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 * @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); } }