array();
     436          }
     437          $factory->set_state(cache_factory::STATE_SAVING);
     438          $writer->config_save();
     439          return true;
     440      }
     441  
     442      /**
     443       * Returns an array of default stores for use.
     444       *
     445       * @return array
     446       */
     447      protected static function get_default_stores() {
     448          global $CFG;
     449  
     450          require_once($CFG->dirroot.'/cache/stores/file/lib.php');
     451          require_once($CFG->dirroot.'/cache/stores/session/lib.php');
     452          require_once($CFG->dirroot.'/cache/stores/static/lib.php');
     453  
     454          return array(
     455              'default_application' => array(
     456                  'name' => 'default_application',
     457                  'plugin' => 'file',
     458                  'configuration' => array(),
     459                  'features' => cachestore_file::get_supported_features(),
     460                  'modes' => cachestore_file::get_supported_modes(),
     461                  'default' => true,
     462              ),
     463              'default_session' => array(
     464                  'name' => 'default_session',
     465                  'plugin' => 'session',
     466                  'configuration' => array(),
     467                  'features' => cachestore_session::get_supported_features(),
     468                  'modes' => cachestore_session::get_supported_modes(),
     469                  'default' => true,
     470              ),
     471              'default_request' => array(
     472                  'name' => 'default_request',
     473                  'plugin' => 'static',
     474                  'configuration' => array(),
     475                  'features' => cachestore_static::get_supported_features(),
     476                  'modes' => cachestore_static::get_supported_modes(),
     477                  'default' => true,
     478              )
     479          );
     480      }
     481  
     482      /**
     483       * Updates the default stores within the MUC config file.
     484       */
     485      public static function update_default_config_stores() {
     486          $factory = cache_factory::instance();
     487          $factory->updating_started();
     488          $config = $factory->create_config_instance(true);
     489          $config->configstores = array_merge($config->configstores, self::get_default_stores());
     490          $config->config_save();
     491          $factory->updating_finished();
     492      }
     493  
     494      /**
     495       * Updates the definition in the configuration from those found in the cache files.
     496       *
     497       * Calls config_save further down, you should redirect immediately or asap after calling this method.
     498       *
     499       * @param bool $coreonly If set to true only core definitions will be updated.
     500       */
     501      public static function update_definitions($coreonly = false) {
     502          $factory = cache_factory::instance();
     503          $factory->updating_started();
     504          $config = $factory->create_config_instance(true);
     505          $config->write_definitions_to_cache(self::locate_definitions($coreonly));
     506          $factory->updating_finished();
     507      }
     508  
     509      /**
     510       * Locates all of the definition files.
     511       *
     512       * @param bool $coreonly If set to true only core definitions will be updated.
     513       * @return array
     514       */
     515      protected static function locate_definitions($coreonly = false) {
     516          global $CFG;
     517  
     518          $files = array();
     519          if (file_exists($CFG->dirroot.'/lib/db/caches.php')) {
     520              $files['core'] = $CFG->dirroot.'/lib/db/caches.php';
     521          }
     522  
     523          if (!$coreonly) {
     524              $plugintypes = core_component::get_plugin_types();
     525              foreach ($plugintypes as $type => $location) {
     526                  $plugins = core_component::get_plugin_list_with_file($type, 'db/caches.php');
     527                  foreach ($plugins as $plugin => $filepath) {
     528                      $component = clean_param($type.'_'.$plugin, PARAM_COMPONENT); // Standardised plugin name.
     529                      $files[$component] = $filepath;
     530                  }
     531              }
     532          }
     533  
     534          $definitions = array();
     535          foreach ($files as $component => $file) {
     536              $filedefs = self::load_caches_file($file);
     537              foreach ($filedefs as $area => $definition) {
     538                  $area = clean_param($area, PARAM_AREA);
     539                  $id = $component.'/'.$area;
     540                  $definition['component'] = $component;
     541                  $definition['area'] = $area;
     542                  if (array_key_exists($id, $definitions)) {
     543                      debugging('Error: duplicate cache definition found with id: '.$id, DEBUG_DEVELOPER);
     544                      continue;
     545                  }
     546                  $definitions[$id] = $definition;
     547              }
     548          }
     549  
     550          return $definitions;
     551      }
     552  
     553      /**
     554       * Writes the updated definitions for the config file.
     555       * @param array $definitions
     556       */
     557      private function write_definitions_to_cache(array $definitions) {
     558  
     559          // Preserve the selected sharing option when updating the definitions.
     560          // This is set by the user and should never come from caches.php.
     561          foreach ($definitions as $key => $definition) {
     562              unset($definitions[$key]['selectedsharingoption']);
     563              unset($definitions[$key]['userinputsharingkey']);
     564              if (isset($this->configdefinitions[$key]) && isset($this->configdefinitions[$key]['selectedsharingoption'])) {
     565                  $definitions[$key]['selectedsharingoption'] = $this->configdefinitions[$key]['selectedsharingoption'];
     566              }
     567              if (isset($this->configdefinitions[$key]) && isset($this->configdefinitions[$key]['userinputsharingkey'])) {
     568                  $definitions[$key]['userinputsharingkey'] = $this->configdefinitions[$key]['userinputsharingkey'];
     569              }
     570          }
     571  
     572          $this->configdefinitions = $definitions;
     573          foreach ($this->configdefinitionmappings as $key => $mapping) {
     574              if (!array_key_exists($mapping['definition'], $definitions)) {
     575                  unset($this->configdefinitionmappings[$key]);
     576              }
     577          }
     578          $this->config_save();
     579      }
     580  
     581      /**
     582       * Loads the caches file if it exists.
     583       * @param string $file Absolute path to the file.
     584       * @return array
     585       */
     586      private static function load_caches_file($file) {
     587          if (!file_exists($file)) {
     588              return array();
     589          }
     590          $definitions = array();
     591          include($file);
     592          return $definitions;
     593      }
     594  
     595      /**
     596       * Sets the mappings for a given definition.
     597       *
     598       * @param string $definition
     599       * @param array $mappings
     600       * @throws coding_exception
     601       */
     602      public function set_definition_mappings($definition, $mappings) {
     603          if (!array_key_exists($definition, $this->configdefinitions)) {
     604              throw new coding_exception('Invalid definition name passed when updating mappings.');
     605          }
     606          foreach ($mappings as $store) {
     607              if (!array_key_exists($store, $this->configstores)) {
     608                  throw new coding_exception('Invalid store name passed when updating definition mappings.');
     609              }
     610          }
     611          foreach ($this->configdefinitionmappings as $key => $mapping) {
     612              if ($mapping['definition'] == $definition) {
     613                  unset($this->configdefinitionmappings[$key]);
     614              }
     615          }
     616          $sort = count($mappings);
     617          foreach ($mappings as $store) {
     618              $this->configdefinitionmappings[] = array(
     619                  'store' => $store,
     620                  'definition' => $definition,
     621                  'sort' => $sort
     622              );
     623              $sort--;
     624          }
     625  
     626          $this->config_save();
     627      }
     628  
     629      /**
     630       * Update the site identifier stored by the cache API.
     631       *
     632       * @param string $siteidentifier
     633       * @return string The new site identifier.
     634       */
     635      public function update_site_identifier($siteidentifier) {
     636          $this->siteidentifier = md5((string)$siteidentifier);
     637          $this->config_save();
     638          return $this->siteidentifier;
     639      }
     640  
     641      /**
     642       * Sets the selected sharing options and key for a definition.
     643       *
     644       * @param string $definition The name of the definition to set for.
     645       * @param int $sharingoption The sharing option to set.
     646       * @param string|null $userinputsharingkey The user input key or null.
     647       * @throws coding_exception
     648       */
     649      public function set_definition_sharing($definition, $sharingoption, $userinputsharingkey = null) {
     650          if (!array_key_exists($definition, $this->configdefinitions)) {
     651              throw new coding_exception('Invalid definition name passed when updating sharing options.');
     652          }
     653          if (!($this->configdefinitions[$definition]['sharingoptions'] & $sharingoption)) {
     654              throw new coding_exception('Invalid sharing option passed when updating definition.');
     655          }
     656          $this->configdefinitions[$definition]['selectedsharingoption'] = (int)$sharingoption;
     657          if (!empty($userinputsharingkey)) {
     658              $this->configdefinitions[$definition]['userinputsharingkey'] = (string)$userinputsharingkey;
     659          }
     660          $this->config_save();
     661      }
     662  
     663  }
     664  
     665  /**
     666   * A cache helper for administration tasks
     667   *
     668   * @package    core
     669   * @category   cache
     670   * @copyright  2012 Sam Hemelryk
     671   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
     672   */
     673  abstract class cache_administration_helper extends cache_helper {
     674  
     675      /**
     676       * Returns an array containing all of the information about stores a renderer needs.
     677       * @return array
     678       */
     679      public static function get_store_instance_summaries() {
     680          $return = array();
     681          $default = array();
     682          $instance = cache_config::instance();
     683          $stores = $instance->get_all_stores();
     684          $locks = $instance->get_locks();
     685          foreach ($stores as $name => $details) {
     686              $class = $details['class'];
     687              $store = new $class($details['name'], $details['configuration']);
     688              $lock = (isset($details['lock'])) ? $locks[$details['lock']] : $instance->get_default_lock();
     689              $record = array(
     690                  'name' => $name,
     691                  'plugin' => $details['plugin'],
     692                  'default' => $details['default'],
     693                  'isready' => $store->is_ready(),
     694                  'requirementsmet' => $class::are_requirements_met(),
     695                  'mappings' => 0,
     696                  'lock' => $lock,
     697                  'modes' => array(
     698                      cache_store::MODE_APPLICATION =>
     699                          ($store->get_supported_modes($return) & cache_store::MODE_APPLICATION) == cache_store::MODE_APPLICATION,
     700                      cache_store::MODE_SESSION =>
     701                          ($store->get_supported_modes($return) & cache_store::MODE_SESSION) == cache_store::MODE_SESSION,
     702                      cache_store::MODE_REQUEST =>
     703                          ($store->get_supported_modes($return) & cache_store::MODE_REQUEST) == cache_store::MODE_REQUEST,
     704                  ),
     705                  'supports' => array(
     706                      'multipleidentifiers' => $store->supports_multiple_identifiers(),
     707                      'dataguarantee' => $store->supports_data_guarantee(),
     708                      'nativettl' => $store->supports_native_ttl(),
     709                      'nativelocking' => ($store instanceof cache_is_lockable),
     710                      'keyawareness' => ($store instanceof cache_is_key_aware),
     711                      'searchable' => ($store instanceof cache_is_searchable)
     712                  ),
     713                  'warnings' => $store->get_warnings()
     714              );
     715              if (empty($details['default'])) {
     716                  $return[$name] = $record;
     717              } else {
     718                  $default[$name] = $record;
     719              }
     720          }
     721  
     722          ksort($return);
     723          ksort($default);
     724          $return = $return + $default;
     725  
     726          foreach ($instance->get_definition_mappings() as $mapping) {
     727              if (!array_key_exists($mapping['store'], $return)) {
     728                  continue;
     729              }
     730              $return[$mapping['store']]['mappings']++;
     731          }
     732  
     733          return $return;
     734      }
     735  
     736      /**
     737       * Returns an array of information about plugins, everything a renderer needs.
     738       * @return array
     739       */
     740      public static function get_store_plugin_summaries() {
     741          $return = array();
     742          $plugins = core_component::get_plugin_list_with_file('cachestore', 'lib.php', true);
     743          foreach ($plugins as $plugin => $path) {
     744              $class = 'cachestore_'.$plugin;
     745              $return[$plugin] = array(
     746                  'name' => get_string('pluginname', 'cachestore_'.$plugin),
     747                  'requirementsmet' => $class::are_requirements_met(),
     748                  'instances' => 0,
     749                  'modes' => array(
     750                      cache_store::MODE_APPLICATION => ($class::get_supported_modes() & cache_store::MODE_APPLICATION),
     751                      cache_store::MODE_SESSION => ($class::get_supported_modes() & cache_store::MODE_SESSION),
     752                      cache_store::MODE_REQUEST => ($class::get_supported_modes() & cache_store::MODE_REQUEST),
     753                  ),
     754                  'supports' => array(
     755                      'multipleidentifiers' => ($class::get_supported_features() & cache_store::SUPPORTS_MULTIPLE_IDENTIFIERS),
     756                      'dataguarantee' => ($class::get_supported_features() & cache_store::SUPPORTS_DATA_GUARANTEE),
     757                      'nativettl' => ($class::get_supported_features() & cache_store::SUPPORTS_NATIVE_TTL),
     758                      'nativelocking' => (in_array('cache_is_lockable', class_implements($class))),
     759                      'keyawareness' => (array_key_exists('cache_is_key_aware', class_implements($class))),
     760                  ),
     761                  'canaddinstance' => ($class::can_add_instance() && $class::are_requirements_met())
     762              );
     763          }
     764  
     765          $instance = cache_config::instance();
     766          $stores = $instance->get_all_stores();
     767          foreach ($stores as $store) {
     768              $plugin = $store['plugin'];
     769              if (array_key_exists($plugin, $return)) {
     770                  $return[$plugin]['instances']++;
     771              }
     772          }
     773  
     774          return $return;
     775      }
     776  
     777      /**
     778       * Returns an array about the definitions. All the information a renderer needs.
     779       * @return array
     780       */
     781      public static function get_definition_summaries() {
     782          $factory = cache_factory::instance();
     783          $config = $factory->create_config_instance();
     784          $storenames = array();
     785          foreach ($config->get_all_stores() as $key => $store) {
     786              if (!empty($store['default'])) {
     787                  $storenames[$key] = new lang_string('store_'.$key, 'cache');
     788              } else {
     789                  $storenames[$store['name']] = $store['name'];
     790              }
     791          }
     792          /* @var cache_definition[] $definitions */
     793          $definitions = array();
     794          foreach ($config->get_definitions() as $key => $definition) {
     795              $definitions[$key] = cache_definition::load($definition['component'].'/'.$definition['area'], $definition);
     796          }
     797          foreach ($definitions as $id => $definition) {
     798              $mappings = array();
     799              foreach (cache_helper::get_stores_suitable_for_definition($definition) as $store) {
     800                  $mappings[] = $storenames[$store->my_name()];
     801              }
     802              $return[$id] = array(
     803                  'id' => $id,
     804                  'name' => $definition->get_name(),
     805                  'mode' => $definition->get_mode(),
     806                  'component' => $definition->get_component(),
     807                  'area' => $definition->get_area(),
     808                  'mappings' => $mappings,
     809                  'canuselocalstore' => $definition->can_use_localstore(),
     810                  'sharingoptions' => self::get_definition_sharing_options($definition->get_sharing_options(), false),
     811                  'selectedsharingoption' => self::get_definition_sharing_options($definition->get_selected_sharing_option(), true),
     812                  'userinputsharingkey' => $definition->get_user_input_sharing_key()
     813              );
     814          }
     815          return $return;
     816      }
     817  
     818      /**
     819       * Given a sharing option hash this function returns an array of strings that can be used to describe it.
     820       *
     821       * @param int $sharingoption The sharing option hash to get strings for.
     822       * @param bool $isselectedoptions Set to true if the strings will be used to view the selected options.
     823       * @return array An array of lang_string's.
     824       */
     825      public static function get_definition_sharing_options($sharingoption, $isselectedoptions = true) {
     826          $options = array();
     827          $prefix = ($isselectedoptions) ? 'sharingselected' : 'sharing';
     828          if ($sharingoption & cache_definition::SHARING_ALL) {
     829              $options[cache_definition::SHARING_ALL] = new lang_string($prefix.'_all', 'cache');
     830          }
     831          if ($sharingoption & cache_definition::SHARING_SITEID) {
     832              $options[cache_definition::SHARING_SITEID] = new lang_string($prefix.'_siteid', 'cache');
     833          }
     834          if ($sharingoption & cache_definition::SHARING_VERSION) {
     835              $options[cache_definition::SHARING_VERSION] = new lang_string($prefix.'_version', 'cache');
     836          }
     837          if ($sharingoption & cache_definition::SHARING_INPUT) {
     838              $options[cache_definition::SHARING_INPUT] = new lang_string($prefix.'_input', 'cache');
     839          }
     840          return $options;
     841      }
     842  
     843      /**
     844       * Returns all of the actions that can be performed on a definition.
     845       * @param context $context
     846       * @return array
     847       */
     848      public static function get_definition_actions(context $context, array $definition) {
     849          if (has_capability('moodle/site:config', $context)) {
     850              $actions = array();
     851              // Edit mappings.
     852              $actions[] = array(
     853                  'text' => get_string('editmappings', 'cache'),
     854                  'url' => new moodle_url('/cache/admin.php', array('action' => 'editdefinitionmapping', 'sesskey' => sesskey()))
     855              );
     856              // Edit sharing.
     857              if (count($definition['sharingoptions']) > 1) {
     858                  $actions[] = array(
     859                      'text' => get_string('editsharing', 'cache'),
     860                      'url' => new moodle_url('/cache/admin.php', array('action' => 'editdefinitionsharing', 'sesskey' => sesskey()))
     861                  );
     862              }
     863              // Purge.
     864              $actions[] = array(
     865                  'text' => get_string('purge', 'cache'),
     866                  'url' => new moodle_url('/cache/admin.php', array('action' => 'purgedefinition', 'sesskey' => sesskey()))
     867              );
     868              return $actions;
     869          }
     870          return array();
     871      }
     872  
     873      /**
     874       * Returns all of the actions that can be performed on a store.
     875       *
     876       * @param string $name The name of the store
     877       * @param array $storedetails
     878       * @return array
     879       */
     880      public static function get_store_instance_actions($name, array $storedetails) {
     881          $actions = array();
     882          if (has_capability('moodle/site:config', context_system::instance())) {
     883              $baseurl = new moodle_url('/cache/admin.php', array('store' => $name, 'sesskey' => sesskey()));
     884              if (empty($storedetails['default'])) {
     885                  $actions[] = array(
     886                      'text' => get_string('editstore', 'cache'),
     887                      'url' => new moodle_url($baseurl, array('action' => 'editstore', 'plugin' => $storedetails['plugin']))
     888                  );
     889                  $actions[] = array(
     890                      'text' => get_string('deletestore', 'cache'),
     891                      'url' => new moodle_url($baseurl, array('action' => 'deletestore'))
     892                  );
     893              }
     894              $actions[] = array(
     895                  'text' => get_string('purge', 'cache'),
     896                  'url' => new moodle_url($baseurl, array('action' => 'purgestore'))
     897              );
     898          }
     899          return $actions;
     900      }
     901  
     902  
     903      /**
     904       * Returns all of the actions that can be performed on a plugin.
     905       *
     906       * @param string $name The name of the plugin
     907       * @param array $plugindetails
     908       * @return array
     909       */
     910      public static function get_store_plugin_actions($name, array $plugindetails) {
     911          $actions = array();
     912          if (has_capability('moodle/site:config', context_system::instance())) {
     913              if (!empty($plugindetails['canaddinstance'])) {
     914                  $url = new moodle_url('/cache/admin.php', array('action' => 'addstore', 'plugin' => $name, 'sesskey' => sesskey()));
     915                  $actions[] = array(
     916                      'text' => get_string('addinstance', 'cache'),
     917                      'url' => $url
     918                  );
     919              }
     920          }
     921          return $actions;
     922      }
     923  
     924      /**
     925       * Returns a form that can be used to add a store instance.
     926       *
     927       * @param string $plugin The plugin to add an instance of
     928       * @return cachestore_addinstance_form
     929       * @throws coding_exception
     930       */
     931      public static function get_add_store_form($plugin) {
     932          global $CFG; // Needed for includes.
     933          $plugins = core_component::get_plugin_list('cachestore');
     934          if (!array_key_exists($plugin, $plugins)) {
     935              throw new coding_exception('Invalid cache plugin used when trying to create an edit form.');
     936          }
     937          $plugindir = $plugins[$plugin];
     938          $class = 'cachestore_addinstance_form';
     939          if (file_exists($plugindir.'/addinstanceform.php')) {
     940              require_once($plugindir.'/addinstanceform.php');
     941              if (class_exists('cachestore_'.$plugin.'_addinstance_form')) {
     942                  $class = 'cachestore_'.$plugin.'_addinstance_form';
     943                  if (!array_key_exists('cachestore_addinstance_form', class_parents($class))) {
     944                      throw new coding_exception('Cache plugin add instance forms must extend cachestore_addinstance_form');
     945                  }
     946              }
     947          }
     948  
     949          $locks = self::get_possible_locks_for_stores($plugindir, $plugin);
     950  
     951          $url = new moodle_url('/cache/admin.php', array('action' => 'addstore'));
     952          return new $class($url, array('plugin' => $plugin, 'store' => null, 'locks' => $locks));
     953      }
     954  
     955      /**
     956       * Returns a form that can be used to edit a store instance.
     957       *
     958       * @param string $plugin
     959       * @param string $store
     960       * @return cachestore_addinstance_form
     961       * @throws coding_exception
     962       */
     963      public static function get_edit_store_form($plugin, $store) {
     964          global $CFG; // Needed for includes.
     965          $plugins = core_component::get_plugin_list('cachestore');
     966          if (!array_key_exists($plugin, $plugins)) {
     967              throw new coding_exception('Invalid cache plugin used when trying to create an edit form.');
     968          }
     969          $factory = cache_factory::instance();
     970          $config = $factory->create_config_instance();
     971          $stores = $config->get_all_stores();
     972          if (!array_key_exists($store, $stores)) {
     973              throw new coding_exception('Invalid store name given when trying to create an edit form.');
     974          }
     975          $plugindir = $plugins[$plugin];
     976          $class = 'cachestore_addinstance_form';
     977          if (file_exists($plugindir.'/addinstanceform.php')) {
     978              require_once($plugindir.'/addinstanceform.php');
     979              if (class_exists('cachestore_'.$plugin.'_addinstance_form')) {
     980                  $class = 'cachestore_'.$plugin.'_addinstance_form';
     981                  if (!array_key_exists('cachestore_addinstance_form', class_parents($class))) {
     982                      throw new coding_exception('Cache plugin add instance forms must extend cachestore_addinstance_form');
     983                  }
     984              }
     985          }
     986  
     987          $locks = self::get_possible_locks_for_stores($plugindir, $plugin);
     988  
     989          $url = new moodle_url('/cache/admin.php', array('action' => 'editstore', 'plugin' => $plugin, 'store' => $store));
     990          $editform = new $class($url, array('plugin' => $plugin, 'store' => $store, 'locks' => $locks));
     991          if (isset($stores[$store]['lock'])) {
     992              $editform->set_data(array('lock' => $stores[$store]['lock']));
     993          }
     994          // See if the cachestore is going to want to load data for the form.
     995          // If it has a customised add instance form then it is going to want to.
     996          $storeclass = 'cachestore_'.$plugin;
     997          $storedata = $stores[$store];
     998          if (array_key_exists('configuration', $storedata) && array_key_exists('cache_is_configurable', class_implements($storeclass))) {
     999              $storeclass::config_set_edit_form_data($editform, $storedata['configuration']);
    1000          }
    1001          return $editform;
    1002      }
    1003  
    1004      /**
    1005       * Returns an array of suitable lock instances for use with this plugin, or false if the plugin handles locking itself.
    1006       *
    1007       * @param string $plugindir
    1008       * @param string $plugin
    1009       * @return array|false
    1010       */
    1011      protected static function get_possible_locks_for_stores($plugindir, $plugin) {
    1012          global $CFG; // Needed for includes.
    1013          $supportsnativelocking = false;
    1014          if (file_exists($plugindir.'/lib.php')) {
    1015              require_once ($plugindir.'/lib.php');
    1016              $pluginclass = 'cachestore_'.$plugin;
    1017              if (class_exists($pluginclass)) {
    1018                  $supportsnativelocking = array_key_exists('cache_is_lockable', class_implements($pluginclass));
    1019              }
    1020          }
    1021  
    1022          if (!$supportsnativelocking) {
    1023              $config = cache_config::instance();
    1024              $locks = array();
    1025              foreach ($config->get_locks() as $lock => $conf) {
    1026                  if (!empty($conf['default'])) {
    1027                      $name = get_string($lock, 'cache');
    1028                  } else {
    1029                      $name = $lock;
    1030                  }
    1031                  $locks[$lock] = $name;
    1032              }
    1033          } else {
    1034              $locks = false;
    1035          }
    1036  
    1037          return $locks;
    1038      }
    1039  
    1040      /**
    1041       * Processes the results of the add/edit instance form data for a plugin returning an array of config information suitable to
    1042       * store in configuration.
    1043       *
    1044       * @param stdClass $data The mform data.
    1045       * @return array
    1046       * @throws coding_exception
    1047       */
    1048      public static function get_store_configuration_from_data(stdClass $data) {
    1049          global $CFG;
    1050          $file = $CFG->dirroot.'/cache/stores/'.$data->plugin.'/lib.php';
    1051          if (!file_exists($file)) {
    1052              throw new coding_exception('Invalid cache plugin provided. '.$file);
    1053          }
    1054          require_once($file);
    1055          $class = 'cachestore_'.$data->plugin;
    1056          if (!class_exists($class)) {
    1057              throw new coding_exception('Invalid cache plugin provided.');
    1058          }
    1059          if (array_key_exists('cache_is_configurable', class_implements($class))) {
    1060              return $class::config_get_configuration_array($data);
    1061          }
    1062          return array();
    1063      }
    1064  
    1065      /**
    1066       * Get an array of stores that are suitable to be used for a given definition.
    1067       *
    1068       * @param string $component
    1069       * @param string $area
    1070       * @return array Array containing 3 elements
    1071       *      1. An array of currently used stores
    1072       *      2. An array of suitable stores
    1073       *      3. An array of default stores
    1074       */
    1075      public static function get_definition_store_options($component, $area) {
    1076          $factory = cache_factory::instance();
    1077          $definition = $factory->create_definition($component, $area);
    1078          $config = cache_config::instance();
    1079          $currentstores = $config->get_stores_for_definition($definition);
    1080          $possiblestores = $config->get_stores($definition->get_mode(), $definition->get_requirements_bin());
    1081  
    1082          $defaults = array();
    1083          foreach ($currentstores as $key => $store) {
    1084              if (!empty($store['default'])) {
    1085                  $defaults[] = $key;
    1086                  unset($currentstores[$key]);
    1087              }
    1088          }
    1089          foreach ($possiblestores as $key => $store) {
    1090              if ($store['default']) {
    1091                  unset($possiblestores[$key]);
    1092                  $possiblestores[$key] = $store;
    1093              }
    1094          }
    1095          return array($currentstores, $possiblestores, $defaults);
    1096      }
    1097  
    1098      /**
    1099       * Get the default stores for all modes.
    1100       *
    1101       * @return array An array containing sub-arrays, one for each mode.
    1102       */
    1103      public static function get_default_mode_stores() {
    1104          global $OUTPUT;
    1105          $instance = cache_config::instance();
    1106          $adequatestores = cache_helper::get_stores_suitable_for_mode_default();
    1107          $icon = new pix_icon('i/warning', new lang_string('inadequatestoreformapping', 'cache'));
    1108          $storenames = array();
    1109          foreach ($instance->get_all_stores() as $key => $store) {
    1110              if (!empty($store['default'])) {
    1111                  $storenames[$key] = new lang_string('store_'.$key, 'cache');
    1112              }
    1113          }
    1114          $modemappings = array(
    1115              cache_store::MODE_APPLICATION => array(),
    1116              cache_store::MODE_SESSION => array(),
    1117              cache_store::MODE_REQUEST => array(),
    1118          );
    1119          foreach ($instance->get_mode_mappings() as $mapping) {
    1120              $mode = $mapping['mode'];
    1121              if (!array_key_exists($mode, $modemappings)) {
    1122                  debugging('Unknown mode in cache store mode mappings', DEBUG_DEVELOPER);
    1123                  continue;
    1124              }
    1125              if (array_key_exists($mapping['store'], $storenames)) {
    1126                  $modemappings[$mode][$mapping['store']] = $storenames[$mapping['store']];
    1127              } else {
    1128                  $modemappings[$mode][$mapping['store']] = $mapping['store'];
    1129              }
    1130              if (!array_key_exists($mapping['store'], $adequatestores)) {
    1131                  $modemappings[$mode][$mapping['store']] = $modemappings[$mode][$mapping['store']].' '.$OUTPUT->render($icon);
    1132              }
    1133          }
    1134          return $modemappings;
    1135      }
    1136  
    1137      /**
    1138       * Returns an array summarising the locks available in the system
    1139       */
    1140      public static function get_lock_summaries() {
    1141          $locks = array();
    1142          $instance = cache_config::instance();
    1143          $stores = $instance->get_all_stores();
    1144          foreach ($instance->get_locks() as $lock) {
    1145              $default = !empty($lock['default']);
    1146              if ($default) {
    1147                  $name = new lang_string($lock['name'], 'cache');
    1148              } else {
    1149                  $name = $lock['name'];
    1150              }
    1151              $uses = 0;
    1152              foreach ($stores as $store) {
    1153                  if (!empty($store['lock']) && $store['lock'] === $lock['name']) {
    1154                      $uses++;
    1155                  }
    1156              }
    1157              $lockdata = array(
    1158                  'name' => $name,
    1159                  'default' => $default,
    1160                  'uses' => $uses,
    1161                  'type' => get_string('pluginname', $lock['type'])
    1162              );
    1163              $locks[$lock['name']] = $lockdata;
    1164          }
    1165          return $locks;
    1166      }
    1167  
    1168      /**
    1169       * Returns an array of lock plugins for which we can add an instance.
    1170       *
    1171       * Suitable for use within an mform select element.
    1172       *
    1173       * @return array
    1174       */
    1175      public static function get_addable_lock_options() {
    1176          $plugins = core_component::get_plugin_list_with_class('cachelock', '', 'lib.php');
    1177          $options = array();
    1178          $len = strlen('cachelock_');
    1179          foreach ($plugins as $plugin => $class) {
    1180              $method = "$class::can_add_instance";
    1181              if (is_callable($method) && !call_user_func($method)) {
    1182                  // Can't add an instance of this plugin.
    1183                  continue;
    1184              }
    1185              $options[substr($plugin, $len)] = get_string('pluginname', $plugin);
    1186          }
    1187          return $options;
    1188      }
    1189  
    1190      /**
    1191       * Gets the form to use when adding a lock instance.
    1192       *
    1193       * @param string $plugin
    1194       * @param array $lockplugin
    1195       * @return cache_lock_form
    1196       * @throws coding_exception
    1197       */
    1198      public static function get_add_lock_form($plugin, array $lockplugin = null) {
    1199          global $CFG; // Needed for includes.
    1200          $plugins = core_component::get_plugin_list('cachelock');
    1201          if (!array_key_exists($plugin, $plugins)) {
    1202              throw new coding_exception('Invalid cache lock plugin requested when trying to create a form.');
    1203          }
    1204          $plugindir = $plugins[$plugin];
    1205          $class = 'cache_lock_form';
    1206          if (file_exists($plugindir.'/addinstanceform.php') && in_array('cache_is_configurable', class_implements($class))) {
    1207              require_once($plugindir.'/addinstanceform.php');
    1208              if (class_exists('cachelock_'.$plugin.'_addinstance_form')) {
    1209                  $class = 'cachelock_'.$plugin.'_addinstance_form';
    1210                  if (!array_key_exists('cache_lock_form', class_parents($class))) {
    1211                      throw new coding_exception('Cache lock plugin add instance forms must extend cache_lock_form');
    1212                  }
    1213              }
    1214          }
    1215          return new $class(null, array('lock' => $plugin));
    1216      }
    1217  
    1218      /**
    1219       * Gets configuration data from a new lock instance form.
    1220       *
    1221       * @param string $plugin
    1222       * @param stdClass $data
    1223       * @return array
    1224       * @throws coding_exception
    1225       */
    1226      public static function get_lock_configuration_from_data($plugin, $data) {
    1227          global $CFG;
    1228          $file = $CFG->dirroot.'/cache/locks/'.$plugin.'/lib.php';
    1229          if (!file_exists($file)) {
    1230              throw new coding_exception('Invalid cache plugin provided. '.$file);
    1231          }
    1232          require_once($file);
    1233          $class = 'cachelock_'.$plugin;
    1234          if (!class_exists($class)) {
    1235              throw new coding_exception('Invalid cache plugin provided.');
    1236          }
    1237          if (array_key_exists('cache_is_configurable', class_implements($class))) {
    1238              return $class::config_get_configuration_array($data);
    1239          }
    1240          return array();
    1241      }
    1242  }
    

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