TMemCache class
TMemCache implements a cache application module based on 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 init is invoked.
The following basic cache operations are implemented:
- get : retrieve the value with a key (if any) from cache
- set : store the value with a key into cache
- add : store the value only if cache does not have this key
- delete : delete the value with the specified key from cache
- flush : delete all values from cache
Each value is associated with an expiration time. The
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,
- $cache=new TMemCache; // TMemCache may also be loaded as a Prado application module
- $cache->init(null);
- $cache->add('object',$object);
- $object2=$cache->get('object');
You can configure TMemCache two different ways. If you only need one memcache server you may use the method as follows.
- <module id="cache" class="System.Caching.TMemCache" Host="localhost" Port="11211" />
If you want a more complex configuration, you may use the method as follows.
- <module id="cache" classs="System.Caching.TMemCache">
- <server Host="localhost" Port="11211" Weight="1" Timeout="300" RetryInterval="15" />
- <server Host="anotherhost" Port="11211" Weight="1" Timeout="300" RetryInterval="15" />
- </module>
If loaded, TMemCache will register itself with TApplication as the cache module. It can be accessed via TApplication::getCache().
TMemCache may be configured in application configuration file as follows
- <module id="cache" class="System.Caching.TMemCache" Host="localhost" Port="11211" />
where
Host and
Port are configurable properties of TMemCache.
Method Details |
addValue
protected boolean addValue |
(string $key , string $value , integer $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.
Input |
string | $key | the key identifying the value to be cached |
string | $value | the value to be cached |
integer | $expire | the number of seconds in which the cached value will expire. 0 means never expire. |
Output |
boolean
| true if the value is successfully stored into cache, false otherwise |
Exception |
|
deleteValue
protected boolean deleteValue |
(string $key ) |
Deletes a value with the specified key from cache This is the implementation of the method declared in the parent class.
Input |
string | $key | the key of the value to be deleted |
Output |
boolean
| if no error happens during deletion |
Exception |
|
flush
Deletes all values from cache.
Be careful of performing this operation if the cache is shared by multiple applications.
|
getHost
Output |
string
| host name of the memcache server |
Exception |
|
getPort
public integer getPort |
() |
Output |
integer
| port number of the memcache server |
Exception |
|
getValue
protected string getValue |
(string $key ) |
Retrieves a value from cache with a specified key.
This is the implementation of the method declared in the parent class.
Input |
string | $key | a unique key identifying the cached value |
Output |
string
| the value stored in cache, false if the value is not in the cache or expired. |
Exception |
|
init
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.
Input |
TApplication | $config | Prado application, can be null |
TXmlElement | 1 | configuration for this module, can be null |
Output |
Exception |
throws | TConfigurationException if memcache extension is not installed or memcache sever connection fails |
|
setHost
public void setHost |
(string $value ) |
Input |
string | $value | host name of the memcache server |
Output |
Exception |
throws | TInvalidOperationException if the module is already initialized |
|
setPort
public void setPort |
(integer $value ) |
Input |
integer | $value | port number of the memcache server |
Output |
Exception |
throws | TInvalidOperationException if the module is already initialized |
|
setValue
protected boolean setValue |
(string $key , string $value , integer $expire ) |
Stores a value identified by a key in cache.
This is the implementation of the method declared in the parent class.
Input |
string | $key | the key identifying the value to be cached |
string | $value | the value to be cached |
integer | $expire | the number of seconds in which the cached value will expire. 0 means never expire. |
Output |
boolean
| true if the value is successfully stored into cache, false otherwise |
Exception |
|