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See Release Notes

  • Bug fixes for general core bugs in 4.2.x will end 22 April 2024 (12 months).
  • Bug fixes for security issues in 4.2.x will end 7 October 2024 (18 months).
  • PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.1.x is supported too.
<?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/>.

/**
 * Redis Cache Store - Main library
 *
 * @package   cachestore_redis
 * @copyright 2013 Adam Durana
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

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

/**
 * Redis Cache Store
 *
 * To allow separation of definitions in Moodle and faster purging, each cache
 * is implemented as a Redis hash.  That is a trade-off between having functionality of TTL
 * and being able to manage many caches in a single redis instance.  Given the recommendation
 * not to use TTL if at all possible and the benefits of having many stores in Redis using the
 * hash configuration, the hash implementation has been used.
 *
 * @copyright   2013 Adam Durana
 * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class cachestore_redis extends cache_store implements cache_is_key_aware, cache_is_lockable,
        cache_is_configurable, cache_is_searchable {
    /**
     * Compressor: none.
     */
    const COMPRESSOR_NONE = 0;

    /**
     * Compressor: PHP GZip.
     */
    const COMPRESSOR_PHP_GZIP = 1;

    /**
     * Compressor: PHP Zstandard.
     */
    const COMPRESSOR_PHP_ZSTD = 2;

    /**
     * @var string Suffix used on key name (for hash) to store the TTL sorted list
     */
    const TTL_SUFFIX = '_ttl';

    /**
     * @var int Number of items to delete from cache in one batch when expiring old TTL data.
     */
    const TTL_EXPIRE_BATCH = 10000;

    /**
     * Name of this store.
     *
     * @var string
     */
    protected $name;

    /**
     * The definition hash, used for hash key
     *
     * @var string
     */
    protected $hash;

    /**
     * Flag for readiness!
     *
     * @var boolean
     */
    protected $isready = false;

    /**
     * Cache definition for this store.
     *
     * @var cache_definition
     */
    protected $definition = null;

    /**
     * Connection to Redis for this store.
     *
     * @var Redis
     */
    protected $redis;

    /**
     * Serializer for this store.
     *
     * @var int
     */
    protected $serializer = Redis::SERIALIZER_PHP;

    /**
     * Compressor for this store.
     *
     * @var int
     */
    protected $compressor = self::COMPRESSOR_NONE;

    /**
     * Bytes read or written by last call to set()/get() or set_many()/get_many().
     *
     * @var int
     */
    protected $lastiobytes = 0;

> /** @var int Maximum number of seconds to wait for a lock before giving up. */ /** > protected $lockwait = 60; * Determines if the requirements for this type of store are met. > * > /** @var int Timeout before lock is automatically released (in case of crashes) */ * @return bool > protected $locktimeout = 600; */ > public static function are_requirements_met() { > /** @var ?array Array of current locks, or null if we haven't registered shutdown function */ return class_exists('Redis'); > protected $currentlocks = null; } >
/** * Determines if this type of store supports a given mode. * * @param int $mode * @return bool */ public static function is_supported_mode($mode) { return ($mode === self::MODE_APPLICATION || $mode === self::MODE_SESSION); } /** * Get the features of this type of cache store. * * @param array $configuration * @return int */ public static function get_supported_features(array $configuration = array()) { // Although this plugin now supports TTL I did not add SUPPORTS_NATIVE_TTL here, because // doing so would cause Moodle to stop adding a 'TTL wrapper' to data items which enforces // the precise specified TTL. Unless the scheduled task is set to run rather frequently, // this could cause change in behaviour. Maybe later this should be reconsidered... return self::SUPPORTS_DATA_GUARANTEE + self::DEREFERENCES_OBJECTS + self::IS_SEARCHABLE; } /** * Get the supported modes of this type of cache store. * * @param array $configuration * @return int */ public static function get_supported_modes(array $configuration = array()) { return self::MODE_APPLICATION + self::MODE_SESSION; } /** * Constructs an instance of this type of store. * * @param string $name * @param array $configuration */ public function __construct($name, array $configuration = array()) { $this->name = $name; if (!array_key_exists('server', $configuration) || empty($configuration['server'])) { return; } if (array_key_exists('serializer', $configuration)) { $this->serializer = (int)$configuration['serializer']; } if (array_key_exists('compressor', $configuration)) { $this->compressor = (int)$configuration['compressor']; } $password = !empty($configuration['password']) ? $configuration['password'] : ''; $prefix = !empty($configuration['prefix']) ? $configuration['prefix'] : '';
> if (array_key_exists('lockwait', $configuration)) { $this->redis = $this->new_redis($configuration['server'], $prefix, $password); > $this->lockwait = (int)$configuration['lockwait']; } > } > if (array_key_exists('locktimeout', $configuration)) { /** > $this->locktimeout = (int)$configuration['locktimeout']; * Create a new Redis instance and > }
* connect to the server. * * @param string $server The server connection string * @param string $prefix The key prefix * @param string $password The server connection password * @return Redis */ protected function new_redis($server, $prefix = '', $password = '') { $redis = new Redis();
< // Check if it isn't a Unix socket to set default port. < $port = ($server[0] === '/') ? null : 6379; < if (strpos($server, ':')) {
> // Check for Unix socket. > if ($server[0] === '/') { > $port = 0; > } else { > $port = 6379; // No Unix socket so set default port. > if (strpos($server, ':')) { // Check for custom port.
$serverconf = explode(':', $server); $server = $serverconf[0]; $port = $serverconf[1]; }
> }
try { if ($redis->connect($server, $port)) { if (!empty($password)) { $redis->auth($password); } // If using compressor, serialisation will be done at cachestore level, not php-redis. if ($this->compressor == self::COMPRESSOR_NONE) { $redis->setOption(Redis::OPT_SERIALIZER, $this->serializer); } if (!empty($prefix)) { $redis->setOption(Redis::OPT_PREFIX, $prefix); }
< // Database setting option... < $this->isready = $this->ping($redis);
> $this->isready = true;
} else { $this->isready = false; } } catch (\RedisException $e) { $this->isready = false; } return $redis; } /** * See if we can ping Redis server * * @param Redis $redis * @return bool */ protected function ping(Redis $redis) { try { if ($redis->ping() === false) { return false; } } catch (Exception $e) { return false; } return true; } /** * Get the name of the store. * * @return string */ public function my_name() { return $this->name; } /** * Initialize the store. * * @param cache_definition $definition * @return bool */ public function initialise(cache_definition $definition) { $this->definition = $definition; $this->hash = $definition->generate_definition_hash(); return true; } /** * Determine if the store is initialized. * * @return bool */ public function is_initialised() { return ($this->definition !== null); } /** * Determine if the store is ready for use. * * @return bool */ public function is_ready() { return $this->isready; } /** * Get the value associated with a given key. * * @param string $key The key to get the value of. * @return mixed The value of the key, or false if there is no value associated with the key. */ public function get($key) { $value = $this->redis->hGet($this->hash, $key); if ($this->compressor == self::COMPRESSOR_NONE) { return $value; } // When using compression, values are always strings, so strlen will work. $this->lastiobytes = strlen($value); return $this->uncompress($value); } /** * Get the values associated with a list of keys. * * @param array $keys The keys to get the values of. * @return array An array of the values of the given keys. */ public function get_many($keys) { $values = $this->redis->hMGet($this->hash, $keys); if ($this->compressor == self::COMPRESSOR_NONE) { return $values; } $this->lastiobytes = 0; foreach ($values as &$value) { $this->lastiobytes += strlen($value); $value = $this->uncompress($value); } return $values; } /** * Gets the number of bytes read from or written to cache as a result of the last action. * * If compression is not enabled, this function always returns IO_BYTES_NOT_SUPPORTED. The reason is that * when compression is not enabled, data sent to the cache is not serialized, and we would * need to serialize it to compute the size, which would have a significant performance cost. * * @return int Bytes read or written * @since Moodle 4.0 */ public function get_last_io_bytes(): int { if ($this->compressor != self::COMPRESSOR_NONE) { return $this->lastiobytes; } else { // Not supported unless compression is on. return parent::get_last_io_bytes(); } } /** * Set the value of a key. * * @param string $key The key to set the value of. * @param mixed $value The value. * @return bool True if the operation succeeded, false otherwise. */ public function set($key, $value) { if ($this->compressor != self::COMPRESSOR_NONE) { $value = $this->compress($value); $this->lastiobytes = strlen($value); } if ($this->redis->hSet($this->hash, $key, $value) === false) { return false; } if ($this->definition->get_ttl()) { // When TTL is enabled, we also store the key name in a list sorted by the current time. $this->redis->zAdd($this->hash . self::TTL_SUFFIX, [], self::get_time(), $key); // The return value to the zAdd function never indicates whether the operation succeeded // (it returns zero when there was no error if the item is already in the list) so we // ignore it. } return true; } /** * Set the values of many keys. * * @param array $keyvaluearray An array of key/value pairs. Each item in the array is an associative array * with two keys, 'key' and 'value'. * @return int The number of key/value pairs successfuly set. */ public function set_many(array $keyvaluearray) { $pairs = []; $usettl = false; if ($this->definition->get_ttl()) { $usettl = true; $ttlparams = []; $now = self::get_time(); } $this->lastiobytes = 0; foreach ($keyvaluearray as $pair) { $key = $pair['key']; if ($this->compressor != self::COMPRESSOR_NONE) { $pairs[$key] = $this->compress($pair['value']); $this->lastiobytes += strlen($pairs[$key]); } else { $pairs[$key] = $pair['value']; } if ($usettl) { // When TTL is enabled, we also store the key names in a list sorted by the current // time. $ttlparams[] = $now; $ttlparams[] = $key; } } if ($usettl) { // Store all the key values with current time. $this->redis->zAdd($this->hash . self::TTL_SUFFIX, [], ...$ttlparams); // The return value to the zAdd function never indicates whether the operation succeeded // (it returns zero when there was no error if the item is already in the list) so we // ignore it. } if ($this->redis->hMSet($this->hash, $pairs)) { return count($pairs); } return 0; } /** * Delete the given key. * * @param string $key The key to delete. * @return bool True if the delete operation succeeds, false otherwise. */ public function delete($key) { $ok = true; if (!$this->redis->hDel($this->hash, $key)) { $ok = false; } if ($this->definition->get_ttl()) { // When TTL is enabled, also remove the key from the TTL list. $this->redis->zRem($this->hash . self::TTL_SUFFIX, $key); } return $ok; } /** * Delete many keys. * * @param array $keys The keys to delete. * @return int The number of keys successfully deleted. */ public function delete_many(array $keys) { // If there are no keys to delete, do nothing. if (!$keys) { return 0; } $count = $this->redis->hDel($this->hash, ...$keys); if ($this->definition->get_ttl()) { // When TTL is enabled, also remove the keys from the TTL list. $this->redis->zRem($this->hash . self::TTL_SUFFIX, ...$keys); } return $count; } /** * Purges all keys from the store. * * @return bool */ public function purge() { if ($this->definition->get_ttl()) { // Purge the TTL list as well. $this->redis->del($this->hash . self::TTL_SUFFIX); // According to documentation, there is no error return for the 'del' command (it // only returns the number of keys deleted, which could be 0 or 1 in this case) so we // do not need to check the return value. } return ($this->redis->del($this->hash) !== false); } /** * Cleans up after an instance of the store. */ public function instance_deleted() { $this->redis->close(); unset($this->redis); } /** * Determines if the store has a given key. * * @see cache_is_key_aware * @param string $key The key to check for. * @return bool True if the key exists, false if it does not. */ public function has($key) { return !empty($this->redis->hExists($this->hash, $key)); } /** * Determines if the store has any of the keys in a list. * * @see cache_is_key_aware * @param array $keys The keys to check for. * @return bool True if any of the keys are found, false none of the keys are found. */ public function has_any(array $keys) { foreach ($keys as $key) { if ($this->has($key)) { return true; } } return false; } /** * Determines if the store has all of the keys in a list. * * @see cache_is_key_aware * @param array $keys The keys to check for. * @return bool True if all of the keys are found, false otherwise. */ public function has_all(array $keys) { foreach ($keys as $key) { if (!$this->has($key)) { return false; } } return true; } /** * Tries to acquire a lock with a given name. * * @see cache_is_lockable * @param string $key Name of the lock to acquire. * @param string $ownerid Information to identify owner of lock if acquired. * @return bool True if the lock was acquired, false if it was not. */ public function acquire_lock($key, $ownerid) {
< return $this->redis->setnx($key, $ownerid);
> $timelimit = time() + $this->lockwait; > do { > // If the key doesn't already exist, grab it and return true. > if ($this->redis->setnx($key, $ownerid)) { > // Ensure Redis deletes the key after a bit in case something goes wrong. > $this->redis->expire($key, $this->locktimeout); > // If we haven't got it already, better register a shutdown function. > if ($this->currentlocks === null) { > core_shutdown_manager::register_function([$this, 'shutdown_release_locks']); > $this->currentlocks = []; > } > $this->currentlocks[$key] = $ownerid; > return true; > } > // Wait 1 second then retry. > sleep(1); > } while (time() < $timelimit); > return false; > } > > /** > * Releases any locks when the system shuts down, in case there is a crash or somebody forgets > * to use 'try-finally'. > * > * Do not call this function manually (except from unit test). > */ > public function shutdown_release_locks() { > foreach ($this->currentlocks as $key => $ownerid) { > debugging('Automatically releasing Redis cache lock: ' . $key . ' (' . $ownerid . > ') - did somebody forget to call release_lock()?', DEBUG_DEVELOPER); > $this->release_lock($key, $ownerid); > }
} /** * Checks a lock with a given name and owner information. * * @see cache_is_lockable * @param string $key Name of the lock to check. * @param string $ownerid Owner information to check existing lock against. * @return mixed True if the lock exists and the owner information matches, null if the lock does not * exist, and false otherwise. */ public function check_lock_state($key, $ownerid) { $result = $this->redis->get($key);
< if ($result === $ownerid) {
> if ($result === (string)$ownerid) {
return true; } if ($result === false) { return null; } return false; } /** * Finds all of the keys being used by this cache store instance. * * @return array of all keys in the hash as a numbered array. */ public function find_all() { return $this->redis->hKeys($this->hash); } /** * Finds all of the keys whose keys start with the given prefix. * * @param string $prefix * * @return array List of keys that match this prefix. */ public function find_by_prefix($prefix) { $return = []; foreach ($this->find_all() as $key) { if (strpos($key, $prefix) === 0) { $return[] = $key; } } return $return; } /** * Releases a given lock if the owner information matches. * * @see cache_is_lockable * @param string $key Name of the lock to release. * @param string $ownerid Owner information to use. * @return bool True if the lock is released, false if it is not. */ public function release_lock($key, $ownerid) { if ($this->check_lock_state($key, $ownerid)) {
> unset($this->currentlocks[$key]);
return ($this->redis->del($key) !== false); } return false; } /** * Runs TTL expiry process for this cache. * * This is not part of the standard cache API and is intended for use by the scheduled task * \cachestore_redis\ttl. * * @return array Various keys with information about how the expiry went */ public function expire_ttl(): array { $ttl = $this->definition->get_ttl(); if (!$ttl) { throw new \coding_exception('Cache definition ' . $this->definition->get_id() . ' does not use TTL'); } $limit = self::get_time() - $ttl; $count = 0; $batches = 0; $timebefore = microtime(true); $memorybefore = $this->store_total_size(); do { $keys = $this->redis->zRangeByScore($this->hash . self::TTL_SUFFIX, 0, $limit, ['limit' => [0, self::TTL_EXPIRE_BATCH]]); $this->delete_many($keys); $count += count($keys); $batches++; } while (count($keys) === self::TTL_EXPIRE_BATCH); $memoryafter = $this->store_total_size(); $timeafter = microtime(true); $result = ['keys' => $count, 'batches' => $batches, 'time' => $timeafter - $timebefore]; if ($memorybefore !== null) { $result['memory'] = $memorybefore - $memoryafter; } return $result; } /** * Gets the current time for TTL functionality. This wrapper makes it easier to unit-test * the TTL behaviour. * * @return int Current time */ protected static function get_time(): int { global $CFG; if (PHPUNIT_TEST && !empty($CFG->phpunit_cachestore_redis_time)) { return $CFG->phpunit_cachestore_redis_time; } return time(); } /** * Sets the current time (within unit test) for TTL functionality. * * This setting is stored in $CFG so will be automatically reset if you use resetAfterTest. * * @param int $time Current time (set 0 to start using real time). */ public static function set_phpunit_time(int $time = 0): void { global $CFG; if (!PHPUNIT_TEST) { throw new \coding_exception('Function only available during unit test'); } if ($time) { $CFG->phpunit_cachestore_redis_time = $time; } else { unset($CFG->phpunit_cachestore_redis_time); } } /** * Estimates the stored size, taking into account whether compression is turned on. * * @param mixed $key Key name * @param mixed $value Value * @return int Approximate stored size */ public function estimate_stored_size($key, $value): int { if ($this->compressor == self::COMPRESSOR_NONE) { // If uncompressed, use default estimate. return parent::estimate_stored_size($key, $value); } else { // If compressed, compress value. return strlen($this->serialize($key)) + strlen($this->compress($value)); } } /** * Gets Redis reported memory usage. * * @return int|null Memory used by Redis or null if we don't know */ public function store_total_size(): ?int { try { $details = $this->redis->info('MEMORY'); } catch (\RedisException $e) { return null; } if (empty($details['used_memory'])) { return null; } else { return (int)$details['used_memory']; } } /** * Creates a configuration array from given 'add instance' form data. * * @see cache_is_configurable * @param stdClass $data * @return array */ public static function config_get_configuration_array($data) { return array( 'server' => $data->server, 'prefix' => $data->prefix, 'password' => $data->password, 'serializer' => $data->serializer, 'compressor' => $data->compressor, ); } /** * Sets form data from a configuration array. * * @see cache_is_configurable * @param moodleform $editform * @param array $config */ public static function config_set_edit_form_data(moodleform $editform, array $config) { $data = array(); $data['server'] = $config['server']; $data['prefix'] = !empty($config['prefix']) ? $config['prefix'] : ''; $data['password'] = !empty($config['password']) ? $config['password'] : ''; if (!empty($config['serializer'])) { $data['serializer'] = $config['serializer']; } if (!empty($config['compressor'])) { $data['compressor'] = $config['compressor']; } $editform->set_data($data); } /** * Creates an instance of the store for testing. * * @param cache_definition $definition * @return mixed An instance of the store, or false if an instance cannot be created. */ public static function initialise_test_instance(cache_definition $definition) { if (!self::are_requirements_met()) { return false; } $config = get_config('cachestore_redis'); if (empty($config->test_server)) { return false; } $configuration = array('server' => $config->test_server); if (!empty($config->test_serializer)) { $configuration['serializer'] = $config->test_serializer; } if (!empty($config->test_password)) { $configuration['password'] = $config->test_password; } // Make it possible to test TTL performance by hacking a copy of the cache definition. if (!empty($config->test_ttl)) { $definition = clone $definition; $property = (new ReflectionClass($definition))->getProperty('ttl'); $property->setAccessible(true); $property->setValue($definition, 999); } $cache = new cachestore_redis('Redis test', $configuration); $cache->initialise($definition); return $cache; } /** * Return configuration to use when unit testing. * * @return array */ public static function unit_test_configuration() { global $DB; if (!self::are_requirements_met() || !self::ready_to_be_used_for_testing()) { throw new moodle_exception('TEST_CACHESTORE_REDIS_TESTSERVERS not configured, unable to create test configuration'); } return ['server' => TEST_CACHESTORE_REDIS_TESTSERVERS, 'prefix' => $DB->get_prefix(), ]; } /** * Returns true if this cache store instance is both suitable for testing, and ready for testing. * * When TEST_CACHESTORE_REDIS_TESTSERVERS is set, then we are ready to be use d for testing. * * @return bool */ public static function ready_to_be_used_for_testing() { return defined('TEST_CACHESTORE_REDIS_TESTSERVERS'); } /** * Gets an array of options to use as the serialiser. * @return array */ public static function config_get_serializer_options() { $options = array( Redis::SERIALIZER_PHP => get_string('serializer_php', 'cachestore_redis') ); if (defined('Redis::SERIALIZER_IGBINARY')) { $options[Redis::SERIALIZER_IGBINARY] = get_string('serializer_igbinary', 'cachestore_redis'); } return $options; } /** * Gets an array of options to use as the compressor. * * @return array */ public static function config_get_compressor_options() { $arr = [ self::COMPRESSOR_NONE => get_string('compressor_none', 'cachestore_redis'), self::COMPRESSOR_PHP_GZIP => get_string('compressor_php_gzip', 'cachestore_redis'), ]; // Check if the Zstandard PHP extension is installed. if (extension_loaded('zstd')) { $arr[self::COMPRESSOR_PHP_ZSTD] = get_string('compressor_php_zstd', 'cachestore_redis'); } return $arr; } /** * Compress the given value, serializing it first. * * @param mixed $value * @return string */ private function compress($value) { $value = $this->serialize($value); switch ($this->compressor) { case self::COMPRESSOR_NONE: return $value; case self::COMPRESSOR_PHP_GZIP: return gzencode($value); case self::COMPRESSOR_PHP_ZSTD: return zstd_compress($value); default: debugging("Invalid compressor: {$this->compressor}"); return $value; } } /** * Uncompresses (deflates) the data, unserialising it afterwards. * * @param string $value * @return mixed */ private function uncompress($value) { if ($value === false) { return false; } switch ($this->compressor) { case self::COMPRESSOR_NONE: break; case self::COMPRESSOR_PHP_GZIP: $value = gzdecode($value); break; case self::COMPRESSOR_PHP_ZSTD: $value = zstd_uncompress($value); break; default: debugging("Invalid compressor: {$this->compressor}"); } return $this->unserialize($value); } /** * Serializes the data according to the configured serializer. * * @param mixed $value * @return string */ private function serialize($value) { switch ($this->serializer) { case Redis::SERIALIZER_NONE: return $value; case Redis::SERIALIZER_PHP: return serialize($value); case defined('Redis::SERIALIZER_IGBINARY') && Redis::SERIALIZER_IGBINARY: return igbinary_serialize($value); default: debugging("Invalid serializer: {$this->serializer}"); return $value; } } /** * Unserializes the data according to the configured serializer * * @param string $value * @return mixed */ private function unserialize($value) { switch ($this->serializer) { case Redis::SERIALIZER_NONE: return $value; case Redis::SERIALIZER_PHP: return unserialize($value); case defined('Redis::SERIALIZER_IGBINARY') && Redis::SERIALIZER_IGBINARY: return igbinary_unserialize($value); default: debugging("Invalid serializer: {$this->serializer}"); return $value; } } }