ObjectPool (Pentaho Community Edition Project: mondrian 9.0.0.1-426 API)

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 and Description
`protected static int`	`DEFAULT_CAPACITY`
`protected static double`	`DEFAULT_MAX_LOAD_FACTOR`
`protected static double`	`DEFAULT_MIN_LOAD_FACTOR`
`protected int`	`distinct` The number of distinct associations in the map; its "size()".
`protected static byte`	`FREE`
`protected int`	`freeEntries` The number of table entries in state==FREE.
`protected static 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 and Description
`ObjectPool()`
`ObjectPool(int initialCapacity)`
`ObjectPool(int initialCapacity, double minLoadFactor, double maxLoadFactor)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and 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 int`	`chooseHighWaterMark(int capacity, double maxLoad)`
`protected 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 Detail
  - FREE
```
protected static final byte FREE
```
    See Also:
    
    Constant Field Values
  - FULL
```
protected static final byte FULL
```
    See Also:
    
    Constant Field Values
  - DEFAULT_CAPACITY
```
protected static final int DEFAULT_CAPACITY
```
    See Also:
    
    Constant Field Values
  - DEFAULT_MIN_LOAD_FACTOR
```
protected static final double DEFAULT_MIN_LOAD_FACTOR
```
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_LOAD_FACTOR
```
protected static final double DEFAULT_MAX_LOAD_FACTOR
```
    See Also:
    
    Constant Field Values
  - 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 Detail
  - ObjectPool
```
public ObjectPool()
```
  - ObjectPool
```
public ObjectPool(int initialCapacity)
```
  - ObjectPool
```
public ObjectPool(int initialCapacity,
                  double minLoadFactor,
                  double maxLoadFactor)
```
- Method Detail
  - 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)
```

Class ObjectPool<T>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

FREE

FULL

DEFAULT_CAPACITY

DEFAULT_MIN_LOAD_FACTOR

DEFAULT_MAX_LOAD_FACTOR

distinct

highWaterMark

minLoadFactor

maxLoadFactor

values

freeEntries

Constructor Detail

ObjectPool

ObjectPool

ObjectPool

Method Detail

size

trimToSize

contains

add

clear

iterator

chooseGrowCapacity

chooseHighWaterMark

chooseLowWaterMark

nextPrime

setUp

hash

equals

indexOfInsertion

rehash