summaryrefslogtreecommitdiff
path: root/framework/Caching/TMemCache.php
blob: 7c24ae0e8135d8f326970d13ec9483581b42b896 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
<?php
/**
 * TMemCache class file
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.pradosoft.com/
 * @copyright Copyright &copy; 2005 PradoSoft
 * @license http://www.pradosoft.com/license/
 * @version $Revision: $  $Date: $
 * @package System.Caching
 */

/**
 * TMemCache class
 *
 * TMemCache implements a cache application module based on {@link http://www.danga.com/memcached/ memcached}.
 *
 * TMemCache can be configured with the Host and Port properties, which
 * specify the host and port of the memcache server to be used.
 * By default, they take the value 'localhost' and 11211, respectively.
 * These properties must be set before {@link init} is invoked.
 *
 * The following basic cache operations are implemented:
 * - {@link get} : retrieve the value with a key (if any) from cache
 * - {@link set} : store the value with a key into cache
 * - {@link add} : store the value only if cache does not have this key
 * - {@link delete} : delete the value with the specified key from cache
 * - {@link flush} : delete all values from cache
 *
 * Each value is associated with an expiration time. The {@link get} operation
 * ensures that any expired value will not be returned. The expiration time can
 * be specified by the number of seconds (maximum 60*60*24*30)
 * or a UNIX timestamp. A expiration time 0 represents never expire.
 *
 * By definition, cache does not ensure the existence of a value
 * even if it never expires. Cache is not meant to be an persistent storage.
 *
 * Also note, there is no security measure to protected data in memcache.
 * All data in memcache can be accessed by any process running in the system.
 *
 * To use this module, the memcache PHP extension must be loaded.
 *
 * Some usage examples of TMemCache are as follows,
 * <code>
 * $cache=new TMemCache;  // TMemCache may also be loaded as a Prado application module
 * $cache->init(null);
 * $cache->add('object',$object);
 * $object2=$cache->get('object');
 * </code>
 *
 * If loaded, TMemCache will register itself with {@link TApplication} as the
 * cache module. It can be accessed via {@link TApplication::getCache()}.
 *
 * TMemCache may be configured in application configuration file as follows
 * <code>
 * <module id="cache" type="System.Caching.TMemCache" Host="localhost" Port="11211" />
 * </code>
 * where {@link getHost Host} and {@link getPort Port} are configurable properties
 * of TMemCache.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Revision: $  $Date: $
 * @package System.Caching
 * @since 3.0
 */
class TMemCache extends TCache
{
	/**
	 * @var boolean if the module is initialized
	 */
	private $_initialized=false;
	/**
	 * @var Memcache the Memcache instance
	 */
	private $_cache=null;
	/**
	 * @var string a unique prefix used to identify this cache instance from the others
	 */
	private $_prefix=null;
	/**
	 * @var string host name of the memcache server
	 */
	private $_host='localhost';
	/**
	 * @var integer the port number of the memcache server
	 */
	private $_port=11211;

	/**
	 * Destructor.
	 * Disconnect the memcache server.
	 */
	public function __destruct()
	{
		if($this->_cache!==null)
			$this->_cache->close();
	}

	/**
	 * Initializes this module.
	 * This method is required by the IModule interface. It makes sure that
	 * UniquePrefix has been set, creates a Memcache instance and connects
	 * to the memcache server.
	 * @param TApplication Prado application, can be null
	 * @param TXmlElement configuration for this module, can be null
	 * @throws TConfigurationException if memcache extension is not installed or memcache sever connection fails
	 */
	public function init($config)
	{
		if(!extension_loaded('memcache'))
			throw new TConfigurationException('memcache_extension_required');
		$this->_cache=new Memcache;
		if($this->_cache->connect($this->_host,$this->_port)===false)
			throw new TConfigurationException('memcache_connection_failed',$this->_host,$this->_port);
		$this->_initialized=true;
		parent::init($config);
	}

	/**
	 * @return string host name of the memcache server
	 */
	public function getHost()
	{
		return $this->_host;
	}

	/**
	 * @param string host name of the memcache server
	 * @throws TInvalidOperationException if the module is already initialized
	 */
	public function setHost($value)
	{
		if($this->_initialized)
			throw new TInvalidOperationException('memcache_host_unchangeable');
		else
			$this->_host=$value;
	}

	/**
	 * @return integer port number of the memcache server
	 */
	public function getPort()
	{
		return $this->_port;
	}

	/**
	 * @param integer port number of the memcache server
	 * @throws TInvalidOperationException if the module is already initialized
	 */
	public function setPort($value)
	{
		if($this->_initialized)
			throw new TInvalidOperationException('memcache_port_unchangeable');
		else
			$this->_port=TPropertyValue::ensureInteger($value);
	}

	/**
	 * Retrieves a value from cache with a specified key.
	 * This is the implementation of the method declared in the parent class.
	 * @param string a unique key identifying the cached value
	 * @return string the value stored in cache, false if the value is not in the cache or expired.
	 */
	protected function getValue($key)
	{
		return $this->_cache->get($key);
	}

	/**
	 * Stores a value identified by a key in cache.
	 * This is the implementation of the method declared in the parent class.
	 *
	 * @param string the key identifying the value to be cached
	 * @param string the value to be cached
	 * @param integer the number of seconds in which the cached value will expire. 0 means never expire.
	 * @return boolean true if the value is successfully stored into cache, false otherwise
	 */
	protected function setValue($key,$value,$expire)
	{
		return $this->_cache->set($key,$value,0,$expire);
	}

	/**
	 * Stores a value identified by a key into cache if the cache does not contain this key.
	 * This is the implementation of the method declared in the parent class.
	 *
	 * @param string the key identifying the value to be cached
	 * @param string the value to be cached
	 * @param integer the number of seconds in which the cached value will expire. 0 means never expire.
	 * @return boolean true if the value is successfully stored into cache, false otherwise
	 */
	protected function addValue($key,$value,$expire)
	{
		return $this->_cache->add($key,$value,0,$expire);
	}

	/**
	 * Deletes a value with the specified key from cache
	 * This is the implementation of the method declared in the parent class.
	 * @param string the key of the value to be deleted
	 * @return boolean if no error happens during deletion
	 */
	protected function deleteValue($key)
	{
		return $this->_cache->delete($key);
	}

	/**
	 * Deletes all values from cache.
	 * Be careful of performing this operation if the cache is shared by multiple applications.
	 */
	public function flush()
	{
		return $this->_cache->flush();
	}
}

?>