/*
 * 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.Callable;

A semi-persistent mapping from keys to values. Cache entries are manually added using get(Object, Callable) or put(Object, Object), 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.

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:
10.0/**
 * A semi-persistent mapping from keys to values. Cache entries are manually added using
 * {@link #get(Object, Callable)} or {@link #put(Object, Object)}, 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>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 10.0
 */
public interface Cache<K, V> {

    
Returns the value associated with key in this cache, or null if there is no cached value for key. 
Since:
11.0/**
     * Returns the value associated with {@code key} in this cache, or {@code null} if there is no
     * cached value for {@code key}.
     *
     * @since 11.0
     */
    V getIfPresent(Object key);

    
Associates value with key in this cache. If the cache previously contained a value associated with key, the old value is replaced by value. 

Prefer get(Object, Callable) when using the conventional "if cached, return; otherwise create, cache and return" pattern. 
Since:
11.0/**
     * Associates {@code value} with {@code key} in this cache. If the cache previously contained a
     * value associated with {@code key}, the old value is replaced by {@code value}.
     * <p>
     * <p>Prefer {@link #get(Object, Callable)} when using the conventional "if cached, return;
     * otherwise create, cache and return" pattern.
     *
     * @since 11.0
     */
    void put(K key, V value);

}