1: <?php
  2: /**
  3:  * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
  4:  * Copyright 2005-2012, Cake Software Foundation, Inc. (http://cakefoundation.org)
  5:  *
  6:  * Licensed under The MIT License
  7:  * Redistributions of files must retain the above copyright notice.
  8:  *
  9:  * @copyright     Copyright 2005-2012, Cake Software Foundation, Inc. (http://cakefoundation.org)
 10:  * @link          http://cakephp.org CakePHP(tm) Project
 11:  * @package       Cake.Cache
 12:  * @since         CakePHP(tm) v 1.2.0.4933
 13:  * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
 14:  */
 15: 
 16: /**
 17:  * Storage engine for CakePHP caching
 18:  *
 19:  * @package       Cake.Cache
 20:  */
 21: abstract class CacheEngine {
 22: 
 23: /**
 24:  * Settings of current engine instance
 25:  *
 26:  * @var array
 27:  */
 28:     public $settings = array();
 29: 
 30: /**
 31:  * Contains the compiled string with all groups
 32:  * prefixes to be prepeded to every key in this cache engine
 33:  *
 34:  * @var string
 35:  **/
 36:     protected $_groupPrefix = null;
 37: 
 38: /**
 39:  * Initialize the cache engine
 40:  *
 41:  * Called automatically by the cache frontend
 42:  *
 43:  * @param array $settings Associative array of parameters for the engine
 44:  * @return boolean True if the engine has been successfully initialized, false if not
 45:  */
 46:     public function init($settings = array()) {
 47:         $settings += $this->settings + array(
 48:             'prefix' => 'cake_',
 49:             'duration' => 3600,
 50:             'probability' => 100,
 51:             'groups' => array()
 52:         );
 53:         $this->settings = $settings;
 54:         if (!empty($this->settings['groups'])) {
 55:             sort($this->settings['groups']);
 56:             $this->_groupPrefix = str_repeat('%s_', count($this->settings['groups']));
 57:         }
 58:         if (!is_numeric($this->settings['duration'])) {
 59:             $this->settings['duration'] = strtotime($this->settings['duration']) - time();
 60:         }
 61:         return true;
 62:     }
 63: 
 64: /**
 65:  * Garbage collection
 66:  *
 67:  * Permanently remove all expired and deleted data
 68:  *
 69:  * @param integer $expires [optional] An expires timestamp, invalidataing all data before.
 70:  * @return void
 71:  */
 72:     public function gc($expires = null) {
 73:     }
 74: 
 75: /**
 76:  * Write value for a key into cache
 77:  *
 78:  * @param string $key Identifier for the data
 79:  * @param mixed $value Data to be cached
 80:  * @param integer $duration How long to cache for.
 81:  * @return boolean True if the data was successfully cached, false on failure
 82:  */
 83:     abstract public function write($key, $value, $duration);
 84: 
 85: /**
 86:  * Read a key from the cache
 87:  *
 88:  * @param string $key Identifier for the data
 89:  * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it
 90:  */
 91:     abstract public function read($key);
 92: 
 93: /**
 94:  * Increment a number under the key and return incremented value
 95:  *
 96:  * @param string $key Identifier for the data
 97:  * @param integer $offset How much to add
 98:  * @return New incremented value, false otherwise
 99:  */
100:     abstract public function increment($key, $offset = 1);
101: 
102: /**
103:  * Decrement a number under the key and return decremented value
104:  *
105:  * @param string $key Identifier for the data
106:  * @param integer $offset How much to subtract
107:  * @return New incremented value, false otherwise
108:  */
109:     abstract public function decrement($key, $offset = 1);
110: 
111: /**
112:  * Delete a key from the cache
113:  *
114:  * @param string $key Identifier for the data
115:  * @return boolean True if the value was successfully deleted, false if it didn't exist or couldn't be removed
116:  */
117:     abstract public function delete($key);
118: 
119: /**
120:  * Delete all keys from the cache
121:  *
122:  * @param boolean $check if true will check expiration, otherwise delete all
123:  * @return boolean True if the cache was successfully cleared, false otherwise
124:  */
125:     abstract public function clear($check);
126: 
127: /**
128:  * Clears all values belonging to a group. Is upt to the implementing engine
129:  * to decide whether actually deete the keys or just simulate it to acheive
130:  * the same result.
131:  *
132:  * @param string $groups name of the group to be cleared
133:  * @return boolean
134:  */
135:     public function clearGroup($group) {
136:         return false;
137:     }
138: 
139: /**
140:  * Does whatever initialization for each group is required
141:  * and returns the `group value` for each of them, this is
142:  * the token representing each group in the cache key
143:  *
144:  * @return array
145:  */
146:     public function groups() {
147:         return $this->settings['groups'];
148:     }
149: 
150: /**
151:  * Cache Engine settings
152:  *
153:  * @return array settings
154:  */
155:     public function settings() {
156:         return $this->settings;
157:     }
158: 
159: /**
160:  * Generates a safe key for use with cache engine storage engines.
161:  *
162:  * @param string $key the key passed over
163:  * @return mixed string $key or false
164:  */
165:     public function key($key) {
166:         if (empty($key)) {
167:             return false;
168:         }
169: 
170:         $prefix = '';
171:         if (!empty($this->_groupPrefix)) {
172:             $prefix = vsprintf($this->_groupPrefix, $this->groups());
173:         }
174: 
175:         $key = preg_replace('/[\s]+/', '_', strtolower(trim(str_replace(array(DS, '/', '.'), '_', strval($key)))));
176:         return $prefix . $key;
177:     }
178: 
179: }
180: