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 library file for the static cache store.

 *

 * This file is part of the static cache store, it contains the API for interacting with an instance of the store.

 * This is used as a default cache store within the Cache API. It should never be deleted.

 *

 * @package    cachestore_static

 * @category   cache

 * @copyright  2012 Sam Hemelryk

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

 */

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

/**

 * The static data store class

 *

 * @copyright  2012 Sam Hemelryk

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

 */

abstract class static_data_store extends cache_store {

    /**

     * An array for storage.

     * @var array

     */

    private static $staticstore = array();

    /**

     * Returns a static store by reference... REFERENCE SUPER IMPORTANT.

     *

     * @param string $id

     * @return array

     */

    protected static function &register_store_id($id) {

        if (!array_key_exists($id, self::$staticstore)) {

            self::$staticstore[$id] = array();

        }

        return self::$staticstore[$id];

    }

    /**

     * Flushes the store of all values for belonging to the store with the given id.

     * @param string $id

     */

    protected static function flush_store_by_id($id) {

        unset(self::$staticstore[$id]);

        self::$staticstore[$id] = array();

    }

    /**

     * Flushes all of the values from all stores.

     *

     * @copyright  2012 Sam Hemelryk

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

     */

    protected static function flush_store() {

        $ids = array_keys(self::$staticstore);

        unset(self::$staticstore);

        self::$staticstore = array();

        foreach ($ids as $id) {

            self::$staticstore[$id] = array();

        }

    }

}

/**

 * The static store class.

 *

 * @copyright  2012 Sam Hemelryk

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

 */

class cachestore_static extends static_data_store implements cache_is_key_aware, cache_is_searchable {

    /**

     * The name of the store

     * @var store

     */

    protected $name;

    /**

     * The store id (should be unique)

     * @var string

     */

    protected $storeid;

    /**

     * The store we use for data.

     * @var array

     */

    protected $store;

    /**

     * The maximum size for the store, or false if there isn't one.

     * @var bool

     */

    protected $maxsize = false;

    /**

     * Where this cache uses simpledata and we don't need to serialize it.

     * @var bool

     */

    protected $simpledata = false;

    /**

     * The number of items currently being stored.

     * @var int

     */

    protected $storecount = 0;

    /**

     * igbinary extension available.

     * @var bool

     */

    protected $igbinaryfound = false;

    /**

     * Constructs the store instance.

     *

     * Noting that this function is not an initialisation. It is used to prepare the store for use.

     * The store will be initialised when required and will be provided with a cache_definition at that time.

     *

     * @param string $name

     * @param array $configuration

     */

    public function __construct($name, array $configuration = array()) {

        $this->name = $name;

    }

    /**

     * Returns the supported features as a combined int.

     *

     * @param array $configuration

     * @return int

     */

    public static function get_supported_features(array $configuration = array()) {

        return self::SUPPORTS_DATA_GUARANTEE +

               self::SUPPORTS_NATIVE_TTL +

               self::IS_SEARCHABLE +

               self::SUPPORTS_MULTIPLE_IDENTIFIERS +

               self::DEREFERENCES_OBJECTS;

    }

    /**

     * Returns true as this store does support multiple identifiers.

     * (This optional function is a performance optimisation; it must be

     * consistent with the value from get_supported_features.)

     *

     * @return bool true

     */

    public function supports_multiple_identifiers() {

        return true;

    }

    /**

     * Returns the supported modes as a combined int.

     *

     * @param array $configuration

     * @return int

     */

    public static function get_supported_modes(array $configuration = array()) {

        return self::MODE_REQUEST;

    }

    /**

     * Returns true if the store requirements are met.

     *

     * @return bool

     */

    public static function are_requirements_met() {

        return true;

    }

    /**

     * Returns true if the given mode is supported by this store.

     *

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

     * @return bool

     */

    public static function is_supported_mode($mode) {

        return ($mode === self::MODE_REQUEST);

    }

    /**

     * Initialises the cache.

     *

     * Once this has been done the cache is all set to be used.

     *

     * @param cache_definition $definition

     */

    public function initialise(cache_definition $definition) {

        $keyarray = $definition->generate_multi_key_parts();

        $this->storeid = $keyarray['mode'].'/'.$keyarray['component'].'/'.$keyarray['area'].'/'.$keyarray['siteidentifier'];

        $this->store = &self::register_store_id($this->storeid);

        $maxsize = $definition->get_maxsize();

        $this->simpledata = $definition->uses_simple_data();

        $this->igbinaryfound = extension_loaded('igbinary');

        if ($maxsize !== null) {

            // Must be a positive int.

            $this->maxsize = abs((int)$maxsize);

            $this->storecount = count($this->store);

        }

    }

    /**

     * Returns true once this instance has been initialised.

     *

     * @return bool

     */

    public function is_initialised() {

        return (is_array($this->store));

    }

    /**

     * Uses igbinary serializer if igbinary extension is loaded.

     * Fallback to PHP serializer.

     *

     * @param mixed $data

     * The value to be serialized.

     * @return string a string containing a byte-stream representation of

     * value that can be stored anywhere.

     */

    protected function serialize($data) {

        if ($this->igbinaryfound) {

            return igbinary_serialize($data);

        } else {

            return serialize($data);

        }

    }

    /**

     * Uses igbinary unserializer if igbinary extension is loaded.

     * Fallback to PHP unserializer.

     *

     * @param string $str

     * The serialized string.

     * @return mixed The converted value is returned, and can be a boolean,

     * integer, float, string,

     * array or object.

     */

    protected function unserialize($str) {

        if ($this->igbinaryfound) {

            return igbinary_unserialize($str);

        } else {

            return unserialize($str);

        }

    }

    /**

     * Retrieves an item from the cache store given its key.

     *

     * @param string $key The key to retrieve

     * @return mixed The data that was associated with the key, or false if the key did not exist.

     */

    public function get($key) {

        if (!is_array($key)) {

            $key = array('key' => $key);

        }

        $key = $key['key'];

        if (isset($this->store[$key])) {

            if ($this->store[$key]['serialized']) {

                return $this->unserialize($this->store[$key]['data']);

            } else {

                return $this->store[$key]['data'];

            }

        }

        return false;

    }

    /**

     * Retrieves several items from the cache store in a single transaction.

     *

     * If not all of the items are available in the cache then the data value for those that are missing will be set to false.

     *

     * @param array $keys The array of keys to retrieve

     * @return array An array of items from the cache. There will be an item for each key, those that were not in the store will

     *      be set to false.

     */

    public function get_many($keys) {

        $return = array();

        foreach ($keys as $key) {

            if (!is_array($key)) {

                $key = array('key' => $key);

            }

            $key = $key['key'];

            $return[$key] = false;

            if (isset($this->store[$key])) {

                if ($this->store[$key]['serialized']) {

                    $return[$key] = $this->unserialize($this->store[$key]['data']);

                } else {

                    $return[$key] = $this->store[$key]['data'];

                }

            }

        }

        return $return;

    }

    /**

     * Sets an item in the cache given its key and data value.

     *

     * @param string $key The key to use.

     * @param mixed $data The data to set.

     * @param bool $testmaxsize If set to true then we test the maxsize arg and reduce if required.

     * @return bool True if the operation was a success false otherwise.

     */

    public function set($key, $data, $testmaxsize = true) {

        if (!is_array($key)) {

            $key = array('key' => $key);

        }

        $key = $key['key'];

        $testmaxsize = ($testmaxsize && $this->maxsize !== false);

        if ($testmaxsize) {

            $increment = (!isset($this->store[$key]));

        }

        if ($this->simpledata || is_scalar($data)) {

            $this->store[$key]['data'] = $data;

            $this->store[$key]['serialized'] = false;

        } else {

            $this->store[$key]['data'] = $this->serialize($data);

            $this->store[$key]['serialized'] = true;

        }

        if ($testmaxsize && $increment) {

            $this->storecount++;

            if ($this->storecount > $this->maxsize) {

                $this->reduce_for_maxsize();

            }

        }

        return true;

    }

    /**

     * Sets many items in the cache in a single transaction.

     *

     * @param array $keyvaluearray An array of key value pairs. Each item in the array will be an associative array with two

     *      keys, 'key' and 'value'.

     * @return int The number of items successfully set. It is up to the developer to check this matches the number of items

     *      sent ... if they care that is.

     */

    public function set_many(array $keyvaluearray) {

        $count = 0;

        foreach ($keyvaluearray as $pair) {

            if (!is_array($pair['key'])) {

                $pair['key'] = array('key' => $pair['key']);

            }

            // Don't test the maxsize here. We'll do it once when we are done.

            $this->set($pair['key']['key'], $pair['value'], false);

            $count++;

        }

        if ($this->maxsize !== false) {

            $this->storecount += $count;

            if ($this->storecount > $this->maxsize) {

                $this->reduce_for_maxsize();

            }

        }

        return $count;

    }

    /**

     * Checks if the store has a record for the given key and returns true if so.

     *

     * @param string $key

     * @return bool

     */

    public function has($key) {

        if (is_array($key)) {

            $key = $key['key'];

        }

        return isset($this->store[$key]);

    }

    /**

     * Returns true if the store contains records for all of the given keys.

     *

     * @param array $keys

     * @return bool

     */

    public function has_all(array $keys) {

        foreach ($keys as $key) {

            if (!is_array($key)) {

                $key = array('key' => $key);

            }

            $key = $key['key'];

            if (!isset($this->store[$key])) {

                return false;

            }

        }

        return true;

    }

    /**

     * Returns true if the store contains records for any of the given keys.

     *

     * @param array $keys

     * @return bool

     */

    public function has_any(array $keys) {

        foreach ($keys as $key) {

            if (!is_array($key)) {

                $key = array('key' => $key);

            }

            $key = $key['key'];

            if (isset($this->store[$key])) {

                return true;

            }

        }

        return false;

    }

    /**

     * Deletes an item from the cache store.

     *

     * @param string $key The key to delete.

     * @return bool Returns true if the operation was a success, false otherwise.

     */

    public function delete($key) {

        if (!is_array($key)) {

            $key = array('key' => $key);

        }

        $key = $key['key'];

        $result = isset($this->store[$key]);

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

        if ($this->maxsize !== false) {

            $this->storecount--;

        }

        return $result;

    }

    /**

     * Deletes several keys from the cache in a single action.

     *

     * @param array $keys The keys to delete

     * @return int The number of items successfully deleted.

     */

    public function delete_many(array $keys) {

        $count = 0;

        foreach ($keys as $key) {

            if (!is_array($key)) {

                $key = array('key' => $key);

            }

            $key = $key['key'];

            if (isset($this->store[$key])) {

                $count++;

            }

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

        }

        if ($this->maxsize !== false) {

            $this->storecount -= $count;

        }

        return $count;

    }

    /**

     * Purges the cache deleting all items within it.

     *

     * @return boolean True on success. False otherwise.

     */

    public function purge() {

        $this->flush_store_by_id($this->storeid);

        $this->store = &self::register_store_id($this->storeid);

        // Don't worry about checking if we're using max size just set it as thats as fast as the check.

        $this->storecount = 0;

        return true;

    }

    /**

     * Reduces the size of the array if maxsize has been hit.

     *

     * This function reduces the size of the store reducing it by 10% of its maxsize.

     * It removes the oldest items in the store when doing this.

     * The reason it does this an doesn't use a least recently used system is purely the overhead such a system

     * requires. The current approach is focused on speed, MUC already adds enough overhead to static/session caches

     * and avoiding more is of benefit.

     *

     * @return int

     */

    protected function reduce_for_maxsize() {

        $diff = $this->storecount - $this->maxsize;

        if ($diff < 1) {

            return 0;

        }

        // Reduce it by an extra 10% to avoid calling this repetitively if we are in a loop.

        $diff += floor($this->maxsize / 10);

        $this->store = array_slice($this->store, $diff, null, true);

        $this->storecount -= $diff;

        return $diff;

    }

    /**

     * Returns true if the user can add an instance of the store plugin.

     *

     * @return bool

     */

    public static function can_add_instance() {

        return false;

    }

    /**

     * Performs any necessary clean up when the store instance is being deleted.

     */

    public function instance_deleted() {

        $this->purge();

    }

    /**

     * Generates an instance of the cache store that can be used for testing.

     *

     * @param cache_definition $definition

     * @return cachestore_static

     */

    public static function initialise_test_instance(cache_definition $definition) {

        // Do something here perhaps.

        $cache = new cachestore_static('Static store');

        $cache->initialise($definition);

        return $cache;

    }

    /**

     * Generates the appropriate configuration required for unit testing.

     *

     * @return array Array of unit test configuration data to be used by initialise().

     */

    public static function unit_test_configuration() {

        return array();

    }

    /**

     * Returns the name of this instance.

     * @return string

     */

    public function my_name() {

        return $this->name;

    }

    /**

     * Finds all of the keys being stored in the cache store instance.

     *

     * @return array

     */

    public function find_all() {

        return array_keys($this->store);

    }

    /**

     * Finds all of the keys whose keys start with the given prefix.

     *

     * @param string $prefix

     */

    public function find_by_prefix($prefix) {

        $return = array();

        foreach ($this->find_all() as $key) {

            if (strpos($key, $prefix) === 0) {

                $return[] = $key;

            }

        }

        return $return;

    }

}