Top Description Inners Fields Constructors Methods

io.undertow.server.handlers.cache

public Class LRUCache<K, V>

Class Inheritance

extends Object

java.lang.Object
io.undertow.server.handlers.cache.LRUCache

Imports

java.util.concurrent.ConcurrentHashMap, .ConcurrentMap, java.util.concurrent.atomic.AtomicIntegerFieldUpdater, .AtomicReferenceFieldUpdater, io.undertow.util.ConcurrentDirectDeque

A non-blocking cache where entries are indexed by a key.

To reduce contention, entry allocation and eviction execute in a sampling fashion (entry hits modulo N). Eviction follows an LRU approach (oldest sampled entries are removed first) when the cache is out of capacity.

This cache can also be configured to run in FIFO mode, rather than LRU.

Authors: Jason T. Greene, Stuart Douglas

Nested and Inner Type Summary

Modifier and Type	Class and Description
public static class	LRUCache.CacheEntry<K, V>

Field Summary

Modifier and Type	Field and Description
private final ConcurrentDirectDeque<LRUCache.CacheEntry<K, V>>	accessQueue
private final ConcurrentMap<K, LRUCache.CacheEntry<K, V>>	cache
private final boolean	fifo
private final int	maxAge How long an item can stay in the cache in milliseconds
private final int	maxEntries Max active entries that are present in the cache.
private static final int	SAMPLE_INTERVAL

Constructor Summary

Access	Constructor and Description
public	LRUCache(int maxEntries, final int maxAge)
public	LRUCache(int maxEntries, final int maxAge, boolean fifo)

Method Summary

Modifier and Type	Method and Description
public void	add(K key, V newValue)
private void	bumpAccess(LRUCache.CacheEntry<K, V> cacheEntry)
public void	clear()
public V	get(K key)
public V	remove(K key)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

accessQueue	back to summary
private final ConcurrentDirectDeque<LRUCache.CacheEntry<K, V>> accessQueue

cache	back to summary
private final ConcurrentMap<K, LRUCache.CacheEntry<K, V>> cache

fifo	back to summary
private final boolean fifo

maxAge	back to summary
private final int maxAge How long an item can stay in the cache in milliseconds

maxEntries	back to summary
private final int maxEntries Max active entries that are present in the cache.

SAMPLE_INTERVAL	back to summary
private static final int SAMPLE_INTERVAL

Constructor Detail

LRUCache	back to summary
public LRUCache(int maxEntries, final int maxAge)

LRUCache	back to summary
public LRUCache(int maxEntries, final int maxAge, boolean fifo)

Method Detail

add	back to summary
public void add(K key, V newValue)

bumpAccess	back to summary
private void bumpAccess(LRUCache.CacheEntry<K, V> cacheEntry)

clear	back to summary
public void clear()

get	back to summary
public V get(K key)

remove	back to summary
public V remove(K key)

io.undertow.server.handlers.cache back to summary

public final Class LRUCache.CacheEntry<K, V>

Class Inheritance

extends Object

java.lang.Object
io.undertow.server.handlers.cache.LRUCache.CacheEntry

Field Summary

Modifier and Type	Field and Description
private volatile Object	accessToken
private static final Object	CLAIM_TOKEN
private final long	expires
private volatile int	hits
private static final AtomicIntegerFieldUpdater<LRUCache.CacheEntry<K, V>>	hitsUpdater
private final K	key
private static final AtomicReferenceFieldUpdater<LRUCache.CacheEntry<K, V>, Object>	tokenUpdator
private volatile V	value

Constructor Summary

Access	Constructor and Description
private	CacheEntry(K key, V value, final long expires)

Method Summary

Modifier and Type	Method and Description
pack-priv Object	claimToken()
pack-priv Object	clearToken()
public long	getExpires()
public V	getValue()
public int	hit()
public K	key()
pack-priv boolean	setToken(Object token)
public void	setValue(final V value)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

accessToken	back to summary
private volatile Object accessToken

CLAIM_TOKEN	back to summary
private static final Object CLAIM_TOKEN

expires	back to summary
private final long expires

hits	back to summary
private volatile int hits

hitsUpdater	back to summary
private static final AtomicIntegerFieldUpdater<LRUCache.CacheEntry<K, V>> hitsUpdater

key	back to summary
private final K key

tokenUpdator	back to summary
private static final AtomicReferenceFieldUpdater<LRUCache.CacheEntry<K, V>, Object> tokenUpdator

value	back to summary
private volatile V value

Constructor Detail

CacheEntry	back to summary
private CacheEntry(K key, V value, final long expires)

Method Detail

claimToken	back to summary
pack-priv Object claimToken()

clearToken	back to summary
pack-priv Object clearToken()

getExpires	back to summary
public long getExpires()

getValue	back to summary
public V getValue()

hit	back to summary
public int hit()

key	back to summary
public K key()

setToken	back to summary
pack-priv boolean setToken(Object token)

setValue	back to summary
public void setValue(final V value)