org.apache.lucene.search

Class UsageTrackingFilterCachingPolicy

java.lang.Object

org.apache.lucene.search.UsageTrackingFilterCachingPolicy

All Implemented Interfaces:

FilterCachingPolicy

public final class UsageTrackingFilterCachingPolicy
extends Object
implements FilterCachingPolicy

A FilterCachingPolicy that tracks usage statistics of recently-used filters in order to decide on which filters are worth caching. It also uses some heuristics on segments, filters and the doc id sets that they produce in order to cache more aggressively when the execution cost significantly outweighs the caching overhead.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.lucene.search.FilterCachingPolicy

FilterCachingPolicy.CacheOnLargeSegments

Field Summary

Fields inherited from interface org.apache.lucene.search.FilterCachingPolicy

ALWAYS_CACHE

Constructor Summary

Constructors

Constructor and Description
UsageTrackingFilterCachingPolicy() Create a new instance with sensible defaults.
UsageTrackingFilterCachingPolicy(float minSizeRatio, int historySize, int minFrequencyCostlyFilters, int minFrequencyCheapFilters, int minFrequencyOtherFilters) Create a new instance.

Method Summary

Methods

Modifier and Type	Method and Description
void	onUse(Filter filter) Callback that is called every time that a cached filter is used.
boolean	shouldCache(Filter filter, LeafReaderContext context, DocIdSet set) Whether the given DocIdSet should be cached on a given segment.

Methods inherited from class java.lang.Object

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

Constructor Detail

UsageTrackingFilterCachingPolicy

public UsageTrackingFilterCachingPolicy(float minSizeRatio,
                                int historySize,
                                int minFrequencyCostlyFilters,
                                int minFrequencyCheapFilters,
                                int minFrequencyOtherFilters)

Create a new instance.

Parameters:

minSizeRatio - the minimum size ratio for segments to be cached, see FilterCachingPolicy.CacheOnLargeSegments

historySize - the number of recently used filters to track

minFrequencyCostlyFilters - how many times filters whose getDocIdSet method is expensive should have been seen before being cached

minFrequencyCheapFilters - how many times filters that produce DocIdSets that are cheap to cached should have been seen before being cached

minFrequencyOtherFilters - how many times other filters should have been seen before being cached

UsageTrackingFilterCachingPolicy

public UsageTrackingFilterCachingPolicy()

Create a new instance with sensible defaults.

Method Detail

onUse

public void onUse(Filter filter)

Description copied from interface: FilterCachingPolicy

Callback that is called every time that a cached filter is used. This is typically useful if the policy wants to track usage statistics in order to make decisions.

Specified by:

onUse in interface FilterCachingPolicy

shouldCache

public boolean shouldCache(Filter filter,
                  LeafReaderContext context,
                  DocIdSet set)
                    throws IOException

Description copied from interface: FilterCachingPolicy

Whether the given DocIdSet should be cached on a given segment. This method will be called on each leaf context to know if the filter should be cached on this particular leaf. The filter cache will first attempt to load a DocIdSet from the cache. If it is not cached yet and this method returns true then a cache entry will be generated. Otherwise an uncached set will be returned.

Specified by:

shouldCache in interface FilterCachingPolicy

Throws:

IOException