Class TSqliteCache
TSqliteCache class
TSqliteCache implements a cache application module based on SQLite database. To use this module, the sqlite PHP extension must be loaded. Note, Sqlite extension is no longer loaded by default since PHP 5.1. Sine PRADO v3.1.0, a new DB-based cache module called TDbCache is provided. If you have PDO extension installed, you may consider using the new cache module instead as it allows you to use different database to store the cached data. The database file is specified by the DbFile property. If not set, the database file will be created under the system state path. If the specified database file does not exist, it will be created automatically. Make sure the directory containing the specified DB file and the file itself is writable by the Web server process. 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 by the number of seconds. 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. Do not use the same database file for multiple applications using TSqliteCache. Also note, cache is shared by all user sessions of an application. Some usage examples of TSqliteCache are as follows, - $cache=new TSqliteCache; // TSqliteCache may also be loaded as a Prado application module
- $cache->setDbFile($dbFilePath);
- $cache->init(null);
- $cache->add('object',$object);
- $object2=$cache->get('object');
If loaded, TSqliteCache will register itself with TApplication as the cache module. It can be accessed via TApplication::getCache(). TSqliteCache may be configured in application configuration file as follows - <module id="cache" class="System.Caching.TSqliteCache" DbFile="Application.Data.site" />
where DbFile is a property specifying the location of the SQLite DB file (in the namespace format).
Method Summary |
protected
boolean
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addValue
( string $key, string $value, integer $expire)
Stores a value identified by a key into cache if the cache does not contain this key.
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protected
boolean
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Deletes a value with the specified key from cache This is the implementation of the method declared in the parent class.
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void
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Deletes all values from cache.
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string
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protected
string
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Retrieves a value from cache with a specified key.
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void
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Initializes this module.
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void
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protected
boolean
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setValue
( string $key, string $value, integer $expire)
Stores a value identified by a key in cache.
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Methods Inherited From TCache |
TCache::add(), TCache::delete(), TCache::flush(), TCache::generateUniqueKey(), TCache::get(), TCache::getKeyPrefix(), TCache::getPrimaryCache(), TCache::init(), TCache::offsetExists(), TCache::offsetGet(), TCache::offsetSet(), TCache::offsetUnset(), TCache::set(), TCache::setKeyPrefix(), TCache::setPrimaryCache(),
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Methods Inherited From TComponent |
TComponent::addParsedObject(), TComponent::attachEventHandler(), TComponent::canGetProperty(), TComponent::canSetProperty(), TComponent::createdOnTemplate(), TComponent::detachEventHandler(), TComponent::evaluateExpression(), TComponent::evaluateStatements(), TComponent::getEventHandlers(), TComponent::getSubProperty(), TComponent::hasEvent(), TComponent::hasEventHandler(), TComponent::hasProperty(), TComponent::raiseEvent(), TComponent::setSubProperty(), TComponent::__get(), TComponent::__set()
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Constant Summary |
string
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CACHE_TABLE |
name of the table storing cache data
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string
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DB_FILE_EXT |
extension of the db file name
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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 |
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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 |
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flush
Deletes all values from cache.
Be careful of performing this operation if the cache is shared by multiple applications.
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getDbFile
public string getDbFile |
() |
Output |
string
| database file path (in namespace form) |
Exception |
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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 |
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init
Initializes this module.
This method is required by the IModule interface. It checks if the DbFile property is set, and creates a SQLiteDatabase instance for it. The database or the cache table does not exist, they will be created. Expired values are also deleted.
Input |
TXmlElement | $config | configuration for this module, can be null |
Output |
Exception |
throws | TConfigurationException if sqlite extension is not installed, DbFile is set invalid, or any error happens during creating database or cache table. |
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setDbFile
public void setDbFile |
(string $value ) |
Input |
string | $value | database file path (in namespace form) |
Output |
Exception |
throws | TInvalidOperationException if the module is already initialized |
throws | TConfigurationException if the file is not in proper namespace format |
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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 |
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Constant Details |
CACHE_TABLE
name of the table storing cache data
Type:
string
Value:
'cache'
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DB_FILE_EXT
extension of the db file name
Type:
string
Value:
'.db'
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