程序包 cn.taketoday.util

类 ConcurrentLruCache<K,V>

java.lang.Object

cn.taketoday.util.ConcurrentLruCache<K,V>

类型参数:

K - the type of the key used for cache retrieval

V - the type of the cached values, does not allow null values

public final class ConcurrentLruCache<K,V>
extends Object

Simple LRU (Least Recently Used) cache, bounded by a specified cache capacity.

This is a simplified, opinionated implementation of a LRU cache for internal use in Infra Framework. It is inspired from ConcurrentLinkedHashMap.

Read and write operations are internally recorded in dedicated buffers, then drained at chosen times to avoid contention.

从以下版本开始:

4.0

作者:

Brian Clozel, Ben Manes, Harry Yang

另请参阅:

• get(Object)

嵌套类概要

嵌套类

修饰符和类型	类	说明
private final class	ConcurrentLruCache.AddTask	Write operation recorded when a new entry is added to the cache.
private static final record	ConcurrentLruCache.CacheEntry<V>
private static enum	ConcurrentLruCache.CacheEntryState
private static enum	ConcurrentLruCache.DrainStatus	Draining status for the read/write buffers.
private static final class	ConcurrentLruCache.EvictionQueue<K,V>
private static final class	ConcurrentLruCache.Node<K,V>
private static final class	ConcurrentLruCache.ReadOperations<K,V>
private final class	ConcurrentLruCache.RemovalTask	Write operation recorded when an entry is removed to the cache.
private static final class	ConcurrentLruCache.WriteOperations

字段概要

字段

修饰符和类型	字段	说明
private final ConcurrentMap<K,ConcurrentLruCache.Node<K,V>>	cache
private final int	capacity
private final AtomicInteger	currentSize
private final AtomicReference<ConcurrentLruCache.DrainStatus>	drainStatus
private final ReentrantLock	evictionLock
private final ConcurrentLruCache.EvictionQueue<K,V>	evictionQueue	Queue that contains all ACTIVE cache entries, ordered with least recently used entries first.
private final Function<K,V>	generator
private final ConcurrentLruCache.ReadOperations<K,V>	readOperations
private final ConcurrentLruCache.WriteOperations	writeOperations

构造器概要

构造器

限定符	构造器	说明
	ConcurrentLruCache(int capacity, Function<K,V> generator)	Create a new cache instance with the given capacity and generator function.
private	ConcurrentLruCache(int capacity, Function<K,V> generator, int concurrencyLevel)

方法概要

修饰符和类型	方法	说明
int	capacity()	Return the maximum number of entries in the cache.
void	clear()	Immediately remove all entries from this cache.
boolean	contains(K key)	Determine whether the given key is present in this cache.
private void	drainOperations()
V	get(K key)	Retrieve an entry from the cache, potentially triggering generation of the value.
private void	markAsRemoved(ConcurrentLruCache.Node<K,V> node)	Transition the node to the removed state and decrement the current size of the cache.
private void	markForRemoval(ConcurrentLruCache.Node<K,V> node)	Transition the node from the active state to the pending removal state, if the transition is valid.
private void	processRead(ConcurrentLruCache.Node<K,V> node)
private void	processWrite(Runnable task)
private void	put(K key, V value)
boolean	remove(K key)	Immediately remove the given key and any associated value.
int	size()	Return the current size of the cache.

从类继承的方法 java.lang.Object

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

字段详细资料

capacity

private final int capacity

currentSize

private final AtomicInteger currentSize

cache

private final ConcurrentMap<K,ConcurrentLruCache.Node<K,V>> cache

generator

private final Function<K,V> generator

readOperations

private final ConcurrentLruCache.ReadOperations<K,V> readOperations

writeOperations

private final ConcurrentLruCache.WriteOperations writeOperations

evictionLock

private final ReentrantLock evictionLock

evictionQueue

private final ConcurrentLruCache.EvictionQueue<K,V> evictionQueue

Queue that contains all ACTIVE cache entries, ordered with least recently used entries first. Read and write operations are buffered and periodically processed to reorder the queue.

drainStatus

private final AtomicReference<ConcurrentLruCache.DrainStatus> drainStatus

构造器详细资料

ConcurrentLruCache

public ConcurrentLruCache(int capacity,
 Function<K,V> generator)

Create a new cache instance with the given capacity and generator function.

参数:

capacity - the maximum number of entries in the cache (0 indicates no caching, always generating a new value)

generator - a function to generate a new value for a given key

ConcurrentLruCache

private ConcurrentLruCache(int capacity,
 Function<K,V> generator,
 int concurrencyLevel)

方法详细资料

get

public V get(K key)

Retrieve an entry from the cache, potentially triggering generation of the value.

参数:

key - the key to retrieve the entry for

返回:

the cached or newly generated value

put

private void put(K key,
 V value)

processRead

private void processRead(ConcurrentLruCache.Node<K,V> node)

processWrite

private void processWrite(Runnable task)

drainOperations

private void drainOperations()

capacity

public int capacity()

Return the maximum number of entries in the cache.

另请参阅:

• size()

size

public int size()

Return the current size of the cache.

另请参阅:

• capacity()

clear

public void clear()

Immediately remove all entries from this cache.

markAsRemoved

private void markAsRemoved(ConcurrentLruCache.Node<K,V> node)

Transition the node to the removed state and decrement the current size of the cache.

contains

public boolean contains(K key)

Determine whether the given key is present in this cache.

参数:

key - the key to check for

返回:

true if the key is present, false if there was no matching key

remove

public boolean remove(K key)

Immediately remove the given key and any associated value.

参数:

key - the key to evict the entry for

返回:

true if the key was present before, false if there was no matching key

markForRemoval

private void markForRemoval(ConcurrentLruCache.Node<K,V> node)

Transition the node from the active state to the pending removal state, if the transition is valid.