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

Class BufferPool

java.lang.Object

org.apache.hadoop.fs.impl.prefetch.BufferPool

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class BufferPool
extends java.lang.Object
implements java.io.Closeable

Manages a fixed pool of ByteBuffer instances.

Avoids creating a new buffer if a previously created buffer is already available.

Constructor Summary

Constructors

Constructor	Description
BufferPool(int size, int bufferSize, PrefetchingStatistics prefetchingStatistics)	Initializes a new instance of the BufferPool class.

Method Summary

Modifier and Type	Method	Description
BufferData	acquire(int blockNumber)	Acquires a ByteBuffer; blocking if necessary until one becomes available.
void	close()
java.util.List<BufferData>	getAll()	Gets a list of all blocks in this pool.
int	numAvailable()
int	numCreated()
void	release(BufferData data)	Releases a previously acquired resource.
java.lang.String	toString()
BufferData	tryAcquire(int blockNumber)	Acquires a buffer if one is immediately available.

Methods inherited from class java.lang.Object

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

Constructor Detail

BufferPool

public BufferPool(int size,
                  int bufferSize,
                  PrefetchingStatistics prefetchingStatistics)

Initializes a new instance of the BufferPool class.

Parameters:

size - number of buffer in this pool.

bufferSize - size in bytes of each buffer.

prefetchingStatistics - statistics for this stream.

Throws:

java.lang.IllegalArgumentException - if size is zero or negative.

java.lang.IllegalArgumentException - if bufferSize is zero or negative.

Method Detail

getAll

public java.util.List<BufferData> getAll()

Gets a list of all blocks in this pool.

Returns:

a list of all blocks in this pool.

acquire

public BufferData acquire(int blockNumber)

Acquires a ByteBuffer; blocking if necessary until one becomes available.

Parameters:

blockNumber - the id of the block to acquire.

Returns:

the acquired block's BufferData.

tryAcquire

public BufferData tryAcquire(int blockNumber)

Acquires a buffer if one is immediately available. Otherwise returns null.

Parameters:

blockNumber - the id of the block to try acquire.

Returns:

the acquired block's BufferData or null.

release

public void release(BufferData data)

Releases a previously acquired resource.

Parameters:

data - the BufferData instance to release.

Throws:

java.lang.IllegalArgumentException - if data is null.

java.lang.IllegalArgumentException - if data cannot be released due to its state.

close

public void close()

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

numCreated

public int numCreated()

numAvailable

public int numAvailable()