Package org.apache.hadoop.io

Class WeakReferencedElasticByteBufferPool

java.lang.Object

org.apache.hadoop.io.ElasticByteBufferPool

org.apache.hadoop.io.WeakReferencedElasticByteBufferPool

All Implemented Interfaces:

ByteBufferPool

@Private
@Unstable
public final class WeakReferencedElasticByteBufferPool
extends ElasticByteBufferPool

Buffer pool implementation which uses weak references to store buffers in the pool, such that they are garbage collected when there are no references to the buffer during a gc run. This is important as direct buffers don't get garbage collected automatically during a gc run as they are not stored on heap memory. Also the buffers are stored in a tree map which helps in returning smallest buffer whose size is just greater than requested length. This is a thread safe implementation.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.io.ElasticByteBufferPool

ElasticByteBufferPool.Key

Constructor Summary

Constructors

Constructor	Description
WeakReferencedElasticByteBufferPool()

Method Summary

Modifier and Type	Method	Description
java.nio.ByteBuffer	getBuffer(boolean direct, int length)	Get a new direct ByteBuffer.
int	getCurrentBuffersCount(boolean isDirect)	Get current buffers count in the pool.
void	putBuffer(java.nio.ByteBuffer buffer)	Return buffer to the pool.
void	release()	Clear the buffer pool thus releasing all the buffers.

Methods inherited from class org.apache.hadoop.io.ElasticByteBufferPool

size

Methods inherited from class java.lang.Object

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

Constructor Detail

WeakReferencedElasticByteBufferPool

public WeakReferencedElasticByteBufferPool()

Method Detail

getBuffer

public java.nio.ByteBuffer getBuffer(boolean direct,
                                     int length)

Get a new direct ByteBuffer. The pool can provide this from removing a buffer from its internal cache, or by allocating a new buffer.

Specified by:

getBuffer in interface ByteBufferPool

Overrides:

getBuffer in class ElasticByteBufferPool

Parameters:

direct - whether we want a direct byte buffer or a heap one.

length - length of requested buffer.

Returns:

returns equal or next greater than capacity buffer from pool if already available and not garbage collected else creates a new buffer and return it.

putBuffer

public void putBuffer(java.nio.ByteBuffer buffer)

Return buffer to the pool.

Specified by:

putBuffer in interface ByteBufferPool

Overrides:

putBuffer in class ElasticByteBufferPool

Parameters:

buffer - buffer to be returned.

release

public void release()

Clear the buffer pool thus releasing all the buffers. The caller must remove all references of existing buffers before calling this method to avoid memory leaks.

getCurrentBuffersCount

@VisibleForTesting
public int getCurrentBuffersCount(boolean isDirect)

Get current buffers count in the pool.

Parameters:

isDirect - whether we want to count the heap or direct buffers.

Returns:

count of buffers.