Package org.zkoss.util

Class MultiCache<K,​V>

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable, Cache<K,​V>
    public class MultiCache<K,​V>
extends java.lang.Object
implements Cache<K,​V>, java.io.Serializable, java.lang.Cloneable
    A CacheMap that uses multiple instanceof CacheMap to speed up the performance. It creates multiple instances of CacheMap, called the internal caches, and then distributes the access across them. Thus, the performance is proportional to the number of internal caches.

    Thread safe.

    Since:
    3.0.0
    Author:
    tomyeh
    See Also:
    Serialized Form

    • Constructor Summary

      Constructors 
      Constructor Description
      MultiCache()
      Constructs a multi cache with 17 initial caches.
      MultiCache​(int nCache)
      Constructs a multi cache with the specified number of internal caches.
      MultiCache​(int nCache, int maxSize, int lifetime)
      Constructs a multi cache with the specified number of internal caches, the max size and the lifetime.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Clears all objects being cached.
      java.lang.Object clone()  
      boolean containsKey​(java.lang.Object key)
      Returns whether the specified key is stored.
      V get​(java.lang.Object key)
      Returns the object of the specified key, or null if not found.
      protected int getInnerCacheHashCode​(java.lang.Object key)
      Returns an integer used to identify the instance of inner caches to use.
      int getLifetime()
      Returns the minimal lifetime, unit=milliseconds.
      int getMaxSize()
      Returns the maximal allowed size.
      V put​(K key, V value)
      Stores an object to the cache.
      V remove​(java.lang.Object key)
      Removes an object from the cache.
      void setLifetime​(int lifetime)
      Sets the minimal lifetime.
      void setMaxSize​(int maxsize)
      Sets the maximal allowed size.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • MultiCache

        public MultiCache()
        Constructs a multi cache with 17 initial caches.

      • MultiCache

        public MultiCache​(int nCache,
                  int maxSize,
                  int lifetime)
        Constructs a multi cache with the specified number of internal caches, the max size and the lifetime.
        Parameters:
        nCache - the positive number of the internal caches. The large the number the fast the performance.
        maxSize - the maximal allowed size of each cache

      • MultiCache

        public MultiCache​(int nCache)
        Constructs a multi cache with the specified number of internal caches.

        The default lifetime is Cache.DEFAULT_LIFETIME, and the default maximal allowed size of each cache is (Cache.DEFAULT_MAX_SIZE / 10).

        Parameters:
        nCache - the positive number of the internal caches. The large the number the fast the performance.

    • Method Detail

      • containsKey

        public boolean containsKey​(java.lang.Object key)
        Description copied from interface: Cache
        Returns whether the specified key is stored.
        Specified by:
        containsKey in interface Cache<K,​V>

      • get

        public V get​(java.lang.Object key)
        Description copied from interface: Cache
        Returns the object of the specified key, or null if not found.
        Specified by:
        get in interface Cache<K,​V>

      • put

        public V put​(K key,
             V value)
        Description copied from interface: Cache
        Stores an object to the cache.
        Specified by:
        put in interface Cache<K,​V>
        Returns:
        the previous value of the same, or null if no such value

      • remove

        public V remove​(java.lang.Object key)
        Description copied from interface: Cache
        Removes an object from the cache.
        Specified by:
        remove in interface Cache<K,​V>
        Returns:
        the object if found.

      • clear

        public void clear()
        Description copied from interface: Cache
        Clears all objects being cached.
        Specified by:
        clear in interface Cache<K,​V>

      • getInnerCacheHashCode

        protected int getInnerCacheHashCode​(java.lang.Object key)
        Returns an integer used to identify the instance of inner caches to use. By default, this method returns the hash code of the given key and the current thread. It means the value of the same key might be stored in different cache (in favor of performance). If different threads of your application usually access different keys, you can override this method to return the hash code of the given key only.
        Since:
        6.0.0

      • getLifetime

        public int getLifetime()
        Description copied from interface: Cache
        Returns the minimal lifetime, unit=milliseconds. An mapping won't be removed by GC unless the minimal lifetime or the maximal allowed size exceeds.
        Specified by:
        getLifetime in interface Cache<K,​V>
        See Also:
        Cache.getMaxSize()

      • setLifetime

        public void setLifetime​(int lifetime)
        Description copied from interface: Cache
        Sets the minimal lifetime. Default: Cache.DEFAULT_LIFETIME.
        Specified by:
        setLifetime in interface Cache<K,​V>
        Parameters:
        lifetime - the lifetime, unit=milliseconds; if non-positive, they will be removed immediately.
        See Also:
        Cache.getLifetime()

      • getMaxSize

        public int getMaxSize()
        Description copied from interface: Cache
        Returns the maximal allowed size. Default: Cache.DEFAULT_MAX_SIZE. An mapping won't be removed by GC unless the minimal lifetime or the maximal allowed size exceeds.
        Specified by:
        getMaxSize in interface Cache<K,​V>
        See Also:
        Cache.getLifetime()

      • setMaxSize

        public void setMaxSize​(int maxsize)
        Description copied from interface: Cache
        Sets the maximal allowed size.
        Specified by:
        setMaxSize in interface Cache<K,​V>
        See Also:
        Cache.getMaxSize()

      • clone

        public java.lang.Object clone()
        Overrides:
        clone in class java.lang.Object