001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.utils;
014
015import java.util.concurrent.atomic.*;
016
017/**
018 * Predefined ID generators.
019 */
020public class IdGenerators {
021
022   /**
023    * Creates an ID generator using {@link AtomicInteger} initialized to value <code>1</code>.
024    *
025    * @param initValue The initial value.
026    * @return A new ID generator.
027    */
028   public static IdGenerator<Integer> createIntGenerator(final int initValue) {
029      return new IdGenerator<Integer>() {
030         private final AtomicInteger i = new AtomicInteger(initValue);
031
032         @Override /* IdGenerator */
033         public synchronized Integer next() {
034            return i.getAndIncrement();
035         }
036
037         @Override
038         public synchronized void lb(Integer k) {
039            i.set(Math.max(k + 1, i.get()));
040         }
041      };
042   }
043
044   /**
045    * Creates an ID generator using {@link AtomicInteger} initialized to the specified value.
046    *
047    * @return A new ID generator.
048    */
049   public static IdGenerator<Integer> createIntGenerator() {
050      return createIntGenerator(1);
051   }
052
053   /**
054    * Creates an ID generator using {@link AtomicLong} initialized to value <code>1</code>.
055    *
056    * @param initValue The initial value.
057    * @return A new ID generator.
058    */
059   public static IdGenerator<Long> createLongGenerator(final long initValue) {
060      return new IdGenerator<Long>() {
061         private final AtomicLong l = new AtomicLong(initValue);
062
063         @Override /* IdGenerator */
064         public synchronized Long next() {
065            return l.getAndIncrement();
066         }
067
068         @Override
069         public synchronized void lb(Long k) {
070            l.set(Math.max(k + 1, l.get()));
071         }
072      };
073   }
074
075   /**
076    * Creates an ID generator using {@link AtomicLong} initialized to the specified value.
077    *
078    * @return A new ID generator.
079    */
080   public static IdGenerator<Long> createLongGenerator() {
081      return createLongGenerator(1);
082   }
083}