Package com.opencqrs.framework.command.cache

Class LruInMemoryStateRebuildingCache

java.lang.Object

com.opencqrs.framework.command.cache.LruInMemoryStateRebuildingCache

All Implemented Interfaces:

StateRebuildingCache

public class LruInMemoryStateRebuildingCache
extends Object
implements StateRebuildingCache

StateRebuildingCache implementation backed by a synchronized LinkedHashMap with configurable maximum capacity and LRU semantics.

Nested Class Summary

Nested classes/interfaces inherited from interface com.opencqrs.framework.command.cache.StateRebuildingCache

StateRebuildingCache.CacheKey<I>, StateRebuildingCache.CacheValue<I>

Constructor Summary

Constructors

Constructor	Description
LruInMemoryStateRebuildingCache(int capacity)	Configures this with a maximum capacity.

Method Summary

Modifier and Type	Method	Description
<I> StateRebuildingCache.CacheValue<I>	fetchAndMerge(StateRebuildingCache.CacheKey<I> key, Function<StateRebuildingCache.CacheValue<I>,StateRebuildingCache.CacheValue<I>> mergeFunction)	Method supposed to fetch a StateRebuildingCache.CacheValue from the underlying cache based on the given StateRebuildingCache.CacheKey.

Methods inherited from class java.lang.Object

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

Constructor Details

LruInMemoryStateRebuildingCache

public LruInMemoryStateRebuildingCache(int capacity)

Configures this with a maximum capacity.

Parameters:

capacity - the maximum number of StateRebuildingCache.CacheValues to keep, before discarding exceed entries

Method Details

fetchAndMerge

public <I> StateRebuildingCache.CacheValue<I> fetchAndMerge(StateRebuildingCache.CacheKey<I> key,
 Function<StateRebuildingCache.CacheValue<I>,StateRebuildingCache.CacheValue<I>> mergeFunction)

Description copied from interface: StateRebuildingCache

Method supposed to fetch a StateRebuildingCache.CacheValue from the underlying cache based on the given StateRebuildingCache.CacheKey. The cached value is applied to the given mergeFunction, the underlying cache updated with the merged StateRebuildingCache.CacheValue, before it is returned to the caller. Implementations may choose to return an even newer StateRebuildingCache.CacheValue, if concurrent merges occur.

Specified by:

fetchAndMerge in interface StateRebuildingCache

Type Parameters:

I - the generic instance type being cached

Parameters:

key - the cache key

mergeFunction - a merge function updating a StateRebuildingCache.CacheValue previously cached, typically by fetching newer events, applying them to the instance and returning the merged value, which will then be applied to the underlying cache (if no newer value has already been applied concurrently, depending on the concurrency guarantees of the implementation). In case of a cache miss, a StateRebuildingCache.CacheValue with null contents will be passed to the merge function, as annotated.

Returns:

the fetched and merged cache value