$directoryLevel public property The level of sub-directories to store cache files. Defaults to 1. If the system has huge number of cache files (e.g. one million), you may use a bigger value (usually no bigger than 3). Using sub-directories is mainly to ensure the file system is not over burdened with a single directory having too many files. public integer $directoryLevel = 1

$cachePath public property The directory to store cache files. You may use path alias here. If not set, it will use the "cache" subdirectory under the application runtime path. public string $cachePath = '@runtime/cache'

$gcProbability public property The probability (parts per million) that garbage collection (GC) should be performed when storing a piece of data in the cache. Defaults to 10, meaning 0.001% chance. This number should be between 0 and 1000000. A value 0 means no GC will be performed at all. public integer $gcProbability = 10

$cacheFileSuffix public property Cache file suffix. Defaults to '.bin'. public string $cacheFileSuffix = '.bin'

$expression public property The string representation of a PHP expression whose result is used to determine the dependency. A PHP expression can be any PHP code that evaluates to a value. To learn more about what an expression is, please refer to the php manual. public string $expression = 'true'

$params public property Custom parameters associated with this dependency. You may get the value of this property in $expression using $this->params. public mixed $params = null

generateDependencyData() protected method Generates the data needed to determine if dependency has been changed. This method returns the result of the PHP expression. protected mixed generateDependencyData ( $cache )$cache yii\caching\Cache The cache component that is currently evaluating this dependency return mixed The data needed to determine if dependency has been changed.

flushValues() protected method Deletes all values from cache. This is the implementation of the method declared in the parent class. protected boolean flushValues ( )return boolean Whether the flush operation was successful.

setValue() protected method Stores a value identified by a key in cache. This is the implementation of the method declared in the parent class. protected boolean setValue ( $key, $value, $duration )$key string The key identifying the value to be cached $value mixed The value to be cached $duration 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

deleteValue() protected method Deletes a value with the specified key from cache This is the implementation of the method declared in the parent class. protected boolean deleteValue ( $key )$key string The key of the value to be deleted return boolean If no error happens during deletion