Sam Hemelryk
654 lines
21 KiB
PHP
654 lines
21 KiB
PHP
<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* The library file for the file cache store.
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*
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* This file is part of the file cache store, it contains the API for interacting with an instance of the store.
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* This is used as a default cache store within the Cache API. It should never be deleted.
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*
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* @package cachestore_file
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* @category cache
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* @copyright 2012 Sam Hemelryk
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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/**
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* The file store class.
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*
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* Configuration options
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* path: string: path to the cache directory, if left empty one will be created in the cache directory
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* autocreate: true, false
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* prescan: true, false
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*
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* @copyright 2012 Sam Hemelryk
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class cachestore_file extends cache_store implements cache_is_key_aware, cache_is_configurable {
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/**
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* The name of the store.
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* @var string
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*/
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protected $name;
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/**
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* The path to use for the file storage.
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* @var string
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*/
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protected $path = null;
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/**
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* Set to true when a prescan has been performed.
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* @var bool
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*/
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protected $prescan = false;
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/**
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* Set to true if we should store files within a single directory.
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* By default we use a nested structure in order to reduce the chance of conflicts and avoid any file system
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* limitations such as maximum files per directory.
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* @var bool
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*/
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protected $singledirectory = false;
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/**
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* Set to true when the path should be automatically created if it does not yet exist.
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* @var bool
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*/
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protected $autocreate = false;
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/**
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* Set to true if a custom path is being used.
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* @var bool
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*/
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protected $custompath = false;
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/**
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* An array of keys we are sure about presently.
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* @var array
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*/
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protected $keys = array();
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/**
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* True when the store is ready to be initialised.
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* @var bool
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*/
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protected $isready = false;
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/**
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* The cache definition this instance has been initialised with.
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* @var cache_definition
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*/
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protected $definition;
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/**
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* Constructs the store instance.
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*
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* Noting that this function is not an initialisation. It is used to prepare the store for use.
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* The store will be initialised when required and will be provided with a cache_definition at that time.
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*
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* @param string $name
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* @param array $configuration
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*/
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public function __construct($name, array $configuration = array()) {
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$this->name = $name;
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if (array_key_exists('path', $configuration) && $configuration['path'] !== '') {
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$this->custompath = true;
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$this->autocreate = !empty($configuration['autocreate']);
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$path = (string)$configuration['path'];
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if (!is_dir($path)) {
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if ($this->autocreate) {
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if (!make_writable_directory($path, false)) {
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$path = false;
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debugging('Error trying to autocreate file store path. '.$path, DEBUG_DEVELOPER);
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}
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} else {
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$path = false;
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debugging('The given file cache store path does not exist. '.$path, DEBUG_DEVELOPER);
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}
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}
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if ($path !== false && !is_writable($path)) {
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$path = false;
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debugging('The file cache store path is not writable for `'.$name.'`', DEBUG_DEVELOPER);
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}
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} else {
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$path = make_cache_directory('cachestore_file/'.preg_replace('#[^a-zA-Z0-9\.\-_]+#', '', $name));
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}
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$this->isready = $path !== false;
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$this->path = $path;
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// Check if we should prescan the directory.
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if (array_key_exists('prescan', $configuration)) {
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$this->prescan = (bool)$configuration['prescan'];
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} else {
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// Default is no, we should not prescan.
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$this->prescan = false;
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}
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// Check if we should be storing in a single directory.
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if (array_key_exists('singledirectory', $configuration)) {
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$this->singledirectory = (bool)$configuration['singledirectory'];
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} else {
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// Default: No, we will use multiple directories.
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$this->singledirectory = false;
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}
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}
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/**
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* Returns true if this store instance is ready to be used.
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* @return bool
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*/
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public function is_ready() {
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return $this->isready;
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}
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/**
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* Returns true once this instance has been initialised.
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*
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* @return bool
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*/
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public function is_initialised() {
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return true;
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}
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/**
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* Returns the supported features as a combined int.
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*
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* @param array $configuration
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* @return int
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*/
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public static function get_supported_features(array $configuration = array()) {
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$supported = self::SUPPORTS_DATA_GUARANTEE +
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self::SUPPORTS_NATIVE_TTL;
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return $supported;
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}
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/**
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* Returns the supported modes as a combined int.
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*
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* @param array $configuration
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* @return int
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*/
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public static function get_supported_modes(array $configuration = array()) {
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return self::MODE_APPLICATION + self::MODE_SESSION;
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}
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/**
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* Returns true if the store requirements are met.
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*
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* @return bool
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*/
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public static function are_requirements_met() {
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return true;
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}
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/**
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* Returns true if the given mode is supported by this store.
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*
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* @param int $mode One of cache_store::MODE_*
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* @return bool
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*/
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public static function is_supported_mode($mode) {
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return ($mode === self::MODE_APPLICATION || $mode === self::MODE_SESSION);
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}
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/**
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* Initialises the cache.
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*
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* Once this has been done the cache is all set to be used.
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*
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* @param cache_definition $definition
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*/
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public function initialise(cache_definition $definition) {
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$this->definition = $definition;
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$hash = preg_replace('#[^a-zA-Z0-9]+#', '_', $this->definition->get_id());
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$this->path .= '/'.$hash;
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make_writable_directory($this->path);
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if ($this->prescan && $definition->get_mode() !== self::MODE_REQUEST) {
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$this->prescan = false;
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}
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if ($this->prescan) {
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$this->prescan_keys();
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}
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}
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/**
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* Pre-scan the cache to see which keys are present.
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*/
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protected function prescan_keys() {
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$files = glob($this->glob_keys_pattern(), GLOB_MARK | GLOB_NOSORT);
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if (is_array($files)) {
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foreach ($files as $filename) {
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$this->keys[basename($filename)] = filemtime($filename);
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}
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}
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}
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/**
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* Gets a pattern suitable for use with glob to find all keys in the cache.
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* @return string The pattern.
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*/
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protected function glob_keys_pattern() {
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if ($this->singledirectory) {
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return $this->path . '/*.cache';
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} else {
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return $this->path . '/*/*.cache';
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}
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}
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/**
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* Returns the file path to use for the given key.
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*
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* @param string $key The key to generate a file path for.
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* @param bool $create If set to the true the directory structure the key requires will be created.
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* @return string The full path to the file that stores a particular cache key.
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*/
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protected function file_path_for_key($key, $create = false) {
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if ($this->singledirectory) {
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// Its a single directory, easy, just the store instances path + the file name.
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return $this->path . '/' . $key . '.cache';
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} else {
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// We are using a single subdirectory to achieve 1 level.
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$subdir = substr($key, 0, 3);
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$dir = $this->path . '/' . $subdir;
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if ($create) {
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// Create the directory. This function does it recursivily!
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make_writable_directory($dir);
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}
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return $dir . '/' . $key . '.cache';
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}
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}
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/**
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* Retrieves an item from the cache store given its key.
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*
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* @param string $key The key to retrieve
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* @return mixed The data that was associated with the key, or false if the key did not exist.
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*/
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public function get($key) {
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$filename = $key.'.cache';
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$file = $this->file_path_for_key($key);
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$ttl = $this->definition->get_ttl();
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if ($ttl) {
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$maxtime = cache::now() - $ttl;
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}
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$readfile = false;
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if ($this->prescan && array_key_exists($key, $this->keys)) {
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if (!$ttl || $this->keys[$filename] >= $maxtime && file_exists($file)) {
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$readfile = true;
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} else {
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$this->delete($key);
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}
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} else if (file_exists($file) && (!$ttl || filemtime($file) >= $maxtime)) {
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$readfile = true;
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}
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if (!$readfile) {
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return false;
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}
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// Check the filesize first, likely not needed but important none the less.
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$filesize = filesize($file);
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if (!$filesize) {
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return false;
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}
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// Open ensuring the file for writing, truncating it and setting the pointer to the start.
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if (!$handle = fopen($file, 'rb')) {
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return false;
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}
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// Lock it up!
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// We don't care if this succeeds or not, on some systems it will, on some it won't, meah either way.
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flock($handle, LOCK_SH);
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// HACK ALERT
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// There is a problem when reading from the file during PHPUNIT tests. For one reason or another the filesize is not correct
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// Doesn't happen during normal operation, just during unit tests.
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// Read it.
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$data = fread($handle, $filesize+128);
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// Unlock it.
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flock($handle, LOCK_UN);
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// Return it unserialised.
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return $this->prep_data_after_read($data);
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}
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/**
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* Retrieves several items from the cache store in a single transaction.
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*
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* 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.
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*
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* @param array $keys The array of keys to retrieve
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* @return array An array of items from the cache. There will be an item for each key, those that were not in the store will
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* be set to false.
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*/
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public function get_many($keys) {
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$result = array();
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foreach ($keys as $key) {
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$result[$key] = $this->get($key);
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}
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return $result;
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}
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/**
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* Deletes an item from the cache store.
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*
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* @param string $key The key to delete.
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* @return bool Returns true if the operation was a success, false otherwise.
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*/
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public function delete($key) {
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$filename = $key.'.cache';
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$file = $this->file_path_for_key($key);
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if (@unlink($file)) {
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unset($this->keys[$filename]);
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return true;
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}
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return false;
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}
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/**
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* Deletes several keys from the cache in a single action.
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*
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* @param array $keys The keys to delete
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* @return int The number of items successfully deleted.
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*/
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public function delete_many(array $keys) {
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$count = 0;
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foreach ($keys as $key) {
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if ($this->delete($key)) {
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$count++;
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}
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}
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return $count;
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}
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/**
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* Sets an item in the cache given its key and data value.
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*
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* @param string $key The key to use.
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* @param mixed $data The data to set.
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* @return bool True if the operation was a success false otherwise.
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*/
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public function set($key, $data) {
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$this->ensure_path_exists();
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$filename = $key.'.cache';
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$file = $this->file_path_for_key($key, true);
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$result = $this->write_file($file, $this->prep_data_before_save($data));
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if (!$result) {
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// Couldn't write the file.
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return false;
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}
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// Record the key if required.
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if ($this->prescan) {
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$this->keys[$filename] = cache::now() + 1;
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}
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// Return true.. it all worked **miracles**.
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return true;
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}
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/**
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* Prepares data to be stored in a file.
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*
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* @param mixed $data
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* @return string
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*/
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protected function prep_data_before_save($data) {
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return serialize($data);
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}
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/**
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* Prepares the data it has been read from the cache. Undoing what was done in prep_data_before_save.
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*
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* @param string $data
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* @return mixed
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* @throws coding_exception
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*/
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protected function prep_data_after_read($data) {
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$result = @unserialize($data);
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if ($result === false) {
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throw new coding_exception('Failed to unserialise data from file. Either failed to read, or failed to write.');
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}
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return $result;
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}
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/**
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* Sets many items in the cache in a single transaction.
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*
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* @param array $keyvaluearray An array of key value pairs. Each item in the array will be an associative array with two
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* keys, 'key' and 'value'.
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* @return int The number of items successfully set. It is up to the developer to check this matches the number of items
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* sent ... if they care that is.
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*/
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public function set_many(array $keyvaluearray) {
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$count = 0;
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foreach ($keyvaluearray as $pair) {
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if ($this->set($pair['key'], $pair['value'])) {
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$count++;
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}
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}
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return $count;
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}
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/**
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* Checks if the store has a record for the given key and returns true if so.
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*
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* @param string $key
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* @return bool
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*/
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public function has($key) {
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$filename = $key.'.cache';
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$maxtime = cache::now() - $this->definition->get_ttl();
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if ($this->prescan) {
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return array_key_exists($filename, $this->keys) && $this->keys[$filename] >= $maxtime;
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}
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$file = $this->file_path_for_key($key);
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return (file_exists($file) && ($this->definition->get_ttl() == 0 || filemtime($file) >= $maxtime));
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}
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/**
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* Returns true if the store contains records for all of the given keys.
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*
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* @param array $keys
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* @return bool
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*/
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public function has_all(array $keys) {
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foreach ($keys as $key) {
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if (!$this->has($key)) {
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return false;
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}
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}
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return true;
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}
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/**
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* Returns true if the store contains records for any of the given keys.
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*
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* @param array $keys
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* @return bool
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*/
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public function has_any(array $keys) {
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foreach ($keys as $key) {
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if ($this->has($key)) {
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return true;
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}
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}
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return false;
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}
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/**
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* Purges the cache deleting all items within it.
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*
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* @return boolean True on success. False otherwise.
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*/
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public function purge() {
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$files = glob($this->glob_keys_pattern(), GLOB_MARK | GLOB_NOSORT);
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if (is_array($files)) {
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foreach ($files as $filename) {
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@unlink($filename);
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}
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}
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$this->keys = array();
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return true;
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}
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/**
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* Given the data from the add instance form this function creates a configuration array.
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*
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* @param stdClass $data
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* @return array
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*/
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public static function config_get_configuration_array($data) {
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$config = array();
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if (isset($data->path)) {
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$config['path'] = $data->path;
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}
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if (isset($data->autocreate)) {
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$config['autocreate'] = $data->autocreate;
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}
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if (isset($data->singledirectory)) {
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$config['singledirectory'] = $data->singledirectory;
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}
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if (isset($data->prescan)) {
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$config['prescan'] = $data->prescan;
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}
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return $config;
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}
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/**
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* Allows the cache store to set its data against the edit form before it is shown to the user.
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*
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* @param moodleform $editform
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* @param array $config
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*/
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public static function config_set_edit_form_data(moodleform $editform, array $config) {
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$data = array();
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if (!empty($config['path'])) {
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$data['path'] = $config['path'];
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}
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if (isset($config['autocreate'])) {
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$data['autocreate'] = (bool)$config['autocreate'];
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}
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if (isset($config['singledirectory'])) {
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$data['singledirectory'] = (bool)$config['singledirectory'];
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}
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if (isset($config['prescan'])) {
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$data['prescan'] = (bool)$config['prescan'];
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}
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$editform->set_data($data);
|
|
}
|
|
|
|
/**
|
|
* Checks to make sure that the path for the file cache exists.
|
|
*
|
|
* @return bool
|
|
* @throws coding_exception
|
|
*/
|
|
protected function ensure_path_exists() {
|
|
if (!is_writable($this->path)) {
|
|
if ($this->custompath && !$this->autocreate) {
|
|
throw new coding_exception('File store path does not exist. It must exist and be writable by the web server.');
|
|
}
|
|
if (!make_writable_directory($this->path, false)) {
|
|
throw new coding_exception('File store path does not exist and can not be created.');
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Performs any necessary clean up when the store instance is being deleted.
|
|
*
|
|
* 1. Purges the cache directory.
|
|
* 2. Deletes the directory we created for this cache instances data.
|
|
*/
|
|
public function cleanup() {
|
|
$this->purge();
|
|
@rmdir($this->path);
|
|
}
|
|
|
|
/**
|
|
* 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));
|
|
$cache->initialise($definition);
|
|
return $cache;
|
|
}
|
|
|
|
/**
|
|
* 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, $file);
|
|
if (!$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;
|
|
}
|
|
}
|