Class MultiLevelSkipListWriter

This abstract class writes skip lists with multiple levels.

Example for skipInterval = 3:
                                                    c            (skip level 2)
                c                 c                 c            (skip level 1)
    x     x     x     x     x     x     x     x     x     x      (skip level 0)
d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d  (posting list)
    3     6     9     12    15    18    21    24    27    30     (df)

d - document
x - skip data
c - skip data with child pointer

Skip level i contains every skipInterval-th entry from skip level i-1.
Therefore the number of entries on level i is: floor(df / ((skipInterval ^ (i + 1))).

Each skip entry on a level i>0 contains a pointer to the corresponding skip entry in list i-1.
this guarantees a logarithmic amount of skips to find the target document.

While this class takes care of writing the different skip levels,
subclasses must define the actual format of the skip data.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk

Inheritance

System.Object

MultiLevelSkipListWriter

Namespace: Lucene.Net.Codecs

Assembly: Lucene.Net.dll

Syntax

public abstract class MultiLevelSkipListWriter : object

Constructors

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MultiLevelSkipListWriter(Int32, Int32, Int32)

Creates a MultiLevelSkipListWriter, where Lucene.Net.Codecs.MultiLevelSkipListWriter.skipInterval and Lucene.Net.Codecs.MultiLevelSkipListWriter.skipMultiplier are the same.

Declaration

protected MultiLevelSkipListWriter(int skipInterval, int maxSkipLevels, int df)

Parameters

Type	Name	Description
System.Int32	skipInterval
System.Int32	maxSkipLevels
System.Int32	df

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MultiLevelSkipListWriter(Int32, Int32, Int32, Int32)

Creates a MultiLevelSkipListWriter.

Declaration

protected MultiLevelSkipListWriter(int skipInterval, int skipMultiplier, int maxSkipLevels, int df)

Parameters

Type	Name	Description
System.Int32	skipInterval
System.Int32	skipMultiplier
System.Int32	maxSkipLevels
System.Int32	df

Fields

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m_numberOfSkipLevels

Number of levels in this skip list.

Declaration

protected int m_numberOfSkipLevels

Field Value

Type	Description
System.Int32

Methods

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BufferSkip(Int32)

Writes the current skip data to the buffers. The current document frequency determines the max level is skip data is to be written to.

Declaration

public virtual void BufferSkip(int df)

Parameters

Type	Name	Description
System.Int32	df	The current document frequency.

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Init()

Allocates internal skip buffers.

Declaration

protected virtual void Init()

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ResetSkip()

Creates new buffers or empties the existing ones.

Declaration

public virtual void ResetSkip()

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WriteSkip(IndexOutput)

Writes the buffered skip lists to the given output.

Declaration

public virtual long WriteSkip(IndexOutput output)

Parameters

Type	Name	Description
IndexOutput	output	The IndexOutput the skip lists shall be written to.

Returns

Type	Description
System.Int64	The pointer the skip list starts.

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WriteSkipData(Int32, IndexOutput)

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

Declaration

protected abstract void WriteSkipData(int level, IndexOutput skipBuffer)

Parameters

Type	Name	Description
System.Int32	level	The level skip data shall be writing for.
IndexOutput	skipBuffer	The skip buffer to write to.