Package org.aksw.commons.io.hadoop.binseach.bz2

Class BufferOverInputStream

java.lang.Object

org.aksw.commons.io.hadoop.binseach.bz2.BufferOverInputStream

All Implemented Interfaces:

AutoCloseable, ChannelFactory<Seekable>

@ThreadSafe
public class BufferOverInputStream
extends Object
implements ChannelFactory<Seekable>

FIXME This class should be removed because it is superseded by BufferOverReadableChannel in aksw-commons-io! Implementation of a byte array that caches data in buckets from an InputStream. Instances of these class are thread safe, but the obtained channels are not; each channel should only be operated on by one thread. Differences to BufferedInputStream - this class caches all data read from the inputstream hence there is no mark / reset mechanism - buffer is split into buckets (no data copying required when allocating more space) - data is loaded on demand based on (possibly concurrent) requests to the seekable channels obtained with newChannel() Closest known-to-me Hadoop counterpart is BufferedFSInputStream (which is based on BufferedInputStream)

Author:

raven

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	BufferOverInputStream.BucketPointer
class	BufferOverInputStream.ByteArrayChannel

Field Summary

Fields

Modifier and Type	Field	Description
protected BufferOverInputStream.BucketPointer	activeEnd	End marker with two components (idx, pos) it is wrapped in an object to enable atomic replacement of the reference The pointer is monotonous in the sense that the end marker's logical linear location is only increased Reading an old version while a new one has been set will only cause a read to return on the old boundary, but a subsequent synchronized check for whether loading of additional data is needed is then made anyway
protected byte[][]	buckets	The buffered data
protected InputStream	dataSupplier	Supplier for additional data
protected boolean	isDataSupplierConsumed	Flag to indicate that the dataSupplier has been consumed This is the case when dataSupplier(buffer) returns -1
protected long	knownDataSize	The number of cached bytes.
protected int	maxReadSize	Maximum number to read from the dataSupplier in one request
protected int	minReadSize

Constructor Summary

Constructors

Constructor	Description
BufferOverInputStream(int initialBucketSize, InputStream dataSupplier)

Method Summary

Modifier and Type	Method	Description
void	close()
static BufferOverInputStream	create(InputStream in, int maxReadSize, int... preconfiguredBucketSizes)
int	doRead(BufferOverInputStream.ByteArrayChannel reader, ByteBuffer dst)
protected void	ensureCapacityInActiveBucket()
long	getKnownDataSize()
static BufferOverInputStream.BucketPointer	getPointer(byte[][] buckets, BufferOverInputStream.BucketPointer end, long pos)
static long	getPosition(byte[][] buckets, int idx, int pos)
boolean	isDataSupplierConsumed()
protected void	loadData(int needed)	fetch a chunk from the input stream
protected void	loadDataUpTo(long requestedPos)	Preload data up to including the requested position.
static void	main(String[] args)
static void	main2(String[] args)
Seekable	newChannel()
protected int	nextBucketSize()

Methods inherited from class java.lang.Object

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

Field Details

buckets

protected byte[][] buckets

The buffered data

activeEnd

protected BufferOverInputStream.BucketPointer activeEnd

End marker with two components (idx, pos) it is wrapped in an object to enable atomic replacement of the reference The pointer is monotonous in the sense that the end marker's logical linear location is only increased Reading an old version while a new one has been set will only cause a read to return on the old boundary, but a subsequent synchronized check for whether loading of additional data is needed is then made anyway

knownDataSize

protected long knownDataSize

The number of cached bytes. Corresponds to the linear representation of activeEnd.

dataSupplier

protected InputStream dataSupplier

Supplier for additional data

minReadSize

protected int minReadSize

maxReadSize

protected int maxReadSize

Maximum number to read from the dataSupplier in one request

isDataSupplierConsumed

protected boolean isDataSupplierConsumed

Flag to indicate that the dataSupplier has been consumed This is the case when dataSupplier(buffer) returns -1

Constructor Details

BufferOverInputStream

public BufferOverInputStream(int initialBucketSize,
 InputStream dataSupplier)

Method Details

getKnownDataSize

public long getKnownDataSize()

isDataSupplierConsumed

public boolean isDataSupplierConsumed()

create

public static BufferOverInputStream create(InputStream in,
 int maxReadSize,
 int... preconfiguredBucketSizes)

Parameters:

maxReadSize - Maximum number of bytes to request form the input stream at once

in -

maxReadSize -

preconfiguredBucketSizes -

Returns:

getPosition

public static long getPosition(byte[][] buckets,
 int idx,
 int pos)

getPointer

public static BufferOverInputStream.BucketPointer getPointer(byte[][] buckets,
 BufferOverInputStream.BucketPointer end,
 long pos)

Parameters:

buckets -

pos -

Returns:

Pointer to a valid location in the know data block or null

newChannel

public Seekable newChannel()

Specified by:

newChannel in interface ChannelFactory<Seekable>

nextBucketSize

protected int nextBucketSize()

doRead

public int doRead(BufferOverInputStream.ByteArrayChannel reader,
 ByteBuffer dst)

loadDataUpTo

protected void loadDataUpTo(long requestedPos)

Preload data up to including the requested position. It is inclusive in order to allow for checking whether the requested position is in range.

Parameters:

requestedPos -

loadData

protected void loadData(int needed)

fetch a chunk from the input stream

ensureCapacityInActiveBucket

protected void ensureCapacityInActiveBucket()

main

public static void main(String[] args)
                 throws Exception

Throws:

Exception

main2

public static void main2(String[] args)
                  throws Exception

Throws:

Exception

close

public void close()
           throws Exception

Specified by:

close in interface AutoCloseable

Throws:

Exception