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<?php
/**
* Cache class file.
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*
* @link http://www.yiiframework.com/
* @copyright Copyright &copy; 2008 Yii Software LLC
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* @license http://www.yiiframework.com/license/
*/
namespace yii\caching;
use yii\base\ApplicationComponent;
use yii\base\InvalidCallException;
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/**
* Cache is the base class for cache classes supporting different cache storage implementation.
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*
* A data item can be stored in cache by calling [[set()]] and be retrieved back
* later (in the same or different request) by [[get()]]. In both operations,
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* a key identifying the data item is required. An expiration time and/or a [[Dependency|dependency]]
* can also be specified when calling [[set()]]. If the data item expires or the dependency
* changes at the time of calling [[get()]], the cache will return no data.
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*
* Derived classes should implement the following methods:
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*
* - [[getValue]]: retrieve the value with a key (if any) from cache
* - [[setValue]]: store the value with a key into cache
* - [[addValue]]: store the value only if the cache does not have this key before
* - [[deleteValue]]: delete the value with the specified key from cache
* - [[flushValues]]: delete all values from cache
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*
* Because Cache implements the ArrayAccess interface, it can be used like an array. For example,
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*
* ~~~
* $cache['foo'] = 'some data';
* echo $cache['foo'];
* ~~~
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*
* @author Qiang Xue <qiang.xue@gmail.com>
* @since 2.0
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*/
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abstract class Cache extends ApplicationComponent implements \ArrayAccess
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{
/**
* @var string a string prefixed to every cache key so that it is unique. Defaults to null, meaning using
* the value of [[Application::id]] as the key prefix. You may set this property to be an empty string
* if you don't want to use key prefix. It is recommended that you explicitly set this property to some
* static value if the cached data needs to be shared among multiple applications.
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*/
public $keyPrefix;
/**
* @var array|boolean 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](http://pecl.php.net/package/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
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* you are using [[Dependency|cache dependency]], because it relies on data serialization.
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*/
public $serializer;
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/**
* Initializes the application component.
* This method overrides the parent implementation by setting default cache key prefix.
*/
public function init()
{
parent::init();
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if ($this->keyPrefix === null) {
$this->keyPrefix = \Yii::$application->id;
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}
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}
/**
* Generates a cache key from one or multiple parameters.
* The cache key generated is safe to be used to access cache via methods such as [[get()]], [[set()]].
* For example:
*
* ~~~
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* $key = $cache->buildKey($className, $method, $id);
* ~~~
*
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* @param string $id the
* @return string the cache key
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* @throws InvalidCallException if the method receives no parameter
*/
public function generateKey($id)
{
$n = func_num_args();
if ($n === 1 && is_string($id) && ctype_alnum($id) && strlen($id) <= 32) {
return $this->keyPrefix . $id;
} elseif ($n < 1) {
throw new InvalidCallException(__METHOD__ . ' requires at least one parameter.');
} else {
$params = func_get_args();
return $this->keyPrefix . md5(serialize($params));
}
}
/**
* Generates a normalized key from a given key.
* The normalized key is obtained by hashing the given key via MD5 and then prefixing it with [[keyPrefix]].
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* @param string $key a key identifying a value to be cached
* @return string a key generated from the provided key which ensures the uniqueness across applications
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*/
protected function generateKey($key)
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{
return $this->keyPrefix . md5($key);
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}
/**
* Retrieves a value from cache with a specified key.
* @param string $id a key identifying the cached value
* @return mixed the value stored in cache, false if the value is not in the cache, expired,
* or the dependency associated with the cached data has changed.
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*/
public function get($id)
{
$value = $this->getValue($this->generateKey($id));
if ($value === false || $this->serializer === false) {
return $value;
} elseif ($this->serializer === null) {
$value = unserialize($value);
} else {
$value = call_user_func($this->serializer[1], $value);
}
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if (is_array($value) && ($value[1] instanceof Dependency) || !$value[1]->getHasChanged()) {
return $value[0];
} else {
return false;
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}
}
/**
* Retrieves multiple values from cache with the specified keys.
* Some caches (such as memcache, apc) allow retrieving multiple cached values at the same time,
* which may improve the performance. In case a cache does not support this feature natively,
* this method will try to simulate it.
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* @param array $ids list of keys identifying the cached values
* @return array list of cached values corresponding to the specified keys. The array
* is returned in terms of (key,value) pairs.
* If a value is not cached or expired, the corresponding array value will be false.
*/
public function mget($ids)
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{
$uids = array();
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foreach ($ids as $id) {
$uids[$id] = $this->generateKey($id);
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}
$values = $this->getValues($uids);
$results = array();
if ($this->serializer === false) {
foreach ($uids as $id => $uid) {
$results[$id] = isset($values[$uid]) ? $values[$uid] : false;
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}
} 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]);
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if (is_array($value) && (!($value[1] instanceof Dependency) || !$value[1]->getHasChanged())) {
$results[$id] = $value[0];
}
}
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}
}
return $results;
}
/**
* 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, respectively.
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*
* @param string $id the key identifying the value to be cached
* @param mixed $value the value to be cached
* @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
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* @param Dependency $dependency dependency of the cached item. If the dependency changes,
* the corresponding value in the cache will be invalidated when it is fetched via [[get()]].
* @return boolean whether the value is successfully stored into cache
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*/
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public function set($id, $value, $expire = 0, $dependency = null)
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{
if ($dependency !== null && $this->serializer !== false) {
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$dependency->evaluateDependency();
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}
if ($this->serializer === null) {
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$value = serialize(array($value, $dependency));
} elseif ($this->serializer !== false) {
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$value = call_user_func($this->serializer[0], array($value, $dependency));
}
return $this->setValue($this->generateKey($id), $value, $expire);
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}
/**
* 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.
* @param string $id the key identifying the value to be cached
* @param mixed $value the value to be cached
* @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
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* @param Dependency $dependency dependency of the cached item. If the dependency changes,
* the corresponding value in the cache will be invalidated when it is fetched via [[get()]].
* @return boolean whether the value is successfully stored into cache
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*/
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public function add($id, $value, $expire = 0, $dependency = null)
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{
if ($dependency !== null && $this->serializer !== false) {
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$dependency->evaluateDependency();
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}
if ($this->serializer === null) {
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$value = serialize(array($value, $dependency));
} elseif ($this->serializer !== false) {
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$value = call_user_func($this->serializer[0], array($value, $dependency));
}
return $this->addValue($this->generateKey($id), $value, $expire);
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}
/**
* Deletes a value with the specified key from cache
* @param string $id the key of the value to be deleted
* @return boolean if no error happens during deletion
*/
public function delete($id)
{
return $this->deleteValue($this->generateKey($id));
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}
/**
* Deletes all values from cache.
* Be careful of performing this operation if the cache is shared among multiple applications.
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* @return boolean whether the flush operation was successful.
*/
public function flush()
{
return $this->flushValues();
}
/**
* 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.
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* @param string $key a unique key identifying the cached value
* @return string the value stored in cache, false if the value is not in the cache or expired.
*/
abstract protected function getValue($key);
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/**
* 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.
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* @param string $key the key identifying the value to be cached
* @param string $value the value to be cached
* @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
* @return boolean true if the value is successfully stored into cache, false otherwise
*/
abstract protected function setValue($key, $value, $expire);
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/**
* 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.
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* @param string $key the key identifying the value to be cached
* @param string $value the value to be cached
* @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
* @return boolean true if the value is successfully stored into cache, false otherwise
*/
abstract protected function addValue($key, $value, $expire);
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/**
* 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.
* @param string $key the key of the value to be deleted
* @return boolean if no error happens during deletion
*/
abstract protected function deleteValue($key);
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/**
* Deletes all values from cache.
* Child classes may implement this method to realize the flush operation.
* @return boolean whether the flush operation was successful.
*/
abstract protected function flushValues();
/**
* Retrieves multiple values from cache with the specified keys.
* The default implementation 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.
* @param array $keys a list of keys identifying the cached values
* @return array a list of cached values indexed by the keys
*/
protected function getValues($keys)
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{
$results = array();
foreach ($keys as $key) {
$results[$key] = $this->getValue($key);
}
return $results;
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}
/**
* Returns whether there is a cache entry with a specified key.
* This method is required by the interface ArrayAccess.
* @param string $id a key identifying the cached value
* @return boolean
*/
public function offsetExists($id)
{
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return $this->get($id) !== false;
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}
/**
* Retrieves the value from cache with a specified key.
* This method is required by the interface ArrayAccess.
* @param string $id a key identifying the cached value
* @return mixed the value stored in cache, false if the value is not in the cache or expired.
*/
public function offsetGet($id)
{
return $this->get($id);
}
/**
* 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.
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* This method is required by the interface ArrayAccess.
* @param string $id the key identifying the value to be cached
* @param mixed $value the value to be cached
*/
public function offsetSet($id, $value)
{
$this->set($id, $value);
}
/**
* Deletes the value with the specified key from cache
* This method is required by the interface ArrayAccess.
* @param string $id the key of the value to be deleted
*/
public function offsetUnset($id)
{
$this->delete($id);
}
}