Package org.apache.lucene.codecs
Class MultiLevelSkipListReader
- java.lang.Object
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- org.apache.lucene.codecs.MultiLevelSkipListReader
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
- Direct Known Subclasses:
Lucene50SkipReader
,Lucene84SkipReader
public abstract class MultiLevelSkipListReader extends java.lang.Object implements java.io.Closeable
This abstract class reads skip lists with multiple levels. SeeMultiLevelSkipListWriter
for the information about the encoding of the multi level skip lists. Subclasses must implement the abstract methodreadSkipData(int, IndexInput)
which defines the actual format of the skip data.
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Nested Class Summary
Nested Classes Modifier and Type Class Description private static class
MultiLevelSkipListReader.SkipBuffer
used to buffer the top skip levels
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Field Summary
Fields Modifier and Type Field Description private long[]
childPointer
Child pointer of current skip entry per level.private int
docCount
private boolean
inputIsBuffered
private long
lastChildPointer
childPointer of last read skip entry with docId <= target.private int
lastDoc
Doc id of last read skip entry with docId <= target.protected int
maxNumberOfSkipLevels
the maximum number of skip levels possible for this indexprivate int
numberOfLevelsToBuffer
protected int
numberOfSkipLevels
number of levels in this skip listprivate int[]
numSkipped
Number of docs skipped per level.protected int[]
skipDoc
Doc id of current skip entry per level.private int[]
skipInterval
skipInterval of each level.private int
skipMultiplier
private long[]
skipPointer
The start pointer of each skip level.private IndexInput[]
skipStream
skipStream for each level.
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Constructor Summary
Constructors Modifier Constructor Description protected
MultiLevelSkipListReader(IndexInput skipStream, int maxSkipLevels, int skipInterval)
Creates aMultiLevelSkipListReader
, whereskipInterval
andskipMultiplier
are the same.protected
MultiLevelSkipListReader(IndexInput skipStream, int maxSkipLevels, int skipInterval, int skipMultiplier)
Creates aMultiLevelSkipListReader
.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description void
close()
int
getDoc()
Returns the id of the doc to which the last call ofskipTo(int)
has skipped.void
init(long skipPointer, int df)
Initializes the reader, for reuse on a new term.private boolean
loadNextSkip(int level)
private void
loadSkipLevels()
Loads the skip levelsprotected 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 levelprotected void
setLastSkipData(int level)
Copies the values of the last read skip entry on this levelint
skipTo(int target)
Skips entries to the first beyond the current whose document number is greater than or equal to target.
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Field Detail
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maxNumberOfSkipLevels
protected int maxNumberOfSkipLevels
the maximum number of skip levels possible for this index
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numberOfSkipLevels
protected int numberOfSkipLevels
number of levels in this skip list
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numberOfLevelsToBuffer
private int numberOfLevelsToBuffer
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docCount
private int docCount
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skipStream
private IndexInput[] skipStream
skipStream for each level.
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skipPointer
private long[] skipPointer
The start pointer of each skip level.
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skipInterval
private int[] skipInterval
skipInterval of each level.
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numSkipped
private int[] numSkipped
Number of docs skipped per level. It's possible for some values to overflow a signed int, but this has been accounted for.
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skipDoc
protected int[] skipDoc
Doc id of current skip entry per level.
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lastDoc
private int lastDoc
Doc id of last read skip entry with docId <= target.
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childPointer
private long[] childPointer
Child pointer of current skip entry per level.
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lastChildPointer
private long lastChildPointer
childPointer of last read skip entry with docId <= target.
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inputIsBuffered
private boolean inputIsBuffered
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skipMultiplier
private final int skipMultiplier
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Constructor Detail
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MultiLevelSkipListReader
protected MultiLevelSkipListReader(IndexInput skipStream, int maxSkipLevels, int skipInterval, int skipMultiplier)
Creates aMultiLevelSkipListReader
.
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MultiLevelSkipListReader
protected MultiLevelSkipListReader(IndexInput skipStream, int maxSkipLevels, int skipInterval)
Creates aMultiLevelSkipListReader
, whereskipInterval
andskipMultiplier
are the same.
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Method Detail
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getDoc
public int getDoc()
Returns the id of the doc to which the last call ofskipTo(int)
has skipped.
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skipTo
public int skipTo(int target) throws java.io.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:
java.io.IOException
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loadNextSkip
private boolean loadNextSkip(int level) throws java.io.IOException
- Throws:
java.io.IOException
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seekChild
protected void seekChild(int level) throws java.io.IOException
Seeks the skip entry on the given level- Throws:
java.io.IOException
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close
public void close() throws java.io.IOException
- Specified by:
close
in interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
- Throws:
java.io.IOException
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init
public void init(long skipPointer, int df) throws java.io.IOException
Initializes the reader, for reuse on a new term.- Throws:
java.io.IOException
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loadSkipLevels
private void loadSkipLevels() throws java.io.IOException
Loads the skip levels- Throws:
java.io.IOException
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readSkipData
protected abstract int readSkipData(int level, IndexInput skipStream) throws java.io.IOException
Subclasses must implement the actual skip data encoding in this method.- Parameters:
level
- the level skip data shall be read fromskipStream
- the skip stream to read from- Throws:
java.io.IOException
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setLastSkipData
protected void setLastSkipData(int level)
Copies the values of the last read skip entry on this level
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