CCache
| 包 | system.caching |
|---|---|
| 继承 | abstract class CCache » CApplicationComponent » CComponent |
| 实现 | IApplicationComponent, ICache, ArrayAccess |
| 子类 | CApcCache, CDbCache, CEAcceleratorCache, CFileCache, CMemCache, CRedisCache, CWinCache, CXCache, CZendDataCache |
| 可用自 | 1.0 |
| 源码 | framework/caching/CCache.php |
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
- getValues (optional)
- flushValues (optional)
- serializer (optional)
CCache also implements ArrayAccess so that it can be used like an array.
公共属性
| 属性 | 类型 | 描述 | 被定义在 |
|---|---|---|---|
| behaviors | array | the behaviors that should be attached to this component. | CApplicationComponent |
| hashKey | boolean | whether to md5-hash the cache key for normalization purposes. | CCache |
| isInitialized | boolean | Checks if this application component has been initialized. | CApplicationComponent |
| keyPrefix | string | a string prefixed to every cache key so that it is unique. | CCache |
| serializer | array|boolean | the functions used to serialize and unserialize cached data. | CCache |
公共方法
| 方法 | 描述 | 被定义在 |
|---|---|---|
| __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 |
| evaluateExpression() | Evaluates a PHP expression or callback under the context of 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() | Checks if this application component has been initialized. | 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 |
| mget() | Retrieves multiple values from cache with the specified keys. | 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 |
受保护的方法
| 方法 | 描述 | 被定义在 |
|---|---|---|
| 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 |
| flushValues() | Deletes all values from cache. | CCache |
| generateUniqueKey() | CCache | |
| getValue() | Retrieves a value from cache with a specified key. | CCache |
| getValues() | Retrieves multiple values from cache with the specified keys. | CCache |
| setValue() | Stores a value identified by a key in cache. | CCache |
属性详情
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 get(), set(), add() and 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 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.
a string prefixed to every cache key so that it is unique. Defaults to null which means to use the 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.
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 cache dependency, because it relies on data serialization.
方法详情
|
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. |
| $dependency | ICacheDependency | dependency of the cached item. If the dependency changes, the item is labeled invalid. |
| {return} | boolean | true if the value is successfully stored into cache, false otherwise |
public function add($id,$value,$expire=0,$dependency=null)
{
Yii::trace('Adding "'.$id.'" to cache','system.caching.'.get_class($this));
if ($dependency !== null && $this->serializer !== false)
$dependency->evaluateDependency();
if ($this->serializer === null)
$value = serialize(array($value,$dependency));
elseif ($this->serializer !== false)
$value = call_user_func($this->serializer[0], array($value,$dependency));
return $this->addValue($this->generateUniqueKey($id), $value, $expire);
}
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 |
| $expire | integer | the number of seconds in which the cached value will expire. 0 means never expire. |
| {return} | boolean | true if the value is successfully stored into cache, false otherwise |
protected function addValue($key,$value,$expire)
{
throw new CException(Yii::t('yii','{className} does not support add() functionality.',
array('{className}'=>get_class($this))));
}
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)
| ||
| $id | string | the key of the value to be deleted |
| {return} | boolean | if no error happens during deletion |
public function delete($id)
{
Yii::trace('Deleting "'.$id.'" from cache','system.caching.'.get_class($this));
return $this->deleteValue($this->generateUniqueKey($id));
}
Deletes a value with the specified key from cache
|
protected boolean deleteValue(string $key)
| ||
| $key | string | the key of the value to be deleted |
| {return} | boolean | if no error happens during deletion |
protected function deleteValue($key)
{
throw new CException(Yii::t('yii','{className} does not support delete() functionality.',
array('{className}'=>get_class($this))));
}
Deletes a value with the specified key from cache This method should be implemented by child classes to delete the data from actual cache storage.
|
public boolean flush()
| ||
| {return} | boolean | whether the flush operation was successful. |
public function flush()
{
Yii::trace('Flushing cache','system.caching.'.get_class($this));
return $this->flushValues();
}
Deletes all values from cache. Be careful of performing this operation if the cache is shared by multiple applications.
|
protected boolean flushValues()
| ||
| {return} | boolean | whether the flush operation was successful. |
protected function flushValues()
{
throw new CException(Yii::t('yii','{className} does not support flushValues() functionality.',
array('{className}'=>get_class($this))));
}
Deletes all values from cache. Child classes may implement this method to realize the flush operation.
|
protected string generateUniqueKey(string $key)
| ||
| $key | string | a key identifying a value to be cached |
| {return} | string | a key generated from the provided key which ensures the uniqueness across applications |
protected function generateUniqueKey($key)
{
return $this->hashKey ? md5($this->keyPrefix.$key) : $this->keyPrefix.$key;
}
|
public mixed get(string $id)
| ||
| $id | string | a key identifying the cached value |
| {return} | mixed | the value stored in cache, false if the value is not in the cache, expired or the dependency has changed. |
public function get($id)
{
$value = $this->getValue($this->generateUniqueKey($id));
if($value===false || $this->serializer===false)
return $value;
if($this->serializer===null)
$value=unserialize($value);
else
$value=call_user_func($this->serializer[1], $value);
if(is_array($value) && (!$value[1] instanceof ICacheDependency || !$value[1]->getHasChanged()))
{
Yii::trace('Serving "'.$id.'" from cache','system.caching.'.get_class($this));
return $value[0];
}
else
return false;
}
Retrieves a value from cache with a specified key.
|
protected string|boolean getValue(string $key)
| ||
| $key | string | a unique key identifying the cached value |
| {return} | string|boolean | the value stored in cache, false if the value is not in the cache or expired. |
protected function getValue($key)
{
throw new CException(Yii::t('yii','{className} does not support get() functionality.',
array('{className}'=>get_class($this))));
}
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 get() already. So only the implementation of data retrieval is needed.
|
protected array getValues(array $keys)
| ||
| $keys | array | a list of keys identifying the cached values |
| {return} | array | a list of cached values indexed by the keys |
protected function getValues($keys)
{
$results=array();
foreach($keys as $key)
$results[$key]=$this->getValue($key);
return $results;
}
Retrieves multiple values from cache with the specified keys. The default implementation simply calls getValue multiple times to retrieve the cached values one by one. If the underlying cache storage supports multiget, this method should be overridden to exploit that feature.
|
public void init()
|
public function init()
{
parent::init();
if($this->keyPrefix===null)
$this->keyPrefix=Yii::app()->getId();
}
Initializes the application component. This method overrides the parent implementation by setting default cache key prefix.
|
public array mget(array $ids)
| ||
| $ids | array | list of keys identifying the cached values |
| {return} | array | list of cached values corresponding to the specified keys. The array is returned in terms of (key,value) pairs. If a value is not cached or expired, the corresponding array value will be false. |
public function mget($ids)
{
$uids = array();
foreach ($ids as $id)
$uids[$id] = $this->generateUniqueKey($id);
$values = $this->getValues($uids);
$results = array();
if($this->serializer === false)
{
foreach ($uids as $id => $uid)
$results[$id] = isset($values[$uid]) ? $values[$uid] : false;
}
else
{
foreach($uids as $id => $uid)
{
$results[$id] = false;
if(isset($values[$uid]))
{
$value = $this->serializer === null ? unserialize($values[$uid]) : call_user_func($this->serializer[1], $values[$uid]);
if(is_array($value) && (!$value[1] instanceof ICacheDependency || !$value[1]->getHasChanged()))
{
Yii::trace('Serving "'.$id.'" from cache','system.caching.'.get_class($this));
$results[$id] = $value[0];
}
}
}
}
return $results;
}
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.
|
public boolean offsetExists(string $id)
| ||
| $id | string | a key identifying the cached value |
| {return} | boolean | |
public function offsetExists($id)
{
return $this->get($id)!==false;
}
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 |
| $value | mixed | the value to be cached |
public function offsetSet($id, $value)
{
$this->set($id, $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.
|
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. |
| $dependency | ICacheDependency | dependency of the cached item. If the dependency changes, the item is labeled invalid. |
| {return} | boolean | true if the value is successfully stored into cache, false otherwise |
public function set($id,$value,$expire=0,$dependency=null)
{
Yii::trace('Saving "'.$id.'" to cache','system.caching.'.get_class($this));
if ($dependency !== null && $this->serializer !== false)
$dependency->evaluateDependency();
if ($this->serializer === null)
$value = serialize(array($value,$dependency));
elseif ($this->serializer !== false)
$value = call_user_func($this->serializer[0], array($value,$dependency));
return $this->setValue($this->generateUniqueKey($id), $value, $expire);
}
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 |
| $expire | integer | the number of seconds in which the cached value will expire. 0 means never expire. |
| {return} | boolean | true if the value is successfully stored into cache, false otherwise |
protected function setValue($key,$value,$expire)
{
throw new CException(Yii::t('yii','{className} does not support set() functionality.',
array('{className}'=>get_class($this))));
}
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.