org.apache.beam.fn.harness

Interface Cache<K,V>

All Known Implementing Classes:

Caches.ClearableCache

@ThreadSafe
public interface Cache<K,V>

A cache allows for the storage and retrieval of values which are associated with keys.

The cache allows for concurrent access and modification to its content and automatically controls the amount of entries in the cache to stay within configured resource limits.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	Cache.Shrinkable<V> An interface that marks an object that can be reduced in size instead of being evicted completely.

Method Summary

Modifier and Type	Method and Description
V	computeIfAbsent(K key, java.util.function.Function<K,V> loadingFunction) Looks up the specified key and returns the associated value.
java.lang.String	describeStats() Returns a string containing caching statistics.
V	peek(K key) Looks up the specified key returning null if the value is not within the cache.
void	put(K key, V value) Inserts a new value associated with the given key or updates an existing association of the same key with the new value.
void	remove(K key) Removes the mapping for a key from the cache if it is present.

Method Detail

peek

@Nullable
V peek(K key)

Looks up the specified key returning null if the value is not within the cache.

computeIfAbsent

V computeIfAbsent(K key,
                  java.util.function.Function<K,V> loadingFunction)

Looks up the specified key and returns the associated value.

If the key is not present in the cache, the specified function will be used to load and populate the cache.

put

void put(K key,
         V value)

Inserts a new value associated with the given key or updates an existing association of the same key with the new value.

remove

void remove(K key)

Removes the mapping for a key from the cache if it is present.

describeStats

java.lang.String describeStats()

Returns a string containing caching statistics.