001/**
002 * Copyright (C) 2006-2025 Talend Inc. - www.talend.com
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.talend.sdk.component.runtime.manager.util;
017
018import java.util.concurrent.ConcurrentHashMap;
019import java.util.function.Function;
020
021public class LazyMap<A, B> extends ConcurrentHashMap<A, B> {
022
023    private final Function<A, B> lazyFactory;
024
025    public LazyMap(final int capacity, final Function<A, B> lazyFactory) {
026        super(capacity);
027        this.lazyFactory = lazyFactory;
028    }
029
030    @Override
031    public B get(final Object key) {
032        B value = super.get(key);
033        if (value == null) {
034            final A castedKey = (A) (key);
035            synchronized (this) {
036                value = super.get(key);
037                if (value == null) {
038                    final B created = lazyFactory.apply(castedKey);
039                    if (created != null) { // cache
040                        put(castedKey, created);
041                        return created;
042                    }
043                }
044            }
045        }
046        return value;
047    }
048}