public class MLRUItemStateCache extends Object implements ItemStateCache
ItemStateCache
implementation that internally uses a
LinkedMap
to maintain a cache of ItemState
objects. The
cache uses a rough estimate of the memory consumption of the cached item
states for calculating the maximum number of entries. The oldest entries
are flushed once the cache size has exceeded a certain limit.
TODO rename class to something more appropriate, e.g. FIFOItemSateCache since it doesn't use a LRU eviction policy anymore.
Modifier and Type | Field and Description |
---|---|
static int |
DEFAULT_MAX_MEM
default maximum memory to use
|
Constructor and Description |
---|
MLRUItemStateCache(CacheManager cacheMgr) |
Modifier and Type | Method and Description |
---|---|
void |
cache(ItemState state)
Stores the specified
ItemState object in the map
using its ItemId as the key. |
void |
dispose()
Informs the cache that it is no longer in use.
|
void |
evict(ItemId id)
Removes the
ItemState object with the specified id from
this cache if it is present. |
void |
evictAll()
Clears all entries from this cache.
|
boolean |
isCached(ItemId id)
Returns
true if this cache contains an ItemState
object with the specified id . |
boolean |
isEmpty()
Returns
true if this cache contains no entries. |
ItemState |
retrieve(ItemId id)
Returns the
ItemState object with the specified
id if it is present or null if no entry exists
with that id . |
ItemState[] |
retrieveAll()
Returns all the cached item states.
|
public static final int DEFAULT_MAX_MEM
public MLRUItemStateCache(CacheManager cacheMgr)
public boolean isCached(ItemId id)
true
if this cache contains an ItemState
object with the specified id
.isCached
in interface ItemStateCache
id
- id of ItemState
object whose presence should be
tested.true
if there's a corresponding cache entry,
otherwise false
.public ItemState retrieve(ItemId id)
ItemState
object with the specified
id
if it is present or null
if no entry exists
with that id
.retrieve
in interface ItemStateCache
id
- the id of the ItemState
object to be returned.ItemState
object with the specified
id
or or null
if no entry exists
with that id
public ItemState[] retrieveAll()
retrieveAll
in interface ItemStateCache
public void cache(ItemState state)
ItemState
object in the map
using its ItemId
as the key.cache
in interface ItemStateCache
state
- the ItemState
object to cachepublic void evict(ItemId id)
ItemState
object with the specified id from
this cache if it is present.evict
in interface ItemStateCache
id
- the id of the ItemState
object which should be
removed from this cache.public void evictAll()
evictAll
in interface ItemStateCache
public boolean isEmpty()
true
if this cache contains no entries.isEmpty
in interface ItemStateCache
true
if this cache contains no entries.public void dispose()
dispose
in interface ItemStateCache
Copyright © 2004–2021 The Apache Software Foundation. All rights reserved.