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   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Cache configuration reader
  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   * Cache configuration reader.
  33   *
  34   * This class is used to interact with the cache's configuration.
  35   * The configuration is stored in the Moodle data directory.
  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 {
  43  
  44      /**
  45       * The configured stores
  46       * @var array
  47       */
  48      protected $configstores = array();
  49  
  50      /**
  51       * The configured mode mappings
  52       * @var array
  53       */
  54      protected $configmodemappings = array();
  55  
  56      /**
  57       * The configured definitions as picked up from cache.php files
  58       * @var array
  59       */
  60      protected $configdefinitions = array();
  61  
  62      /**
  63       * The definition mappings that have been configured.
  64       * @var array
  65       */
  66      protected $configdefinitionmappings = array();
  67  
  68      /**
  69       * An array of configured cache lock instances.
  70       * @var array
  71       */
  72      protected $configlocks = array();
  73  
  74      /**
  75       * The site identifier used when the cache config was last saved.
  76       * @var string
  77       */
  78      protected $siteidentifier = null;
  79  
  80      /**
  81       * Please use cache_config::instance to get an instance of the cache config that is ready to be used.
  82       */
  83      public function __construct() {
  84          // Nothing to do here but look pretty.
  85      }
  86  
  87      /**
  88       * Gets an instance of the cache_configuration class.
  89       *
  90       * @return cache_config
  91       */
  92      public static function instance() {
  93          $factory = cache_factory::instance();
  94          return $factory->create_config_instance();
  95      }
  96  
  97      /**
  98       * Checks if the configuration file exists.
  99       *
 100       * @return bool True if it exists
 101       */
 102      public static function config_file_exists() {
 103          // Allow for late static binding by using static.
 104          return file_exists(static::get_config_file_path());
 105      }
 106  
 107      /**
 108       * Returns the expected path to the configuration file.
 109       *
 110       * @return string The absolute path
 111       */
 112      protected static function get_config_file_path() {
 113          global $CFG;
 114          if (!empty($CFG->altcacheconfigpath)) {
 115              $path = $CFG->altcacheconfigpath;
 116              if (is_dir($path) && is_writable($path)) {
 117                  // Its a writable directory, thats fine.
 118                  return $path.'/cacheconfig.php';
 119              } else if (is_writable(dirname($path)) && (!file_exists($path) || is_writable($path))) {
 120                  // Its a file, either it doesn't exist and the directory is writable or the file exists and is writable.
 121                  return $path;
 122              }
 123          }
 124          // Return the default location within dataroot.
 125          return $CFG->dataroot.'/muc/config.php';
 126      }
 127  
 128      /**
 129       * Loads the configuration file and parses its contents into the expected structure.
 130       *
 131       * @param array|false $configuration Can be used to force a configuration. Should only be used when truly required.
 132       * @return boolean
 133       */
 134      public function load($configuration = false) {
 135          global $CFG;
 136  
 137          if ($configuration === false) {
 138              $configuration = $this->include_configuration();
 139          }
 140  
 141          $this->configstores = array();
 142          $this->configdefinitions = array();
 143          $this->configlocks = array();
 144          $this->configmodemappings = array();
 145          $this->configdefinitionmappings = array();
 146          $this->configlockmappings = array();
 147  
 148          $siteidentifier = 'unknown';
 149          if (array_key_exists('siteidentifier', $configuration)) {
 150              $siteidentifier = $configuration['siteidentifier'];
 151          }
 152          $this->siteidentifier = $siteidentifier;
 153  
 154          // Filter the lock instances.
 155          $defaultlock = null;
 156          foreach ($configuration['locks'] as $conf) {
 157              if (!is_array($conf)) {
 158                  // Something is very wrong here.
 159                  continue;
 160              }
 161              if (!array_key_exists('name', $conf)) {
 162                  // Not a valid definition configuration.
 163                  continue;
 164              }
 165              $name = $conf['name'];
 166              if (array_key_exists($name, $this->configlocks)) {
 167                  debugging('Duplicate cache lock detected. This should never happen.', DEBUG_DEVELOPER);
 168                  continue;
 169              }
 170              $conf['default'] = (!empty($conf['default']));
 171              if ($defaultlock === null || $conf['default']) {
 172                  $defaultlock = $name;
 173              }
 174              $this->configlocks[$name] = $conf;
 175          }
 176  
 177          // Filter the stores.
 178          $availableplugins = cache_helper::early_get_cache_plugins();
 179          foreach ($configuration['stores'] as $store) {
 180              if (!is_array($store) || !array_key_exists('name', $store) || !array_key_exists('plugin', $store)) {
 181                  // Not a valid instance configuration.
 182                  debugging('Invalid cache store in config. Missing name or plugin.', DEBUG_DEVELOPER);
 183                  continue;
 184              }
 185              $plugin = $store['plugin'];
 186              $class = 'cachestore_'.$plugin;
 187              $exists = array_key_exists($plugin, $availableplugins);
 188              if (!$exists) {
 189                  // Not a valid plugin, or has been uninstalled, just skip it an carry on.
 190                  debugging('Invalid cache store in config. Not an available plugin.', DEBUG_DEVELOPER);
 191                  continue;
 192              }
 193              $file = $CFG->dirroot.'/cache/stores/'.$plugin.'/lib.php';
 194              if (!class_exists($class) && file_exists($file)) {
 195                  require_once($file);
 196              }
 197              if (!class_exists($class)) {
 198                  continue;
 199              }
 200              if (!array_key_exists('cache_store', class_parents($class))) {
 201                  continue;
 202              }
 203              if (!array_key_exists('configuration', $store) || !is_array($store['configuration'])) {
 204                  $store['configuration'] = array();
 205              }
 206              $store['class'] = $class;
 207              $store['default'] = !empty($store['default']);
 208              if (!array_key_exists('lock', $store) || !array_key_exists($store['lock'], $this->configlocks)) {
 209                  $store['lock'] = $defaultlock;
 210              }
 211  
 212              $this->configstores[$store['name']] = $store;
 213          }
 214  
 215          // Filter the definitions.
 216          foreach ($configuration['definitions'] as $id => $conf) {
 217              if (!is_array($conf)) {
 218                  // Something is very wrong here.
 219                  continue;
 220              }
 221              if (!array_key_exists('mode', $conf) || !array_key_exists('component', $conf) || !array_key_exists('area', $conf)) {
 222                  // Not a valid definition configuration.
 223                  continue;
 224              }
 225              if (array_key_exists($id, $this->configdefinitions)) {
 226                  debugging('Duplicate cache definition detected. This should never happen.', DEBUG_DEVELOPER);
 227                  continue;
 228              }
 229              $conf['mode'] = (int)$conf['mode'];
 230              if ($conf['mode'] < cache_store::MODE_APPLICATION || $conf['mode'] > cache_store::MODE_REQUEST) {
 231                  // Invalid cache mode used for the definition.
 232                  continue;
 233              }
 234              if ($conf['mode'] === cache_store::MODE_SESSION || $conf['mode'] === cache_store::MODE_REQUEST) {
 235                  // We force this for session and request caches.
 236                  // They are only allowed to use the default as we don't want people changing them.
 237                  $conf['sharingoptions'] = cache_definition::SHARING_DEFAULT;
 238                  $conf['selectedsharingoption'] = cache_definition::SHARING_DEFAULT;
 239                  $conf['userinputsharingkey'] = '';
 240              } else {
 241                  // Default the sharing option as it was added for 2.5.
 242                  // This can be removed sometime after 2.5 is the minimum version someone can upgrade from.
 243                  if (!isset($conf['sharingoptions'])) {
 244                      $conf['sharingoptions'] = cache_definition::SHARING_DEFAULTOPTIONS;
 245                  }
 246                  // Default the selected sharing option as it was added for 2.5.
 247                  // This can be removed sometime after 2.5 is the minimum version someone can upgrade from.
 248                  if (!isset($conf['selectedsharingoption'])) {
 249                      $conf['selectedsharingoption'] = cache_definition::SHARING_DEFAULT;
 250                  }
 251                  // Default the user input sharing key as it was added for 2.5.
 252                  // This can be removed sometime after 2.5 is the minimum version someone can upgrade from.
 253                  if (!isset($conf['userinputsharingkey'])) {
 254                      $conf['userinputsharingkey'] = '';
 255                  }
 256              }
 257              $this->configdefinitions[$id] = $conf;
 258          }
 259  
 260          // Filter the mode mappings.
 261          foreach ($configuration['modemappings'] as $mapping) {
 262              if (!is_array($mapping) || !array_key_exists('mode', $mapping) || !array_key_exists('store', $mapping)) {
 263                  // Not a valid mapping configuration.
 264                  debugging('A cache mode mapping entry is invalid.', DEBUG_DEVELOPER);
 265                  continue;
 266              }
 267              if (!array_key_exists($mapping['store'], $this->configstores)) {
 268                  // Mapped array instance doesn't exist.
 269                  debugging('A cache mode mapping exists for a mode or store that does not exist.', DEBUG_DEVELOPER);
 270                  continue;
 271              }
 272              $mapping['mode'] = (int)$mapping['mode'];
 273              if ($mapping['mode'] < 0 || $mapping['mode'] > 4) {
 274                  // Invalid cache type used for the mapping.
 275                  continue;
 276              }
 277              if (!array_key_exists('sort', $mapping)) {
 278                  $mapping['sort'] = 0;
 279              }
 280              $this->configmodemappings[] = $mapping;
 281          }
 282  
 283          // Filter the definition mappings.
 284          foreach ($configuration['definitionmappings'] as $mapping) {
 285              if (!is_array($mapping) || !array_key_exists('definition', $mapping) || !array_key_exists('store', $mapping)) {
 286                  // Not a valid mapping configuration.
 287                  continue;
 288              }
 289              if (!array_key_exists($mapping['store'], $this->configstores)) {
 290                  // Mapped array instance doesn't exist.
 291                  continue;
 292              }
 293              if (!array_key_exists($mapping['definition'], $this->configdefinitions)) {
 294                  // Mapped array instance doesn't exist.
 295                  continue;
 296              }
 297              if (!array_key_exists('sort', $mapping)) {
 298                  $mapping['sort'] = 0;
 299              }
 300              $this->configdefinitionmappings[] = $mapping;
 301          }
 302  
 303          usort($this->configmodemappings, array($this, 'sort_mappings'));
 304          usort($this->configdefinitionmappings, array($this, 'sort_mappings'));
 305  
 306          return true;
 307      }
 308  
 309      /**
 310       * Returns the site identifier used by the cache API.
 311       * @return string
 312       */
 313      public function get_site_identifier() {
 314          return $this->siteidentifier;
 315      }
 316  
 317      /**
 318       * Includes the configuration file and makes sure it contains the expected bits.
 319       *
 320       * You need to ensure that the config file exists before this is called.
 321       *
 322       * @return array
 323       * @throws cache_exception
 324       */
 325      protected function include_configuration() {
 326          $configuration = array();
 327          // We need to allow for late static bindings to allow for class path mudling happending for unit tests.
 328          $cachefile = static::get_config_file_path();
 329  
 330          if (!file_exists($cachefile)) {
 331              throw new cache_exception('Default cache config could not be found. It should have already been created by now.');
 332          }
 333          include($cachefile);
 334          if (!is_array($configuration)) {
 335              throw new cache_exception('Invalid cache configuration file');
 336          }
 337          if (!array_key_exists('stores', $configuration) || !is_array($configuration['stores'])) {
 338              $configuration['stores'] = array();
 339          }
 340          if (!array_key_exists('modemappings', $configuration) || !is_array($configuration['modemappings'])) {
 341              $configuration['modemappings'] = array();
 342          }
 343          if (!array_key_exists('definitions', $configuration) || !is_array($configuration['definitions'])) {
 344              $configuration['definitions'] = array();
 345          }
 346          if (!array_key_exists('definitionmappings', $configuration) || !is_array($configuration['definitionmappings'])) {
 347              $configuration['definitionmappings'] = array();
 348          }
 349          if (!array_key_exists('locks', $configuration) || !is_array($configuration['locks'])) {
 350              $configuration['locks'] = array();
 351          }
 352  
 353          return $configuration;
 354      }
 355  
 356      /**
 357       * Used to sort cache config arrays based upon a sort key.
 358       *
 359       * Highest number at the top.
 360       *
 361       * @param array $a
 362       * @param array $b
 363       * @return int
 364       */
 365      protected function sort_mappings(array $a, array $b) {
 366          if ($a['sort'] == $b['sort']) {
 367              return 0;
 368          }
 369          return ($a['sort'] < $b['sort']) ? 1 : -1;
 370      }
 371  
 372      /**
 373       * Gets a definition from the config given its name.
 374       *
 375       * @param string $id
 376       * @return bool
 377       */
 378      public function get_definition_by_id($id) {
 379          if (array_key_exists($id, $this->configdefinitions)) {
 380              return $this->configdefinitions[$id];
 381          }
 382          return false;
 383      }
 384  
 385      /**
 386       * Returns all the known definitions.
 387       *
 388       * @return array
 389       */
 390      public function get_definitions() {
 391          return $this->configdefinitions;
 392      }
 393  
 394      /**
 395       * Returns the definitions mapped into the given store name.
 396       *
 397       * @param string $storename
 398       * @return array Associative array of definitions, id=>definition
 399       */
 400      public function get_definitions_by_store($storename) {
 401          $definitions = array();
 402  
 403          // This function was accidentally made static at some stage in the past.
 404          // It was converted to an instance method but to be backwards compatible
 405          // we must step around this in code.
 406          if (!isset($this)) {
 407              $config = cache_config::instance();
 408          } else {
 409              $config = $this;
 410          }
 411  
 412          $stores = $config->get_all_stores();
 413          if (!array_key_exists($storename, $stores)) {
 414              // The store does not exist.
 415              return false;
 416          }
 417  
 418          $defmappings = $config->get_definition_mappings();
 419          // Create an associative array for the definition mappings.
 420          $thedefmappings = array();
 421          foreach ($defmappings as $defmapping) {
 422              $thedefmappings[$defmapping['definition']] = $defmapping;
 423          }
 424  
 425          // Search for matches in default mappings.
 426          $defs = $config->get_definitions();
 427          foreach($config->get_mode_mappings() as $modemapping) {
 428              if ($modemapping['store'] !== $storename) {
 429                  continue;
 430              }
 431              foreach($defs as $id => $definition) {
 432                  if ($definition['mode'] !== $modemapping['mode']) {
 433                      continue;
 434                  }
 435                  // Exclude custom definitions mapping: they will be managed few lines below.
 436                  if (array_key_exists($id, $thedefmappings)) {
 437                      continue;
 438                  }
 439                  $definitions[$id] = $definition;
 440              }
 441          }
 442  
 443          // Search for matches in the custom definitions mapping
 444          foreach ($defmappings as $defmapping) {
 445              if ($defmapping['store'] !== $storename) {
 446                  continue;
 447              }
 448              $definition = $config->get_definition_by_id($defmapping['definition']);
 449              if ($definition) {
 450                  $definitions[$defmapping['definition']] = $definition;
 451              }
 452          }
 453  
 454          return $definitions;
 455      }
 456  
 457      /**
 458       * Returns all of the stores that are suitable for the given mode and requirements.
 459       *
 460       * @param int $mode One of cache_store::MODE_*
 461       * @param int $requirements The requirements of the cache as a binary flag
 462       * @return array An array of suitable stores.
 463       */
 464      public function get_stores($mode, $requirements = 0) {
 465          $stores = array();
 466          foreach ($this->configstores as $name => $store) {
 467              // If the mode is supported and all of the requirements are provided features.
 468              if (($store['modes'] & $mode) && ($store['features'] & $requirements) === $requirements) {
 469                  $stores[$name] = $store;
 470              }
 471          }
 472          return $stores;
 473      }
 474  
 475      /**
 476       * Gets all of the stores that are to be used for the given definition.
 477       *
 478       * @param cache_definition $definition
 479       * @return array
 480       */
 481      public function get_stores_for_definition(cache_definition $definition) {
 482          // Check if MUC has been disabled.
 483          $factory = cache_factory::instance();
 484          if ($factory->stores_disabled()) {
 485              // Yip its been disabled.
 486              // To facilitate this we are going to always return an empty array of stores to use.
 487              // This will force all cache instances to use the cachestore_dummy.
 488              // MUC will still be used essentially so that code using it will still continue to function but because no cache stores
 489              // are being used interaction with MUC will be purely based around a static var.
 490              return array();
 491          }
 492  
 493          $availablestores = $this->get_stores($definition->get_mode(), $definition->get_requirements_bin());
 494          $stores = array();
 495          $id = $definition->get_id();
 496  
 497          // Now get any mappings and give them priority.
 498          foreach ($this->configdefinitionmappings as $mapping) {
 499              if ($mapping['definition'] !== $id) {
 500                  continue;
 501              }
 502              $storename = $mapping['store'];
 503              if (!array_key_exists($storename, $availablestores)) {
 504                  continue;
 505              }
 506              if (array_key_exists($storename, $stores)) {
 507                  $store = $stores[$storename];
 508                  unset($stores[$storename]);
 509                  $stores[$storename] = $store;
 510              } else {
 511                  $stores[$storename] = $availablestores[$storename];
 512              }
 513          }
 514  
 515          if (empty($stores) && !$definition->is_for_mappings_only()) {
 516              $mode = $definition->get_mode();
 517              // Load the default stores.
 518              foreach ($this->configmodemappings as $mapping) {
 519                  if ($mapping['mode'] === $mode && array_key_exists($mapping['store'], $availablestores)) {
 520                      $store = $availablestores[$mapping['store']];
 521                      if (empty($store['mappingsonly'])) {
 522                          $stores[$mapping['store']] = $store;
 523                      }
 524                  }
 525              }
 526          }
 527  
 528          return $stores;
 529      }
 530  
 531      /**
 532       * Returns all of the configured stores
 533       * @return array
 534       */
 535      public function get_all_stores() {
 536          return $this->configstores;
 537      }
 538  
 539      /**
 540       * Returns all of the configured mode mappings
 541       * @return array
 542       */
 543      public function get_mode_mappings() {
 544          return $this->configmodemappings;
 545      }
 546  
 547      /**
 548       * Returns all of the known definition mappings.
 549       * @return array
 550       */
 551      public function get_definition_mappings() {
 552          return $this->configdefinitionmappings;
 553      }
 554  
 555      /**
 556       * Returns an array of the configured locks.
 557       * @return array Array of name => config
 558       */
 559      public function get_locks() {
 560          return $this->configlocks;
 561      }
 562  
 563      /**
 564       * Returns the lock store configuration to use with a given store.
 565       * @param string $storename
 566       * @return array
 567       * @throws cache_exception
 568       */
 569      public function get_lock_for_store($storename) {
 570          if (array_key_exists($storename, $this->configstores)) {
 571              if (array_key_exists($this->configstores[$storename]['lock'], $this->configlocks)) {
 572                  $lock = $this->configstores[$storename]['lock'];
 573                  return $this->configlocks[$lock];
 574              }
 575          }
 576          return $this->get_default_lock();
 577      }
 578  
 579      /**
 580       * Gets the default lock instance.
 581       *
 582       * @return array
 583       * @throws cache_exception
 584       */
 585      public function get_default_lock() {
 586          foreach ($this->configlocks as $lockconf) {
 587              if (!empty($lockconf['default'])) {
 588                  return $lockconf;
 589              }
 590          }
 591          throw new cache_exception('ex_nodefaultlock');
 592      }
 593  }