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/>.

use core_cache\configurable_cache_interface;

use core_cache\definition;

use core_cache\key_aware_cache_interface;

use core_cache\store;

/**

 * The APCu cache store class.

 *

 * @package    cachestore_apcu

 * @copyright  2012 Sam Hemelryk

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

 */

class cachestore_apcu extends store implements configurable_cache_interface, key_aware_cache_interface {

    /**

     * The required version of APCu for this extension.

     */

    const REQUIRED_VERSION = '4.0.0';

    /**

     * The name of this store instance.

     * @var string

     */

    protected $name;

    /**

     * The definition used when this instance was initialised.

     * @var definition

     */

    protected $definition = null;

    /**

     * The storeprefix to use on all instances of this store.  Configured as part store setup.

     * @var string

     */

    protected $storeprefix = null;

    /**

     * The prefix added specifically for this cache.

     * @var string

     */

    protected $cacheprefix = null;

    /**

     * Static method to check that the APCu stores requirements have been met.

     *

     * It checks that the APCu extension has been loaded and that it has been enabled.

     *

     * @return bool True if the stores software/hardware requirements have been met and it can be used. False otherwise.

     */

    public static function are_requirements_met() {

        $enabled = ini_get('apc.enabled') && (php_sapi_name() != "cli" || ini_get('apc.enable_cli'));

        if (!extension_loaded('apcu') || !$enabled) {

            return false;

        }

        $version = phpversion('apcu');

        return $version && version_compare($version, self::REQUIRED_VERSION, '>=');

    }

    /**

     * Static method to check if a store is usable with the given mode.

     *

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

     * @return bool True if the mode is supported.

     */

    public static function is_supported_mode($mode) {

        return ($mode === self::MODE_APPLICATION || $mode === self::MODE_SESSION);

    }

    /**

     * Returns the supported features as a binary flag.

     *

     * @param array $configuration The configuration of a store to consider specifically.

     * @return int The supported features.

     */

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

        return self::SUPPORTS_NATIVE_TTL;

    }

    /**

     * Returns the supported modes as a binary flag.

     *

     * @param array $configuration The configuration of a store to consider specifically.

     * @return int The supported modes.

     */

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

        return self::MODE_APPLICATION + self::MODE_SESSION;

    }

    /**

     * Constructs an instance of the cache store.

     *

     * This method should not create connections or perform and processing, it should be used

     *

     * @param string $name The name of the cache store

     * @param array $configuration The configuration for this store instance.

     */

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

        global $CFG;

        $this->name = $name;

        $this->storeprefix = $CFG->prefix;

        if (isset($configuration['prefix'])) {

            $this->storeprefix = $configuration['prefix'];

        }

    }

    /**

     * Returns the name of this store instance.

     * @return string

     */

    public function my_name() {

        return $this->name;

    }

    /**

     * Initialises a new instance of the cache store given the definition the instance is to be used for.

     *

     * This function should prepare any given connections etc.

     *

     * @param definition $definition

     * @return bool

     */

    public function initialise(definition $definition) {

        $this->definition = $definition;

        $this->cacheprefix = $this->storeprefix.$definition->generate_definition_hash().'__';

        return true;

    }

    /**

     * Returns true if this cache store instance has been initialised.

     * @return bool

     */

    public function is_initialised() {

        return ($this->definition !== null);

    }

    /**

     * Prepares the given key for use.

     *

     * Should be called before all interaction.

     *

     * @param string $key The key to prepare for storing in APCu.

     *

     * @return string

     */

    protected function prepare_key($key) {

        return $this->cacheprefix . $key;

    }

    /**

     * 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) {

        $key = $this->prepare_key($key);

        $success = false;

        $outcome = apcu_fetch($key, $success);

        if ($success) {

            return $outcome;

        }

        return $success;

    }

    /**

     * 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) {

        $map = array();

        foreach ($keys as $key) {

            $map[$key] = $this->prepare_key($key);

        }

        $outcomes = array();

        $success = false;

        $results = apcu_fetch($map, $success);

        if ($success) {

            foreach ($map as $key => $used) {

                if (array_key_exists($used, $results)) {

                    $outcomes[$key] = $results[$used];

                } else {

                    $outcomes[$key] = false;

                }

            }

        } else {

            $outcomes = array_fill_keys($keys, false);

        }

        return $outcomes;

    }

    /**

     * 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.

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

     */

    public function set($key, $data) {

        $key = $this->prepare_key($key);

        return apcu_store($key, $data, $this->definition->get_ttl());

    }

    /**

     * 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) {

        $map = array();

        foreach ($keyvaluearray as $pair) {

            $key = $this->prepare_key($pair['key']);

            $map[$key] = $pair['value'];

        }

        $result = apcu_store($map, null, $this->definition->get_ttl());

        return count($map) - count($result);

    }

    /**

     * 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) {

        $key = $this->prepare_key($key);

        return apcu_delete($key);

    }

    /**

     * 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 ($this->delete($key)) {

                $count++;

            }

        }

        return $count;

    }

    /**

     * Purges the cache deleting all items within it.

     *

     * @return boolean True on success. False otherwise.

     */

    public function purge() {

        if (class_exists('APCUIterator', false)) {

            $iterator = new APCUIterator('#^' . preg_quote($this->cacheprefix, '#') . '#');

        } else {

            $iterator = new APCIterator('user', '#^' . preg_quote($this->cacheprefix, '#') . '#');

        }

        return apcu_delete($iterator);

    }

    /**

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

     */

    public function instance_deleted() {

        if (class_exists('APCUIterator', false)) {

            $iterator = new APCUIterator('#^' . preg_quote($this->storeprefix, '#') . '#');

        } else {

            $iterator = new APCIterator('user', '#^' . preg_quote($this->storeprefix, '#') . '#');

        }

        return apcu_delete($iterator);

    }

    /**

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

     *

     * Returns an instance of the cache store, or false if one cannot be created.

     *

     * @param definition $definition

     * @return store

     */

    public static function initialise_test_instance(definition $definition) {

        $testperformance = get_config('cachestore_apcu', 'testperformance');

        if (empty($testperformance)) {

            return false;

        }

        if (!self::are_requirements_met()) {

            return false;

        }

        $name = 'APCu test';

        $cache = new cachestore_apcu($name);

        // No need to check if is_ready() as this has already being done by requirement check.

        $cache->initialise($definition);

        return $cache;

    }

    /**

     * Test is a cache has a key.

     *

     * @param string|int $key

     * @return bool True if the cache has the requested key, false otherwise.

     */

    public function has($key) {

        $key = $this->prepare_key($key);

        return apcu_exists($key);

    }

    /**

     * Test if a cache has at least one of the given keys.

     *

     * @param array $keys

     * @return bool True if the cache has at least one of the given keys

     */

    public function has_any(array $keys) {

        foreach ($keys as $arraykey => $key) {

            $keys[$arraykey] = $this->prepare_key($key);

        }

        $result = apcu_exists($keys);

        return count($result) > 0;

    }

    /**

     * Test is a cache has all of the given keys.

     *

     * @param array $keys

     * @return bool True if the cache has all of the given keys, false otherwise.

     */

    public function has_all(array $keys) {

        foreach ($keys as $arraykey => $key) {

            $keys[$arraykey] = $this->prepare_key($key);

        }

        $result = apcu_exists($keys);

        return count($result) === count($keys);

    }

    /**

     * 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('prefix' => 'phpunit');

    }

    /**

     * Given the data from the add instance form this function creates a configuration array.

     *

     * @param stdClass $data

     * @return array

     */

    public static function config_get_configuration_array($data) {

        $config = array();

        if (isset($data->prefix)) {

            $config['prefix'] = $data->prefix;

        }

        return $config;

    }

    /**

     * Allows the cache store to set its data against the edit form before it is shown to the user.

     *

     * @param moodleform $editform

     * @param array $config

     */

    public static function config_set_edit_form_data(moodleform $editform, array $config) {

        if (isset($config['prefix'])) {

            $data['prefix'] = $config['prefix'];

        } else {

            $data['prefix'] = '';

        }

        $editform->set_data($data);

    }

    /**

     * Returns true if this cache store instance is both suitable for testing, and ready for testing.

     *

     * Cache stores that support being used as the default store for unit and acceptance testing should

     * override this function and return true if there requirements have been met.

     *

     * @return bool

     */

    public static function ready_to_be_used_for_testing() {

        return true;

    }

}