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/>.

namespace core_cache;

/**

 * Cache Loader.

 *

 * This cache loader interface provides the required structure for classes that wish to be interacted with as a

 * means of accessing and interacting with a cache.

 *

 * Can be implemented by any class wishing to be a cache loader.

 * @package core_cache

 * @copyright Sam Hemelryk

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

 */

interface loader_interface {

    /**

     * Retrieves the value for the given key from the cache.

     *

     * @param string|int $key The key for the data being requested.

     * @param int $strictness One of IGNORE_MISSING or MUST_EXIST.

     * @return mixed The data retrieved from the cache, or false if the key did not exist within the cache.

     *      If MUST_EXIST was used then an exception will be thrown if the key does not exist within the cache.

     */

    public function get($key, $strictness = IGNORE_MISSING);

    /**

     * Retrieves the value and actual version for the given key, with at least the required version.

     *

     * If there is no value for the key, or there is a value but it doesn't have the required

     * version, then this function will return false (or throw an exception if you set strictness

     * to MUST_EXIST).

     *

     * This function can be used to make it easier to support localisable caches (where the cache

     * could be stored on a local server as well as a shared cache). Specifying the version means

     * that it will automatically retrieve the correct version if available, either from the local

     * server or [if that has an older version] from the shared server.

     *

     * If the cached version is newer than specified version, it will be returned regardless. For

     * example, if you request version 4, but the locally cached version is 5, it will be returned.

     * If you request version 6, and the locally cached version is 5, then the system will look in

     * higher-level caches (if any); if there still isn't a version 6 or greater, it will return

     * null.

     *

     * You must use this function if you use set_versioned.

     *

     * @param string|int $key The key for the data being requested.

     * @param int $requiredversion Minimum required version of the data

     * @param int $strictness One of IGNORE_MISSING or MUST_EXIST.

     * @param mixed $actualversion If specified, will be set to the actual version number retrieved

     * @return mixed Data from the cache, or false if the key did not exist or was too old

     */

    public function get_versioned($key, int $requiredversion, int $strictness = IGNORE_MISSING, &$actualversion = null);

    /**

     * Retrieves an array of values for an array of keys.

     *

     * Using this function comes with potential performance implications.

     * Not all cache stores will support get_many/set_many operations and in order to replicate this functionality will call

     * the equivalent singular method for each item provided.

     * This should not deter you from using this function as there is a performance benefit in situations where the cache

     * store does support it, but you should be aware of this fact.

     *

     * @param array $keys The keys of the data being requested.

     * @param int $strictness One of IGNORE_MISSING or MUST_EXIST.

     * @return array An array of key value pairs for the items that could be retrieved from the cache.

     *      If MUST_EXIST was used and not all keys existed within the cache then an exception will be thrown.

     *      Otherwise any key that did not exist will have a data value of false within the results.

     */

    public function get_many(array $keys, $strictness = IGNORE_MISSING);

    /**

     * Sends a key => value pair to the cache.

     *

     * <code>

     * // This code will add four entries to the cache, one for each url.

     * $cache->set('main', 'http://moodle.org');

     * $cache->set('docs', 'http://docs.moodle.org');

     * $cache->set('tracker', 'http://tracker.moodle.org');

     * $cache->set('qa', 'http://qa.moodle.net');

     * </code>

     *

     * @param string|int $key The key for the data being requested.

     * @param mixed $data The data to set against the key.

     * @return bool True on success, false otherwise.

     */

    public function set($key, $data);

    /**

     * Sets the value for the given key with the given version.

     *

     * The cache does not store multiple versions - any existing version will be overwritten with

     * this one. This function should only be used if there is a known 'current version' (e.g.

     * stored in a database table). It only ensures that the cache does not return outdated data.

     *

     * This function can be used to help implement localisable caches (where the cache could be

     * stored on a local server as well as a shared cache). The version will be recorded alongside

     * the item and get_versioned will always return the correct version.

     *

     * The version number must be an integer that always increases. This could be based on the

     * current time, or a stored value that increases by 1 each time it changes, etc.

     *

     * If you use this function you must use get_versioned to retrieve the data.

     *

     * @param string|int $key The key for the data being set.

     * @param int $version Integer for the version of the data

     * @param mixed $data The data to set against the key.

     * @return bool True on success, false otherwise.

     */

    public function set_versioned($key, int $version, $data): bool;

    /**

     * Sends several key => value pairs to the cache.

     *

     * Using this function comes with potential performance implications.

     * Not all cache stores will support get_many/set_many operations and in order to replicate this functionality will call

     * the equivalent singular method for each item provided.

     * This should not deter you from using this function as there is a performance benefit in situations where the cache store

     * does support it, but you should be aware of this fact.

     *

     * <code>

     * // This code will add four entries to the cache, one for each url.

     * $cache->set_many(array(

     *     'main' => 'http://moodle.org',

     *     'docs' => 'http://docs.moodle.org',

     *     'tracker' => 'http://tracker.moodle.org',

     *     'qa' => ''http://qa.moodle.net'

     * ));

     * </code>

     *

     * @param array $keyvaluearray An array of key => value pairs to send to the cache.

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

     *      ... if they care that is.

     */

    public function set_many(array $keyvaluearray);

    /**

     * Test is a cache has a key.

     *

     * The use of the has methods is strongly discouraged. In a high load environment the cache may well change between the

     * test and any subsequent action (get, set, delete etc).

     * Instead it is recommended to write your code in such a way they it performs the following steps:

     * <ol>

     * <li>Attempt to retrieve the information.</li>

     * <li>Generate the information.</li>

     * <li>Attempt to set the information</li>

     * </ol>

     *

     * Its also worth mentioning that not all stores support key tests.

     * For stores that don't support key tests this functionality is mimicked by using the equivalent get method.

     * Just one more reason you should not use these methods unless you have a very good reason to do so.

     *

     * @param string|int $key

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

     */

    public function has($key);

    /**

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

     *

     * It is strongly recommended to avoid the use of this function if not absolutely required.

     * In a high load environment the cache may well change between the test and any subsequent action (get, set, delete etc).

     *

     * Its also worth mentioning that not all stores support key tests.

     * For stores that don't support key tests this functionality is mimicked by using the equivalent get method.

     * Just one more reason you should not use these methods unless you have a very good reason to do so.

     *

     * @param array $keys

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

     */

    public function has_any(array $keys);

    /**

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

     *

     * It is strongly recommended to avoid the use of this function if not absolutely required.

     * In a high load environment the cache may well change between the test and any subsequent action (get, set, delete etc).

     *

     * Its also worth mentioning that not all stores support key tests.

     * For stores that don't support key tests this functionality is mimicked by using the equivalent get method.

     * Just one more reason you should not use these methods unless you have a very good reason to do so.

     *

     * @param array $keys

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

     */

    public function has_all(array $keys);

    /**

     * Delete the given key from the cache.

     *

     * @param string|int $key The key to delete.

     * @param bool $recurse When set to true the key will also be deleted from all stacked cache loaders and their stores.

     *     This happens by default and ensure that all the caches are consistent. It is NOT recommended to change this.

     * @return bool True of success, false otherwise.

     */

    public function delete($key, $recurse = true);

    /**

     * Delete all of the given keys from the cache.

     *

     * @param array $keys The key to delete.

     * @param bool $recurse When set to true the key will also be deleted from all stacked cache loaders and their stores.

     *     This happens by default and ensure that all the caches are consistent. It is NOT recommended to change this.

     * @return int The number of items successfully deleted.

     */

    public function delete_many(array $keys, $recurse = true);

}

// Alias this class to the old name.

// This file will be autoloaded by the legacyclasses autoload system.

// In future all uses of this class will be corrected and the legacy references will be removed.

class_alias(loader_interface::class, \cache_loader::class);