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/*
* 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 {@link Function}, a cache yields the same result as invoking
* {@link #getUnchecked}.
*
*
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 extends Cache, Function {
/**
* 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.
*
*
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.
*
*
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.
*
*
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 even if
* computation was interrupted by an {@code InterruptedException}.)
* @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 {@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);
}