CCache
| Package | system.caching |
|---|---|
| Inheritance | abstract class CCache » CApplicationComponent » CComponent |
| Implements | IApplicationComponent, ICache, ArrayAccess |
| Subclasses | CApcCache, CDbCache, CMemCache, CXCache |
| Since | 1.0 |
| Version | $Id: CCache.php 433 2008-12-30 22:59:17Z qiang.xue $ |
A data item can be stored in cache by calling set and be retrieved back later by 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 set. If the data item expires or the dependency changes, calling 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:
- 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
Child classes must implement the following methods:
- getValue
- setValue
- addValue
- deleteValue
- flush (optional)
CCache also implements ArrayAccess so that it can be used like an array.
Public Properties
| Property | Type | Description | Defined By |
|---|---|---|---|
| behaviors | array | the behaviors that should be attached to this component. | CApplicationComponent |
| isInitialized | boolean | whether this application component has been initialized (i. | CApplicationComponent |
| keyPrefix | string | a string prefixed to every cache key so that it is unique. | CCache |
Public Methods
| Method | Description | Defined By |
|---|---|---|
| __call() | Calls the named method which is not a class method. | CComponent |
| __get() | Returns a property value, an event handler list or a behavior based on its name. | CComponent |
| __isset() | Checks if a property value is null. | CComponent |
| __set() | Sets value of a component property. | CComponent |
| __unset() | Sets a component property to be null. | CComponent |
| add() | Stores a value identified by a key into cache if the cache does not contain this key. | CCache |
| asa() | Returns the named behavior object. | CComponent |
| attachBehavior() | Attaches a behavior to this component. | CComponent |
| attachBehaviors() | Attaches a list of behaviors to the component. | CComponent |
| attachEventHandler() | Attaches an event handler to an event. | CComponent |
| canGetProperty() | Determines whether a property can be read. | CComponent |
| canSetProperty() | Determines whether a property can be set. | CComponent |
| delete() | Deletes a value with the specified key from cache | CCache |
| detachBehavior() | Detaches a behavior from the component. | CComponent |
| detachBehaviors() | Detaches all behaviors from the component. | CComponent |
| detachEventHandler() | Detaches an existing event handler. | CComponent |
| disableBehavior() | Disables an attached behavior. | CComponent |
| disableBehaviors() | Disables all behaviors attached to this component. | CComponent |
| enableBehavior() | Enables an attached behavior. | CComponent |
| enableBehaviors() | Enables all behaviors attached to this component. | CComponent |
| flush() | Deletes all values from cache. | CCache |
| get() | Retrieves a value from cache with a specified key. | CCache |
| getEventHandlers() | Returns the list of attached event handlers for an event. | CComponent |
| getIsInitialized() | CApplicationComponent | |
| hasEvent() | Determines whether an event is defined. | CComponent |
| hasEventHandler() | Checks whether the named event has attached handlers. | CComponent |
| hasProperty() | Determines whether a property is defined. | CComponent |
| init() | Initializes the application component. | CCache |
| offsetExists() | Returns whether there is a cache entry with a specified key. | CCache |
| offsetGet() | Retrieves the value from cache with a specified key. | CCache |
| offsetSet() | Stores the value identified by a key into cache. | CCache |
| offsetUnset() | Deletes the value with the specified key from cache | CCache |
| raiseEvent() | Raises an event. | CComponent |
| set() | Stores a value identified by a key into cache. | CCache |
Protected Methods
| Method | Description | Defined By |
|---|---|---|
| addValue() | Stores a value identified by a key into cache if the cache does not contain this key. | CCache |
| deleteValue() | Deletes a value with the specified key from cache | CCache |
| generateUniqueKey() | CCache | |
| getValue() | Retrieves a value from cache with a specified key. | CCache |
| setValue() | Stores a value identified by a key in cache. | CCache |
Property Details
a string prefixed to every cache key so that it is unique. Defaults to application ID.
Method Details
|
public boolean add(string $id, mixed $value, integer $expire=0, ICacheDependency $dependency=NULL)
| ||
| $id | string | the key identifying the value to be cached |
| $value | mixed | the value to be cached |
| $expire | integer | the number of seconds in which the cached value will expire. 0 means never expire. |
| $dependency | ICacheDependency | dependency of the cached item. If the dependency changes, the item is labeled invalid. |
| {return} | boolean | true if the value is successfully stored into cache, false otherwise |
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.
|
protected boolean addValue(string $key, string $value, integer $expire)
| ||
| $key | string | the key identifying the value to be cached |
| $value | string | the value to be cached |
| $expire | 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 |
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 add() already. So only the implementation of data storage is needed.
|
public boolean delete(string $id)
| ||
| $id | string | the key of the value to be deleted |
| {return} | boolean | if no error happens during deletion |
Deletes a value with the specified key from cache
|
protected boolean deleteValue(string $key)
| ||
| $key | string | the key of the value to be deleted |
| {return} | boolean | if no error happens during deletion |
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.
|
public void flush()
|
Deletes all values from cache. Be careful of performing this operation if the cache is shared by multiple applications. Child classes may implement this method to realize the flush operation.
|
protected sring generateUniqueKey(string $key)
| ||
| $key | string | a key identifying a value to be cached |
| {return} | sring | a key generated from the provided key which ensures the uniqueness across applications |
|
public mixed get(string $id)
| ||
| $id | string | a key identifying the cached value |
| {return} | mixed | the value stored in cache, false if the value is not in the cache, expired or the dependency has changed. |
Retrieves a value from cache with a specified key.
|
protected string getValue(string $key)
| ||
| $key | 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. |
Retrieves a value from cache with a specified key. This method should be implemented by child classes to store the data in specific cache storage. The uniqueness and dependency are handled in get() already. So only the implementation of data retrieval is needed.
|
public void init()
|
Initializes the application component. This method overrides the parent implementation by setting default cache key prefix.
|
public boolean offsetExists(string $id)
| ||
| $id | string | a key identifying the cached value |
| {return} | boolean | |
Returns whether there is a cache entry with a specified key. This method is required by the interface ArrayAccess.
|
public mixed offsetGet(string $id)
| ||
| $id | string | a key identifying the cached value |
| {return} | mixed | the value stored in cache, false if the value is not in the cache or expired. |
Retrieves the value from cache with a specified key. This method is required by the interface ArrayAccess.
|
public void offsetSet(string $id, mixed $value)
| ||
| $id | string | the key identifying the value to be cached |
| $value | mixed | the value to be cached |
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.
|
public boolean offsetUnset(string $id)
| ||
| $id | string | the key of the value to be deleted |
| {return} | boolean | if no error happens during deletion |
Deletes the value with the specified key from cache This method is required by the interface ArrayAccess.
|
public boolean set(string $id, mixed $value, integer $expire=0, ICacheDependency $dependency=NULL)
| ||
| $id | string | the key identifying the value to be cached |
| $value | mixed | the value to be cached |
| $expire | integer | the number of seconds in which the cached value will expire. 0 means never expire. |
| $dependency | ICacheDependency | dependency of the cached item. If the dependency changes, the item is labeled invalid. |
| {return} | boolean | true if the value is successfully stored into cache, false otherwise |
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.
|
protected boolean setValue(string $key, string $value, integer $expire)
| ||
| $key | string | the key identifying the value to be cached |
| $value | string | the value to be cached |
| $expire | 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 |
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 set() already. So only the implementation of data storage is needed.