001/*
002 * The contents of this file are subject to the terms of the Common Development and
003 * Distribution License (the License). You may not use this file except in compliance with the
004 * License.
005 *
006 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
007 * specific language governing permission and limitations under the License.
008 *
009 * When distributing Covered Software, include this CDDL Header Notice in each file and include
010 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
011 * Header, with the fields enclosed by brackets [] replaced by your own identifying
012 * information: "Portions copyright [year] [name of copyright owner]".
013 *
014 * Copyright 2015 ForgeRock AS.
015 */
016
017package org.forgerock.util.generator;
018
019import java.util.UUID;
020import java.util.concurrent.atomic.AtomicLong;
021
022import org.forgerock.util.annotations.VisibleForTesting;
023
024/**
025 * Defines the contract to generate global unique identifiers.
026 */
027public interface IdGenerator {
028
029    /**
030     * Returns a new globally unique identifier.
031     * @return a new globally unique identifier.
032     */
033    String generate();
034
035    /**
036     * The default implementation of {@link IdGenerator}.
037     */
038    IdGenerator DEFAULT = new SequenceUuidIdGenerator(UUID.randomUUID());
039
040    /**
041     * Default implementation of the {@link IdGenerator} that will output some ids based on the following pattern :
042     * {@code <uuid> + '-' + an incrementing sequence}.
043     */
044    final class SequenceUuidIdGenerator implements IdGenerator {
045
046        private final String prefix;
047        private final AtomicLong sequence = new AtomicLong();
048
049        @VisibleForTesting
050        SequenceUuidIdGenerator(UUID uuid) {
051            this.prefix = uuid.toString();
052        }
053
054        @Override
055        public String generate() {
056            return prefix + '-' + sequence.getAndIncrement();
057        }
058    }
059}