Package freemarker.cache

Class MruCacheStorage

  • All Implemented Interfaces:
    CacheStorage
    public class MruCacheStorage
extends Object
implements CacheStorage
    A cache storage that implements a two-level Most Recently Used cache. In the first level, items are strongly referenced up to the specified maximum. When the maximum is exceeded, the least recently used item is moved into the second level cache, where they are softly referenced, up to another specified maximum. When the second level maximum is also exceeded, the least recently used item is discarded altogether. This cache storage is a generalization of both StrongCacheStorage and SoftCacheStorage - the effect of both of them can be achieved by setting one maximum to zero and the other to the largest positive integer. On the other hand, if you wish to use this storage in a strong-only mode, or in a soft-only mode, you might consider using StrongCacheStorage or SoftCacheStorage instead, as they can be used by TemplateCache concurrently without any synchronization on a 5.0 or later JRE. This class is NOT thread-safe. If it is accessed from multiple threads concurrently, proper synchronization must be provided by the callers. Note that TemplateCache, the natural user of this class provides the necessary synchronizations when it uses the class. Also you might consider whether you need this sort of a mixed storage at all in your solution, as in most cases SoftCacheStorage can also be sufficient. SoftCacheStorage will use Java soft references, and they already use access timestamps internally to bias the garbage collector against clearing recently used references, so you can get reasonably good (and memory-sensitive) most-recently-used caching through SoftCacheStorage as well.

    • Constructor Detail

      • MruCacheStorage

        public MruCacheStorage​(int maxStrongSize,
                       int maxSoftSize)
        Creates a new MRU cache storage with specified maximum cache sizes. Each cache size can vary between 0 and Integer.MAX_VALUE.
        Parameters:
        maxStrongSize - the maximum number of strongly referenced templates
        maxSoftSize - the maximum number of softly referenced templates

    • Method Detail

      • get

        public Object get​(Object key)
        Description copied from interface: CacheStorage
        Retrieve a cached value associated with a key
        Specified by:
        get in interface CacheStorage
        Parameters:
        key - the key for retrieving an associated value
        Returns:
        the cached value associated with the key, or null if no value is associated with the key.

      • put

        public void put​(Object key,
                Object value)
        Description copied from interface: CacheStorage
        Associates a key with a cached value
        Specified by:
        put in interface CacheStorage
        Parameters:
        key - the key to associate with a value
        value - the value associated with the key.

      • remove

        public void remove​(Object key)
        Description copied from interface: CacheStorage
        Removes the value associated with a key, if it exists. If it doesn't exist, this method does nothing.
        Specified by:
        remove in interface CacheStorage
        Parameters:
        key - the key whose associated value is removed from the cache.

      • clear

        public void clear()
        Description copied from interface: CacheStorage
        Removes all values from this cache
        Specified by:
        clear in interface CacheStorage