https://projects.eclipse.org/projects/ee4j.jersey/jersey-common: Jersey core common packages (Eclipse Foundation) 
/*
 * Copyright (C) 2011 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.glassfish.jersey.internal.guava;

import java.util.concurrent.ExecutionException;
import java.util.function.Function;


A semi-persistent mapping from keys to values. Values are automatically loaded by the cache,
and are stored in the cache until either evicted or manually invalidated.



Implementations of this interface are expected to be thread-safe, and can be safely accessed
by multiple concurrent threads.



When evaluated as a Function, a cache yields the same result as invoking getUnchecked. 


Note that while this class is still annotated as Beta, the API is frozen from a consumer's standpoint. In other words existing methods are all considered non-Beta and won't be changed without going through an 18 month deprecation cycle; however new methods may be added at any time. 
Author:Charles Fry
Since:11.0
/**
 * A semi-persistent mapping from keys to values. Values are automatically loaded by the cache,
 * and are stored in the cache until either evicted or manually invalidated.
 * <p>
 * <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
 * by multiple concurrent threads.
 * <p>
 * <p>When evaluated as a {@link Function}, a cache yields the same result as invoking
 * {@link #getUnchecked}.
 * <p>
 * <p>Note that while this class is still annotated as {@link Beta}, the API is frozen from a
 * consumer's standpoint. In other words existing methods are all considered {@code non-Beta} and
 * won't be changed without going through an 18 month deprecation cycle; however new methods may be
 * added at any time.
 *
 * @author Charles Fry
 * @since 11.0
 */
public interface LoadingCache<K, V> extends Cache<K, V>, Function<K, V> {

    
Returns the value associated with key in this cache, first loading that value if necessary. No observable state associated with this cache is modified until loading completes. 


If another call to get or getUnchecked is currently loading the value for key, simply waits for that thread to finish and returns its loaded value. Note that multiple threads can concurrently load values for distinct keys. 


Caches loaded by a CacheLoader will call CacheLoader.load to load new values into the cache. Newly loaded values are added to the cache using Cache.asMap().putIfAbsent after loading has completed; if another value was associated with key while the new value was loading then a removal notification will be sent for the new value. 


If the cache loader associated with this cache is known not to throw checked exceptions, then prefer getUnchecked over this method. 
Throws:
/**
     * Returns the value associated with {@code key} in this cache, first loading that value if
     * necessary. No observable state associated with this cache is modified until loading completes.
     * <p>
     * <p>If another call to {@link #get} or {@link #getUnchecked} is currently loading the value for
     * {@code key}, simply waits for that thread to finish and returns its loaded value. Note that
     * multiple threads can concurrently load values for distinct keys.
     * <p>
     * <p>Caches loaded by a {@link CacheLoader} will call {@link CacheLoader#load} to load new values
     * into the cache. Newly loaded values are added to the cache using
     * {@code Cache.asMap().putIfAbsent} after loading has completed; if another value was associated
     * with {@code key} while the new value was loading then a removal notification will be sent for
     * the new value.
     * <p>
     * <p>If the cache loader associated with this cache is known not to throw checked
     * exceptions, then prefer {@link #getUnchecked} over this method.
     *
     * @throws ExecutionException          if a checked exception was thrown while loading the value. ({@code
     *                                     ExecutionException} is thrown <a
     *                                     href="http://code.google.com/p/guava-libraries/wiki/CachesExplained#Interruption">even if
     *                                     computation was interrupted by an {@code InterruptedException}</a>.)
     * @throws UncheckedExecutionException if an unchecked exception was thrown while loading the
     *                                     value
     * @throws ExecutionError              if an error was thrown while loading the value
     */
    V get(K key) throws ExecutionException;

    
Throws:
  • UncheckedExecutionException – if an exception was thrown while loading the value. (As described in the documentation for getUnchecked, LoadingCache should be used as a Function only with cache loaders that throw only unchecked exceptions.)
Deprecated:Provided to satisfy the Function interface; use get or getUnchecked instead.
/**
     * @throws UncheckedExecutionException if an exception was thrown while loading the value. (As
     *                                     described in the documentation for {@link #getUnchecked}, {@code LoadingCache} should be
     *                                     used as a {@code Function} only with cache loaders that throw only unchecked exceptions.)
     * @deprecated Provided to satisfy the {@code Function} interface; use {@link #get} or
     * {@link #getUnchecked} instead.
     */
    @Deprecated
    @Override
    V apply(K key);

}