Package org.apache.hadoop.fs.impl.prefetch

Class ResourcePool<T>

java.lang.Object

org.apache.hadoop.fs.impl.prefetch.ResourcePool<T>

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

Direct Known Subclasses:

BoundedResourcePool

public abstract class ResourcePool<T>
extends java.lang.Object
implements java.io.Closeable

Manages a fixed pool of resources. Avoids creating a new resource if a previously created instance is already available.

Constructor Summary

Constructors

Constructor	Description
ResourcePool()

Method Summary

Modifier and Type	Method	Description
abstract T	acquire()	Acquires a resource blocking if necessary until one becomes available.
void	close()
protected void	close(T item)	Derived classes may implement a way to cleanup each item.
protected abstract T	createNew()	Derived classes must implement a way to create an instance of a resource.
abstract void	release(T item)	Releases a previously acquired resource.
abstract T	tryAcquire()	Acquires a resource blocking if one is immediately available.

Methods inherited from class java.lang.Object

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

Constructor Detail

ResourcePool

public ResourcePool()

Method Detail

acquire

public abstract T acquire()

Acquires a resource blocking if necessary until one becomes available.

Returns:

the acquired resource instance.

tryAcquire

public abstract T tryAcquire()

Acquires a resource blocking if one is immediately available. Otherwise returns null.

Returns:

the acquired resource instance (if immediately available) or null.

release

public abstract void release(T item)

Releases a previously acquired resource.

Parameters:

item - the resource to release.

close

public void close()

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

close

protected void close(T item)

Derived classes may implement a way to cleanup each item.

Parameters:

item - the resource to close.

createNew

protected abstract T createNew()

Derived classes must implement a way to create an instance of a resource.

Returns:

the created instance.