cascading.util.cache
Class LRUHashMapCache<Key,Value>

java.lang.Object
  extended by cascading.util.cache.LRUHashMapCache<Key,Value>
All Implemented Interfaces:
CascadingCache<Key,Value>, Map<Key,Value>

public class LRUHashMapCache<Key,Value>
extends Object
implements CascadingCache<Key,Value>

Implementation of the CascadingCache interface backed by a LinkedHashMap configured to evict the least recently used key.

That is, if duplicate keys are clustered near each other in the incoming tuple stream, this cache will provide the most benefit as keys that begin to occur less frequently or not at all will be evicted as the key capacity is reached.

If the keys are very random, if not uniformly distributed in the stream, consider using the DirectMappedCache to reduce the amount of hash and equality comparisons.

This implementation is used by default by Unique and AggregateBy and their subclasses.

See Also:
Unique, AggregateBy, LRUHashMapCacheFactory, DirectMappedCacheFactory, DirectMappedCache

Nested Class Summary
 
Nested classes/interfaces inherited from interface java.util.Map
Map.Entry<K,V>
 
Constructor Summary
LRUHashMapCache()
           
 
Method Summary
 void clear()
           
 boolean containsKey(Object key)
           
 boolean containsValue(Object value)
           
 Set<Map.Entry<Key,Value>> entrySet()
           
 Value get(Object key)
           
 int getCapacity()
          Returns the capacity of this cache.
 void initialize()
          Method to initialize the Cache.
 boolean isEmpty()
           
 Set<Key> keySet()
           
 Value put(Key key, Value value)
           
 void putAll(Map<? extends Key,? extends Value> m)
           
 Value remove(Object key)
           
 void setCacheEvictionCallback(CacheEvictionCallback cacheEvictionCallback)
          Sets the CacheEvictionCallback of this Cache.
 void setCapacity(int capacity)
          Sets the capacity of the Cache.
 int size()
           
 Collection<Value> values()
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface java.util.Map
equals, hashCode
 

Constructor Detail

LRUHashMapCache

public LRUHashMapCache()
Method Detail

getCapacity

public int getCapacity()
Description copied from interface: CascadingCache
Returns the capacity of this cache.

Specified by:
getCapacity in interface CascadingCache<Key,Value>

setCacheEvictionCallback

public void setCacheEvictionCallback(CacheEvictionCallback cacheEvictionCallback)
Description copied from interface: CascadingCache
Sets the CacheEvictionCallback of this Cache.

Specified by:
setCacheEvictionCallback in interface CascadingCache<Key,Value>

setCapacity

public void setCapacity(int capacity)
Description copied from interface: CascadingCache
Sets the capacity of the Cache.

Specified by:
setCapacity in interface CascadingCache<Key,Value>

initialize

public void initialize()
Description copied from interface: CascadingCache
Method to initialize the Cache. Any setup should be done in here.

Specified by:
initialize in interface CascadingCache<Key,Value>

size

public int size()
Specified by:
size in interface Map<Key,Value>

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface Map<Key,Value>

containsKey

public boolean containsKey(Object key)
Specified by:
containsKey in interface Map<Key,Value>

containsValue

public boolean containsValue(Object value)
Specified by:
containsValue in interface Map<Key,Value>

get

public Value get(Object key)
Specified by:
get in interface Map<Key,Value>

put

public Value put(Key key,
                 Value value)
Specified by:
put in interface Map<Key,Value>

remove

public Value remove(Object key)
Specified by:
remove in interface Map<Key,Value>

putAll

public void putAll(Map<? extends Key,? extends Value> m)
Specified by:
putAll in interface Map<Key,Value>

clear

public void clear()
Specified by:
clear in interface Map<Key,Value>

keySet

public Set<Key> keySet()
Specified by:
keySet in interface Map<Key,Value>

values

public Collection<Value> values()
Specified by:
values in interface Map<Key,Value>

entrySet

public Set<Map.Entry<Key,Value>> entrySet()
Specified by:
entrySet in interface Map<Key,Value>


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