| package org.onlab.onos.store.common; |
| |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutionException; |
| |
| import com.google.common.base.Optional; |
| import com.google.common.cache.ForwardingLoadingCache.SimpleForwardingLoadingCache; |
| import com.google.common.cache.LoadingCache; |
| |
| /** |
| * Wrapper around LoadingCache to handle negative hit scenario. |
| * <p> |
| * When the LoadingCache returned Absent, |
| * this implementation will invalidate the entry immediately to avoid |
| * caching negative hits. |
| * |
| * @param <K> Cache key type |
| * @param <V> Cache value type. (Optional{@literal <V>}) |
| */ |
| public class AbsentInvalidatingLoadingCache<K, V> extends |
| SimpleForwardingLoadingCache<K, Optional<V>> { |
| |
| /** |
| * Constructor. |
| * |
| * @param delegate actual {@link LoadingCache} to delegate loading. |
| */ |
| public AbsentInvalidatingLoadingCache(LoadingCache<K, Optional<V>> delegate) { |
| super(delegate); |
| } |
| |
| @Override |
| public Optional<V> get(K key) throws ExecutionException { |
| Optional<V> v = super.get(key); |
| if (!v.isPresent()) { |
| invalidate(key); |
| } |
| return v; |
| } |
| |
| @Override |
| public Optional<V> getUnchecked(K key) { |
| Optional<V> v = super.getUnchecked(key); |
| if (!v.isPresent()) { |
| invalidate(key); |
| } |
| return v; |
| } |
| |
| @Override |
| public Optional<V> apply(K key) { |
| return getUnchecked(key); |
| } |
| |
| @Override |
| public Optional<V> getIfPresent(Object key) { |
| Optional<V> v = super.getIfPresent(key); |
| if (!v.isPresent()) { |
| invalidate(key); |
| } |
| return v; |
| } |
| |
| @Override |
| public Optional<V> get(K key, Callable<? extends Optional<V>> valueLoader) |
| throws ExecutionException { |
| |
| Optional<V> v = super.get(key, valueLoader); |
| if (!v.isPresent()) { |
| invalidate(key); |
| } |
| return v; |
| } |
| |
| // TODO should we be also checking getAll, etc. |
| } |