org.apache.solr.util

Class ConcurrentLRUCache<K,V>

java.lang.Object

org.apache.solr.util.ConcurrentLRUCache<K,V>

All Implemented Interfaces:

Accountable, Cache<K,V>

public class ConcurrentLRUCache<K,V>
extends Object
implements Cache<K,V>, Accountable

A LRU cache implementation based upon ConcurrentHashMap and other techniques to reduce contention and synchronization overhead to utilize multiple CPU cores more effectively.

Note that the implementation does not follow a true LRU (least-recently-used) eviction strategy. Instead it strives to remove least recently used items but when the initial cleanup does not remove enough items to reach the 'acceptableWaterMark' limit, it can remove more items forcefully regardless of access order.

Since:

solr 1.4

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ConcurrentLRUCache.CacheEntry<K,V>
static interface	ConcurrentLRUCache.EvictionListener<K,V>
static class	ConcurrentLRUCache.Stats

Constructor Summary

Constructors

Constructor and Description
ConcurrentLRUCache(int size, int lowerWatermark)
ConcurrentLRUCache(int upperWaterMark, int lowerWaterMark, int acceptableWatermark, int initialSize, boolean runCleanupThread, boolean runNewThreadForCleanup, ConcurrentLRUCache.EvictionListener<K,V> evictionListener)
ConcurrentLRUCache(long ramLowerWatermark, long ramUpperWatermark, boolean runCleanupThread, ConcurrentLRUCache.EvictionListener<K,V> evictionListener)

Method Summary

Modifier and Type	Method and Description
void	clear()
void	destroy()
protected void	finalize()
V	get(K key)
Collection<Accountable>	getChildResources()
Map<K,V>	getLatestAccessedItems(int n)
Map<Object,ConcurrentLRUCache.CacheEntry<K,V>>	getMap()
Map<K,V>	getOldestAccessedItems(int n) Returns 'n' number of oldest accessed entries present in this cache.
ConcurrentLRUCache.Stats	getStats()
V	put(K key, V val)
long	ramBytesUsed()
V	remove(K key)
void	setAlive(boolean live)
int	size()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.solr.common.util.Cache

computeIfAbsent

Constructor Detail

ConcurrentLRUCache

public ConcurrentLRUCache(long ramLowerWatermark,
                          long ramUpperWatermark,
                          boolean runCleanupThread,
                          ConcurrentLRUCache.EvictionListener<K,V> evictionListener)

ConcurrentLRUCache

public ConcurrentLRUCache(int upperWaterMark,
                          int lowerWaterMark,
                          int acceptableWatermark,
                          int initialSize,
                          boolean runCleanupThread,
                          boolean runNewThreadForCleanup,
                          ConcurrentLRUCache.EvictionListener<K,V> evictionListener)

ConcurrentLRUCache

public ConcurrentLRUCache(int size,
                          int lowerWatermark)

Method Detail

setAlive

public void setAlive(boolean live)

get

public V get(K key)

Specified by:

get in interface Cache<K,V>

remove

public V remove(K key)

Specified by:

remove in interface Cache<K,V>

put

public V put(K key,
             V val)

Specified by:

put in interface Cache<K,V>

getOldestAccessedItems

public Map<K,V> getOldestAccessedItems(int n)

Returns 'n' number of oldest accessed entries present in this cache. This uses a TreeSet to collect the 'n' oldest items ordered by ascending last access time and returns a LinkedHashMap containing 'n' or less than 'n' entries.

Parameters:

n - the number of oldest items needed

Returns:

a LinkedHashMap containing 'n' or less than 'n' entries

getLatestAccessedItems

public Map<K,V> getLatestAccessedItems(int n)

size

public int size()

clear

public void clear()

Specified by:

clear in interface Cache<K,V>

getMap

public Map<Object,ConcurrentLRUCache.CacheEntry<K,V>> getMap()

destroy

public void destroy()

getStats

public ConcurrentLRUCache.Stats getStats()

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable

ramBytesUsed

public long ramBytesUsed()

Specified by:

ramBytesUsed in interface Accountable

getChildResources

public Collection<Accountable> getChildResources()

Specified by:

getChildResources in interface Accountable