Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * Cache configuration reader

 *

 * This file is part of Moodle's cache API, affectionately called MUC.

 * It contains the components that are requried in order to use caching.

 *

 * @package    core

 * @category   cache

 * @copyright  2012 Sam Hemelryk

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

defined('MOODLE_INTERNAL') || die();

/**

 * Cache configuration reader.

 *

 * This class is used to interact with the cache's configuration.

 * The configuration is stored in the Moodle data directory.

 *

 * @package    core

 * @category   cache

 * @copyright  2012 Sam Hemelryk

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class cache_config {

    /**

     * The configured stores

     * @var array

     */

    protected $configstores = array();

    /**

     * The configured mode mappings

     * @var array

     */

    protected $configmodemappings = array();

    /**

     * The configured definitions as picked up from cache.php files

     * @var array

     */

    protected $configdefinitions = array();

    /**

     * The definition mappings that have been configured.

     * @var array

     */

    protected $configdefinitionmappings = array();

    /**

     * An array of configured cache lock instances.

     * @var array

     */

    protected $configlocks = array();

    /**

     * The site identifier used when the cache config was last saved.

     * @var string

     */

    protected $siteidentifier = null;

    /**

     * Please use cache_config::instance to get an instance of the cache config that is ready to be used.

     */

    public function __construct() {

        // Nothing to do here but look pretty.

    }

    /**

     * Gets an instance of the cache_configuration class.

     *

     * @return cache_config

     */

    public static function instance() {

        $factory = cache_factory::instance();

        return $factory->create_config_instance();

    }

    /**

     * Checks if the configuration file exists.

     *

     * @return bool True if it exists

     */

    public static function config_file_exists() {

        // Allow for late static binding by using static.

        return file_exists(static::get_config_file_path());

    }

    /**

     * Returns the expected path to the configuration file.

     *

     * @return string The absolute path

     */

    protected static function get_config_file_path() {

        global $CFG;

        if (!empty($CFG->altcacheconfigpath)) {

            $path = $CFG->altcacheconfigpath;

            if (is_dir($path) && is_writable($path)) {

                // Its a writable directory, thats fine.

                return $path.'/cacheconfig.php';

            } else if (is_writable(dirname($path)) && (!file_exists($path) || is_writable($path))) {

                // Its a file, either it doesn't exist and the directory is writable or the file exists and is writable.

                return $path;

            }

        }

        // Return the default location within dataroot.

        return $CFG->dataroot.'/muc/config.php';

    }

    /**

     * Loads the configuration file and parses its contents into the expected structure.

     *

     * @param array|false $configuration Can be used to force a configuration. Should only be used when truly required.

     * @return boolean

     */

    public function load($configuration = false) {

        global $CFG;

        if ($configuration === false) {

            $configuration = $this->include_configuration();

        }

        $this->configstores = array();

        $this->configdefinitions = array();

        $this->configlocks = array();

        $this->configmodemappings = array();

        $this->configdefinitionmappings = array();

        $siteidentifier = 'unknown';

        if (array_key_exists('siteidentifier', $configuration)) {

            $siteidentifier = $configuration['siteidentifier'];

        }

        $this->siteidentifier = $siteidentifier;

        // Filter the lock instances.

        $defaultlock = null;

        foreach ($configuration['locks'] as $conf) {

            if (!is_array($conf)) {

                // Something is very wrong here.

                continue;

            }

            if (!array_key_exists('name', $conf)) {

                // Not a valid definition configuration.

                continue;

            }

            $name = $conf['name'];

            if (array_key_exists($name, $this->configlocks)) {

                debugging('Duplicate cache lock detected. This should never happen.', DEBUG_DEVELOPER);

                continue;

            }

            $conf['default'] = (!empty($conf['default']));

            if ($defaultlock === null || $conf['default']) {

                $defaultlock = $name;

            }

            $this->configlocks[$name] = $conf;

        }

        // Filter the stores.

        $availableplugins = cache_helper::early_get_cache_plugins();

        foreach ($configuration['stores'] as $store) {

            if (!is_array($store) || !array_key_exists('name', $store) || !array_key_exists('plugin', $store)) {

                // Not a valid instance configuration.

                debugging('Invalid cache store in config. Missing name or plugin.', DEBUG_DEVELOPER);

                continue;

            }

            $plugin = $store['plugin'];

            $class = 'cachestore_'.$plugin;

            $exists = array_key_exists($plugin, $availableplugins);

            if (!$exists) {

                // Not a valid plugin, or has been uninstalled, just skip it an carry on.

                debugging('Invalid cache store in config. Not an available plugin.', DEBUG_DEVELOPER);

                continue;

            }

            $file = $CFG->dirroot.'/cache/stores/'.$plugin.'/lib.php';

            if (!class_exists($class) && file_exists($file)) {

                require_once($file);

            }

            if (!class_exists($class)) {

                continue;

            }

            if (!array_key_exists('cache_store', class_parents($class))) {

                continue;

            }

            if (!array_key_exists('configuration', $store) || !is_array($store['configuration'])) {

                $store['configuration'] = array();

            }

            $store['class'] = $class;

            $store['default'] = !empty($store['default']);

            if (!array_key_exists('lock', $store) || !array_key_exists($store['lock'], $this->configlocks)) {

                $store['lock'] = $defaultlock;

            }

            $this->configstores[$store['name']] = $store;

        }

        // Filter the definitions.

        foreach ($configuration['definitions'] as $id => $conf) {

            if (!is_array($conf)) {

                // Something is very wrong here.

                continue;

            }

            if (!array_key_exists('mode', $conf) || !array_key_exists('component', $conf) || !array_key_exists('area', $conf)) {

                // Not a valid definition configuration.

                continue;

            }

            if (array_key_exists($id, $this->configdefinitions)) {

                debugging('Duplicate cache definition detected. This should never happen.', DEBUG_DEVELOPER);

                continue;

            }

            $conf['mode'] = (int)$conf['mode'];

            if ($conf['mode'] < cache_store::MODE_APPLICATION || $conf['mode'] > cache_store::MODE_REQUEST) {

                // Invalid cache mode used for the definition.

                continue;

            }

            if ($conf['mode'] === cache_store::MODE_SESSION || $conf['mode'] === cache_store::MODE_REQUEST) {

                // We force this for session and request caches.

                // They are only allowed to use the default as we don't want people changing them.

                $conf['sharingoptions'] = cache_definition::SHARING_DEFAULT;

                $conf['selectedsharingoption'] = cache_definition::SHARING_DEFAULT;

                $conf['userinputsharingkey'] = '';

            } else {

                // Default the sharing option as it was added for 2.5.

                // This can be removed sometime after 2.5 is the minimum version someone can upgrade from.

                if (!isset($conf['sharingoptions'])) {

                    $conf['sharingoptions'] = cache_definition::SHARING_DEFAULTOPTIONS;

                }

                // Default the selected sharing option as it was added for 2.5.

                // This can be removed sometime after 2.5 is the minimum version someone can upgrade from.

                if (!isset($conf['selectedsharingoption'])) {

                    $conf['selectedsharingoption'] = cache_definition::SHARING_DEFAULT;

                }

                // Default the user input sharing key as it was added for 2.5.

                // This can be removed sometime after 2.5 is the minimum version someone can upgrade from.

                if (!isset($conf['userinputsharingkey'])) {

                    $conf['userinputsharingkey'] = '';

                }

            }

            $this->configdefinitions[$id] = $conf;

        }

        // Filter the mode mappings.

        foreach ($configuration['modemappings'] as $mapping) {

            if (!is_array($mapping) || !array_key_exists('mode', $mapping) || !array_key_exists('store', $mapping)) {

                // Not a valid mapping configuration.

                debugging('A cache mode mapping entry is invalid.', DEBUG_DEVELOPER);

                continue;

            }

            if (!array_key_exists($mapping['store'], $this->configstores)) {

                // Mapped array instance doesn't exist.

                debugging('A cache mode mapping exists for a mode or store that does not exist.', DEBUG_DEVELOPER);

                continue;

            }

            $mapping['mode'] = (int)$mapping['mode'];

            if ($mapping['mode'] < 0 || $mapping['mode'] > 4) {

                // Invalid cache type used for the mapping.

                continue;

            }

            if (!array_key_exists('sort', $mapping)) {

                $mapping['sort'] = 0;

            }

            $this->configmodemappings[] = $mapping;

        }

        // Filter the definition mappings.

        foreach ($configuration['definitionmappings'] as $mapping) {

            if (!is_array($mapping) || !array_key_exists('definition', $mapping) || !array_key_exists('store', $mapping)) {

                // Not a valid mapping configuration.

                continue;

            }

            if (!array_key_exists($mapping['store'], $this->configstores)) {

                // Mapped array instance doesn't exist.

                continue;

            }

            if (!array_key_exists($mapping['definition'], $this->configdefinitions)) {

                // Mapped array instance doesn't exist.

                continue;

            }

            if (!array_key_exists('sort', $mapping)) {

                $mapping['sort'] = 0;

            }

            $this->configdefinitionmappings[] = $mapping;

        }

        usort($this->configmodemappings, array($this, 'sort_mappings'));

        usort($this->configdefinitionmappings, array($this, 'sort_mappings'));

        return true;

    }

    /**

     * Returns the site identifier used by the cache API.

     * @return string

     */

    public function get_site_identifier() {

        return $this->siteidentifier;

    }

    /**

     * Includes the configuration file and makes sure it contains the expected bits.

     *

     * You need to ensure that the config file exists before this is called.

     *

     * @return array

     * @throws cache_exception

     */

    protected function include_configuration() {

        $configuration = null;

        // We need to allow for late static bindings to allow for class path mudling happending for unit tests.

        $cachefile = static::get_config_file_path();

        if (!file_exists($cachefile)) {

            throw new cache_exception('Default cache config could not be found. It should have already been created by now.');

        }

        if (!include($cachefile)) {

            throw new cache_exception('Unable to load the cache configuration file');

        }

        if (!is_array($configuration)) {

            throw new cache_exception('Invalid cache configuration file');

        }

        if (!array_key_exists('stores', $configuration) || !is_array($configuration['stores'])) {

            $configuration['stores'] = array();

        }

        if (!array_key_exists('modemappings', $configuration) || !is_array($configuration['modemappings'])) {

            $configuration['modemappings'] = array();

        }

        if (!array_key_exists('definitions', $configuration) || !is_array($configuration['definitions'])) {

            $configuration['definitions'] = array();

        }

        if (!array_key_exists('definitionmappings', $configuration) || !is_array($configuration['definitionmappings'])) {

            $configuration['definitionmappings'] = array();

        }

        if (!array_key_exists('locks', $configuration) || !is_array($configuration['locks'])) {

            $configuration['locks'] = array();

        }

        return $configuration;

    }

    /**

     * Used to sort cache config arrays based upon a sort key.

     *

     * Highest number at the top.

     *

     * @param array $a

     * @param array $b

     * @return int

     */

    protected function sort_mappings(array $a, array $b) {

        if ($a['sort'] == $b['sort']) {

            return 0;

        }

        return ($a['sort'] < $b['sort']) ? 1 : -1;

    }

    /**

     * Gets a definition from the config given its name.

     *

     * @param string $id

     * @return bool

     */

    public function get_definition_by_id($id) {

        if (array_key_exists($id, $this->configdefinitions)) {

            return $this->configdefinitions[$id];

        }

        return false;

    }

    /**

     * Returns all the known definitions.

     *

     * @return array

     */

    public function get_definitions() {

        return $this->configdefinitions;

    }

    /**

     * Returns the definitions mapped into the given store name.

     *

     * @param string $storename

     * @return array Associative array of definitions, id=>definition

     */

    public function get_definitions_by_store($storename) {

        $definitions = array();

        // This function was accidentally made static at some stage in the past.

        // It was converted to an instance method but to be backwards compatible

        // we must step around this in code.

        if (!isset($this)) {

            $config = cache_config::instance();

        } else {

            $config = $this;

        }

        $stores = $config->get_all_stores();

        if (!array_key_exists($storename, $stores)) {

            // The store does not exist.

            return false;

        }

        $defmappings = $config->get_definition_mappings();

        // Create an associative array for the definition mappings.

        $thedefmappings = array();

        foreach ($defmappings as $defmapping) {

            $thedefmappings[$defmapping['definition']] = $defmapping;

        }

        // Search for matches in default mappings.

        $defs = $config->get_definitions();

        foreach($config->get_mode_mappings() as $modemapping) {

            if ($modemapping['store'] !== $storename) {

                continue;

            }

            foreach($defs as $id => $definition) {

                if ($definition['mode'] !== $modemapping['mode']) {

                    continue;

                }

                // Exclude custom definitions mapping: they will be managed few lines below.

                if (array_key_exists($id, $thedefmappings)) {

                    continue;

                }

                $definitions[$id] = $definition;

            }

        }

        // Search for matches in the custom definitions mapping

        foreach ($defmappings as $defmapping) {

            if ($defmapping['store'] !== $storename) {

                continue;

            }

            $definition = $config->get_definition_by_id($defmapping['definition']);

            if ($definition) {

                $definitions[$defmapping['definition']] = $definition;

            }

        }

        return $definitions;

    }

    /**

     * Returns all of the stores that are suitable for the given mode and requirements.

     *

     * @param int $mode One of cache_store::MODE_*

     * @param int $requirements The requirements of the cache as a binary flag

     * @return array An array of suitable stores.

     */

    public function get_stores($mode, $requirements = 0) {

        $stores = array();

        foreach ($this->configstores as $name => $store) {

            // If the mode is supported and all of the requirements are provided features.

            if (($store['modes'] & $mode) && ($store['features'] & $requirements) === $requirements) {

                $stores[$name] = $store;

            }

        }

        return $stores;

    }

    /**

     * Gets all of the stores that are to be used for the given definition.

     *

     * @param cache_definition $definition

     * @return array

     */

    public function get_stores_for_definition(cache_definition $definition) {

        // Check if MUC has been disabled.

        $factory = cache_factory::instance();

        if ($factory->stores_disabled()) {

            // Yip its been disabled.

            // To facilitate this we are going to always return an empty array of stores to use.

            // This will force all cache instances to use the cachestore_dummy.

            // MUC will still be used essentially so that code using it will still continue to function but because no cache stores

            // are being used interaction with MUC will be purely based around a static var.

            return array();

        }

        $availablestores = $this->get_stores($definition->get_mode(), $definition->get_requirements_bin());

        $stores = array();

        $id = $definition->get_id();

        // Now get any mappings and give them priority.

        foreach ($this->configdefinitionmappings as $mapping) {

            if ($mapping['definition'] !== $id) {

                continue;

            }

            $storename = $mapping['store'];

            if (!array_key_exists($storename, $availablestores)) {

                continue;

            }

            if (array_key_exists($storename, $stores)) {

                $store = $stores[$storename];

                unset($stores[$storename]);

                $stores[$storename] = $store;

            } else {

                $stores[$storename] = $availablestores[$storename];

            }

        }

        if (empty($stores) && !$definition->is_for_mappings_only()) {

            $mode = $definition->get_mode();

            // Load the default stores.

            foreach ($this->configmodemappings as $mapping) {

                if ($mapping['mode'] === $mode && array_key_exists($mapping['store'], $availablestores)) {

                    $store = $availablestores[$mapping['store']];

                    if (empty($store['mappingsonly'])) {

                        $stores[$mapping['store']] = $store;

                    }

                }

            }

        }

        return $stores;

    }

    /**

     * Returns all of the configured stores

     * @return array

     */

    public function get_all_stores() {

        return $this->configstores;

    }

    /**

     * Returns all of the configured mode mappings

     * @return array

     */

    public function get_mode_mappings() {

        return $this->configmodemappings;

    }

    /**

     * Returns all of the known definition mappings.

     * @return array

     */

    public function get_definition_mappings() {

        return $this->configdefinitionmappings;

    }

    /**

     * Returns an array of the configured locks.

     * @return array Array of name => config

     */

    public function get_locks() {

        return $this->configlocks;

    }

    /**

     * Returns the lock store configuration to use with a given store.

     * @param string $storename

     * @return array

     * @throws cache_exception

     */

    public function get_lock_for_store($storename) {

        if (array_key_exists($storename, $this->configstores)) {

            if (array_key_exists($this->configstores[$storename]['lock'], $this->configlocks)) {

                $lock = $this->configstores[$storename]['lock'];

                return $this->configlocks[$lock];

            }

        }

        return $this->get_default_lock();

    }

    /**

     * Gets the default lock instance.

     *

     * @return array

     * @throws cache_exception

     */

    public function get_default_lock() {

        foreach ($this->configlocks as $lockconf) {

            if (!empty($lockconf['default'])) {

                return $lockconf;

            }

        }

        throw new cache_exception('ex_nodefaultlock');

    }

}