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Long Term Support Release
<?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 file cache store. * * This file is part of the file 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_file * @category cache * @copyright 2012 Sam Hemelryk * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later */ /** * The file store class. * * Configuration options * path: string: path to the cache directory, if left empty one will be created in the cache directory * autocreate: true, false * prescan: true, false * * @copyright 2012 Sam Hemelryk * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later */< class cachestore_file extends cache_store implements cache_is_key_aware, cache_is_configurable, cache_is_searchable {> class cachestore_file extends cache_store implements cache_is_key_aware, cache_is_configurable, cache_is_searchable, > cache_is_lockable {/** * The name of the store. * @var string */ protected $name; /** * The path used to store files for this store and the definition it was initialised with. * @var string */ protected $path = false; /** * The path in which definition specific sub directories will be created for caching. * @var string */ protected $filestorepath = false; /** * Set to true when a prescan has been performed. * @var bool */ protected $prescan = false; /** * Set to true if we should store files within a single directory. * By default we use a nested structure in order to reduce the chance of conflicts and avoid any file system * limitations such as maximum files per directory. * @var bool */ protected $singledirectory = false; /** * Set to true when the path should be automatically created if it does not yet exist. * @var bool */ protected $autocreate = false; /**> * Set to true if new cache revision directory needs to be created. Old directory will be purged asynchronously * Set to true if a custom path is being used. > * via Schedule task. * @var bool > * @var bool */ > */ protected $custompath = false; > protected $asyncpurge = false; > /** > /*** An array of keys we are sure about presently. * @var array */ protected $keys = array(); /** * True when the store is ready to be initialised. * @var bool */ protected $isready = false; /** * The cache definition this instance has been initialised with. * @var cache_definition */ protected $definition; /**> * Bytes read or written by last call to set()/get() or set_many()/get_many(). * A reference to the global $CFG object. > * * > * @var int * You may be asking yourself why on earth this is here, but there is a good reason. > */ * By holding onto a reference of the $CFG object we can be absolutely sure that it won't be destroyed before > protected $lastiobytes = 0; * we are done with it. > * This makes it possible to use a cache within a destructor method for the purposes of > /*** delayed writes. Like how the session mechanisms work. * * @var stdClass */ private $cfg = null;> /** @var int Maximum number of seconds to wait for a lock before giving up. */ /** > protected $lockwait = 60; * Constructs the store instance. > * > /** * Noting that this function is not an initialisation. It is used to prepare the store for use. > * Instance of file_lock_factory configured to create locks in the cache directory. * The store will be initialised when required and will be provided with a cache_definition at that time. > * * > * @var \core\lock\file_lock_factory $lockfactory * @param string $name > */ * @param array $configuration > protected $lockfactory = null; */ > public function __construct($name, array $configuration = array()) { > /** global $CFG; > * List of current locks. > * if (isset($CFG)) { > * @var array $locks // Hold onto a reference of the global $CFG object. > */ $this->cfg = $CFG; > protected $locks = []; } >$this->name = $name; if (array_key_exists('path', $configuration) && $configuration['path'] !== '') { $this->custompath = true; $this->autocreate = !empty($configuration['autocreate']); $path = (string)$configuration['path']; if (!is_dir($path)) { if ($this->autocreate) { if (!make_writable_directory($path, false)) { $path = false; debugging('Error trying to autocreate file store path. '.$path, DEBUG_DEVELOPER); } } else { $path = false; debugging('The given file cache store path does not exist. '.$path, DEBUG_DEVELOPER); } } if ($path !== false && !is_writable($path)) { $path = false; debugging('The file cache store path is not writable for `'.$name.'`', DEBUG_DEVELOPER); } } else { $path = make_cache_directory('cachestore_file/'.preg_replace('#[^a-zA-Z0-9\.\-_]+#', '', $name)); } $this->isready = $path !== false; $this->filestorepath = $path; // This will be updated once the store has been initialised for a definition. $this->path = $path; // Check if we should prescan the directory. if (array_key_exists('prescan', $configuration)) { $this->prescan = (bool)$configuration['prescan']; } else { // Default is no, we should not prescan. $this->prescan = false; } // Check if we should be storing in a single directory. if (array_key_exists('singledirectory', $configuration)) { $this->singledirectory = (bool)$configuration['singledirectory']; } else { // Default: No, we will use multiple directories. $this->singledirectory = false; }> // Check if directory needs to be purged asynchronously. } > if (array_key_exists('asyncpurge', $configuration)) { > $this->asyncpurge = (bool)$configuration['asyncpurge']; /** > } else { * Performs any necessary operation when the file store instance has been created. > $this->asyncpurge = false; */ > } public function instance_created() { > if ($this->isready && !$this->prescan) { > // Leverage cachelock_file to provide native locking, to avoid duplicating logic. // It is supposed the store instance to expect an empty folder. > // This will store locks alongside the cache, so local cache uses local locks. $this->purge_all_definitions(); > $lockdir = $path . '/filelocks'; } > if (!file_exists($lockdir)) { } > make_writable_directory($lockdir); > } /** > if (array_key_exists('lockwait', $configuration)) { * Returns true if this store instance is ready to be used. > $this->lockwait = (int)$configuration['lockwait']; * @return bool > } */ > $this->lockfactory = new \core\lock\file_lock_factory('cachestore_file', $lockdir); public function is_ready() { > if (!$this->lockfactory->is_available()) { return $this->isready; > // File locking is disabled in config, fall back to default lock factory. } > $this->lockfactory = \core\lock\lock_config::get_lock_factory('cachestore_file'); > }/** * Returns true once this instance has been initialised. * * @return bool */ public function is_initialised() { return true; } /** * Returns the supported features as a combined int. * * @param array $configuration * @return int */ public static function get_supported_features(array $configuration = array()) { $supported = self::SUPPORTS_DATA_GUARANTEE + self::SUPPORTS_NATIVE_TTL + self::IS_SEARCHABLE + self::DEREFERENCES_OBJECTS; return $supported; } /** * Returns false as this store does not support multiple identifiers. * (This optional function is a performance optimisation; it must be * consistent with the value from get_supported_features.) * * @return bool False */ public function supports_multiple_identifiers() { return false; } /** * 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_APPLICATION + self::MODE_SESSION; } /** * 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_APPLICATION || $mode === self::MODE_SESSION); } /** * 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) {> global $CFG; $this->definition = $definition; >$hash = preg_replace('#[^a-zA-Z0-9]+#', '_', $this->definition->get_id()); $this->path = $this->filestorepath.'/'.$hash; make_writable_directory($this->path, false);> if ($this->prescan && $definition->get_mode() !== self::MODE_REQUEST) { > if ($this->asyncpurge) { $this->prescan = false; > $timestampfile = $this->path . '/.lastpurged'; } > if (!file_exists($timestampfile)) { if ($this->prescan) { > touch($timestampfile); $this->prescan_keys(); > @chmod($timestampfile, $CFG->filepermissions); } > } } > $cacherev = gmdate("YmdHis", filemtime($timestampfile)); > // Update file path with new cache revision. /** > $this->path .= '/' . $cacherev; * Pre-scan the cache to see which keys are present. > make_writable_directory($this->path, false); */ > } protected function prescan_keys() { >$files = glob($this->glob_keys_pattern(), GLOB_MARK | GLOB_NOSORT); if (is_array($files)) { foreach ($files as $filename) { $this->keys[basename($filename)] = filemtime($filename); } } } /** * Gets a pattern suitable for use with glob to find all keys in the cache. * * @param string $prefix A prefix to use. * @return string The pattern. */ protected function glob_keys_pattern($prefix = '') { if ($this->singledirectory) { return $this->path . '/'.$prefix.'*.cache'; } else { return $this->path . '/*/'.$prefix.'*.cache'; } } /** * Returns the file path to use for the given key. * * @param string $key The key to generate a file path for. * @param bool $create If set to the true the directory structure the key requires will be created. * @return string The full path to the file that stores a particular cache key. */ protected function file_path_for_key($key, $create = false) { if ($this->singledirectory) { // Its a single directory, easy, just the store instances path + the file name. return $this->path . '/' . $key . '.cache'; } else { // We are using a single subdirectory to achieve 1 level. // We suffix the subdir so it does not clash with any windows // reserved filenames like 'con'. $subdir = substr($key, 0, 3) . '-cache'; $dir = $this->path . '/' . $subdir; if ($create) { // Create the directory. This function does it recursivily! make_writable_directory($dir, false); } return $dir . '/' . $key . '.cache'; } } /** * 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) {> $this->lastiobytes = 0;$filename = $key.'.cache'; $file = $this->file_path_for_key($key); $ttl = $this->definition->get_ttl(); $maxtime = 0; if ($ttl) { $maxtime = cache::now() - $ttl; } $readfile = false; if ($this->prescan && array_key_exists($filename, $this->keys)) { if ((!$ttl || $this->keys[$filename] >= $maxtime) && file_exists($file)) { $readfile = true; } else { $this->delete($key); } } else if (file_exists($file) && (!$ttl || filemtime($file) >= $maxtime)) { $readfile = true; } if (!$readfile) { return false; } // Open ensuring the file for reading in binary format. if (!$handle = fopen($file, 'rb')) { return false; } // Note: There is no need to perform any file locking here. // The cache file is only ever written to in the `write_file` function, where it does so by writing to a temp // file and performing an atomic rename of that file. The target file is never locked, so there is no benefit to // obtaining a lock (shared or exclusive) here. $data = ''; // Read the data in 1Mb chunks. Small caches will not loop more than once. We don't use filesize as it may // be cached with a different value than what we need to read from the file. do { $data .= fread($handle, 1048576); } while (!feof($handle));> $this->lastiobytes = strlen($data); > // Return it unserialised. > if ($this->lastiobytes == 0) { return $this->prep_data_after_read($data); > // Potentially statcache is stale. File can be deleted, let's clear cache and recheck. } > clearstatcache(true, $file); > if (!file_exists($file)) { /** > // It's a completely normal condition. Just ignore and keep going. * Retrieves several items from the cache store in a single transaction. > return false; * > } * 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. > }< return $this->prep_data_after_read($data);> return $this->prep_data_after_read($data, $file);* @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) { $result = array();> $total = 0;foreach ($keys as $key) { $result[$key] = $this->get($key);> $total += $this->lastiobytes;}> $this->lastiobytes = $total;return $result; } /**> * Gets bytes read by last get() or get_many(), or written by set() or set_many(). * Deletes an item from the cache store. > * * > * @return int Bytes read or written * @param string $key The key to delete. > * @since Moodle 4.0 * @return bool Returns true if the operation was a success, false otherwise. > */ */ > public function get_last_io_bytes(): int { public function delete($key) { > return $this->lastiobytes; $filename = $key.'.cache'; > } $file = $this->file_path_for_key($key); > if (file_exists($file) && @unlink($file)) { > /**unset($this->keys[$filename]); return true; } return false; } /** * 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; } /** * 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) { $this->ensure_path_exists(); $filename = $key.'.cache'; $file = $this->file_path_for_key($key, true);< $result = $this->write_file($file, $this->prep_data_before_save($data));> $serialized = $this->prep_data_before_save($data); > $this->lastiobytes = strlen($serialized); > $result = $this->write_file($file, $serialized);if (!$result) { // Couldn't write the file. return false; } // Record the key if required. if ($this->prescan) { $this->keys[$filename] = cache::now() + 1; } // Return true.. it all worked **miracles**. return true; } /** * Prepares data to be stored in a file. * * @param mixed $data * @return string */ protected function prep_data_before_save($data) { return serialize($data); } /** * Prepares the data it has been read from the cache. Undoing what was done in prep_data_before_save. * * @param string $data> * @param string $path* @return mixed< * @throws coding_exception*/< protected function prep_data_after_read($data) {> protected function prep_data_after_read($data, $path) {$result = @unserialize($data); if ($result === false && $data != serialize(false)) {< throw new coding_exception('Failed to unserialise data from file. Either failed to read, or failed to write.');> debugging('Failed to unserialise data from cache file: ' . $path . '. Data: ' . $data, DEBUG_DEVELOPER); > return false;} return $result; } /** * 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;> $totaliobytes = 0;foreach ($keyvaluearray as $pair) { if ($this->set($pair['key'], $pair['value'])) {> $totaliobytes += $this->lastiobytes;$count++; } }> $this->lastiobytes = $totaliobytes;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) { $filename = $key.'.cache'; $maxtime = cache::now() - $this->definition->get_ttl(); if ($this->prescan) { return array_key_exists($filename, $this->keys) && $this->keys[$filename] >= $maxtime; } $file = $this->file_path_for_key($key); return (file_exists($file) && ($this->definition->get_ttl() == 0 || filemtime($file) >= $maxtime)); } /** * 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 $key) { if (!$this->has($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 $key) { if ($this->has($key)) { return true; } } return false; } /** * Purges the cache definition deleting all the items within it. * * @return boolean True on success. False otherwise. */ public function purge() {> global $CFG;if ($this->isready) {> // If asyncpurge = true, create a new cache revision directory and adhoc task to delete old directory. $files = glob($this->glob_keys_pattern(), GLOB_MARK | GLOB_NOSORT); > if ($this->asyncpurge && isset($this->definition)) { if (is_array($files)) { > $hash = preg_replace('#[^a-zA-Z0-9]+#', '_', $this->definition->get_id()); foreach ($files as $filename) { > $filepath = $this->filestorepath . '/' . $hash; @unlink($filename); > $timestampfile = $filepath . '/.lastpurged'; } > if (file_exists($timestampfile)) { } > $oldcacherev = gmdate("YmdHis", filemtime($timestampfile)); $this->keys = array(); > $oldcacherevpath = $filepath . '/' . $oldcacherev; } > // Delete old cache revision file. return true; > @unlink($timestampfile); } > > // Create adhoc task to delete old cache revision folder. /** > $purgeoldcacherev = new \cachestore_file\task\asyncpurge(); * Purges all the cache definitions deleting all items within them. > $purgeoldcacherev->set_custom_data(['path' => $oldcacherevpath]); * > \core\task\manager::queue_adhoc_task($purgeoldcacherev); * @return boolean True on success. False otherwise. > } */ > touch($timestampfile, time()); protected function purge_all_definitions() { > @chmod($timestampfile, $CFG->filepermissions); // Warning: limit the deletion to what file store is actually able > $newcacherev = gmdate("YmdHis", filemtime($timestampfile)); // to create using the internal {@link purge()} providing the > $filepath .= '/' . $newcacherev; // {@link $path} with a wildcard to perform a purge action over all the definitions. > make_writable_directory($filepath, false); $currpath = $this->path; > } else {< $this->keys = array();> $this->keys = []; > }$result = $this->purge(); $this->path = $currpath; return $result; } /** * 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->path)) { $config['path'] = $data->path; } if (isset($data->autocreate)) { $config['autocreate'] = $data->autocreate; } if (isset($data->singledirectory)) { $config['singledirectory'] = $data->singledirectory; } if (isset($data->prescan)) { $config['prescan'] = $data->prescan; }> if (isset($data->asyncpurge)) { > $config['asyncpurge'] = $data->asyncpurge; return $config; > } } > if (isset($data->lockwait)) { > $config['lockwait'] = $data->lockwait; /** > }* 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) { $data = array(); if (!empty($config['path'])) { $data['path'] = $config['path']; } if (isset($config['autocreate'])) { $data['autocreate'] = (bool)$config['autocreate']; } if (isset($config['singledirectory'])) { $data['singledirectory'] = (bool)$config['singledirectory']; } if (isset($config['prescan'])) { $data['prescan'] = (bool)$config['prescan']; }> if (isset($config['asyncpurge'])) { $editform->set_data($data); > $data['asyncpurge'] = (bool)$config['asyncpurge']; } > } > if (isset($config['lockwait'])) { /** > $data['lockwait'] = (int)$config['lockwait']; * Checks to make sure that the path for the file cache exists. > }* * @return bool * @throws coding_exception */ protected function ensure_path_exists() { global $CFG; if (!is_writable($this->path)) { if ($this->custompath && !$this->autocreate) { throw new coding_exception('File store path does not exist. It must exist and be writable by the web server.'); } $createdcfg = false; if (!isset($CFG)) { // This can only happen during destruction of objects. // A cache is being used within a destructor, php is ending a request and $CFG has // already being cleaned up. // Rebuild $CFG with directory permissions just to complete this write. $CFG = $this->cfg; $createdcfg = true; } if (!make_writable_directory($this->path, false)) { throw new coding_exception('File store path does not exist and can not be created.'); } if ($createdcfg) { // We re-created it so we'll clean it up. unset($CFG); } } return true; } /** * Performs any necessary clean up when the file store instance is being deleted. * * 1. Purges the cache directory. * 2. Deletes the directory we created for the given definition. */ public function instance_deleted() { $this->purge_all_definitions(); @rmdir($this->filestorepath); } /** * 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 cache_definition $definition * @return cachestore_file */ public static function initialise_test_instance(cache_definition $definition) { $name = 'File test'; $path = make_cache_directory('cachestore_file_test'); $cache = new cachestore_file($name, array('path' => $path)); if ($cache->is_ready()) { $cache->initialise($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(); } /** * Writes your madness to a file. * * There are several things going on in this function to try to ensure what we don't end up with partial writes etc. * 1. Files for writing are opened with the mode xb, the file must be created and can not already exist. * 2. Renaming, data is written to a temporary file, where it can be verified using md5 and is then renamed. * * @param string $file Absolute file path * @param string $content The content to write. * @return bool */ protected function write_file($file, $content) { // Generate a temp file that is going to be unique. We'll rename it at the end to the desired file name. // in this way we avoid partial writes. $path = dirname($file); while (true) { $tempfile = $path.'/'.uniqid(sesskey().'.', true) . '.temp'; if (!file_exists($tempfile)) { break; } } // Open the file with mode=x. This acts to create and open the file for writing only. // If the file already exists this will return false. // We also force binary. $handle = @fopen($tempfile, 'xb+'); if ($handle === false) { // File already exists... lock already exists, return false. return false; } fwrite($handle, $content); fflush($handle); // Close the handle, we're done. fclose($handle); if (md5_file($tempfile) !== md5($content)) { // The md5 of the content of the file must match the md5 of the content given to be written. @unlink($tempfile); return false; } // Finally rename the temp file to the desired file, returning the true|false result. $result = rename($tempfile, $file); @chmod($file, $this->cfg->filepermissions); if (!$result) { // Failed to rename, don't leave files lying around. @unlink($tempfile); } return $result; } /** * Returns the name of this instance. * @return string */ public function my_name() { return $this->name; } /** * Finds all of the keys being used by this cache store instance. * * @return array */ public function find_all() { $this->ensure_path_exists(); $files = glob($this->glob_keys_pattern(), GLOB_MARK | GLOB_NOSORT); $return = array(); if ($files === false) { return $return; } foreach ($files as $file) { $return[] = substr(basename($file), 0, -6); } return $return; } /** * Finds all of the keys whose keys start with the given prefix. * * @param string $prefix */ public function find_by_prefix($prefix) { $this->ensure_path_exists(); $prefix = preg_replace('#(\*|\?|\[)#', '[$1]', $prefix); $files = glob($this->glob_keys_pattern($prefix), GLOB_MARK | GLOB_NOSORT); $return = array(); if ($files === false) { return $return; } foreach ($files as $file) { // Trim off ".cache" from the end. $return[] = substr(basename($file), 0, -6); } return $return;> } } > } > /** > * Gets total size for the directory used by the cache store. > * > * @return int Total size in bytes > */ > public function store_total_size(): ?int { > return get_directory_size($this->filestorepath); > } > > /** > * Gets total size for a specific cache. > * > * With the file cache we can just look at the directory listing without having to > * actually load any files, so the $samplekeys parameter is ignored. > * > * @param int $samplekeys Unused > * @return stdClass Cache details > */ > public function cache_size_details(int $samplekeys = 50): stdClass { > $result = (object)[ > 'supported' => true, > 'items' => 0, > 'mean' => 0, > 'sd' => 0, > 'margin' => 0 > ]; > > // Find all the files in this cache. > $this->ensure_path_exists(); > $files = glob($this->glob_keys_pattern(), GLOB_MARK | GLOB_NOSORT); > if ($files === false || count($files) === 0) { > return $result; > } > > // Get the sizes and count of files. > $sizes = []; > foreach ($files as $file) { > $result->items++; > $sizes[] = filesize($file); > } > > // Work out mean and standard deviation. > $total = array_sum($sizes); > $result->mean = $total / $result->items; > $squarediff = 0; > foreach ($sizes as $size) { > $squarediff += ($size - $result->mean) ** 2; > } > $squarediff /= $result->items; > $result->sd = sqrt($squarediff); > return $result; > } > > /** > * Use lock factory to determine the lock state. > * > * @param string $key Lock identifier > * @param string $ownerid Cache identifier > * @return bool|null > */ > public function check_lock_state($key, $ownerid) : ?bool { > if (!array_key_exists($key, $this->locks)) { > return null; // Lock does not exist. > } > if (!array_key_exists($ownerid, $this->locks[$key])) { > return false; // Lock exists, but belongs to someone else. > } > if ($this->locks[$key][$ownerid] instanceof \core\lock\lock) { > return true; // Lock exists, and we own it. > } > // Try to get the lock with an immediate timeout. If this succeeds, the lock does not currently exist. > $lock = $this->lockfactory->get_lock($key, 0); > if ($lock) { > // Lock was not already held. > $lock->release(); > return null; > } else { > // Lock is held by someone else. > return false; > } > } > > /** > * Use lock factory to acquire a lock. > * > * @param string $key Lock identifier > * @param string $ownerid Cache identifier > * @return bool > * @throws cache_exception > */ > public function acquire_lock($key, $ownerid) : bool { > $lock = $this->lockfactory->get_lock($key, $this->lockwait); > if ($lock) { > $this->locks[$key][$ownerid] = $lock; > } > return (bool)$lock; > } > > /** > * Use lock factory to release a lock. > * > * @param string $key Lock identifier > * @param string $ownerid Cache identifier > * @return bool > */ > public function release_lock($key, $ownerid) : bool { > if (!array_key_exists($key, $this->locks)) { > return false; // No lock to release. > } > if (!array_key_exists($ownerid, $this->locks[$key])) { > return false; // Tried to release someone else's lock. > } > $unlocked = $this->locks[$key][$ownerid]->release(); > if ($unlocked) { > unset($this->locks[$key]); > } > return $unlocked;