Package org.eclipse.jgit.util

Class SimpleLruCache<K,V>

java.lang.Object

org.eclipse.jgit.util.SimpleLruCache<K,V>

Type Parameters:

K - the type of keys maintained by this cache

V - the type of mapped values

public class SimpleLruCache<K,V>
extends Object

Simple limited size cache based on ConcurrentHashMap purging entries in LRU order when reaching size limit

Since:

5.1.9

Constructor Summary

Constructors

Constructor	Description
SimpleLruCache(int maxSize, float purgeFactor)	Create a new cache

Method Summary

Modifier and Type	Method	Description
void	configure(int maxSize, float purgeFactor)	Reconfigures the cache.
V	get(Object key)	Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
V	put(K key, V value)	Maps the specified key to the specified value in this cache.
int	size()	Returns the current size of this cache

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleLruCache

public SimpleLruCache(int maxSize,
                      float purgeFactor)

Create a new cache

Parameters:

maxSize - maximum size of the cache, to reduce need for synchronization this is not a hard limit. The real size of the cache could be slightly above this maximum if multiple threads put new values concurrently

purgeFactor - when the size of the map reaches maxSize the oldest entries will be purged to free up some space for new entries, purgeFactor is the fraction of maxSize to purge when this happens

Method Detail

get

public V get(Object key)

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

More formally, if this cache contains a mapping from a key k to a value v such that key.equals(k), then this method returns v; otherwise it returns null. (There can be at most one such mapping.)

Parameters:

key - the key

Returns:

value mapped for this key, or null if no value is mapped

Throws:

NullPointerException - if the specified key is null

put

public V put(@NonNull
             K key,
             @NonNull
             V value)

Maps the specified key to the specified value in this cache. Neither the key nor the value can be null.

The value can be retrieved by calling the get method with a key that is equal to the original key.

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with key, or null if there was no mapping for key

Throws:

NullPointerException - if the specified key or value is null

size

public int size()

Returns the current size of this cache

Returns:

the number of key-value mappings in this cache

configure

public void configure(int maxSize,
                      float purgeFactor)

Reconfigures the cache. If maxSize is reduced some entries will be purged.

Parameters:

maxSize - maximum size of the cache

purgeFactor - when the size of the map reaches maxSize the oldest entries will be purged to free up some space for new entries, purgeFactor is the fraction of maxSize to purge when this happens