Class CCache

CCache is the base class for cache classes with different cache storage implementation.

A data item can be stored in cache by calling CCache::set() and be retrieved back later by CCache::get(). In both operations, a key identifying the data item is required. An expiration time and/or a dependency can also be specified when calling CCache::set(). If the data item expires or the dependency changes, calling CCache::get() will not return back the data item.

Note, by definition, cache does not ensure the existence of a value even if it does not expire. Cache is not meant to be a persistent storage.

CCache implements the interface ICache with the following methods:

CCache::get() : retrieve the value with a key (if any) from cache
CCache::set() : store the value with a key into cache
CCache::add() : store the value only if cache does not have this key
CCache::delete() : delete the value with the specified key from cache
CCache::flush() : delete all values from cache

Child classes must implement the following methods:

CCache also implements ArrayAccess so that it can be used like an array.

CComponent

CApplicationComponent implements IApplicationComponent

CCache implements ICache, ArrayAccess

Direct known subclasses

CApcCache, CDbCache, CEAcceleratorCache, CFileCache, CMemCache, CRedisCache, CWinCache, CXCache, CZendDataCache

Indirect known subclasses

X2FileCache

Abstract
Package: system\caching
Copyright: 2008-2013 Yii Software LLC
License: http://www.yiiframework.com/license/
Author: Qiang Xue <qiang.xue@gmail.com>
Since: 1.0
Located at x2engine/framework/caching/CCache.php

Methods summary
`public`	# `init( )` Initializes the application component. This method overrides the parent implementation by setting default cache key prefix. Initializes the application component. This method overrides the parent implementation by setting default cache key prefix. Overrides `CApplicationComponent::init()`
`protected string`	# `generateUniqueKey( string $key )` Parameters `$key` `string` $key a key identifying a value to be cached Returns `string` a key generated from the provided key which ensures the uniqueness across applications
`public mixed`	# `get( string $id )` Retrieves a value from cache with a specified key. Retrieves a value from cache with a specified key. Parameters `$id` `string` $id a key identifying the cached value Returns `mixed` the value stored in cache, false if the value is not in the cache, expired or the dependency has changed. Implementation of `ICache::get()`
`public array`	# `mget( array $ids )` Retrieves multiple values from cache with the specified keys. Some caches (such as memcache, apc) allow retrieving multiple cached values at one time, which may improve the performance since it reduces the communication cost. In case a cache does not support this feature natively, it will be simulated by this method. Retrieves multiple values from cache with the specified keys. Some caches (such as memcache, apc) allow retrieving multiple cached values at one time, which may improve the performance since it reduces the communication cost. In case a cache does not support this feature natively, it will be simulated by this method. Parameters `$ids` `array` $ids list of keys identifying the cached values Returns `array` list of cached values corresponding to the specified keys. The array is returned in terms of (key,value) pairs. If a value is not cached or expired, the corresponding array value will be false. Implementation of `ICache::mget()`
`public boolean`	# `set( string $id, mixed $value, integer $expire = 0, ICacheDependency $dependency = null )` Stores a value identified by a key into cache. If the cache already contains such a key, the existing value and expiration time will be replaced with the new ones. Stores a value identified by a key into cache. If the cache already contains such a key, the existing value and expiration time will be replaced with the new ones. Parameters `$id` `string` $id the key identifying the value to be cached `$value` `mixed` $value the value to be cached `$expire` `integer` $expire the number of seconds in which the cached value will expire. 0 means never expire. `$dependency` `ICacheDependency` $dependency dependency of the cached item. If the dependency changes, the item is labeled invalid. Returns `boolean` true if the value is successfully stored into cache, false otherwise Implementation of `ICache::set()`
`public boolean`	# `add( string $id, mixed $value, integer $expire = 0, ICacheDependency $dependency = null )` Stores a value identified by a key into cache if the cache does not contain this key. Nothing will be done if the cache already contains the key. Stores a value identified by a key into cache if the cache does not contain this key. Nothing will be done if the cache already contains the key. Parameters `$id` `string` $id the key identifying the value to be cached `$value` `mixed` $value the value to be cached `$expire` `integer` $expire the number of seconds in which the cached value will expire. 0 means never expire. `$dependency` `ICacheDependency` $dependency dependency of the cached item. If the dependency changes, the item is labeled invalid. Returns `boolean` true if the value is successfully stored into cache, false otherwise Implementation of `ICache::add()`
`public boolean`	# `delete( string $id )` Deletes a value with the specified key from cache Deletes a value with the specified key from cache Parameters `$id` `string` $id the key of the value to be deleted Returns `boolean` if no error happens during deletion Implementation of `ICache::delete()`
`public boolean`	# `flush( )` Deletes all values from cache. Be careful of performing this operation if the cache is shared by multiple applications. Deletes all values from cache. Be careful of performing this operation if the cache is shared by multiple applications. Returns `boolean` whether the flush operation was successful. Implementation of `ICache::flush()`
`protected string\|boolean`	# `getValue( string $key )` Retrieves a value from cache with a specified key. This method should be implemented by child classes to retrieve the data from specific cache storage. The uniqueness and dependency are handled in `CCache::get()` already. So only the implementation of data retrieval is needed. Retrieves a value from cache with a specified key. This method should be implemented by child classes to retrieve the data from specific cache storage. The uniqueness and dependency are handled in `CCache::get()` already. So only the implementation of data retrieval is needed. Parameters `$key` `string` $key a unique key identifying the cached value Returns `string\|boolean` the value stored in cache, false if the value is not in the cache or expired. Throws `CException` if this method is not overridden by child classes
`protected array`	# `getValues( array $keys )` Retrieves multiple values from cache with the specified keys. The default implementation simply calls `CCache::getValue()` multiple times to retrieve the cached values one by one. If the underlying cache storage supports multiget, this method should be overridden to exploit that feature. Retrieves multiple values from cache with the specified keys. The default implementation simply calls `CCache::getValue()` multiple times to retrieve the cached values one by one. If the underlying cache storage supports multiget, this method should be overridden to exploit that feature. Parameters `$keys` `array` $keys a list of keys identifying the cached values Returns `array` a list of cached values indexed by the keys
`protected boolean`	# `setValue( string $key, string $value, integer $expire )` Stores a value identified by a key in cache. This method should be implemented by child classes to store the data in specific cache storage. The uniqueness and dependency are handled in `CCache::set()` already. So only the implementation of data storage is needed. Stores a value identified by a key in cache. This method should be implemented by child classes to store the data in specific cache storage. The uniqueness and dependency are handled in `CCache::set()` already. So only the implementation of data storage is needed. Parameters `$key` `string` $key the key identifying the value to be cached `$value` `string` $value the value to be cached `$expire` `integer` $expire the number of seconds in which the cached value will expire. 0 means never expire. Returns `boolean` true if the value is successfully stored into cache, false otherwise Throws `CException` if this method is not overridden by child classes
`protected boolean`	# `addValue( string $key, string $value, integer $expire )` Stores a value identified by a key into cache if the cache does not contain this key. This method should be implemented by child classes to store the data in specific cache storage. The uniqueness and dependency are handled in `CCache::add()` already. So only the implementation of data storage is needed. Stores a value identified by a key into cache if the cache does not contain this key. This method should be implemented by child classes to store the data in specific cache storage. The uniqueness and dependency are handled in `CCache::add()` already. So only the implementation of data storage is needed. Parameters `$key` `string` $key the key identifying the value to be cached `$value` `string` $value the value to be cached `$expire` `integer` $expire the number of seconds in which the cached value will expire. 0 means never expire. Returns `boolean` true if the value is successfully stored into cache, false otherwise Throws `CException` if this method is not overridden by child classes
`protected boolean`	# `deleteValue( string $key )` Deletes a value with the specified key from cache This method should be implemented by child classes to delete the data from actual cache storage. Deletes a value with the specified key from cache This method should be implemented by child classes to delete the data from actual cache storage. Parameters `$key` `string` $key the key of the value to be deleted Returns `boolean` if no error happens during deletion Throws `CException` if this method is not overridden by child classes
`protected boolean`	# `flushValues( )` Deletes all values from cache. Child classes may implement this method to realize the flush operation. Deletes all values from cache. Child classes may implement this method to realize the flush operation. Returns `boolean` whether the flush operation was successful. Throws `CException` if this method is not overridden by child classes Since 1.1.5
`public boolean`	# `offsetExists( string $id )` Returns whether there is a cache entry with a specified key. This method is required by the interface ArrayAccess. Returns whether there is a cache entry with a specified key. This method is required by the interface ArrayAccess. Parameters `$id` `string` $id a key identifying the cached value Returns `boolean` Implementation of `ArrayAccess::offsetExists()`
`public mixed`	# `offsetGet( string $id )` Retrieves the value from cache with a specified key. This method is required by the interface ArrayAccess. Retrieves the value from cache with a specified key. This method is required by the interface ArrayAccess. Parameters `$id` `string` $id a key identifying the cached value Returns `mixed` the value stored in cache, false if the value is not in the cache or expired. Implementation of `ArrayAccess::offsetGet()`
`public`	# `offsetSet( string $id, mixed $value )` Stores the value identified by a key into cache. If the cache already contains such a key, the existing value will be replaced with the new ones. To add expiration and dependencies, use the set() method. This method is required by the interface ArrayAccess. Stores the value identified by a key into cache. If the cache already contains such a key, the existing value will be replaced with the new ones. To add expiration and dependencies, use the set() method. This method is required by the interface ArrayAccess. Parameters `$id` `string` $id the key identifying the value to be cached `$value` `mixed` $value the value to be cached Implementation of `ArrayAccess::offsetSet()`
`public boolean`	# `offsetUnset( string $id )` Deletes the value with the specified key from cache This method is required by the interface ArrayAccess. Deletes the value with the specified key from cache This method is required by the interface ArrayAccess. Parameters `$id` `string` $id the key of the value to be deleted Returns `boolean` if no error happens during deletion Implementation of `ArrayAccess::offsetUnset()`

Methods inherited from CApplicationComponent
`getIsInitialized()`

Methods inherited from CComponent
`__call(), __get(), __isset(), __set(), __unset(), asa(), attachBehavior(), attachBehaviors(), attachEventHandler(), canGetProperty(), canSetProperty(), detachBehavior(), detachBehaviors(), detachEventHandler(), disableBehavior(), disableBehaviors(), enableBehavior(), enableBehaviors(), evaluateExpression(), getEventHandlers(), hasEvent(), hasEventHandler(), hasProperty(), raiseEvent()`

Properties summary
`public string`	`$keyPrefix`		# a string prefixed to every cache key so that it is unique. Defaults to null which means to use the CApplication::getId() application ID. If different applications need to access the same pool of cached data, the same prefix should be set for each of the applications explicitly. a string prefixed to every cache key so that it is unique. Defaults to null which means to use the CApplication::getId() application ID. If different applications need to access the same pool of cached data, the same prefix should be set for each of the applications explicitly.
`public boolean`	`$hashKey`	`true`	# whether to md5-hash the cache key for normalization purposes. Defaults to true. Setting this property to false makes sure the cache key will not be tampered when calling the relevant methods `CCache::get()`, `CCache::set()`, `CCache::add()` and `CCache::delete()`. This is useful if a Yii application as well as an external application need to access the same cache pool (also see description of `CCache::$keyPrefix` regarding this use case). However, without normalization you should make sure the affected cache backend does support the structure (charset, length, etc.) of all the provided cache keys, otherwise there might be unexpected behavior. whether to md5-hash the cache key for normalization purposes. Defaults to true. Setting this property to false makes sure the cache key will not be tampered when calling the relevant methods `CCache::get()`, `CCache::set()`, `CCache::add()` and `CCache::delete()`. This is useful if a Yii application as well as an external application need to access the same cache pool (also see description of `CCache::$keyPrefix` regarding this use case). However, without normalization you should make sure the affected cache backend does support the structure (charset, length, etc.) of all the provided cache keys, otherwise there might be unexpected behavior. Since 1.1.11
`public array\|boolean`	`$serializer`		# the functions used to serialize and unserialize cached data. Defaults to null, meaning using the default PHP `serialize()` and `unserialize()` functions. If you want to use some more efficient serializer (e.g. igbinary), you may configure this property with a two-element array. The first element specifies the serialization function, and the second the deserialization function. If this property is set false, data will be directly sent to and retrieved from the underlying cache component without any serialization or deserialization. You should not turn off serialization if you are using CCacheDependency cache dependency, because it relies on data serialization. the functions used to serialize and unserialize cached data. Defaults to null, meaning using the default PHP `serialize()` and `unserialize()` functions. If you want to use some more efficient serializer (e.g. igbinary), you may configure this property with a two-element array. The first element specifies the serialization function, and the second the deserialization function. If this property is set false, data will be directly sent to and retrieved from the underlying cache component without any serialization or deserialization. You should not turn off serialization if you are using CCacheDependency cache dependency, because it relies on data serialization.

Properties inherited from CApplicationComponent
`$behaviors`

Magic properties inherited from CApplicationComponent
`$isInitialized`

Packages

Classes

Interfaces

Class CCache

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