cache/classes/dummystore.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * Cache dummy store.
  19  *
  20  * This dummy store is used when a load has no other stores that it can make use of.
  21  * This shouldn't happen in normal operation... I think.
  22  *
  23  * This file is part of Moodle's cache API, affectionately called MUC.
  24  * It contains the components that are requried in order to use caching.
  25  *
  26  * @package    core
  27  * @category   cache
  28  * @copyright  2012 Sam Hemelryk
  29  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  30  */
  31
  32 defined('MOODLE_INTERNAL') || die();
  33
  34 /**
  35  * The cache dummy store.
  36  *
  37  * @copyright  2012 Sam Hemelryk
  38  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  39  */
  40 class cachestore_dummy extends cache_store {
  41
  42     /**
  43      * The name of this store.
  44      * @var string
  45      */
  46     protected $name;
  47
  48     /**
  49      * Gets set to true if this store is going to store data.
  50      * This happens when the definition doesn't require static acceleration as the loader will not be storing information and
  51      * something has to.
  52      * @var bool
  53      */
  54     protected $persist = false;
  55
  56     /**
  57      * The stored data array
  58      * @var array
  59      */
  60     protected $store = array();
  61
  62     /**
  63      * Constructs a dummy store instance.
  64      * @param string $name
  65      * @param array $configuration
  66      */
  67     public function __construct($name = 'Dummy store', array $configuration = array()) {
  68         $this->name = $name;
  69     }
  70
  71     /**
  72      * Returns true if this store plugin is usable.
  73      * @return bool
  74      */
  75     public static function are_requirements_met() {
  76         return true;
  77     }
  78
  79     /**
  80      * Returns true if the user can add an instance.
  81      * @return bool
  82      */
  83     public static function can_add_instance() {
  84         return false;
  85     }
  86
  87     /**
  88      * Returns the supported features.
  89      * @param array $configuration
  90      * @return int
  91      */
  92     public static function get_supported_features(array $configuration = array()) {
  93         return self::SUPPORTS_NATIVE_TTL;
  94     }
  95
  96     /**
  97      * Returns the supported mode.
  98      * @param array $configuration
  99      * @return int
 100      */
 101     public static function get_supported_modes(array $configuration = array()) {
 102         return self::MODE_APPLICATION + self::MODE_REQUEST + self::MODE_SESSION;
 103     }
 104
 105     /**
 106      * Initialises the store instance for a definition.
 107      * @param cache_definition $definition
 108      */
 109     public function initialise(cache_definition $definition) {
 110         // If the definition isn't using static acceleration then we need to be store data here.
 111         // The reasoning behind this is that:
 112         //   - If the definition is using static acceleration then the cache loader is going to
 113         //     store things in its static array.
 114         //   - If the definition is not using static acceleration then the cache loader won't try to store anything
 115         //     and we will need to store it here in order to make sure it is accessible.
 116         if ($definition->get_mode() !== self::MODE_APPLICATION) {
 117             // Neither the request cache nor the session cache provide static acceleration.
 118             $this->persist = true;
 119         } else {
 120             $this->persist = !$definition->use_static_acceleration();
 121         }
 122     }
 123
 124     /**
 125      * Returns true if this has been initialised.
 126      * @return bool
 127      */
 128     public function is_initialised() {
 129         return (!empty($this->definition));
 130     }
 131
 132     /**
 133      * Returns true the given mode is supported.
 134      * @param int $mode
 135      * @return bool
 136      */
 137     public static function is_supported_mode($mode) {
 138         return true;
 139     }
 140
 141     /**
 142      * Returns the data for the given key
 143      * @param string $key
 144      * @return string|false
 145      */
 146     public function get($key) {
 147         if ($this->persist && array_key_exists($key, $this->store)) {
 148             return $this->store[$key];
 149         }
 150         return false;
 151     }
 152
 153     /**
 154      * Gets' the values for many keys
 155      * @param array $keys
 156      * @return bool
 157      */
 158     public function get_many($keys) {
 159         $return = array();
 160         foreach ($keys as $key) {
 161             if ($this->persist && array_key_exists($key, $this->store)) {
 162                 $return[$key] = $this->store[$key];
 163             } else {
 164                 $return[$key] = false;
 165             }
 166         }
 167         return $return;
 168     }
 169
 170     /**
 171      * Sets an item in the cache
 172      * @param string $key
 173      * @param mixed $data
 174      * @return bool
 175      */
 176     public function set($key, $data) {
 177         if ($this->persist) {
 178             $this->store[$key] = $data;
 179         }
 180         return true;
 181     }
 182
 183     /**
 184      * Sets many items in the cache
 185      * @param array $keyvaluearray
 186      * @return int
 187      */
 188     public function set_many(array $keyvaluearray) {
 189         if ($this->persist) {
 190             foreach ($keyvaluearray as $pair) {
 191                 $this->store[$pair['key']] = $pair['value'];
 192             }
 193
 194         }
 195         return count($keyvaluearray);
 196     }
 197
 198     /**
 199      * Deletes an item from the cache
 200      * @param string $key
 201      * @return bool
 202      */
 203     public function delete($key) {
 204         unset($this->store[$key]);
 205         return true;
 206     }
 207     /**
 208      * Deletes many items from the cache
 209      * @param array $keys
 210      * @return bool
 211      */
 212     public function delete_many(array $keys) {
 213         if ($this->persist) {
 214             foreach ($keys as $key) {
 215                 unset($this->store[$key]);
 216             }
 217         }
 218         return count($keys);
 219     }
 220
 221     /**
 222      * Deletes all of the items from the cache.
 223      * @return bool
 224      */
 225     public function purge() {
 226         $this->store = array();
 227         return true;
 228     }
 229
 230     /**
 231      * Performs any necessary clean up when the store instance is being deleted.
 232      */
 233     public function cleanup() {
 234         $this->purge();
 235     }
 236
 237     /**
 238      * Generates an instance of the cache store that can be used for testing.
 239      *
 240      * @param cache_definition $definition
 241      * @return false
 242      */
 243     public static function initialise_test_instance(cache_definition $definition) {
 244         $cache = new cachestore_dummy('Dummy store test');
 245         $cache->initialise($definition);
 246         return $cache;
 247     }
 248
 249     /**
 250      * Returns the name of this instance.
 251      * @return string
 252      */
 253     public function my_name() {
 254         return $this->name;
 255     }
 256 }