Package org.apache.lucene.codecs

Class MultiLevelSkipListReader

java.lang.Object

org.apache.lucene.codecs.MultiLevelSkipListReader

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

Lucene40SkipListReader

public abstract class MultiLevelSkipListReader
extends Object
implements Closeable

This abstract class reads skip lists with multiple levels. See MultiLevelSkipListWriter for the information about the encoding of the multi level skip lists. Subclasses must implement the abstract method readSkipData(int, IndexInput) which defines the actual format of the skip data.

Field Summary

Fields

Modifier and Type	Field	Description
protected int	maxNumberOfSkipLevels	the maximum number of skip levels possible for this index
protected int[]	skipDoc	Doc id of current skip entry per level.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	MultiLevelSkipListReader(IndexInput skipStream, int maxSkipLevels, int skipInterval)	Creates a MultiLevelSkipListReader, where skipInterval and skipMultiplier are the same.
protected	MultiLevelSkipListReader(IndexInput skipStream, int maxSkipLevels, int skipInterval, int skipMultiplier)	Creates a MultiLevelSkipListReader.

Method Summary

Modifier and Type	Method	Description
void	close()
int	getDoc()	Returns the id of the doc to which the last call of skipTo(int) has skipped.
void	init(long skipPointer, int df)	Initializes the reader, for reuse on a new term.
protected abstract int	readSkipData(int level, IndexInput skipStream)	Subclasses must implement the actual skip data encoding in this method.
protected void	seekChild(int level)	Seeks the skip entry on the given level
protected void	setLastSkipData(int level)	Copies the values of the last read skip entry on this level
int	skipTo(int target)	Skips entries to the first beyond the current whose document number is greater than or equal to target.

Methods inherited from class java.lang.Object

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

Field Detail

maxNumberOfSkipLevels

protected int maxNumberOfSkipLevels

the maximum number of skip levels possible for this index

skipDoc

protected int[] skipDoc

Doc id of current skip entry per level.

Constructor Detail

MultiLevelSkipListReader

protected MultiLevelSkipListReader(IndexInput skipStream,
                                   int maxSkipLevels,
                                   int skipInterval,
                                   int skipMultiplier)

Creates a MultiLevelSkipListReader.

MultiLevelSkipListReader

protected MultiLevelSkipListReader(IndexInput skipStream,
                                   int maxSkipLevels,
                                   int skipInterval)

Creates a MultiLevelSkipListReader, where skipInterval and skipMultiplier are the same.

Method Detail

getDoc

public int getDoc()

Returns the id of the doc to which the last call of skipTo(int) has skipped.

skipTo

public int skipTo(int target)
           throws IOException

Skips entries to the first beyond the current whose document number is greater than or equal to target. Returns the current doc count.

Throws:

IOException

seekChild

protected void seekChild(int level)
                  throws IOException

Seeks the skip entry on the given level

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

init

public void init(long skipPointer,
                 int df)

Initializes the reader, for reuse on a new term.

readSkipData

protected abstract int readSkipData(int level,
                                    IndexInput skipStream)
                             throws IOException

Subclasses must implement the actual skip data encoding in this method.

Parameters:

level - the level skip data shall be read from

skipStream - the skip stream to read from

Throws:

IOException

setLastSkipData

protected void setLastSkipData(int level)

Copies the values of the last read skip entry on this level