Package org.eclipse.handly.util

Class LruCache<K,V>

java.lang.Object
org.eclipse.handly.util.LruCache<K,V>
Direct Known Subclasses:
BoundedLruCache
public class LruCache<K,V> extends Object
An LRU cache. Entries are ordered in the cache from most recently accessed to least recently accessed. When a cache entry is accessed via get or put methods, it is moved to the most recently used position in the cache. No other public methods generate entry accesses.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    protected static class 
    LruCache.Entry<K,V>
    An LRU cache entry.

  • Constructor Summary

    Constructors
    Constructor
    Description
    LruCache()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    protected void
    add(LruCache.Entry<K,V> entry)
    Adds a new entry to this cache in response to put(Object, Object).
    void
    clear()
    Removes all entries from this cache.
    protected void
    doAdd(LruCache.Entry<K,V> entry)
    Actually adds a new entry to this cache.
    protected void
    doRemove(LruCache.Entry<K,V> entry)
    Actually removes an existing entry from this cache.
    protected final LruCache.Entry<K,V>
    entryByKey(Object key)
    Returns the corresponding entry for the given key, or null if this cache contains no entry for the key.
    final V
    get(Object key)
    Returns the corresponding value for the given key and moves the corresponding entry to the most recently used position in this cache.
    protected final LruCache.Entry<K,V>
    getLruEntry()
    Returns the least recently used cache entry, or null if this cache is empty.
    protected final LruCache.Entry<K,V>
    getMruEntry()
    Returns the most recently used cache entry, or null if this cache is empty.
    final boolean
    isEmpty()
    Returns whether this cache is empty.
    protected void
    moveToMru(LruCache.Entry<K,V> entry)
    Moves an existing cache entry to the MRU position.
    protected LruCache.Entry<K,V>
    newEntry(K key, V value)
    Creates a new cache entry with the given key and value.
    final V
    peek(Object key)
    Returns the corresponding value for the given key without disturbing cache ordering, or null if this cache contains no value for the key.
    final V
    put(K key, V value)
    Caches the given value for the given key and moves the corresponding entry to the most recently used position in this cache.
    final V
    remove(Object key)
    Removes the cache entry for the given key if it is present.
    protected void
    remove(LruCache.Entry<K,V> entry)
    Removes an existing entry from this cache in response to remove(Object).
    final int
    size()
    Returns the size of this cache.
    final Map<K,V>
    snapshot()
    Returns a snapshot of the current contents of this cache, ordered from most recently accessed to least recently accessed.
    String
    toString()
     
    protected void
    update(LruCache.Entry<K,V> entry, V value)
    Updates an existing cache entry to change its value and moves it to the MRU position in response to put(Object, Object).

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • LruCache

      public LruCache()

  • Method Details

    • size

      public final int size()
      Returns the size of this cache.
      Returns:
      the size of the cache

    • isEmpty

      public final boolean isEmpty()
      Returns whether this cache is empty.
      Returns:
      true if the cache is empty, and false otherwise

    • get

      public final V get(Object key)
      Returns the corresponding value for the given key and moves the corresponding entry to the most recently used position in this cache. If the cache contains no value for the key, null is returned.
      Parameters:
      key - the key whose corresponding value is to be returned
      Returns:
      the corresponding value for the given key, or null if the cache contains no value for the key

    • peek

      public final V peek(Object key)
      Returns the corresponding value for the given key without disturbing cache ordering, or null if this cache contains no value for the key.
      Parameters:
      key - the key whose corresponding value is to be returned
      Returns:
      the corresponding value for the given key, or null if the cache contains no value for the key

    • put

      public final V put(K key, V value)
      Caches the given value for the given key and moves the corresponding entry to the most recently used position in this cache. Returns the previous value of the updated cache entry, or null if the cache contained no value for the key.
      Parameters:
      key - the key for which the given value is to be cached (not null)
      value - the value to be cached for the given key (not null)
      Returns:
      the previous value of the updated cache entry, or null if the cache contained no value for the key

    • remove

      public final V remove(Object key)
      Removes the cache entry for the given key if it is present. Returns the value of the removed cache entry, or null if this cache contained no value for the key.
      Parameters:
      key - the key whose entry is to be removed from the cache
      Returns:
      the value of the removed cache entry, or null if the cache contained no value for the key

    • clear

      public void clear()
      Removes all entries from this cache.

    • snapshot

      public final Map<K,V> snapshot()
      Returns a snapshot of the current contents of this cache, ordered from most recently accessed to least recently accessed.
      Returns:
      a snapshot of the current contents of the cache (never null)

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getMruEntry

      protected final LruCache.Entry<K,V> getMruEntry()
      Returns the most recently used cache entry, or null if this cache is empty.
      Returns:
      the MRU entry, or null if the cache is empty

    • getLruEntry

      protected final LruCache.Entry<K,V> getLruEntry()
      Returns the least recently used cache entry, or null if this cache is empty.
      Returns:
      the LRU entry, or null if the cache is empty

    • entryByKey

      protected final LruCache.Entry<K,V> entryByKey(Object key)
      Returns the corresponding entry for the given key, or null if this cache contains no entry for the key.
      Parameters:
      key - the key whose corresponding entry is to be returned
      Returns:
      the corresponding entry for the given key, or null if the cache contains no entry for the key

    • newEntry

      protected LruCache.Entry<K,V> newEntry(K key, V value)
      Creates a new cache entry with the given key and value.
      Parameters:
      key - the key of the new entry (never null)
      value - the value of the new entry (never null)
      Returns:
      the created entry (not null)

    • add

      protected void add(LruCache.Entry<K,V> entry)
      Adds a new entry to this cache in response to put(Object, Object).

      This implementation invokes doAdd(Entry).

      Parameters:
      entry - the entry to add (never null)

    • update

      protected void update(LruCache.Entry<K,V> entry, V value)
      Updates an existing cache entry to change its value and moves it to the MRU position in response to put(Object, Object).

      This implementation changes the entry value and then invokes moveToMru(Entry).

      Parameters:
      entry - the entry to update (never null)
      value - a new value for the entry (never null)

    • remove

      protected void remove(LruCache.Entry<K,V> entry)
      Removes an existing entry from this cache in response to remove(Object).

      This implementation invokes doRemove(Entry).

      Parameters:
      entry - the entry to remove (never null)

    • doAdd

      protected void doAdd(LruCache.Entry<K,V> entry)
      Actually adds a new entry to this cache.
      Parameters:
      entry - the entry to add (never null)

    • doRemove

      protected void doRemove(LruCache.Entry<K,V> entry)
      Actually removes an existing entry from this cache.
      Parameters:
      entry - the entry to remove (never null)

    • moveToMru

      protected void moveToMru(LruCache.Entry<K,V> entry)
      Moves an existing cache entry to the MRU position.
      Parameters:
      entry - the entry to move (never null)