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yii2-bootstrap/framework/yii/caching/Cache.php

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<?php
/**
* @link http://www.yiiframework.com/
* @copyright Copyright (c) 2008 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
namespace yii\caching;
use Yii;
use yii\base\Component;
use yii\base\InvalidConfigException;
use yii\helpers\StringHelper;
/**
* Cache is the base class for cache classes supporting different cache storage implementation.
*
* 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,
* 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.
*
* A typical usage pattern of cache is like the following:
*
* ~~~
* $key = 'demo';
* $data = $cache->get($key);
* if ($data === false) {
* // ...generate $data here...
* $cache->set($key, $data, $expire, $dependency);
* }
* ~~~
*
* Because Cache implements the ArrayAccess interface, it can be used like an array. For example,
*
* ~~~
* $cache['foo'] = 'some data';
* echo $cache['foo'];
* ~~~
*
* Derived classes should implement the following methods:
*
* - [[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
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @since 2.0
*/
abstract class Cache extends Component implements \ArrayAccess
{
/**
* @var string a string prefixed to every cache key so that it is unique. If not set,
* it will use a prefix generated from [[Application::id]]. 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.
*
* To ensure interoperability, only use alphanumeric characters should be used.
*/
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
* you are using [[Dependency|cache dependency]], because it relies on data serialization.
*/
public $serializer;
/**
* Initializes the application component.
* This method overrides the parent implementation by setting default cache key prefix.
*/
public function init()
{
parent::init();
if ($this->keyPrefix === null) {
$this->keyPrefix = substr(md5(Yii::$app->id), 0, 5);
} elseif (!ctype_alnum($this->keyPrefix)) {
throw new InvalidConfigException(get_class($this) . '::keyPrefix should only contain alphanumeric characters.');
}
}
/**
* Builds a normalized cache key from a given key.
*
* If the given key is a string containing alphanumeric characters only and no more than 32 characters,
* then the key will be returned back prefixed with [[keyPrefix]]. Otherwise, a normalized key
* is generated by serializing the given key, applying MD5 hashing, and prefixing with [[keyPrefix]].
*
* @param mixed $key the key to be normalized
* @return string the generated cache key
*/
protected function buildKey($key)
{
if (is_string($key)) {
$key = ctype_alnum($key) && StringHelper::strlen($key) <= 32 ? $key : md5($key);
} else {
$key = md5(json_encode($key));
}
return $this->keyPrefix . $key;
}
/**
* Retrieves a value from cache with a specified key.
* @param mixed $key a key identifying the cached value. This can be a simple string or
* a complex data structure consisting of factors representing the key.
* @return mixed the value stored in cache, false if the value is not in the cache, expired,
* or the dependency associated with the cached data has changed.
*/
public function get($key)
{
$key = $this->buildKey($key);
$value = $this->getValue($key);
if ($value === false || $this->serializer === false) {
return $value;
} elseif ($this->serializer === null) {
$value = unserialize($value);
} else {
$value = call_user_func($this->serializer[1], $value);
}
if (is_array($value) && !($value[1] instanceof Dependency && $value[1]->getHasChanged($this))) {
return $value[0];
} else {
return false;
}
}
/**
* Checks whether a specified key exists in the cache.
* This can be faster than getting the value from the cache if the data is big.
* In case a cache does not support this feature natively, this method will try to simulate it
* but has no performance improvement over getting it.
* Note that this method does not check whether the dependency associated
* with the cached data, if there is any, has changed. So a call to [[get]]
* may return false while exists returns true.
* @param mixed $key a key identifying the cached value. This can be a simple string or
* a complex data structure consisting of factors representing the key.
* @return boolean true if a value exists in cache, false if the value is not in the cache or expired.
*/
public function exists($key)
{
$key = $this->buildKey($key);
$value = $this->getValue($key);
return $value !== false;
}
/**
* 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.
* @param array $keys list of keys identifying the cached values
* @return array list of cached values corresponding to the specified keys. The array
* is returned in terms of (key, value) pairs.
* If a value is not cached or expired, the corresponding array value will be false.
*/
public function mget($keys)
{
$keyMap = array();
foreach ($keys as $key) {
$keyMap[$key] = $this->buildKey($key);
}
$values = $this->getValues(array_values($keyMap));
$results = array();
foreach ($keyMap as $key => $newKey) {
$results[$key] = false;
if (isset($values[$newKey])) {
if ($this->serializer === false) {
$results[$key] = $values[$newKey];
} else {
$value = $this->serializer === null ? unserialize($values[$newKey])
: call_user_func($this->serializer[1], $values[$newKey]);
if (is_array($value) && !($value[1] instanceof Dependency && $value[1]->getHasChanged($this))) {
$results[$key] = $value[0];
}
}
}
}
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.
*
* @param mixed $key a key identifying the value to be cached value. This can be a simple string or
* a complex data structure consisting of factors representing the key.
* @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.
* @param Dependency $dependency dependency of the cached item. If the dependency changes,
* the corresponding value in the cache will be invalidated when it is fetched via [[get()]].
* This parameter is ignored if [[serializer]] is false.
* @return boolean whether the value is successfully stored into cache
*/
public function set($key, $value, $expire = 0, $dependency = null)
{
if ($dependency !== null && $this->serializer !== false) {
$dependency->evaluateDependency($this);
}
if ($this->serializer === null) {
$value = serialize(array($value, $dependency));
} elseif ($this->serializer !== false) {
$value = call_user_func($this->serializer[0], array($value, $dependency));
}
$key = $this->buildKey($key);
return $this->setValue($key, $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.
* @param mixed $key a key identifying the value to be cached value. This can be a simple string or
* a complex data structure consisting of factors representing the key.
* @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.
* @param Dependency $dependency dependency of the cached item. If the dependency changes,
* the corresponding value in the cache will be invalidated when it is fetched via [[get()]].
* This parameter is ignored if [[serializer]] is false.
* @return boolean whether the value is successfully stored into cache
*/
public function add($key, $value, $expire = 0, $dependency = null)
{
if ($dependency !== null && $this->serializer !== false) {
$dependency->evaluateDependency($this);
}
if ($this->serializer === null) {
$value = serialize(array($value, $dependency));
} elseif ($this->serializer !== false) {
$value = call_user_func($this->serializer[0], array($value, $dependency));
}
$key = $this->buildKey($key);
return $this->addValue($key, $value, $expire);
}
/**
* Deletes a value with the specified key from cache
* @param mixed $key a key identifying the value to be deleted from cache. This can be a simple string or
* a complex data structure consisting of factors representing the key.
* @return boolean if no error happens during deletion
*/
public function delete($key)
{
$key = $this->buildKey($key);
return $this->deleteValue($key);
}
/**
* Deletes all values from cache.
* Be careful of performing this operation if the cache is shared among multiple applications.
* @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.
* @param string $key a unique key identifying the cached value
* @return string|boolean the value stored in cache, false if the value is not in the cache or expired.
*/
abstract protected function getValue($key);
/**
* 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.
* @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);
/**
* 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.
* @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);
/**
* 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);
/**
* 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)
{
$results = array();
foreach ($keys as $key) {
$results[$key] = $this->getValue($key);
}
return $results;
}
/**
* Returns whether there is a cache entry with a specified key.
* This method is required by the interface ArrayAccess.
* @param string $key a key identifying the cached value
* @return boolean
*/
public function offsetExists($key)
{
return $this->get($key) !== false;
}
/**
* Retrieves the value from cache with a specified key.
* This method is required by the interface ArrayAccess.
* @param string $key a key identifying the cached value
* @return mixed the value stored in cache, false if the value is not in the cache or expired.
*/
public function offsetGet($key)
{
return $this->get($key);
}
/**
* 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.
* @param string $key the key identifying the value to be cached
* @param mixed $value the value to be cached
*/
public function offsetSet($key, $value)
{
$this->set($key, $value);
}
/**
* Deletes the value with the specified key from cache
* This method is required by the interface ArrayAccess.
* @param string $key the key of the value to be deleted
*/
public function offsetUnset($key)
{
$this->delete($key);
}
}