activemq-client/src/main/java/org/apache/activemq/util/LongSequenceGenerator.java

/**
 * 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.activemq.util;

import java.util.concurrent.atomic.AtomicLongFieldUpdater;

/**
 * Updated LongSequenceGenerator that uses an AtomicLongFieldUpdater for performance instead of
 * synchronized methods
 */
public class LongSequenceGenerator {

    private static final AtomicLongFieldUpdater<LongSequenceGenerator> SEQUENCE_UPDATER =
            AtomicLongFieldUpdater.newUpdater(LongSequenceGenerator.class, "lastSequenceId");

    private volatile long lastSequenceId;

    public long getNextSequenceId() {
        return SEQUENCE_UPDATER.incrementAndGet(this);
    }

    public long getLastSequenceId() {
        return lastSequenceId;
    }

    public void setLastSequenceId(long l) {
        SEQUENCE_UPDATER.set(this, l);
    }
}