Class LazyInitializedCacheMap<K,​V>

  • Type Parameters:
    K - The key type
    V - The value type
    All Implemented Interfaces:
    java.util.Map<K,​V>

    public class LazyInitializedCacheMap<K,​V>
    extends java.lang.Object
    implements java.util.Map<K,​V>
    This map is specially useful when reads are much more frequent than writes and if the cost of instantiating the values is high like allocating an IoBuffer for example. Based on the final implementation of Memoizer written by Brian Goetz and Tim Peierls. This implementation will return an UnsupportedOperationException on each method that is not intended to be called by user code for performance reasons.
    Since:
    MINA 2.0.0-M2
    Author:
    Apache MINA Project
    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      class  LazyInitializedCacheMap.NoopInitializer
      This class provides a noop LazyInitializer meaning it will return the same object it received when instantiated.
      • Nested classes/interfaces inherited from interface java.util.Map

        java.util.Map.Entry<K extends java.lang.Object,​V extends java.lang.Object>
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      boolean containsKey​(java.lang.Object key)
      boolean containsValue​(java.lang.Object value)
      Throws UnsupportedOperationException as this method would imply performance drops.
      java.util.Set<java.util.Map.Entry<K,​V>> entrySet()
      Throws UnsupportedOperationException as this method would imply performance drops.
      V get​(java.lang.Object key)
      java.util.Collection<LazyInitializer<V>> getValues()  
      boolean isEmpty()
      java.util.Set<K> keySet()
      V put​(K key, V value)
      void putAll​(java.util.Map<? extends K,​? extends V> m)
      V putIfAbsent​(K key, LazyInitializer<V> value)
      If the specified key is not already associated with a value, associate it with the given value.
      V remove​(java.lang.Object key)
      int size()
      java.util.Collection<V> values()
      Throws UnsupportedOperationException as this method would imply performance drops.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
      • Methods inherited from interface java.util.Map

        compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll
    • Constructor Detail

      • LazyInitializedCacheMap

        public LazyInitializedCacheMap()
        Default constructor. Uses the default parameters to initialize its internal ConcurrentHashMap.
      • LazyInitializedCacheMap

        public LazyInitializedCacheMap​(java.util.concurrent.ConcurrentHashMap<K,​LazyInitializer<V>> map)
        This constructor allows to provide a fine tuned ConcurrentHashMap to stick with each special case the user needs.
        Parameters:
        map - The map to use as a cache
    • Method Detail

      • get

        public V get​(java.lang.Object key)
        Specified by:
        get in interface java.util.Map<K,​V>
      • remove

        public V remove​(java.lang.Object key)
        Specified by:
        remove in interface java.util.Map<K,​V>
      • putIfAbsent

        public V putIfAbsent​(K key,
                             LazyInitializer<V> value)
        If the specified key is not already associated with a value, associate it with the given value. This is equivalent to
           if (!map.containsKey(key))
               return map.put(key, value);
           else
               return map.get(key);
        except that the action is performed atomically.
        Parameters:
        key - key with which the specified value is to be associated
        value - a lazy initialized value object.
        Returns:
        the previous value associated with the specified key, or null if there was no mapping for the key
      • put

        public V put​(K key,
                     V value)
        Specified by:
        put in interface java.util.Map<K,​V>
      • containsValue

        public boolean containsValue​(java.lang.Object value)
        Throws UnsupportedOperationException as this method would imply performance drops.
        Specified by:
        containsValue in interface java.util.Map<K,​V>
      • values

        public java.util.Collection<V> values()
        Throws UnsupportedOperationException as this method would imply performance drops.
        Specified by:
        values in interface java.util.Map<K,​V>
      • entrySet

        public java.util.Set<java.util.Map.Entry<K,​V>> entrySet()
        Throws UnsupportedOperationException as this method would imply performance drops.
        Specified by:
        entrySet in interface java.util.Map<K,​V>
      • putAll

        public void putAll​(java.util.Map<? extends K,​? extends V> m)
        Specified by:
        putAll in interface java.util.Map<K,​V>
      • getValues

        public java.util.Collection<LazyInitializer<V>> getValues()
        Returns:
        return the values from the cache
      • clear

        public void clear()
        Specified by:
        clear in interface java.util.Map<K,​V>
      • containsKey

        public boolean containsKey​(java.lang.Object key)
        Specified by:
        containsKey in interface java.util.Map<K,​V>
      • isEmpty

        public boolean isEmpty()
        Specified by:
        isEmpty in interface java.util.Map<K,​V>
      • keySet

        public java.util.Set<K> keySet()
        Specified by:
        keySet in interface java.util.Map<K,​V>
      • size

        public int size()
        Specified by:
        size in interface java.util.Map<K,​V>