java.lang.Object
- org.apache.lucene.codecs.MultiLevelSkipListReader

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. 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.

Nested Class Summary

Nested Classes
Modifier and Type Class Description

private static class MultiLevelSkipListReader.SkipBuffer
used to buffer the top skip levels

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 index
`private int`	`numberOfLevelsToBuffer`
`protected int`	`numberOfSkipLevels`	number of levels in this skip list
`private 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.

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

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 of `skipTo(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 levels
`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
  - numberOfSkipLevels
```
protected int numberOfSkipLevels
```
    number of levels in this skip list
  - numberOfLevelsToBuffer
```
private int numberOfLevelsToBuffer
```
  - docCount
```
private int docCount
```
  - skipStream
```
private IndexInput[] skipStream
```
    skipStream for each level.
  - skipPointer
```
private long[] skipPointer
```
    The start pointer of each skip level.
  - skipInterval
```
private int[] skipInterval
```
    skipInterval of each level.
  - 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.
  - skipDoc
```
protected int[] skipDoc
```
    Doc id of current skip entry per level.
  - lastDoc
```
private int lastDoc
```
    Doc id of last read skip entry with docId <= target.
  - childPointer
```
private long[] childPointer
```
    Child pointer of current skip entry per level.
  - lastChildPointer
```
private long lastChildPointer
```
    childPointer of last read skip entry with docId <= target.
  - inputIsBuffered
```
private boolean inputIsBuffered
```
  - skipMultiplier
```
private final int skipMultiplier
```
- 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 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
  - loadNextSkip
```
private boolean loadNextSkip(int level)
                      throws java.io.IOException
```
    Throws:
    
    java.io.IOException
  - seekChild
```
protected void seekChild(int level)
                  throws java.io.IOException
```
    Seeks the skip entry on the given level
    
    Throws:
    
    java.io.IOException
  - close
```
public void close()
           throws java.io.IOException
```
    Specified by:
    
    close in interface java.lang.AutoCloseable
    
    Specified by:
    
    close in interface java.io.Closeable
    
    Throws:
    
    java.io.IOException
  - 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
  - loadSkipLevels
```
private void loadSkipLevels()
                     throws java.io.IOException
```
    Loads the skip levels
    
    Throws:
    
    java.io.IOException
  - 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 from
    
    skipStream - the skip stream to read from
    
    Throws:
    
    java.io.IOException
  - setLastSkipData
```
protected void setLastSkipData(int level)
```
    Copies the values of the last read skip entry on this level

Class MultiLevelSkipListReader

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

maxNumberOfSkipLevels

numberOfSkipLevels

numberOfLevelsToBuffer

docCount

skipStream

skipPointer

skipInterval

numSkipped

skipDoc

lastDoc

childPointer

lastChildPointer

inputIsBuffered

skipMultiplier

Constructor Detail

MultiLevelSkipListReader

MultiLevelSkipListReader

Method Detail

getDoc

skipTo

loadNextSkip

seekChild

close

init

loadSkipLevels

readSkipData

setLastSkipData