Package com.fasterxml.jackson.databind.util

Class LRUMap<K,​V>

  • All Implemented Interfaces:
    java.io.Serializable
    public class LRUMap<K,​V>
extends java.lang.Object
implements java.io.Serializable
    Helper for simple bounded maps used for reusing lookup values.

    Note that serialization behavior is such that contents are NOT serialized, on assumption that all use cases are for caching where persistence does not make sense. The only thing serialized is the cache size of Map.

    NOTE: since version 2.4.2, this is NOT an LRU-based at all; reason being that it is not possible to use JDK components that do LRU _AND_ perform well wrt synchronization on multi-core systems. So we choose efficient synchronization over potentially more efficient handling of entries.

    And yes, there are efficient LRU implementations such as concurrentlinkedhashmap; but at this point we really try to keep external deps to minimum. But perhaps a shaded variant may be used one day.

    See Also:
    Serialized Form

    • Constructor Summary

      Constructors 
      Constructor Description
      LRUMap​(int initialEntries, int maxEntries)  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()  
      V get​(java.lang.Object key)  
      V put​(K key, V value)  
      V putIfAbsent​(K key, V value)  
      int size()  

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • LRUMap

        public LRUMap​(int initialEntries,
              int maxEntries)

    • Method Detail

      • put

        public V put​(K key,
             V value)

      • putIfAbsent

        public V putIfAbsent​(K key,
                     V value)
        Since:
        2.5

      • get

        public V get​(java.lang.Object key)

      • clear

        public void clear()

      • size

        public int size()