Package mondrian.util

Class ObjectPool<T>

java.lang.Object
mondrian.util.ObjectPool<T>
public class ObjectPool<T> extends Object
An ObjectPool is a low-memory replacement for a HashSet. A HashSet contains a HashMap which in turn has an array of Entry objects, the Entry objects themselves, and the key and value objects. An ObjectPool has simply an array of objects and the objects themselves which server as both key and value.

This is like the String intern method, but works for an Object type and whereas the String intern method is global an ObjectPool can be used within a context and then garbage collected. Objects can not removed from an ObjectPool except by calling the clear method which removes all objects.

Just as with a HashSet's key objects, objects to be placed into an ObjectPool must implement the equals and hashCode methods.

This implementation is NOT thread safe.

Author:
Richard Emberson

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected static final int
    DEFAULT_CAPACITY
     
    protected static final double
    DEFAULT_MAX_LOAD_FACTOR
     
    protected static final double
    DEFAULT_MIN_LOAD_FACTOR
     
    protected int
    distinct
    The number of distinct associations in the map; its "size()".
    protected static final byte
    FREE
     
    protected int
    freeEntries
    The number of table entries in state==FREE.
    protected static final byte
    FULL
     
    protected int
    highWaterMark
     
    protected double
    maxLoadFactor
    The maximum load factor for the hashtable.
    protected double
    minLoadFactor
    The minimum load factor for the hashtable.
    protected T[]
    values
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    ObjectPool()
     
    ObjectPool(int initialCapacity)
     
    ObjectPool(int initialCapacity, double minLoadFactor, double maxLoadFactor)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    T
    add(T key)
    Adds an object to the ObjectPool if it is not already in the pool or returns the object that is already in the pool that matches the object being added.
    protected int
    chooseGrowCapacity(int size, double minLoad, double maxLoad)
     
    protected final int
    chooseHighWaterMark(int capacity, double maxLoad)
     
    protected final int
    chooseLowWaterMark(int capacity, double minLoad)
     
    void
    clear()
    Removes all objects from the pool but keeps the current size of the internal storage.
    boolean
    contains(T key)
    Returns true it the Object is already in the ObjectPool and false otherwise.
    protected boolean
    equals(T t, T key)
     
    protected int
    hash(T key)
     
    protected int
    indexOfInsertion(T key)
     
    Iterator<T>
    iterator()
    Returns an Iterator of this ObjectPool.
    protected int
    nextPrime(int desiredCapacity)
     
    protected void
    rehash(int newCapacity)
     
    protected void
    setUp(int initialCapacity, double minLoadFactor, double maxLoadFactor)
     
    int
    size()
    Return the number of entries in the ObjectPool.
    void
    trimToSize()
    Reduce the size of the internal arrays to a size just big enough to hold the current set of entries.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • FREE

      protected static final byte FREE
      See Also:

    • FULL

      protected static final byte FULL
      See Also:

    • DEFAULT_CAPACITY

      protected static final int DEFAULT_CAPACITY
      See Also:

    • DEFAULT_MIN_LOAD_FACTOR

      protected static final double DEFAULT_MIN_LOAD_FACTOR
      See Also:

    • DEFAULT_MAX_LOAD_FACTOR

      protected static final double DEFAULT_MAX_LOAD_FACTOR
      See Also:

    • distinct

      protected int distinct
      The number of distinct associations in the map; its "size()".

    • highWaterMark

      protected int highWaterMark

    • minLoadFactor

      protected double minLoadFactor
      The minimum load factor for the hashtable.

    • maxLoadFactor

      protected double maxLoadFactor
      The maximum load factor for the hashtable.

    • values

      protected T[] values

    • freeEntries

      protected int freeEntries
      The number of table entries in state==FREE.

  • Constructor Details

    • ObjectPool

      public ObjectPool()

    • ObjectPool

      public ObjectPool(int initialCapacity)

    • ObjectPool

      public ObjectPool(int initialCapacity, double minLoadFactor, double maxLoadFactor)

  • Method Details

    • size

      public int size()
      Return the number of entries in the ObjectPool.
      Returns:
      number of entries.

    • trimToSize

      public void trimToSize()
      Reduce the size of the internal arrays to a size just big enough to hold the current set of entries. Generally, this should only be called after all entries have been added. Calling this causes a new, smaller array to be allocated, the objects are copied to the new array and then the old array is free to be garbage collected; there is a small time when both arrays are in memory.

    • contains

      public boolean contains(T key)
      Returns true it the Object is already in the ObjectPool and false otherwise.
      Parameters:
      key - Object to test if member already or not.
      Returns:
      true is already member

    • add

      public T add(T key)
      Adds an object to the ObjectPool if it is not already in the pool or returns the object that is already in the pool that matches the object being added.
      Parameters:
      key - Object to add to pool
      Returns:
      Equivalent object, if it exists, otherwise key

    • clear

      public void clear()
      Removes all objects from the pool but keeps the current size of the internal storage.

    • iterator

      public Iterator<T> iterator()
      Returns an Iterator of this ObjectPool. The order of the Objects returned by the Iterator can not be counted on to be in the same order as they were inserted into the ObjectPool. The Iterator returned does not support the removal of ObjectPool members.

    • chooseGrowCapacity

      protected int chooseGrowCapacity(int size, double minLoad, double maxLoad)

    • chooseHighWaterMark

      protected final int chooseHighWaterMark(int capacity, double maxLoad)

    • chooseLowWaterMark

      protected final int chooseLowWaterMark(int capacity, double minLoad)

    • nextPrime

      protected int nextPrime(int desiredCapacity)

    • setUp

      protected void setUp(int initialCapacity, double minLoadFactor, double maxLoadFactor)

    • hash

      protected int hash(T key)

    • equals

      protected boolean equals(T t, T key)

    • indexOfInsertion

      protected int indexOfInsertion(T key)

    • rehash

      protected void rehash(int newCapacity)