1: <?php
  2: /**
  3:  * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
  4:  * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
  5:  *
  6:  * Licensed under The MIT License
  7:  * For full copyright and license information, please see the LICENSE.txt
  8:  * Redistributions of files must retain the above copyright notice.
  9:  *
 10:  * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 11:  * @link          http://cakephp.org CakePHP(tm) Project
 12:  * @package       Cake.Cache
 13:  * @since         CakePHP(tm) v 1.2.0.4933
 14:  * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 15:  */
 16: 
 17: /**
 18:  * Storage engine for CakePHP caching
 19:  *
 20:  * @package       Cake.Cache
 21:  */
 22: abstract class CacheEngine {
 23: 
 24: /**
 25:  * Settings of current engine instance
 26:  *
 27:  * @var array
 28:  */
 29:     public $settings = array();
 30: 
 31: /**
 32:  * Contains the compiled string with all groups
 33:  * prefixes to be prepended to every key in this cache engine
 34:  *
 35:  * @var string
 36:  */
 37:     protected $_groupPrefix = null;
 38: 
 39: /**
 40:  * Initialize the cache engine
 41:  *
 42:  * Called automatically by the cache frontend
 43:  *
 44:  * @param array $settings Associative array of parameters for the engine
 45:  * @return bool True if the engine has been successfully initialized, false if not
 46:  */
 47:     public function init($settings = array()) {
 48:         $settings += $this->settings + array(
 49:             'prefix' => 'cake_',
 50:             'duration' => 3600,
 51:             'probability' => 100,
 52:             'groups' => array()
 53:         );
 54:         $this->settings = $settings;
 55:         if (!empty($this->settings['groups'])) {
 56:             sort($this->settings['groups']);
 57:             $this->_groupPrefix = str_repeat('%s_', count($this->settings['groups']));
 58:         }
 59:         if (!is_numeric($this->settings['duration'])) {
 60:             $this->settings['duration'] = strtotime($this->settings['duration']) - time();
 61:         }
 62:         return true;
 63:     }
 64: 
 65: /**
 66:  * Garbage collection
 67:  *
 68:  * Permanently remove all expired and deleted data
 69:  *
 70:  * @param int $expires [optional] An expires timestamp, invalidating all data before.
 71:  * @return void
 72:  */
 73:     public function gc($expires = null) {
 74:     }
 75: 
 76: /**
 77:  * Write value for a key into cache
 78:  *
 79:  * @param string $key Identifier for the data
 80:  * @param mixed $value Data to be cached
 81:  * @param int $duration How long to cache for.
 82:  * @return bool True if the data was successfully cached, false on failure
 83:  */
 84:     abstract public function write($key, $value, $duration);
 85: 
 86: /**
 87:  * Read a key from the cache
 88:  *
 89:  * @param string $key Identifier for the data
 90:  * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it
 91:  */
 92:     abstract public function read($key);
 93: 
 94: /**
 95:  * Increment a number under the key and return incremented value
 96:  *
 97:  * @param string $key Identifier for the data
 98:  * @param int $offset How much to add
 99:  * @return New incremented value, false otherwise
100:  */
101:     abstract public function increment($key, $offset = 1);
102: 
103: /**
104:  * Decrement a number under the key and return decremented value
105:  *
106:  * @param string $key Identifier for the data
107:  * @param int $offset How much to subtract
108:  * @return New incremented value, false otherwise
109:  */
110:     abstract public function decrement($key, $offset = 1);
111: 
112: /**
113:  * Delete a key from the cache
114:  *
115:  * @param string $key Identifier for the data
116:  * @return bool True if the value was successfully deleted, false if it didn't exist or couldn't be removed
117:  */
118:     abstract public function delete($key);
119: 
120: /**
121:  * Delete all keys from the cache
122:  *
123:  * @param bool $check if true will check expiration, otherwise delete all
124:  * @return bool True if the cache was successfully cleared, false otherwise
125:  */
126:     abstract public function clear($check);
127: 
128: /**
129:  * Clears all values belonging to a group. Is up to the implementing engine
130:  * to decide whether actually delete the keys or just simulate it to achieve
131:  * the same result.
132:  *
133:  * @param string $group name of the group to be cleared
134:  * @return bool
135:  */
136:     public function clearGroup($group) {
137:         return false;
138:     }
139: 
140: /**
141:  * Does whatever initialization for each group is required
142:  * and returns the `group value` for each of them, this is
143:  * the token representing each group in the cache key
144:  *
145:  * @return array
146:  */
147:     public function groups() {
148:         return $this->settings['groups'];
149:     }
150: 
151: /**
152:  * Cache Engine settings
153:  *
154:  * @return array settings
155:  */
156:     public function settings() {
157:         return $this->settings;
158:     }
159: 
160: /**
161:  * Generates a safe key for use with cache engine storage engines.
162:  *
163:  * @param string $key the key passed over
164:  * @return mixed string $key or false
165:  */
166:     public function key($key) {
167:         if (empty($key)) {
168:             return false;
169:         }
170: 
171:         $prefix = '';
172:         if (!empty($this->_groupPrefix)) {
173:             $prefix = vsprintf($this->_groupPrefix, $this->groups());
174:         }
175: 
176:         $key = preg_replace('/[\s]+/', '_', strtolower(trim(str_replace(array(DS, '/', '.'), '_', strval($key)))));
177:         return $prefix . $key;
178:     }
179: 
180: }
181: