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/>.

/**

 * The supplementary cache API.

 *

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

 * It contains elements of the API that are not required in order to use caching.

 * Things in here are more in line with administration and management of the cache setup and configuration.

 *

 * @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 writer.

 *

 * This class should only be used when you need to write to the config, all read operations exist within the cache_config.

 *

 * @package    core

 * @category   cache

 * @copyright  2012 Sam Hemelryk

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

 */

class cache_config_writer extends cache_config {

    /**

     * Switch that gets set to true when ever a cache_config_writer instance is saving the cache configuration file.

     * If this is set to true when save is next called we must avoid the trying to save and instead return the

     * generated config so that is may be used instead of the file.

     * @var bool

     */

    protected static $creatingconfig = false;

    /**

     * Returns an instance of the configuration writer.

     *

     * @return cache_config_writer

     */

    public static function instance() {

        $factory = cache_factory::instance();

        return $factory->create_config_instance(true);

    }

    /**

     * Saves the current configuration.

     *

     * Exceptions within this function are tolerated but must be of type cache_exception.

     * They are caught during initialisation and written to the error log. This is required in order to avoid

     * infinite loop situations caused by the cache throwing exceptions during its initialisation.

     */

    protected function config_save() {

        global $CFG;

        static $confighash = '';

        $cachefile = static::get_config_file_path();

        $directory = dirname($cachefile);

        if ($directory !== $CFG->dataroot && !file_exists($directory)) {

            $result = make_writable_directory($directory, false);

            if (!$result) {

                throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Cannot create config directory. Check the permissions on your moodledata directory.');

            }

        }

        if (!file_exists($directory) || !is_writable($directory)) {

            throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Config directory is not writable. Check the permissions on the moodledata/muc directory.');

        }

        // Prepare a configuration array to store.

        $configuration = $this->generate_configuration_array();

        // Prepare the file content.

        $content = "<?php defined('MOODLE_INTERNAL') || die();\n \$configuration = ".var_export($configuration, true).";";

        // Do both file content and hash based detection because this might be called

        // many times within a single request.

        $hash = sha1($content);

        if (($hash === $confighash) || (file_exists($cachefile) && $content === file_get_contents($cachefile))) {

            // Config is unchanged so don't bother locking and writing.

            $confighash = $hash;

            return;

        }

        // We need to create a temporary cache lock instance for use here. Remember we are generating the config file

        // it doesn't exist and thus we can't use the normal API for this (it'll just try to use config).

        $lockconf = reset($this->configlocks);

        if ($lockconf === false) {

            debugging('Your cache configuration file is out of date and needs to be refreshed.', DEBUG_DEVELOPER);

            // Use the default

            $lockconf = array(

                'name' => 'cachelock_file_default',

                'type' => 'cachelock_file',

                'dir' => 'filelocks',

                'default' => true

            );

        }

        $factory = cache_factory::instance();

        $locking = $factory->create_lock_instance($lockconf);

        if ($locking->lock('configwrite', 'config', true)) {

            $tempcachefile = "{$cachefile}.tmp";

            // Its safe to use w mode here because we have already acquired the lock.

            $handle = fopen($tempcachefile, 'w');

            fwrite($handle, $content);

            fflush($handle);

            fclose($handle);

            $locking->unlock('configwrite', 'config');

            @chmod($tempcachefile, $CFG->filepermissions);

            rename($tempcachefile, $cachefile);

            // Tell PHP to recompile the script.

            core_component::invalidate_opcode_php_cache($cachefile);

        } else {

            throw new cache_exception('ex_configcannotsave', 'cache', '', null, 'Unable to open the cache config file.');

        }

    }

    /**

     * Generates a configuration array suitable to be written to the config file.

     * @return array

     */

    protected function generate_configuration_array() {

        $configuration = array();

        $configuration['siteidentifier'] = $this->siteidentifier;

        $configuration['stores'] = $this->configstores;

        $configuration['modemappings'] = $this->configmodemappings;

        $configuration['definitions'] = $this->configdefinitions;

        $configuration['definitionmappings'] = $this->configdefinitionmappings;

        $configuration['locks'] = $this->configlocks;

        return $configuration;

    }

    /**

     * Adds a plugin instance.

     *

     * This function also calls save so you should redirect immediately, or at least very shortly after

     * calling this method.

     *

     * @param string $name The name for the instance (must be unique)

     * @param string $plugin The name of the plugin.

     * @param array $configuration The configuration data for the plugin instance.

     * @return bool

     * @throws cache_exception

     */

    public function add_store_instance($name, $plugin, array $configuration = array()) {

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

            throw new cache_exception('Duplicate name specificed for cache plugin instance. You must provide a unique name.');

        }

        $class = 'cachestore_'.$plugin;

        if (!class_exists($class)) {

            $plugins = core_component::get_plugin_list_with_file('cachestore', 'lib.php');

            if (!array_key_exists($plugin, $plugins)) {

                throw new cache_exception('Invalid plugin name specified. The plugin does not exist or is not valid.');

            }

            $file = $plugins[$plugin];

            if (file_exists($file)) {

                require_once($file);

            }

            if (!class_exists($class)) {

                throw new cache_exception('Invalid cache plugin specified. The plugin does not contain the required class.');

            }

        }

        $reflection = new ReflectionClass($class);

        if (!$reflection->isSubclassOf('cache_store')) {

            throw new cache_exception('Invalid cache plugin specified. The plugin does not extend the required class.');

        }

        if (!$class::are_requirements_met()) {

            throw new cache_exception('Unable to add new cache plugin instance. The requested plugin type is not supported.');

        }

        $this->configstores[$name] = array(

            'name' => $name,

            'plugin' => $plugin,

            'configuration' => $configuration,

            'features' => $class::get_supported_features($configuration),

            'modes' => $class::get_supported_modes($configuration),

            'mappingsonly' => !empty($configuration['mappingsonly']),

            'class' => $class,

            'default' => false

        );

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

            $this->configstores[$name]['lock'] = $configuration['lock'];

            unset($this->configstores[$name]['configuration']['lock']);

        }

        // Call instance_created()

        $store = new $class($name, $this->configstores[$name]['configuration']);

        $store->instance_created();

        $this->config_save();

        return true;

    }

    /**

     * Adds a new lock instance to the config file.

     *

     * @param string $name The name the user gave the instance. PARAM_ALHPANUMEXT

     * @param string $plugin The plugin we are creating an instance of.

     * @param string $configuration Configuration data from the config instance.

     * @throws cache_exception

     */

    public function add_lock_instance($name, $plugin, $configuration = array()) {

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

            throw new cache_exception('Duplicate name specificed for cache lock instance. You must provide a unique name.');

        }

        $class = 'cachelock_'.$plugin;

        if (!class_exists($class)) {

            $plugins = core_component::get_plugin_list_with_file('cachelock', 'lib.php');

            if (!array_key_exists($plugin, $plugins)) {

                throw new cache_exception('Invalid lock name specified. The plugin does not exist or is not valid.');

            }

            $file = $plugins[$plugin];

            if (file_exists($file)) {

                require_once($file);

            }

            if (!class_exists($class)) {

                throw new cache_exception('Invalid lock plugin specified. The plugin does not contain the required class.');

            }

        }

        $reflection = new ReflectionClass($class);

        if (!$reflection->implementsInterface('cache_lock_interface')) {

            throw new cache_exception('Invalid lock plugin specified. The plugin does not implement the required interface.');

        }

        $this->configlocks[$name] = array_merge($configuration, array(

            'name' => $name,

            'type' => 'cachelock_'.$plugin,

            'default' => false

        ));

        $this->config_save();

    }

    /**

     * Deletes a lock instance given its name.

     *

     * @param string $name The name of the plugin, PARAM_ALPHANUMEXT.

     * @return bool

     * @throws cache_exception

     */

    public function delete_lock_instance($name) {

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

            throw new cache_exception('The requested store does not exist.');

        }

        if ($this->configlocks[$name]['default']) {

            throw new cache_exception('You can not delete the default lock.');

        }

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

            if (isset($store['lock']) && $store['lock'] === $name) {

                throw new cache_exception('You cannot delete a cache lock that is being used by a store.');

            }

        }

        unset($this->configlocks[$name]);

        $this->config_save();

        return true;

    }

    /**

     * Sets the mode mappings.

     *

     * These determine the default caches for the different modes.

     * This function also calls save so you should redirect immediately, or at least very shortly after

     * calling this method.

     *

     * @param array $modemappings

     * @return bool

     * @throws cache_exception

     */

    public function set_mode_mappings(array $modemappings) {

        $mappings = array(

            cache_store::MODE_APPLICATION => array(),

            cache_store::MODE_SESSION => array(),

            cache_store::MODE_REQUEST => array(),

        );

        foreach ($modemappings as $mode => $stores) {

            if (!array_key_exists($mode, $mappings)) {

                throw new cache_exception('The cache mode for the new mapping does not exist');

            }

            $sort = 0;

            foreach ($stores as $store) {

                if (!array_key_exists($store, $this->configstores)) {

                    throw new cache_exception('The instance name for the new mapping does not exist');

                }

                if (array_key_exists($store, $mappings[$mode])) {

                    throw new cache_exception('This cache mapping already exists');

                }

                $mappings[$mode][] = array(

                    'store' => $store,

                    'mode' => $mode,

                    'sort' => $sort++

                );

            }

        }

        $this->configmodemappings = array_merge(

            $mappings[cache_store::MODE_APPLICATION],

            $mappings[cache_store::MODE_SESSION],

            $mappings[cache_store::MODE_REQUEST]

        );

        $this->config_save();

        return true;

    }

    /**

     * Edits a give plugin instance.

     *

     * The plugin instance is determined by its name, hence you cannot rename plugins.

     * This function also calls save so you should redirect immediately, or at least very shortly after

     * calling this method.

     *

     * @param string $name

     * @param string $plugin

     * @param array $configuration

     * @return bool

     * @throws cache_exception

     */

    public function edit_store_instance($name, $plugin, $configuration) {

        if (!array_key_exists($name, $this->configstores)) {

            throw new cache_exception('The requested instance does not exist.');

        }

        $plugins = core_component::get_plugin_list_with_file('cachestore', 'lib.php');

        if (!array_key_exists($plugin, $plugins)) {

            throw new cache_exception('Invalid plugin name specified. The plugin either does not exist or is not valid.');

        }

        $class = 'cachestore_'.$plugin;

        $file = $plugins[$plugin];

        if (!class_exists($class)) {

            if (file_exists($file)) {

                require_once($file);

            }

            if (!class_exists($class)) {

                throw new cache_exception('Invalid cache plugin specified. The plugin does not contain the required class.'.$class);

            }

        }

        $this->configstores[$name] = array(

            'name' => $name,

            'plugin' => $plugin,

            'configuration' => $configuration,

            'features' => $class::get_supported_features($configuration),

            'modes' => $class::get_supported_modes($configuration),

            'mappingsonly' => !empty($configuration['mappingsonly']),

            'class' => $class,

            'default' => $this->configstores[$name]['default'] // Can't change the default.

        );

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

            $this->configstores[$name]['lock'] = $configuration['lock'];

            unset($this->configstores[$name]['configuration']['lock']);

        }

        $this->config_save();

        return true;

    }

    /**

     * Deletes a store instance.

     *

     * This function also calls save so you should redirect immediately, or at least very shortly after

     * calling this method.

     *

     * @param string $name The name of the instance to delete.

     * @return bool

     * @throws cache_exception

     */

    public function delete_store_instance($name) {

        if (!array_key_exists($name, $this->configstores)) {

            throw new cache_exception('The requested store does not exist.');

        }

        if ($this->configstores[$name]['default']) {

            throw new cache_exception('The can not delete the default stores.');

        }

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

            if ($mapping['store'] === $name) {

                throw new cache_exception('You cannot delete a cache store that has mode mappings.');

            }

        }

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

            if ($mapping['store'] === $name) {

                throw new cache_exception('You cannot delete a cache store that has definition mappings.');

            }

        }

        // Call instance_deleted()

        $class = 'cachestore_'.$this->configstores[$name]['plugin'];

        $store = new $class($name, $this->configstores[$name]['configuration']);

        $store->instance_deleted();

        unset($this->configstores[$name]);

        $this->config_save();

        return true;

    }

    /**

     * Creates the default configuration and saves it.

     *

     * This function calls config_save, however it is safe to continue using it afterwards as this function should only ever

     * be called when there is no configuration file already.

     *

     * @param bool $forcesave If set to true then we will forcefully save the default configuration file.

     * @return true|array Returns true if the default configuration was successfully created.

     *     Returns a configuration array if it could not be saved. This is a bad situation. Check your error logs.

     */

    public static function create_default_configuration($forcesave = false) {

        // HACK ALERT.

        // We probably need to come up with a better way to create the default stores, or at least ensure 100% that the

        // default store plugins are protected from deletion.

        $writer = new self;

        $writer->configstores = self::get_default_stores();

        $writer->configdefinitions = self::locate_definitions();

        $writer->configmodemappings = array(

            array(

                'mode' => cache_store::MODE_APPLICATION,

                'store' => 'default_application',

                'sort' => -1

            ),

            array(

                'mode' => cache_store::MODE_SESSION,

                'store' => 'default_session',

                'sort' => -1

            ),

            array(

                'mode' => cache_store::MODE_REQUEST,

                'store' => 'default_request',

                'sort' => -1

            )

        );

        $writer->configlocks = array(

            'default_file_lock' => array(

                'name' => 'cachelock_file_default',

                'type' => 'cachelock_file',

                'dir' => 'filelocks',

                'default' => true

            )

        );

        $factory = cache_factory::instance();

        // We expect the cache to be initialising presently. If its not then something has gone wrong and likely

        // we are now in a loop.

        if (!$forcesave && $factory->get_state() !== cache_factory::STATE_INITIALISING) {

            return $writer->generate_configuration_array();

        }

        $factory->set_state(cache_factory::STATE_SAVING);

        $writer->config_save();

        return true;

    }

    /**

     * Returns an array of default stores for use.

     *

     * @return array

     */

    protected static function get_default_stores() {

        global $CFG;

        require_once($CFG->dirroot.'/cache/stores/file/lib.php');

        require_once($CFG->dirroot.'/cache/stores/session/lib.php');

        require_once($CFG->dirroot.'/cache/stores/static/lib.php');

        return array(

            'default_application' => array(

                'name' => 'default_application',

                'plugin' => 'file',

                'configuration' => array(),

                'features' => cachestore_file::get_supported_features(),

                'modes' => cachestore_file::get_supported_modes(),

                'default' => true,

            ),

            'default_session' => array(

                'name' => 'default_session',

                'plugin' => 'session',

                'configuration' => array(),

                'features' => cachestore_session::get_supported_features(),

                'modes' => cachestore_session::get_supported_modes(),

                'default' => true,

            ),

            'default_request' => array(

                'name' => 'default_request',

                'plugin' => 'static',

                'configuration' => array(),

                'features' => cachestore_static::get_supported_features(),

                'modes' => cachestore_static::get_supported_modes(),

                'default' => true,

            )

        );

    }

    /**

     * Updates the default stores within the MUC config file.

     */

    public static function update_default_config_stores() {

        $factory = cache_factory::instance();

        $factory->updating_started();

        $config = $factory->create_config_instance(true);

        $config->configstores = array_merge($config->configstores, self::get_default_stores());

        $config->config_save();

        $factory->updating_finished();

    }

    /**

     * Updates the definition in the configuration from those found in the cache files.

     *

     * Calls config_save further down, you should redirect immediately or asap after calling this method.

     *

     * @param bool $coreonly If set to true only core definitions will be updated.

     */

    public static function update_definitions($coreonly = false) {

        $factory = cache_factory::instance();

        $factory->updating_started();

        $config = $factory->create_config_instance(true);

        $config->write_definitions_to_cache(self::locate_definitions($coreonly));

        $factory->updating_finished();

    }

    /**

     * Locates all of the definition files.

     *

     * @param bool $coreonly If set to true only core definitions will be updated.

     * @return array

     */

    protected static function locate_definitions($coreonly = false) {

        global $CFG;

        $files = array();

        if (file_exists($CFG->dirroot.'/lib/db/caches.php')) {

            $files['core'] = $CFG->dirroot.'/lib/db/caches.php';

        }

        if (!$coreonly) {

            $plugintypes = core_component::get_plugin_types();

            foreach ($plugintypes as $type => $location) {

                $plugins = core_component::get_plugin_list_with_file($type, 'db/caches.php');

                foreach ($plugins as $plugin => $filepath) {

                    $component = clean_param($type.'_'.$plugin, PARAM_COMPONENT); // Standardised plugin name.

                    $files[$component] = $filepath;

                }

            }

        }

        $definitions = array();

        foreach ($files as $component => $file) {

            $filedefs = self::load_caches_file($file);

            foreach ($filedefs as $area => $definition) {

                $area = clean_param($area, PARAM_AREA);

                $id = $component.'/'.$area;

                $definition['component'] = $component;

                $definition['area'] = $area;

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

                    debugging('Error: duplicate cache definition found with id: '.$id, DEBUG_DEVELOPER);

                    continue;

                }

                $definitions[$id] = $definition;

            }

        }

        return $definitions;

    }

    /**

     * Writes the updated definitions for the config file.

     * @param array $definitions

     */

    private function write_definitions_to_cache(array $definitions) {

        // Preserve the selected sharing option when updating the definitions.

        // This is set by the user and should never come from caches.php.

        foreach ($definitions as $key => $definition) {

            unset($definitions[$key]['selectedsharingoption']);

            unset($definitions[$key]['userinputsharingkey']);

            if (isset($this->configdefinitions[$key]) && isset($this->configdefinitions[$key]['selectedsharingoption'])) {

                $definitions[$key]['selectedsharingoption'] = $this->configdefinitions[$key]['selectedsharingoption'];

            }

            if (isset($this->configdefinitions[$key]) && isset($this->configdefinitions[$key]['userinputsharingkey'])) {

                $definitions[$key]['userinputsharingkey'] = $this->configdefinitions[$key]['userinputsharingkey'];

            }

        }

        $this->configdefinitions = $definitions;

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

            if (!array_key_exists($mapping['definition'], $definitions)) {

                unset($this->configdefinitionmappings[$key]);

            }

        }

        $this->config_save();

    }

    /**

     * Loads the caches file if it exists.

     * @param string $file Absolute path to the file.

     * @return array

     */

    private static function load_caches_file($file) {

        if (!file_exists($file)) {

            return array();

        }

        $definitions = array();

        include($file);

        return $definitions;

    }

    /**

     * Sets the mappings for a given definition.

     *

     * @param string $definition

     * @param array $mappings

     * @throws coding_exception

     */

    public function set_definition_mappings($definition, $mappings) {

        if (!array_key_exists($definition, $this->configdefinitions)) {

            throw new coding_exception('Invalid definition name passed when updating mappings.');

        }

        foreach ($mappings as $store) {

            if (!array_key_exists($store, $this->configstores)) {

                throw new coding_exception('Invalid store name passed when updating definition mappings.');

            }

        }

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

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

                unset($this->configdefinitionmappings[$key]);

            }

        }

        $sort = count($mappings);

        foreach ($mappings as $store) {

            $this->configdefinitionmappings[] = array(

                'store' => $store,

                'definition' => $definition,

                'sort' => $sort

            );

            $sort--;

        }

        $this->config_save();

    }

    /**

     * Update the site identifier stored by the cache API.

     *

     * @param string $siteidentifier

     * @return string The new site identifier.

     */

    public function update_site_identifier($siteidentifier) {

        $this->siteidentifier = md5((string)$siteidentifier);

        $this->config_save();

        return $this->siteidentifier;

    }

    /**

     * Sets the selected sharing options and key for a definition.

     *

     * @param string $definition The name of the definition to set for.

     * @param int $sharingoption The sharing option to set.

     * @param string|null $userinputsharingkey The user input key or null.

     * @throws coding_exception

     */

    public function set_definition_sharing($definition, $sharingoption, $userinputsharingkey = null) {

        if (!array_key_exists($definition, $this->configdefinitions)) {

            throw new coding_exception('Invalid definition name passed when updating sharing options.');

        }

        if (!($this->configdefinitions[$definition]['sharingoptions'] & $sharingoption)) {

            throw new coding_exception('Invalid sharing option passed when updating definition.');

        }

        $this->configdefinitions[$definition]['selectedsharingoption'] = (int)$sharingoption;

        if (!empty($userinputsharingkey)) {

            $this->configdefinitions[$definition]['userinputsharingkey'] = (string)$userinputsharingkey;

        }

        $this->config_save();

    }

}