org.apache.hadoop.hbase.util

类 WeakObjectPool<K,V>

java.lang.Object

org.apache.hadoop.hbase.util.WeakObjectPool<K,V>

@InterfaceAudience.Private
public class WeakObjectPool<K,V>
extends Object

A WeakReference based shared object pool. The objects are kept in weak references and associated with keys which are identified by the equals method. The objects are created by WeakObjectPool.ObjectFactory on demand. The object creation is expected to be lightweight, and the objects may be excessively created and discarded. Thread safe.

嵌套类概要

嵌套类

限定符和类型	类和说明
static interface	WeakObjectPool.ObjectFactory<K,V> An ObjectFactory object is used to create new shared objects on demand.

字段概要

字段

限定符和类型	字段和说明
static int	DEFAULT_CONCURRENCY_LEVEL The default concurrency level, used when not otherwise specified in a constructor.
static int	DEFAULT_INITIAL_CAPACITY The default initial capacity, used when not otherwise specified in a constructor.

构造器概要

构造器

构造器和说明
WeakObjectPool(WeakObjectPool.ObjectFactory<K,V> objectFactory) Creates a new pool with the default initial capacity (16) and the default concurrency level (16).
WeakObjectPool(WeakObjectPool.ObjectFactory<K,V> objectFactory, int initialCapacity) Creates a new pool with the given initial capacity and the default concurrency level (16).
WeakObjectPool(WeakObjectPool.ObjectFactory<K,V> objectFactory, int initialCapacity, int concurrencyLevel) Creates a new pool with the given initial capacity and the given concurrency level.

方法概要

方法

限定符和类型	方法和说明
V	get(K key) Returns a shared object associated with the given key, which is identified by the equals method.
void	purge() Removes stale references of shared objects from the pool.
int	size() Returns an estimated count of objects kept in the pool.

从类继承的方法 java.lang.Object

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

字段详细资料

DEFAULT_INITIAL_CAPACITY

public static final int DEFAULT_INITIAL_CAPACITY

The default initial capacity, used when not otherwise specified in a constructor.

另请参阅:

常量字段值

DEFAULT_CONCURRENCY_LEVEL

public static final int DEFAULT_CONCURRENCY_LEVEL

The default concurrency level, used when not otherwise specified in a constructor.

另请参阅:

常量字段值

构造器详细资料

WeakObjectPool

public WeakObjectPool(WeakObjectPool.ObjectFactory<K,V> objectFactory)

Creates a new pool with the default initial capacity (16) and the default concurrency level (16).

参数:

objectFactory - the factory to supply new objects on demand

抛出:

NullPointerException - if objectFactory is null

WeakObjectPool

public WeakObjectPool(WeakObjectPool.ObjectFactory<K,V> objectFactory,
              int initialCapacity)

Creates a new pool with the given initial capacity and the default concurrency level (16).

参数:

objectFactory - the factory to supply new objects on demand

initialCapacity - the initial capacity to keep objects in the pool

抛出:

NullPointerException - if objectFactory is null

IllegalArgumentException - if initialCapacity is negative

WeakObjectPool

public WeakObjectPool(WeakObjectPool.ObjectFactory<K,V> objectFactory,
              int initialCapacity,
              int concurrencyLevel)

Creates a new pool with the given initial capacity and the given concurrency level.

参数:

objectFactory - the factory to supply new objects on demand

initialCapacity - the initial capacity to keep objects in the pool

concurrencyLevel - the estimated count of concurrently accessing threads

抛出:

NullPointerException - if objectFactory is null

IllegalArgumentException - if initialCapacity is negative or concurrencyLevel is non-positive

方法详细资料

purge

public void purge()

Removes stale references of shared objects from the pool. References newly becoming stale may still remain. The implementation of this method is expected to be lightweight when there is no stale reference.

get

public V get(K key)

Returns a shared object associated with the given key, which is identified by the equals method.

抛出:

NullPointerException - if key is null

size

public int size()

Returns an estimated count of objects kept in the pool. This also counts stale references, and you might want to call purge() beforehand.