| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more contributor license |
| * agreements. See the NOTICE file distributed with this work for additional information regarding |
| * copyright ownership. The ASF licenses this file to You 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.apache.geode.management.internal.beans; |
| |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| import org.apache.geode.annotations.internal.MakeNotStatic; |
| |
| /** |
| * Class to give a consistent sequence number to notifications |
| * |
| * |
| */ |
| public class SequenceNumber { |
| |
| /** Sequence number for resource related notifications **/ |
| @MakeNotStatic |
| private static final AtomicLong sequenceNumber = new AtomicLong(1); |
| |
| public static long next() { |
| long retVal = sequenceNumber.incrementAndGet(); |
| |
| if (retVal == Long.MAX_VALUE || retVal < 0) {// retVal <0 is checked for cases where other |
| // threads might have incremented sequenceNumber |
| // beyond Long.MAX_VALUE |
| |
| synchronized (SequenceNumber.class) { |
| long currentValue = sequenceNumber.get(); |
| if (currentValue == Long.MAX_VALUE || retVal < 0) { |
| sequenceNumber.set(1); |
| retVal = sequenceNumber.get(); |
| } else { |
| retVal = currentValue; |
| } |
| } |
| } |
| return retVal; |
| } |
| |
| } |