org.aksw.jena_sparql_api.io.binseach

Class SeekableFromBlock

java.lang.Object

org.aksw.jena_sparql_api.io.binseach.SeekableFromBlock

All Implemented Interfaces:

Closeable, AutoCloseable, Channel, ReadableByteChannel, Seekable

public class SeekableFromBlock
extends Object
implements Seekable

Segment could have predecessor / successor methods, but how can we slice segments we request? The use case is to scan backward until a condition is no longer satisfied, maybe we don't need slicing then

Author:

raven

Field Summary

Fields

Modifier and Type	Field and Description
protected long	actualPos
protected Block	currentBlock
protected Reference<Block>	currentBlockRef
protected Seekable	currentSeekable
protected long	exposedStartPos The start position exposed - may be non-zero or even negative!
protected long	maxPos
protected long	minPos
protected Reference<Block>	startBlockRef
protected int	startPosInStartSegment

Constructor Summary

Constructors

Constructor and Description
SeekableFromBlock(Reference<Block> startBlockRef, int posInStartSegment, long exposedStartPos)
SeekableFromBlock(Reference<Block> startBlockRef, int posInStartSegment, long exposedStartPos, long minPos, long maxPos)

Method Summary

Modifier and Type	Method and Description
int	checkNext(int len, boolean changePos) Attempt to advance the position by the given number of bytes.
int	checkPrev(int len, boolean changePos)
Seekable	clone()
void	close()
int	compareToPrefix(byte[] prefix) Compare the bytes at the current position to a given sequence of bytes If there are fewer bytes available in the seekable than provide for comparison, then only that many are compared.
byte	get() Read a byte at the current position
long	getPos() Optional operation.
protected void	init()
boolean	isOpen()
boolean	isPosAfterEnd() The state of a seekable may be one unit beyond the end.
boolean	isPosBeforeStart() The state of a seekable may be one unit before the start.
protected boolean	loadNextBlock()
void	posToEnd() Optional operation.
int	posToNext(byte delimiter, boolean changePos) positive: relative position issue: 0 means no position change, but it does not tell whether the current position is a match or not we could return a pair with +0 with current position matches and -0 current position does not match but no further bytes are available
void	posToStart() Optional operation.
int	read(ByteBuffer dst)
int	readBroken(ByteBuffer dst)
String	readString(int len)
void	setPos(long pos) Optional operation.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.aksw.jena_sparql_api.io.binseach.Seekable

binarySearch, cloneObject, compareArrays, deltaPos, get, nextPos, peekNextBytes, posToNext, posToPrev, prevPos, size

Field Detail

startBlockRef

protected Reference<Block> startBlockRef

startPosInStartSegment

protected int startPosInStartSegment

exposedStartPos

protected long exposedStartPos

The start position exposed - may be non-zero or even negative!

maxPos

protected long maxPos

minPos

protected long minPos

currentBlockRef

protected Reference<Block> currentBlockRef

currentBlock

protected Block currentBlock

currentSeekable

protected Seekable currentSeekable

actualPos

protected long actualPos

Constructor Detail

SeekableFromBlock

public SeekableFromBlock(Reference<Block> startBlockRef,
                         int posInStartSegment,
                         long exposedStartPos)

SeekableFromBlock

public SeekableFromBlock(Reference<Block> startBlockRef,
                         int posInStartSegment,
                         long exposedStartPos,
                         long minPos,
                         long maxPos)

Method Detail

init

protected void init()

isOpen

public boolean isOpen()

Specified by:

isOpen in interface Channel

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Channel

Specified by:

close in interface Seekable

Throws:

IOException

clone

public Seekable clone()

Specified by:

clone in interface Seekable

Overrides:

clone in class Object

getPos

public long getPos()
            throws IOException

Description copied from interface: Seekable

Optional operation. Get the position in this seekable

Specified by:

getPos in interface Seekable

Returns:

Throws:

IOException

setPos

public void setPos(long pos)
            throws IOException

Description copied from interface: Seekable

Optional operation. Get the position in this seekable

Specified by:

setPos in interface Seekable

Throws:

IOException

posToStart

public void posToStart()
                throws IOException

Description copied from interface: Seekable

Optional operation. Move one unit before the start of the seekable; raises an exception on infinite seekables

Specified by:

posToStart in interface Seekable

Throws:

IOException

posToEnd

public void posToEnd()
              throws IOException

Description copied from interface: Seekable

Optional operation. Move to one unit beyond the end of the seekable; raises an exception on infinite seekables

Specified by:

posToEnd in interface Seekable

Throws:

IOException

isPosBeforeStart

public boolean isPosBeforeStart()
                         throws IOException

Description copied from interface: Seekable

The state of a seekable may be one unit before the start. In this state, if the seekable is non-empty, nextPos(1) must be a valid position

Specified by:

isPosBeforeStart in interface Seekable

Returns:

Throws:

IOException

isPosAfterEnd

public boolean isPosAfterEnd()
                      throws IOException

Description copied from interface: Seekable

The state of a seekable may be one unit beyond the end. In this state, if the seekable is non-empty, prevPos(1) must be a valid position

Specified by:

isPosAfterEnd in interface Seekable

Returns:

Throws:

IOException

loadNextBlock

protected boolean loadNextBlock()
                         throws IOException

Throws:

IOException

posToNext

public int posToNext(byte delimiter,
                     boolean changePos)
              throws IOException

positive: relative position issue: 0 means no position change, but it does not tell whether the current position is a match or not we could return a pair with +0 with current position matches and -0 current position does not match but no further bytes are available

Specified by:

posToNext in interface Seekable

changePos - If no delimiter is found, move the pos to the end

Returns:

Throws:

IOException

compareToPrefix

public int compareToPrefix(byte[] prefix)
                    throws IOException

Description copied from interface: Seekable

Compare the bytes at the current position to a given sequence of bytes If there are fewer bytes available in the seekable than provide for comparison, then only that many are compared. This default implementation uses read(ByteBuffer). Other implementations may override this behavior to compare the given prefix directly against their internal data structures without the intermediate buffer copy due to read.

Specified by:

compareToPrefix in interface Seekable

Returns:

Throws:

IOException

checkNext

public int checkNext(int len,
                     boolean changePos)
              throws IOException

Description copied from interface: Seekable

Attempt to advance the position by the given number of bytes. Return the number of bytes by which the position was changed. Returning less bytes than requested implies that a end position was reached which cannot be passed. This method cannot pass beyond the end - i.e. isPosAfterEnd cannot change from false to true by calling this method.

Specified by:

checkNext in interface Seekable

Returns:

Throws:

IOException

checkPrev

public int checkPrev(int len,
                     boolean changePos)
              throws IOException

Specified by:

checkPrev in interface Seekable

Throws:

IOException

get

public byte get()
         throws IOException

Description copied from interface: Seekable

Read a byte at the current position

Specified by:

get in interface Seekable

Returns:

The byte at the current position if the position is valid

Throws:

IOException

read

public int read(ByteBuffer dst)
         throws IOException

Specified by:

read in interface ReadableByteChannel

Specified by:

read in interface Seekable

Throws:

IOException

readBroken

public int readBroken(ByteBuffer dst)
               throws IOException

Throws:

IOException

readString

public String readString(int len)
                  throws IOException

Specified by:

readString in interface Seekable

Throws:

IOException