Java AtomicLong getDateSafe()

Description

Returns a unique Date considering the last stored timestamp.

License

Open Source License

Declaration

public static Date getDateSafe() 

Method Source Code

//package com.java2s;
/*/*w  w  w.  j  a v a 2 s .c  o m*/
 * Copyright (C) 2008-2012, fluid Operations AG
 *
 * This library 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 library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

import java.util.Date;
import java.util.concurrent.atomic.AtomicLong;

public class Main {
    /**
      * The timestamp that was used for the last Context. We compare to this
      * value to have unique/synchronized values across different contexts
      */
    private static AtomicLong lastTimestampUsed = new AtomicLong(0L);

    /**
     * Returns a unique Date considering the last stored timestamp. If the current
     * timestamp is equal to the last one, one millisecond is added. The last step is
     * repeated until a distinct timestamp is found.
     *  
     * @return a unique Date
     * @return
     */
    public static Date getDateSafe() {
        return new Date(getTimestampSafe());
    }

    /**
    * Returns a unique timestamp considering the last stored timestamp. If the current
    * timestamp is equal to the last one, one millisecond is added. The last step is
    * repeated until a distinct timestamp is found.
    *  
    * @return a unique timestamp
    */
    public static long getTimestampSafe() {
        long timestamp = System.currentTimeMillis();

        boolean repeat = true;
        while (repeat) {
            long lastUsed = lastTimestampUsed.get();
            if (timestamp > lastUsed) {
                repeat = !lastTimestampUsed.compareAndSet(lastUsed, timestamp);
            } else {
                timestamp = lastUsed + 1;
            }
        }

        return timestamp;
    }
}

Related

1. getAndAddCap(AtomicLongFieldUpdater updater, T instance, long n)
2. getAndAddRequest(AtomicLong requested, long n)
3. getAndAddRequest(AtomicLongFieldUpdater requested, T object, long n)
4. getAtomicLongArraySameLengthAsList(List list)
5. getBench(Map times, int amount)
6. getForeverUniqueID()
7. getGlobalTimeStamp()
8. getList(AtomicLongArray atomicLongArray)
9. getMessageId()