Package com.atlassian.jira.util.cache

Class CompositeKeyCache<R,S,T>

java.lang.Object
com.atlassian.jira.util.cache.CompositeKeyCache<R,S,T>
Type Parameters:
R - the first key, usually a string. Must be a type that can be used as a map key (ie. immutable with correct equals/hashcode).
S - the field name, usually a string. Must be a type that can be used as a map key (ie. immutable with correct equals/hashcode).
T - the result thing.
public class CompositeKeyCache<R,S,T> extends Object
Cache of (R, S) -> T. Designed to be used for general mappings of things to a field in an index.

Usage: 

 CompositeKeyCache<IndexReader, String, Collection<String>[]> cache = CompositeKeyCache.createWeakFirstKeySoftValueCache();
 cache.get(reader, fieldName,
     new Supplier<Collection<String>[]>()
     {
         public Collection<String>[] get()
         {
             return doStuff(reader, fieldName);
         }
     }
 );

  • Method Details

    • createWeakFirstKeySoftValueCache

      public static <R, S, T> CompositeKeyCache<R,S,T> createWeakFirstKeySoftValueCache(String cacheName)
      This cache caches the first (R) reference weakly, the second (S) reference strongly and the value (T) reference softly. This is specifically designed for use with Lucene where the IndexReader is being recycled regularly (the R) and the terms (T) may be softly referenced.
      Type Parameters:
      R - the first key type
      S - the second key type
      T - the value type
      Parameters:
      cacheName - A Name to use when we instrument an instance of this cache. If null the cache will not be instrumented
      Returns:
      a cache with weak references to the first key and soft references to the value.

    • createWeakFirstKeySoftValueCache

      @Deprecated public static <R, S, T> CompositeKeyCache<R,S,T> createWeakFirstKeySoftValueCache()
      Deprecated.
      A useful way to build the cche for testing as instrumentation requires the ComponentAccessor to be initialised.
      Since:
      v5.2 please supply a name so we can instrument this cache.

    • get

      public T get(@Nonnull R one, @Nonnull S two, Supplier<T> supplier)
      Get the thing mapped to this key for the specified reader.
      Parameters:
      one - the first one
      two - the second one
      supplier - to generate the value if not already there, only called if not already cached.
      Returns:
      the cached value