Package org.apache.lucene.search

Class TopScoreDocCollectorManager

java.lang.Object

org.apache.lucene.search.TopScoreDocCollectorManager

All Implemented Interfaces:

CollectorManager<TopScoreDocCollector,TopDocs>

public class TopScoreDocCollectorManager
extends Object
implements CollectorManager<TopScoreDocCollector,TopDocs>

Create a TopScoreDocCollectorManager which uses a shared hit counter to maintain number of hits and a shared MaxScoreAccumulator to propagate the minimum score across segments

Note that a new collectorManager should be created for each search due to its internal states.

Constructor Summary

Constructors

Constructor	Description
TopScoreDocCollectorManager(int numHits, int totalHitsThreshold)	Creates a new TopScoreDocCollectorManager given the number of hits to collect and the number of hits to count accurately, with thread-safe internal states.
TopScoreDocCollectorManager(int numHits, ScoreDoc after, int totalHitsThreshold)	Creates a new TopScoreDocCollectorManager given the number of hits to collect and the number of hits to count accurately, with thread-safe internal states.
TopScoreDocCollectorManager(int numHits, ScoreDoc after, int totalHitsThreshold, boolean supportsConcurrency)	Creates a new TopScoreDocCollectorManager given the number of hits to collect and the number of hits to count accurately.

Method Summary

Modifier and Type	Method	Description
TopScoreDocCollector	newCollector()	Return a new Collector.
TopDocs	reduce(Collection<TopScoreDocCollector> collectors)	Reduce the results of individual collectors into a meaningful result.

Methods inherited from class java.lang.Object

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

Constructor Detail

TopScoreDocCollectorManager

public TopScoreDocCollectorManager(int numHits,
                                   ScoreDoc after,
                                   int totalHitsThreshold,
                                   boolean supportsConcurrency)

Creates a new TopScoreDocCollectorManager given the number of hits to collect and the number of hits to count accurately.

NOTE: If the total hit count of the top docs is less than or exactly totalHitsThreshold then this value is accurate. On the other hand, if the TopDocs.totalHits value is greater than totalHitsThreshold then its value is a lower bound of the hit count. A value of Integer.MAX_VALUE will make the hit count accurate but will also likely make query processing slower.

NOTE: The instances returned by this method pre-allocate a full array of length numHits, and fill the array with sentinel objects.

Parameters:

numHits - the number of results to collect.

after - the previous doc after which matching docs will be collected.

totalHitsThreshold - the number of docs to count accurately. If the query matches more than totalHitsThreshold hits then its hit count will be a lower bound. On the other hand if the query matches less than or exactly totalHitsThreshold hits then the hit count of the result will be accurate. Integer.MAX_VALUE may be used to make the hit count accurate, but this will also make query processing slower.

supportsConcurrency - to use thread-safe and slower internal states for count tracking.

TopScoreDocCollectorManager

public TopScoreDocCollectorManager(int numHits,
                                   ScoreDoc after,
                                   int totalHitsThreshold)

Creates a new TopScoreDocCollectorManager given the number of hits to collect and the number of hits to count accurately, with thread-safe internal states.

NOTE: If the total hit count of the top docs is less than or exactly totalHitsThreshold then this value is accurate. On the other hand, if the TopDocs.totalHits value is greater than totalHitsThreshold then its value is a lower bound of the hit count. A value of Integer.MAX_VALUE will make the hit count accurate but will also likely make query processing slower.

NOTE: The instances returned by this method pre-allocate a full array of length numHits, and fill the array with sentinel objects.

Parameters:

numHits - the number of results to collect.

after - the previous doc after which matching docs will be collected.

totalHitsThreshold - the number of docs to count accurately. If the query matches more than totalHitsThreshold hits then its hit count will be a lower bound. On the other hand if the query matches less than or exactly totalHitsThreshold hits then the hit count of the result will be accurate. Integer.MAX_VALUE may be used to make the hit count accurate, but this will also make query processing slower.

TopScoreDocCollectorManager

public TopScoreDocCollectorManager(int numHits,
                                   int totalHitsThreshold)

Creates a new TopScoreDocCollectorManager given the number of hits to collect and the number of hits to count accurately, with thread-safe internal states.

NOTE: If the total hit count of the top docs is less than or exactly totalHitsThreshold then this value is accurate. On the other hand, if the TopDocs.totalHits value is greater than totalHitsThreshold then its value is a lower bound of the hit count. A value of Integer.MAX_VALUE will make the hit count accurate but will also likely make query processing slower.

NOTE: The instances returned by this method pre-allocate a full array of length numHits, and fill the array with sentinel objects.

Parameters:

numHits - the number of results to collect.

totalHitsThreshold - the number of docs to count accurately. If the query matches more than totalHitsThreshold hits then its hit count will be a lower bound. On the other hand if the query matches less than or exactly totalHitsThreshold hits then the hit count of the result will be accurate. Integer.MAX_VALUE may be used to make the hit count accurate, but this will also make query processing slower.

Method Detail

newCollector

public TopScoreDocCollector newCollector()

Description copied from interface: CollectorManager

Return a new Collector. This must return a different instance on each call.

Specified by:

newCollector in interface CollectorManager<TopScoreDocCollector,TopDocs>

reduce

public TopDocs reduce(Collection<TopScoreDocCollector> collectors)
               throws IOException

Description copied from interface: CollectorManager

Reduce the results of individual collectors into a meaningful result. For instance a TopDocsCollector would compute the top docs of each collector and then merge them using TopDocs.merge(int, TopDocs[]). This method must be called after collection is finished on all provided collectors.

Specified by:

reduce in interface CollectorManager<TopScoreDocCollector,TopDocs>

Throws:

IOException