org.apache.lucene.facet.complements
Class TotalFacetCountsCache

java.lang.Object
  org.apache.lucene.facet.complements.TotalFacetCountsCache

public final class TotalFacetCountsCache
extends Object

Manage an LRU cache for TotalFacetCounts per index, taxonomy, and facet indexing params.

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

Field Summary

static int

DEFAULT_CACHE_SIZE Default size of in memory cache for computed total facet counts.

Method Summary

void	clear() Clear the cache.
int	getCacheSize()
static TotalFacetCountsCache	getSingleton() Get the single instance of this cache
TotalFacetCounts	getTotalCounts(IndexReader indexReader, TaxonomyReader taxonomy, FacetIndexingParams facetIndexingParams) Get the total facet counts for a reader/taxonomy pair and facet indexing parameters.
void	load(File inputFile, IndexReader indexReader, TaxonomyReader taxonomy, FacetIndexingParams facetIndexingParams) Load TotalFacetCounts matching input parameters from the provided outputFile and add them into the cache for the provided indexReader, taxonomy, and facetIndexingParams.
void	setCacheSize(int size) Set the number of TotalFacetCounts arrays that will remain in memory cache.
void	store(File outputFile, IndexReader indexReader, TaxonomyReader taxonomy, FacetIndexingParams facetIndexingParams) Store the TotalFacetCounts matching input parameters into the provided outputFile, making them available for a later call to load(File, IndexReader, TaxonomyReader, FacetIndexingParams).

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CACHE_SIZE

public static final int DEFAULT_CACHE_SIZE

Default size of in memory cache for computed total facet counts. Set to 2 for the case when an application reopened a reader and the original one is still in use (Otherwise there will be switching again and again between the two.)

See Also:

Constant Field Values

Method Detail

getSingleton

public static TotalFacetCountsCache getSingleton()

Get the single instance of this cache

getTotalCounts

public TotalFacetCounts getTotalCounts(IndexReader indexReader,
                                       TaxonomyReader taxonomy,
                                       FacetIndexingParams facetIndexingParams)
                                throws IOException

Get the total facet counts for a reader/taxonomy pair and facet indexing parameters. If not in cache, computed here and added to the cache for later use.

Parameters:

indexReader - the documents index

taxonomy - the taxonomy index

facetIndexingParams - facet indexing parameters

Returns:

the total facet counts.

Throws:

IOException

load

public void load(File inputFile,
                 IndexReader indexReader,
                 TaxonomyReader taxonomy,
                 FacetIndexingParams facetIndexingParams)
          throws IOException

Load TotalFacetCounts matching input parameters from the provided outputFile and add them into the cache for the provided indexReader, taxonomy, and facetIndexingParams. If a TotalFacetCounts for these parameters already exists in the cache, it will be replaced by the loaded one.

Parameters:

inputFile - file from which to read the data

indexReader - the documents index

taxonomy - the taxonomy index

facetIndexingParams - the facet indexing parameters

Throws:

IOException - on error

store

public void store(File outputFile,
                  IndexReader indexReader,
                  TaxonomyReader taxonomy,
                  FacetIndexingParams facetIndexingParams)
           throws IOException

Store the TotalFacetCounts matching input parameters into the provided outputFile, making them available for a later call to load(File, IndexReader, TaxonomyReader, FacetIndexingParams). If these TotalFacetCounts are available in the cache, they are used. But if they are not in the cache, this call will first compute them (which will also add them to the cache).

Parameters:

outputFile - file to store in.

indexReader - the documents index

taxonomy - the taxonomy index

facetIndexingParams - the facet indexing parameters

Throws:

IOException - on error

See Also:

load(File, IndexReader, TaxonomyReader, FacetIndexingParams)

clear

public void clear()

Clear the cache.

getCacheSize

public int getCacheSize()

Returns:

the maximal cache size

setCacheSize

public void setCacheSize(int size)

Set the number of TotalFacetCounts arrays that will remain in memory cache.

If new size is smaller than current size, the cache is appropriately trimmed.

Minimal size is 1, so passing zero or negative size would result in size of 1.

Parameters:

size - new size to set