org.jdiameter.client.impl.helpers.UIDGenerator Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jdiameter-impl Show documentation
There is a newer version: 1.7.1-123
/*
 * JBoss, Home of Professional Open Source
 * Copyright 2006, Red Hat, Inc. and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.jdiameter.client.impl.helpers;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * This class provide uid range generator functionality
 * 
 * @author [email protected]
 * @author  Alexandre Mendonca 
 * @author  Bartosz Baranowski 
 */
public class UIDGenerator {  // todo remove or redesign

  private /*static*/ long value; // static causes repetitions
  private final static Lock mutex = new ReentrantLock();
  private final static ThreadLocal ranges = new ThreadLocal() {
        protected synchronized Delta initialValue() {
            return new Delta();
        }
    };

    private static class Delta {
        long start;
        long stop;

        public long update(long value) {
            start = value;
            stop  = value + 1;
            return stop;
        }
    }

    /**
     * Create instance of class
     */
    public UIDGenerator() {
        value = System.currentTimeMillis();
    }

    /**
     * Create instance of class with predefined start value
     * 
     * @param startValue start value of counter
     */
    public UIDGenerator(long startValue) {
        value = startValue;
    }

    /**
     * Return next uid as int
     * 
     * @return  uid
     */
    public int nextInt() {
        return (int) (0x7FFFFFFF & nextLong());
    }

    /**
     * Return next uid as long
     * 
     * @return uid as long
     */
    public long nextLong() {
        Delta d = ranges.get();
        if (d.start <= d.stop) {
            mutex.lock();
            value = d.update(value);
            mutex.unlock();
        }
        return d.start++;
    }
}