com.sun.faces.util.Cache Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of jakarta.faces-api Show documentation

Jakarta Faces defines an MVC framework for building user interfaces for web applications, including UI components, state management, event handing, input validation, page navigation, and support for internationalization and accessibility.

There is a newer version: 4.1.2

Show newest version

/*
 * Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package com.sun.faces.util;

import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.function.Function;

/**
 * A concurrent caching mechanism.
 */
public class Cache {

    /**
     * Factory interface for creating various cacheable objects.
     */
    public interface Factory extends Function {

        V newInstance(final K arg) throws InterruptedException;

        @Override
        default V apply(K key) {
            try {
                return newInstance( key );
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }

    }

    private final ConcurrentMap cache = new ConcurrentHashMap<>();
    private final Factory factory;

    // -------------------------------------------------------- Constructors

    /**
     * Constructs this cache using the specified Factory.
     *
     * @param factory a factory to create or retrieve the element that need to be cached
     */
    public Cache(Factory factory) {

        this.factory = factory;
    }

    // ------------------------------------------------------ Public Methods

    /**
     * If a value isn't associated with the specified key, a new {@link java.util.concurrent.Callable} will be created
     * wrapping the Factory specified via the constructor and passed to a
     * {@link java.util.concurrent.FutureTask}. This task will be passed to the backing ConcurrentMap. When
     * {@link java.util.concurrent.FutureTask#get()} is invoked, the Factory will return the new Value which will be cached
     * by the {@link java.util.concurrent.FutureTask}.
     *
     * @param key the key the value is associated with
     * @return the value for the specified key, if any
     */
    public V get(final K key) {
        Objects.requireNonNull(key);

        return cache.computeIfAbsent( key , factory );
    }

    public V remove(final K key) {
        return cache.remove(key);

    }

}