Module io.helidon.common.configurable
Package io.helidon.common.configurable

Class LruCache<K,V>

java.lang.Object
io.helidon.common.configurable.LruCache<K,V>
Type Parameters:
K - type of the keys of the map
V - type of the values of the map
public final class LruCache<K,V> extends Object
Least recently used cache. This cache has a capacity. When the capacity is reached, the oldest record is removed from the cache when a new one is added.

  • Field Details

    • DEFAULT_CAPACITY

      public static final int DEFAULT_CAPACITY
      Default capacity of the cache: 10000.
      See Also:

  • Method Details

    • builder

      public static <K, V> LruCache.Builder<K,V> builder()
      Create a new builder.
      Type Parameters:
      K - key type
      V - value type
      Returns:
      a new fluent API builder instance

    • create

      public static <K, V> LruCache<K,V> create()
      Create an instance with default configuration.
      Type Parameters:
      K - key type
      V - value type
      Returns:
      a new cache instance
      See Also:

    • get

      public Optional<V> get(K key)
      Get a value from the cache.
      Parameters:
      key - key to retrieve
      Returns:
      value if present or empty

    • remove

      public Optional<V> remove(K key)
      Remove a value from the cache.
      Parameters:
      key - key of the record to remove
      Returns:
      the value that was mapped to the key, or empty if none was

    • put

      public Optional<V> put(K key, V value)
      Put a value to the cache.
      Parameters:
      key - key to add
      value - value to add
      Returns:
      value that was already mapped or empty if the value was not mapped

    • computeValue

      public Optional<V> computeValue(K key, Supplier<Optional<V>> valueSupplier)
      Either return a cached value or compute it and cache it. In case this method is called in parallel for the same key, the value actually present in the map may be from any of the calls. This method always returns either the existing value from the map, or the value provided by the supplier. It never returns a result from another thread's supplier.
      Parameters:
      key - key to check/insert value for
      valueSupplier - supplier called if the value is not yet cached, or is invalid
      Returns:
      current value from the cache, or computed value from the supplier

    • size

      public int size()
      Current size of the map.
      Returns:
      number of records currently cached

    • capacity

      public int capacity()
      Capacity of this cache.
      Returns:
      configured capacity of this cache