Lucene::MultiLevelSkipListWriter Class Reference

This abstract class writes skip lists with multiple levels. More...

#include <MultiLevelSkipListWriter.h>

Inheritance diagram for Lucene::MultiLevelSkipListWriter:

Public Member Functions
	MultiLevelSkipListWriter (int32_t skipInterval, int32_t maxSkipLevels, int32_t df)
virtual	~MultiLevelSkipListWriter ()
virtual String	getClassName ()
boost::shared_ptr< MultiLevelSkipListWriter >	shared_from_this ()
void	bufferSkip (int32_t df)
	Writes the current skip data to the buffers. The current document frequency determines the max level is skip data is to be written to. More...
int64_t	writeSkip (const IndexOutputPtr &output)
	Writes the buffered skip lists to the given output. More...
Public Member Functions inherited from Lucene::LuceneObject
virtual	~LuceneObject ()
virtual void	initialize ()
	Called directly after instantiation to create objects that depend on this object being fully constructed. More...
virtual LuceneObjectPtr	clone (const LuceneObjectPtr &other=LuceneObjectPtr())
	Return clone of this object. More...
virtual int32_t	hashCode ()
	Return hash code for this object. More...
virtual bool	equals (const LuceneObjectPtr &other)
	Return whether two objects are equal. More...
virtual int32_t	compareTo (const LuceneObjectPtr &other)
	Compare two objects. More...
virtual String	toString ()
	Returns a string representation of the object. More...
Public Member Functions inherited from Lucene::LuceneSync
virtual	~LuceneSync ()
virtual SynchronizePtr	getSync ()
	Return this object synchronize lock. More...
virtual LuceneSignalPtr	getSignal ()
	Return this object signal. More...
virtual void	lock (int32_t timeout=0)
	Lock this object using an optional timeout. More...
virtual void	unlock ()
	Unlock this object. More...
virtual bool	holdsLock ()
	Returns true if this object is currently locked by current thread. More...
virtual void	wait (int32_t timeout=0)
	Wait for signal using an optional timeout. More...
virtual void	notifyAll ()
	Notify all threads waiting for signal. More...

Static Public Member Functions
static String	_getClassName ()

Protected Member Functions
void	init ()
virtual void	resetSkip ()
virtual void	writeSkipData (int32_t level, const IndexOutputPtr &skipBuffer)=0
	Subclasses must implement the actual skip data encoding in this method. More...
Protected Member Functions inherited from Lucene::LuceneObject
	LuceneObject ()

Protected Attributes
int32_t	numberOfSkipLevels
	number of levels in this skip list More...
int32_t	skipInterval
	the skip interval in the list with level = 0 More...
Collection< RAMOutputStreamPtr >	skipBuffer
	for every skip level a different buffer is used More...
Protected Attributes inherited from Lucene::LuceneSync
SynchronizePtr	objectLock
LuceneSignalPtr	objectSignal

Detailed Description

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.

Constructor & Destructor Documentation

Lucene::MultiLevelSkipListWriter::MultiLevelSkipListWriter	(	int32_t	skipInterval,
		int32_t	maxSkipLevels,
		int32_t	df
	)

virtual Lucene::MultiLevelSkipListWriter::~MultiLevelSkipListWriter ( )

virtual

Member Function Documentation

static String Lucene::MultiLevelSkipListWriter::_getClassName ( )

inlinestatic

void Lucene::MultiLevelSkipListWriter::bufferSkip

(

int32_t

df

)

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

Parameters

df	the current document frequency

virtual String Lucene::MultiLevelSkipListWriter::getClassName ( )

inlinevirtual

Reimplemented in Lucene::DefaultSkipListWriter.

void Lucene::MultiLevelSkipListWriter::init ( )

protected

virtual void Lucene::MultiLevelSkipListWriter::resetSkip ( )

protectedvirtual

Reimplemented in Lucene::DefaultSkipListWriter.

boost::shared_ptr< MultiLevelSkipListWriter > Lucene::MultiLevelSkipListWriter::shared_from_this ( )

inline

int64_t Lucene::MultiLevelSkipListWriter::writeSkip

(

const IndexOutputPtr &

output

)

Writes the buffered skip lists to the given output.

Parameters

output

the IndexOutput the skip lists shall be written to

Returns

the pointer the skip list starts

virtual void Lucene::MultiLevelSkipListWriter::writeSkipData ( int32_t  level, const IndexOutputPtr &  skipBuffer  )

protectedpure virtual

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

Parameters

level	the level skip data shall be writing for
skipBuffer	the skip buffer to write to

Implemented in Lucene::DefaultSkipListWriter.

Field Documentation

int32_t Lucene::MultiLevelSkipListWriter::numberOfSkipLevels

protected

number of levels in this skip list

Collection<RAMOutputStreamPtr> Lucene::MultiLevelSkipListWriter::skipBuffer

protected

for every skip level a different buffer is used

int32_t Lucene::MultiLevelSkipListWriter::skipInterval

protected

the skip interval in the list with level = 0

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The documentation for this class was generated from the following file:

• MultiLevelSkipListWriter.h