Class Cl2oTaxonomyWriterCache
- java.lang.Object
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- org.apache.lucene.facet.taxonomy.writercache.cl2o.Cl2oTaxonomyWriterCache
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- All Implemented Interfaces:
TaxonomyWriterCache
public class Cl2oTaxonomyWriterCache extends Object implements TaxonomyWriterCache
TaxonomyWriterCache
usingCompactLabelToOrdinal
. Although called cache, it maintains in memory all the mappings from category to ordinal, relying on thatCompactLabelToOrdinal
is an efficient mapping for this purpose.- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Constructor Summary
Constructors Constructor Description Cl2oTaxonomyWriterCache(int initialCapcity, float loadFactor, int numHashArrays)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
close()
Let go of whatever resources the cache is holding.int
get(CategoryPath categoryPath)
Lookup a category in the cache, returning its ordinal, or a negative number if the category is not in the cache.int
get(CategoryPath categoryPath, int length)
LikeTaxonomyWriterCache.get(CategoryPath)
, but for a given prefix of the category path.int
getMemoryUsage()
Returns the number of bytes in memory used by this object.boolean
hasRoom(int n)
Sometimes the cache is either unlimited in size, or limited by a very big size, and in that case when we add a lot of categories it might make sense to pre-load the cache with all the existing categories.boolean
put(CategoryPath categoryPath, int ordinal)
Add a category to the cache, with the given ordinal as the value.boolean
put(CategoryPath categoryPath, int prefixLen, int ordinal)
LikeTaxonomyWriterCache.put(CategoryPath, int)
, but for a given prefix of the category path.
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Method Detail
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close
public void close()
Description copied from interface:TaxonomyWriterCache
Let go of whatever resources the cache is holding. After a close(), this object can no longer be used.- Specified by:
close
in interfaceTaxonomyWriterCache
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hasRoom
public boolean hasRoom(int n)
Description copied from interface:TaxonomyWriterCache
Sometimes the cache is either unlimited in size, or limited by a very big size, and in that case when we add a lot of categories it might make sense to pre-load the cache with all the existing categories. However, this pre-load does not make sense when the allowed cache size is small. The hasRoom() method allows to differentiate between these cases.After hasRoom(n) returned
true
, the following n put() should return false (meaning that the cache was not cleared).- Specified by:
hasRoom
in interfaceTaxonomyWriterCache
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get
public int get(CategoryPath categoryPath)
Description copied from interface:TaxonomyWriterCache
Lookup a category in the cache, returning its ordinal, or a negative number if the category is not in the cache.It is up to the caller to remember what a negative response means: If the caller knows the cache is complete (it was initially fed with all the categories, and since then put() never returned true) it means the category does not exist. Otherwise, the category might still exist, but just be missing from the cache.
- Specified by:
get
in interfaceTaxonomyWriterCache
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get
public int get(CategoryPath categoryPath, int length)
Description copied from interface:TaxonomyWriterCache
LikeTaxonomyWriterCache.get(CategoryPath)
, but for a given prefix of the category path.If the given length is negative or bigger than the path's actual length, the full path is taken.
- Specified by:
get
in interfaceTaxonomyWriterCache
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put
public boolean put(CategoryPath categoryPath, int ordinal)
Description copied from interface:TaxonomyWriterCache
Add a category to the cache, with the given ordinal as the value.If the implementation keeps only a partial cache (e.g., an LRU cache) and finds that its cache is full, it should clear up part of the cache and return
true
. Otherwise, it should returnfalse
.The reason why the caller needs to know if part of the cache was cleared is that in that case it will have to commit its on-disk index (so that all the latest category additions can be searched on disk, if we can't rely on the cache to contain them).
Ordinals should be non-negative. Currently there is no defined way to specify that a cache should remember a category does NOT exist. It doesn't really matter, because normally the next thing we do after finding that a category does not exist is to add it.
- Specified by:
put
in interfaceTaxonomyWriterCache
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put
public boolean put(CategoryPath categoryPath, int prefixLen, int ordinal)
Description copied from interface:TaxonomyWriterCache
LikeTaxonomyWriterCache.put(CategoryPath, int)
, but for a given prefix of the category path.If the given length is negative or bigger than the path's actual length, the full path is taken.
- Specified by:
put
in interfaceTaxonomyWriterCache
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getMemoryUsage
public int getMemoryUsage()
Returns the number of bytes in memory used by this object.- Returns:
- Number of bytes in memory used by this object.
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