management/timer/Timer.java

/*
 * Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package javax.management.timer;

import static com.sun.jmx.defaults.JmxProperties.TIMER_LOGGER;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import java.util.Vector;
import java.lang.System.Logger.Level;

// jmx imports
//
import javax.management.InstanceNotFoundException;
import javax.management.MBeanNotificationInfo;
import javax.management.MBeanRegistration;
import javax.management.MBeanServer;
import javax.management.NotificationBroadcasterSupport;
import javax.management.ObjectName;

/**
 *
 * Provides the implementation of the timer MBean.
 * The timer MBean sends out an alarm at a specified time
 * that wakes up all the listeners registered to receive timer notifications.
 * <P>
 *
 * This class manages a list of dated timer notifications.
 * A method allows users to add/remove as many notifications as required.
 * When a timer notification is emitted by the timer and becomes obsolete,
 * it is automatically removed from the list of timer notifications.
 * <BR>Additional timer notifications can be added into regularly repeating notifications.
 * <P>
 *
 * Note:
 * <OL>
 * <LI>When sending timer notifications, the timer updates the notification sequence number
 * irrespective of the notification type.
 * <LI>The timer service relies on the system date of the host where the <CODE>Timer</CODE> class is loaded.
 * Listeners may receive untimely notifications
 * if their host has a different system date.
 * To avoid such problems, synchronize the system date of all host machines where timing is needed.
 * <LI>The default behavior for periodic notifications is <i>fixed-delay execution</i>, as
 *     specified in {@link java.util.Timer}. In order to use <i>fixed-rate execution</i>, use the
 *     overloaded {@link #addNotification(String, String, Object, Date, long, long, boolean)} method.
 * <LI>Notification listeners are potentially all executed in the same
 * thread.  Therefore, they should execute rapidly to avoid holding up
 * other listeners or perturbing the regularity of fixed-delay
 * executions.  See {@link NotificationBroadcasterSupport}.
 * </OL>
 *
 * @since 1.5
 */
public class Timer extends NotificationBroadcasterSupport
        implements TimerMBean, MBeanRegistration {


    /*
     * ------------------------------------------
     *  PUBLIC VARIABLES
     * ------------------------------------------
     */

    /**
     * Number of milliseconds in one second.
     * Useful constant for the <CODE>addNotification</CODE> method.
     */
    public static final long ONE_SECOND = 1000;

    /**
     * Number of milliseconds in one minute.
     * Useful constant for the <CODE>addNotification</CODE> method.
     */
    public static final long ONE_MINUTE = 60*ONE_SECOND;

    /**
     * Number of milliseconds in one hour.
     * Useful constant for the <CODE>addNotification</CODE> method.
     */
    public static final long ONE_HOUR   = 60*ONE_MINUTE;

    /**
     * Number of milliseconds in one day.
     * Useful constant for the <CODE>addNotification</CODE> method.
     */
    public static final long ONE_DAY    = 24*ONE_HOUR;

    /**
     * Number of milliseconds in one week.
     * Useful constant for the <CODE>addNotification</CODE> method.
     */
    public static final long ONE_WEEK   = 7*ONE_DAY;

    /*
     * ------------------------------------------
     *  PRIVATE VARIABLES
     * ------------------------------------------
     */

    /**
     * Table containing all the timer notifications of this timer,
     * with the associated date, period and number of occurrences.
     */
    final private Map<Integer,Object[]> timerTable =
        new HashMap<>();

    /**
     * Past notifications sending on/off flag value.
     * This attribute is used to specify if the timer has to send past notifications after start.
     * <BR>The default value is set to <CODE>false</CODE>.
     */
    private boolean sendPastNotifications = false;

    /**
     * Timer state.
     * The default value is set to <CODE>false</CODE>.
     */
    private transient boolean isActive = false;

    /**
     * Timer sequence number.
     * The default value is set to 0.
     */
    private transient long sequenceNumber = 0;

    // Flags needed to keep the indexes of the objects in the array.
    //
    private static final int TIMER_NOTIF_INDEX     = 0;
    private static final int TIMER_DATE_INDEX      = 1;
    private static final int TIMER_PERIOD_INDEX    = 2;
    private static final int TIMER_NB_OCCUR_INDEX  = 3;
    private static final int ALARM_CLOCK_INDEX     = 4;
    private static final int FIXED_RATE_INDEX      = 5;

    /**
     * The notification counter ID.
     * Used to keep the max key value inserted into the timer table.
     */
    volatile private int counterID = 0;

    private java.util.Timer timer;

    /*
     * ------------------------------------------
     *  CONSTRUCTORS
     * ------------------------------------------
     */

    /**
     * Default constructor.
     */
    public Timer() {
    }

    /*
     * ------------------------------------------
     *  PUBLIC METHODS
     * ------------------------------------------
     */

    /**
     * Allows the timer MBean to perform any operations it needs before being registered
     * in the MBean server.
     * <P>
     * Not used in this context.
     *
     * @param server The MBean server in which the timer MBean will be registered.
     * @param name The object name of the timer MBean.
     *
     * @return The name of the timer MBean registered.
     *
     * @exception java.lang.Exception if something goes wrong
     */
    public ObjectName preRegister(MBeanServer server, ObjectName name)
        throws java.lang.Exception {
        return name;
    }

    /**
     * Allows the timer MBean to perform any operations needed after having been
     * registered in the MBean server or after the registration has failed.
     * <P>
     * Not used in this context.
     */
    public void postRegister (Boolean registrationDone) {
    }

    /**
     * Allows the timer MBean to perform any operations it needs before being unregistered
     * by the MBean server.
     * <P>
     * Stops the timer.
     *
     * @exception java.lang.Exception if something goes wrong
     */
    public void preDeregister() throws java.lang.Exception {

        TIMER_LOGGER.log(Level.TRACE, "stop the timer");

        // Stop the timer.
        //
        stop();
    }

    /**
     * Allows the timer MBean to perform any operations needed after having been
     * unregistered by the MBean server.
     * <P>
     * Not used in this context.
     */
    public void postDeregister() {
    }

    /*
     * This overrides the method in NotificationBroadcasterSupport.
     * Return the MBeanNotificationInfo[] array for this MBean.
     * The returned array has one element to indicate that the MBean
     * can emit TimerNotification.  The array of type strings
     * associated with this entry is a snapshot of the current types
     * that were given to addNotification.
     */
    public synchronized MBeanNotificationInfo[] getNotificationInfo() {
        Set<String> notifTypes = new TreeSet<String>();
        for (Object[] entry : timerTable.values()) {
            TimerNotification notif = (TimerNotification)
                entry[TIMER_NOTIF_INDEX];
            notifTypes.add(notif.getType());
        }
        String[] notifTypesArray =
            notifTypes.toArray(new String[0]);
        return new MBeanNotificationInfo[] {
            new MBeanNotificationInfo(notifTypesArray,
                                      TimerNotification.class.getName(),
                                      "Notification sent by Timer MBean")
        };
    }

    /**
     * Starts the timer.
     * <P>
     * If there is one or more timer notifications before the time in the list of notifications, the notification
     * is sent according to the <CODE>sendPastNotifications</CODE> flag and then, updated
     * according to its period and remaining number of occurrences.
     * If the timer notification date remains earlier than the current date, this notification is just removed
     * from the list of notifications.
     */
    public synchronized void start() {

        TIMER_LOGGER.log(Level.TRACE, "starting the timer");

        // Start the TimerAlarmClock.
        //
        if (isActive == false) {

            timer = new java.util.Timer();

            TimerAlarmClock alarmClock;
            Date date;

            Date currentDate = new Date();

            // Send or not past notifications depending on the flag.
            // Update the date and the number of occurrences of past notifications
            // to make them later than the current date.
            //
            sendPastNotifications(currentDate, sendPastNotifications);

            // Update and start all the TimerAlarmClocks.
            // Here, all the notifications in the timer table are later than the current date.
            //
            for (Object[] obj : timerTable.values()) {

                // Retrieve the date notification and the TimerAlarmClock.
                //
                date = (Date)obj[TIMER_DATE_INDEX];

                // Update all the TimerAlarmClock timeouts and start them.
                //
                boolean fixedRate = ((Boolean)obj[FIXED_RATE_INDEX]).booleanValue();
                if (fixedRate)
                {
                  alarmClock = new TimerAlarmClock(this, date);
                  obj[ALARM_CLOCK_INDEX] = (Object)alarmClock;
                  timer.schedule(alarmClock, alarmClock.next);
                }
                else
                {
                  alarmClock = new TimerAlarmClock(this, (date.getTime() - currentDate.getTime()));
                  obj[ALARM_CLOCK_INDEX] = (Object)alarmClock;
                  timer.schedule(alarmClock, alarmClock.timeout);
                }
            }

            // Set the state to ON.
            //
            isActive = true;

            TIMER_LOGGER.log(Level.TRACE, "timer started");
        } else {
            TIMER_LOGGER.log(Level.TRACE, "the timer is already activated");
        }
    }

    /**
     * Stops the timer.
     */
    public synchronized void stop() {

        TIMER_LOGGER.log(Level.TRACE, "stopping the timer");

        // Stop the TimerAlarmClock.
        //
        if (isActive == true) {

            for (Object[] obj : timerTable.values()) {

                // Stop all the TimerAlarmClock.
                //
                TimerAlarmClock alarmClock = (TimerAlarmClock)obj[ALARM_CLOCK_INDEX];
                if (alarmClock != null) {
//                     alarmClock.interrupt();
//                     try {
//                         // Wait until the thread die.
//                         //
//                         alarmClock.join();
//                     } catch (InterruptedException ex) {
//                         // Ignore...
//                     }
//                     // Remove the reference on the TimerAlarmClock.
//                     //

                    alarmClock.cancel();
                }
            }

            timer.cancel();

            // Set the state to OFF.
            //
            isActive = false;

            TIMER_LOGGER.log(Level.TRACE, "timer stopped");
        } else {
            TIMER_LOGGER.log(Level.TRACE, "the timer is already deactivated");
        }
    }

    /**
     * Creates a new timer notification with the specified <CODE>type</CODE>, <CODE>message</CODE>
     * and <CODE>userData</CODE> and inserts it into the list of notifications with a given date,
     * period and number of occurrences.
     * <P>
     * If the timer notification to be inserted has a date that is before the current date,
     * the method behaves as if the specified date were the current date. <BR>
     * For once-off notifications, the notification is delivered immediately. <BR>
     * For periodic notifications, the first notification is delivered immediately and the
     * subsequent ones are spaced as specified by the period parameter.
     * <P>
     * Note that once the timer notification has been added into the list of notifications,
     * its associated date, period and number of occurrences cannot be updated.
     * <P>
     * In the case of a periodic notification, the value of parameter <i>fixedRate</i> is used to
     * specify the execution scheme, as specified in {@link java.util.Timer}.
     *
     * @param type The timer notification type.
     * @param message The timer notification detailed message.
     * @param userData The timer notification user data object.
     * @param date The date when the notification occurs.
     * @param period The period of the timer notification (in milliseconds).
     * @param nbOccurences The total number the timer notification will be emitted.
     * @param fixedRate If <code>true</code> and if the notification is periodic, the notification
     *                  is scheduled with a <i>fixed-rate</i> execution scheme. If
     *                  <code>false</code> and if the notification is periodic, the notification
     *                  is scheduled with a <i>fixed-delay</i> execution scheme. Ignored if the
     *                  notification is not periodic.
     *
     * @return The identifier of the new created timer notification.
     *
     * @exception java.lang.IllegalArgumentException The date is {@code null} or
     * the period or the number of occurrences is negative.
     *
     * @see #addNotification(String, String, Object, Date, long, long)
     */
// NPCTE fix for bugId 4464388, esc 0,  MR, to be added after modification of jmx spec
//  public synchronized Integer addNotification(String type, String message, Serializable userData,
//                                                Date date, long period, long nbOccurences)
// end of NPCTE fix for bugId 4464388

    public synchronized Integer addNotification(String type, String message, Object userData,
                                                Date date, long period, long nbOccurences, boolean fixedRate)
        throws java.lang.IllegalArgumentException {

        if (date == null) {
            throw new java.lang.IllegalArgumentException("Timer notification date cannot be null.");
        }

        // Check that all the timer notification attributes are valid.
        //

        // Invalid timer period value exception:
        // Check that the period and the nbOccurences are POSITIVE VALUES.
        //
        if ((period < 0) || (nbOccurences < 0)) {
            throw new java.lang.IllegalArgumentException("Negative values for the periodicity");
        }

        Date currentDate = new Date();

        // Update the date if it is before the current date.
        //
        if (currentDate.after(date)) {

            date.setTime(currentDate.getTime());
            if (TIMER_LOGGER.isLoggable(Level.TRACE)) {
                TIMER_LOGGER.log(Level.TRACE,
                        "update timer notification to add with:" +
                        "\n\tNotification date = " + date);
            }
        }

        // Create and add the timer notification into the timer table.
        //
        Integer notifID = Integer.valueOf(++counterID);

        // The sequenceNumber and the timeStamp attributes are updated
        // when the notification is emitted by the timer.
        //
        TimerNotification notif = new TimerNotification(type, this, 0, 0, message, notifID);
        notif.setUserData(userData);

        Object[] obj = new Object[6];

        TimerAlarmClock alarmClock;
        if (fixedRate)
        {
          alarmClock = new TimerAlarmClock(this, date);
        }
        else
        {
          alarmClock = new TimerAlarmClock(this, (date.getTime() - currentDate.getTime()));
        }

        // Fix bug 00417.B
        // The date registered into the timer is a clone from the date parameter.
        //
        Date d = new Date(date.getTime());

        obj[TIMER_NOTIF_INDEX] = (Object)notif;
        obj[TIMER_DATE_INDEX] = (Object)d;
        obj[TIMER_PERIOD_INDEX] = (Object) period;
        obj[TIMER_NB_OCCUR_INDEX] = (Object) nbOccurences;
        obj[ALARM_CLOCK_INDEX] = (Object)alarmClock;
        obj[FIXED_RATE_INDEX] = Boolean.valueOf(fixedRate);

        if (TIMER_LOGGER.isLoggable(Level.TRACE)) {
            StringBuilder strb = new StringBuilder()
            .append("adding timer notification:\n\t")
            .append("Notification source = ")
            .append(notif.getSource())
            .append("\n\tNotification type = ")
            .append(notif.getType())
            .append("\n\tNotification ID = ")
            .append(notifID)
            .append("\n\tNotification date = ")
            .append(d)
            .append("\n\tNotification period = ")
            .append(period)
            .append("\n\tNotification nb of occurrences = ")
            .append(nbOccurences)
            .append("\n\tNotification executes at fixed rate = ")
            .append(fixedRate);
            TIMER_LOGGER.log(Level.TRACE, strb::toString);
        }

        timerTable.put(notifID, obj);

        // Update and start the TimerAlarmClock.
        //
        if (isActive == true) {
          if (fixedRate)
          {
            timer.schedule(alarmClock, alarmClock.next);
          }
          else
          {
            timer.schedule(alarmClock, alarmClock.timeout);
          }
        }

        TIMER_LOGGER.log(Level.TRACE, "timer notification added");
        return notifID;
    }

    /**
     * Creates a new timer notification with the specified <CODE>type</CODE>, <CODE>message</CODE>
     * and <CODE>userData</CODE> and inserts it into the list of notifications with a given date,
     * period and number of occurrences.
     * <P>
     * If the timer notification to be inserted has a date that is before the current date,
     * the method behaves as if the specified date were the current date. <BR>
     * For once-off notifications, the notification is delivered immediately. <BR>
     * For periodic notifications, the first notification is delivered immediately and the
     * subsequent ones are spaced as specified by the period parameter.
     * <P>
     * Note that once the timer notification has been added into the list of notifications,
     * its associated date, period and number of occurrences cannot be updated.
     * <P>
     * In the case of a periodic notification, uses a <i>fixed-delay</i> execution scheme, as specified in
     * {@link java.util.Timer}. In order to use a <i>fixed-rate</i> execution scheme, use
     * {@link #addNotification(String, String, Object, Date, long, long, boolean)} instead.
     *
     * @param type The timer notification type.
     * @param message The timer notification detailed message.
     * @param userData The timer notification user data object.
     * @param date The date when the notification occurs.
     * @param period The period of the timer notification (in milliseconds).
     * @param nbOccurences The total number the timer notification will be emitted.
     *
     * @return The identifier of the new created timer notification.
     *
     * @exception java.lang.IllegalArgumentException The date is {@code null} or
     * the period or the number of occurrences is negative.
     *
     * @see #addNotification(String, String, Object, Date, long, long, boolean)
     */
// NPCTE fix for bugId 4464388, esc 0,  MR , to be added after modification of jmx spec
//  public synchronized Integer addNotification(String type, String message, Serializable userData,
//                                              Date date, long period)
// end of NPCTE fix for bugId 4464388 */

    public synchronized Integer addNotification(String type, String message, Object userData,
                                                Date date, long period, long nbOccurences)
        throws java.lang.IllegalArgumentException {

      return addNotification(type, message, userData, date, period, nbOccurences, false);
    }

    /**
     * Creates a new timer notification with the specified <CODE>type</CODE>, <CODE>message</CODE>
     * and <CODE>userData</CODE> and inserts it into the list of notifications with a given date
     * and period and a null number of occurrences.
     * <P>
     * The timer notification will repeat continuously using the timer period using a <i>fixed-delay</i>
     * execution scheme, as specified in {@link java.util.Timer}. In order to use a <i>fixed-rate</i>
     * execution scheme, use {@link #addNotification(String, String, Object, Date, long, long,
     * boolean)} instead.
     * <P>
     * If the timer notification to be inserted has a date that is before the current date,
     * the method behaves as if the specified date were the current date. The
     * first notification is delivered immediately and the subsequent ones are
     * spaced as specified by the period parameter.
     *
     * @param type The timer notification type.
     * @param message The timer notification detailed message.
     * @param userData The timer notification user data object.
     * @param date The date when the notification occurs.
     * @param period The period of the timer notification (in milliseconds).
     *
     * @return The identifier of the new created timer notification.
     *
     * @exception java.lang.IllegalArgumentException The date is {@code null} or
     * the period is negative.
     */
// NPCTE fix for bugId 4464388, esc 0,  MR , to be added after modification of jmx spec
//  public synchronized Integer addNotification(String type, String message, Serializable userData,
//                                              Date date, long period)
// end of NPCTE fix for bugId 4464388 */

    public synchronized Integer addNotification(String type, String message, Object userData,
                                                Date date, long period)
        throws java.lang.IllegalArgumentException {

        return (addNotification(type, message, userData, date, period, 0));
    }

    /**
     * Creates a new timer notification with the specified <CODE>type</CODE>, <CODE>message</CODE>
     * and <CODE>userData</CODE> and inserts it into the list of notifications with a given date
     * and a null period and number of occurrences.
     * <P>
     * The timer notification will be handled once at the specified date.
     * <P>
     * If the timer notification to be inserted has a date that is before the current date,
     * the method behaves as if the specified date were the current date and the
     * notification is delivered immediately.
     *
     * @param type The timer notification type.
     * @param message The timer notification detailed message.
     * @param userData The timer notification user data object.
     * @param date The date when the notification occurs.
     *
     * @return The identifier of the new created timer notification.
     *
     * @exception java.lang.IllegalArgumentException The date is {@code null}.
     */
// NPCTE fix for bugId 4464388, esc 0,  MR, to be added after modification of jmx spec
//  public synchronized Integer addNotification(String type, String message, Serializable userData, Date date)
//      throws java.lang.IllegalArgumentException {
// end of NPCTE fix for bugId 4464388

    public synchronized Integer addNotification(String type, String message, Object userData, Date date)
        throws java.lang.IllegalArgumentException {


        return (addNotification(type, message, userData, date, 0, 0));
    }

    /**
     * Removes the timer notification corresponding to the specified identifier from the list of notifications.
     *
     * @param id The timer notification identifier.
     *
     * @exception InstanceNotFoundException The specified identifier does not correspond to any timer notification
     * in the list of notifications of this timer MBean.
     */
    public synchronized void removeNotification(Integer id) throws InstanceNotFoundException {

        // Check that the notification to remove is effectively in the timer table.
        //
        if (timerTable.containsKey(id) == false) {
            throw new InstanceNotFoundException("Timer notification to remove not in the list of notifications");
        }

        // Stop the TimerAlarmClock.
        //
        Object[] obj = timerTable.get(id);
        TimerAlarmClock alarmClock = (TimerAlarmClock)obj[ALARM_CLOCK_INDEX];
        if (alarmClock != null) {
//             alarmClock.interrupt();
//             try {
//                 // Wait until the thread die.
//                 //
//                 alarmClock.join();
//             } catch (InterruptedException e) {
//                 // Ignore...
//             }
//             // Remove the reference on the TimerAlarmClock.
//             //
            alarmClock.cancel();
        }

        // Remove the timer notification from the timer table.
        //
        if (TIMER_LOGGER.isLoggable(Level.TRACE)) {
            StringBuilder strb = new StringBuilder()
            .append("removing timer notification:")
            .append("\n\tNotification source = ")
            .append(((TimerNotification)obj[TIMER_NOTIF_INDEX]).getSource())
            .append("\n\tNotification type = ")
            .append(((TimerNotification)obj[TIMER_NOTIF_INDEX]).getType())
            .append("\n\tNotification ID = ")
            .append(((TimerNotification)obj[TIMER_NOTIF_INDEX]).getNotificationID())
            .append("\n\tNotification date = ")
            .append(obj[TIMER_DATE_INDEX])
            .append("\n\tNotification period = ")
            .append(obj[TIMER_PERIOD_INDEX])
            .append("\n\tNotification nb of occurrences = ")
            .append(obj[TIMER_NB_OCCUR_INDEX])
            .append("\n\tNotification executes at fixed rate = ")
            .append(obj[FIXED_RATE_INDEX]);
            TIMER_LOGGER.log(Level.TRACE, strb::toString);
        }

        timerTable.remove(id);

        TIMER_LOGGER.log(Level.TRACE, "timer notification removed");
    }

    /**
     * Removes all the timer notifications corresponding to the specified type from the list of notifications.
     *
     * @param type The timer notification type.
     *
     * @exception InstanceNotFoundException The specified type does not correspond to any timer notification
     * in the list of notifications of this timer MBean.
     */
    public synchronized void removeNotifications(String type) throws InstanceNotFoundException {

        Vector<Integer> v = getNotificationIDs(type);

        if (v.isEmpty())
            throw new InstanceNotFoundException("Timer notifications to remove not in the list of notifications");

        for (Integer i : v)
            removeNotification(i);
    }

    /**
     * Removes all the timer notifications from the list of notifications
     * and resets the counter used to update the timer notification identifiers.
     */
    public synchronized void removeAllNotifications() {

        TimerAlarmClock alarmClock;

        for (Object[] obj : timerTable.values()) {

            // Stop the TimerAlarmClock.
            //
            alarmClock = (TimerAlarmClock)obj[ALARM_CLOCK_INDEX];
//             if (alarmClock != null) {
//                 alarmClock.interrupt();
//                 try {
//                     // Wait until the thread die.
//                     //
//                     alarmClock.join();
//                 } catch (InterruptedException ex) {
//                     // Ignore...
//                 }
                  // Remove the reference on the TimerAlarmClock.
                  //
//             }
            alarmClock.cancel();
        }

        // Remove all the timer notifications from the timer table.
        TIMER_LOGGER.log(Level.TRACE, "removing all timer notifications");

        timerTable.clear();

        TIMER_LOGGER.log(Level.TRACE, "all timer notifications removed");
        // Reset the counterID.
        //
        counterID = 0;

        TIMER_LOGGER.log(Level.TRACE, "timer notification counter ID reset");
    }

    // GETTERS AND SETTERS
    //--------------------

    /**
     * Gets the number of timer notifications registered into the list of notifications.
     *
     * @return The number of timer notifications.
     */
    public synchronized int getNbNotifications() {
        return timerTable.size();
    }

    /**
     * Gets all timer notification identifiers registered into the list of notifications.
     *
     * @return A vector of <CODE>Integer</CODE> objects containing all the timer notification identifiers.
     * <BR>The vector is empty if there is no timer notification registered for this timer MBean.
     */
    public synchronized Vector<Integer> getAllNotificationIDs() {
        return new Vector<Integer>(timerTable.keySet());
    }

    /**
     * Gets all the identifiers of timer notifications corresponding to the specified type.
     *
     * @param type The timer notification type.
     *
     * @return A vector of <CODE>Integer</CODE> objects containing all the identifiers of
     * timer notifications with the specified <CODE>type</CODE>.
     * <BR>The vector is empty if there is no timer notifications registered for this timer MBean
     * with the specified <CODE>type</CODE>.
     */
    public synchronized Vector<Integer> getNotificationIDs(String type) {

        String s;

        Vector<Integer> v = new Vector<Integer>();

        for (Map.Entry<Integer,Object[]> entry : timerTable.entrySet()) {
            Object[] obj = entry.getValue();
            s = ((TimerNotification)obj[TIMER_NOTIF_INDEX]).getType();
            if ((type == null) ? s == null : type.equals(s))
                v.addElement(entry.getKey());
        }
        return v;
    }
    // 5089997: return is Vector<Integer> not Vector<TimerNotification>

    /**
     * Gets the timer notification type corresponding to the specified identifier.
     *
     * @param id The timer notification identifier.
     *
     * @return The timer notification type or null if the identifier is not mapped to any
     * timer notification registered for this timer MBean.
     */
    public synchronized String getNotificationType(Integer id) {

        Object[] obj = timerTable.get(id);
        if (obj != null) {
            return ( ((TimerNotification)obj[TIMER_NOTIF_INDEX]).getType() );
        }
        return null;
    }

    /**
     * Gets the timer notification detailed message corresponding to the specified identifier.
     *
     * @param id The timer notification identifier.
     *
     * @return The timer notification detailed message or null if the identifier is not mapped to any
     * timer notification registered for this timer MBean.
     */
    public synchronized String getNotificationMessage(Integer id) {

        Object[] obj = timerTable.get(id);
        if (obj != null) {
            return ( ((TimerNotification)obj[TIMER_NOTIF_INDEX]).getMessage() );
        }
        return null;
    }

    /**
     * Gets the timer notification user data object corresponding to the specified identifier.
     *
     * @param id The timer notification identifier.
     *
     * @return The timer notification user data object or null if the identifier is not mapped to any
     * timer notification registered for this timer MBean.
     */
    // NPCTE fix for bugId 4464388, esc 0, MR, 03 sept 2001, to be added after modification of jmx spec
    //public Serializable getNotificationUserData(Integer id) {
    // end of NPCTE fix for bugId 4464388

    public synchronized Object getNotificationUserData(Integer id) {
        Object[] obj = timerTable.get(id);
        if (obj != null) {
            return ( ((TimerNotification)obj[TIMER_NOTIF_INDEX]).getUserData() );
        }
        return null;
    }

    /**
     * Gets a copy of the date associated to a timer notification.
     *
     * @param id The timer notification identifier.
     *
     * @return A copy of the date or null if the identifier is not mapped to any
     * timer notification registered for this timer MBean.
     */
    public synchronized Date getDate(Integer id) {

        Object[] obj = timerTable.get(id);
        if (obj != null) {
            Date date = (Date)obj[TIMER_DATE_INDEX];
            return (new Date(date.getTime()));
        }
        return null;
    }

    /**
     * Gets a copy of the period (in milliseconds) associated to a timer notification.
     *
     * @param id The timer notification identifier.
     *
     * @return A copy of the period or null if the identifier is not mapped to any
     * timer notification registered for this timer MBean.
     */
    public synchronized Long getPeriod(Integer id) {

        Object[] obj = timerTable.get(id);
        if (obj != null) {
            return (Long)obj[TIMER_PERIOD_INDEX];
        }
        return null;
    }

    /**
     * Gets a copy of the remaining number of occurrences associated to a timer notification.
     *
     * @param id The timer notification identifier.
     *
     * @return A copy of the remaining number of occurrences or null if the identifier is not mapped to any
     * timer notification registered for this timer MBean.
     */
    public synchronized Long getNbOccurences(Integer id) {

        Object[] obj = timerTable.get(id);
        if (obj != null) {
            return (Long)obj[TIMER_NB_OCCUR_INDEX];
        }
        return null;
    }

    /**
     * Gets a copy of the flag indicating whether a periodic notification is
     * executed at <i>fixed-delay</i> or at <i>fixed-rate</i>.
     *
     * @param id The timer notification identifier.
     *
     * @return A copy of the flag indicating whether a periodic notification is
     *         executed at <i>fixed-delay</i> or at <i>fixed-rate</i>.
     */
    public synchronized Boolean getFixedRate(Integer id) {

      Object[] obj = timerTable.get(id);
      if (obj != null) {
        Boolean fixedRate = (Boolean)obj[FIXED_RATE_INDEX];
        return (Boolean.valueOf(fixedRate.booleanValue()));
      }
      return null;
    }

    /**
     * Gets the flag indicating whether or not the timer sends past notifications.
     * <BR>The default value of the past notifications sending on/off flag is <CODE>false</CODE>.
     *
     * @return The past notifications sending on/off flag value.
     *
     * @see #setSendPastNotifications
     */
    public boolean getSendPastNotifications() {
        return sendPastNotifications;
    }

    /**
     * Sets the flag indicating whether the timer sends past notifications or not.
     * <BR>The default value of the past notifications sending on/off flag is <CODE>false</CODE>.
     *
     * @param value The past notifications sending on/off flag value.
     *
     * @see #getSendPastNotifications
     */
    public void setSendPastNotifications(boolean value) {
        sendPastNotifications = value;
    }

    /**
     * Tests whether the timer MBean is active.
     * A timer MBean is marked active when the {@link #start start} method is called.
     * It becomes inactive when the {@link #stop stop} method is called.
     * <BR>The default value of the active on/off flag is <CODE>false</CODE>.
     *
     * @return <CODE>true</CODE> if the timer MBean is active, <CODE>false</CODE> otherwise.
     */
    public boolean isActive() {
        return isActive;
    }

    /**
     * Tests whether the list of timer notifications is empty.
     *
     * @return <CODE>true</CODE> if the list of timer notifications is empty, <CODE>false</CODE> otherwise.
     */
    public synchronized boolean isEmpty() {
        return (timerTable.isEmpty());
    }

    /*
     * ------------------------------------------
     *  PRIVATE METHODS
     * ------------------------------------------
     */

    /**
     * Sends or not past notifications depending on the specified flag.
     *
     * @param currentDate The current date.
     * @param currentFlag The flag indicating if past notifications must be sent or not.
     */
    private synchronized void sendPastNotifications(Date currentDate, boolean currentFlag) {

        TimerNotification notif;
        Integer notifID;
        Date date;

        ArrayList<Object[]> values =
            new ArrayList<Object[]>(timerTable.values());

        for (Object[] obj : values) {

            // Retrieve the timer notification and the date notification.
            //
            notif = (TimerNotification)obj[TIMER_NOTIF_INDEX];
            notifID = notif.getNotificationID();
            date = (Date)obj[TIMER_DATE_INDEX];

            // Update the timer notification while:
            //  - the timer notification date is earlier than the current date
            //  - the timer notification has not been removed from the timer table.
            //
            while ( (currentDate.after(date)) && (timerTable.containsKey(notifID)) ) {

                if (currentFlag == true) {
                    if (TIMER_LOGGER.isLoggable(Level.TRACE)) {
                        StringBuilder strb = new StringBuilder()
                        .append("sending past timer notification:")
                        .append("\n\tNotification source = ")
                        .append(notif.getSource())
                        .append("\n\tNotification type = ")
                        .append(notif.getType())
                        .append("\n\tNotification ID = ")
                        .append(notif.getNotificationID())
                        .append("\n\tNotification date = ")
                        .append(date)
                        .append("\n\tNotification period = ")
                        .append(obj[TIMER_PERIOD_INDEX])
                        .append("\n\tNotification nb of occurrences = ")
                        .append(obj[TIMER_NB_OCCUR_INDEX])
                        .append("\n\tNotification executes at fixed rate = ")
                        .append(obj[FIXED_RATE_INDEX]);
                        TIMER_LOGGER.log(Level.TRACE, strb::toString);
                    }
                    sendNotification(date, notif);

                    TIMER_LOGGER.log(Level.TRACE, "past timer notification sent");
                }

                // Update the date and the number of occurrences of the timer notification.
                //
                updateTimerTable(notif.getNotificationID());
            }
        }
    }

    /**
     * If the timer notification is not periodic, it is removed from the list of notifications.
     * <P>
     * If the timer period of the timer notification has a non null periodicity,
     * the date of the timer notification is updated by adding the periodicity.
     * The associated TimerAlarmClock is updated by setting its timeout to the period value.
     * <P>
     * If the timer period has a defined number of occurrences, the timer
     * notification is updated if the number of occurrences has not yet been reached.
     * Otherwise it is removed from the list of notifications.
     *
     * @param notifID The timer notification identifier to update.
     */
    private synchronized void updateTimerTable(Integer notifID) {

        // Retrieve the timer notification and the TimerAlarmClock.
        //
        Object[] obj = timerTable.get(notifID);
        Date date = (Date)obj[TIMER_DATE_INDEX];
        Long period = (Long)obj[TIMER_PERIOD_INDEX];
        Long nbOccurences = (Long)obj[TIMER_NB_OCCUR_INDEX];
        Boolean fixedRate = (Boolean)obj[FIXED_RATE_INDEX];
        TimerAlarmClock alarmClock = (TimerAlarmClock)obj[ALARM_CLOCK_INDEX];

        if (period.longValue() != 0) {

            // Update the date and the number of occurrences of the timer notification
            // and the TimerAlarmClock time out.
            // NOTES :
            //   nbOccurences = 0 notifies an infinite periodicity.
            //   nbOccurences = 1 notifies a finite periodicity that has reached its end.
            //   nbOccurences > 1 notifies a finite periodicity that has not yet reached its end.
            //
            if ((nbOccurences.longValue() == 0) || (nbOccurences.longValue() > 1)) {

                date.setTime(date.getTime() + period.longValue());
                obj[TIMER_NB_OCCUR_INDEX] = Long.valueOf(java.lang.Math.max(0L, (nbOccurences.longValue() - 1)));
                nbOccurences = (Long)obj[TIMER_NB_OCCUR_INDEX];

                if (isActive == true) {
                  if (fixedRate.booleanValue())
                  {
                    alarmClock = new TimerAlarmClock(this, date);
                    obj[ALARM_CLOCK_INDEX] = (Object)alarmClock;
                    timer.schedule(alarmClock, alarmClock.next);
                  }
                  else
                  {
                    alarmClock = new TimerAlarmClock(this, period.longValue());
                    obj[ALARM_CLOCK_INDEX] = (Object)alarmClock;
                    timer.schedule(alarmClock, alarmClock.timeout);
                  }
                }
                if (TIMER_LOGGER.isLoggable(Level.TRACE)) {
                    TimerNotification notif = (TimerNotification)obj[TIMER_NOTIF_INDEX];
                    StringBuilder strb = new StringBuilder()
                    .append("update timer notification with:")
                    .append("\n\tNotification source = ")
                    .append(notif.getSource())
                    .append("\n\tNotification type = ")
                    .append(notif.getType())
                    .append("\n\tNotification ID = ")
                    .append(notifID)
                    .append("\n\tNotification date = ")
                    .append(date)
                    .append("\n\tNotification period = ")
                    .append(period)
                    .append("\n\tNotification nb of occurrences = ")
                    .append(nbOccurences)
                    .append("\n\tNotification executes at fixed rate = ")
                    .append(fixedRate);
                    TIMER_LOGGER.log(Level.TRACE, strb::toString);
                }
            }
            else {
                if (alarmClock != null) {
//                     alarmClock.interrupt();
//                     try {
//                         // Wait until the thread die.
//                         //
//                         alarmClock.join();
//                     } catch (InterruptedException e) {
//                         // Ignore...
//                     }
                    alarmClock.cancel();
                }
                timerTable.remove(notifID);
            }
        }
        else {
            if (alarmClock != null) {
//                 alarmClock.interrupt();
//                 try {
//                     // Wait until the thread die.
//                     //
//                     alarmClock.join();
//                 } catch (InterruptedException e) {
//                     // Ignore...
//                 }

                   alarmClock.cancel();
            }
            timerTable.remove(notifID);
        }
    }

    /*
     * ------------------------------------------
     *  PACKAGE METHODS
     * ------------------------------------------
     */

    /**
     * This method is called by the timer each time
     * the TimerAlarmClock has exceeded its timeout.
     *
     * @param notification The TimerAlarmClock notification.
     */
    @SuppressWarnings("deprecation")
    void notifyAlarmClock(TimerAlarmClockNotification notification) {

        TimerNotification timerNotification = null;
        Date timerDate = null;

        // Retrieve the timer notification associated to the alarm-clock.
        //
        TimerAlarmClock alarmClock = (TimerAlarmClock)notification.getSource();

        synchronized(Timer.this) {
            for (Object[] obj : timerTable.values()) {
                if (obj[ALARM_CLOCK_INDEX] == alarmClock) {
                    timerNotification = (TimerNotification)obj[TIMER_NOTIF_INDEX];
                    timerDate = (Date)obj[TIMER_DATE_INDEX];
                    break;
                }
            }
        }

        // Notify the timer.
        //
        sendNotification(timerDate, timerNotification);

        // Update the notification and the TimerAlarmClock timeout.
        //
        updateTimerTable(timerNotification.getNotificationID());
    }

    /**
     * This method is used by the timer MBean to update and send a timer
     * notification to all the listeners registered for this kind of notification.
     *
     * @param timeStamp The notification emission date.
     * @param notification The timer notification to send.
     */
    void sendNotification(Date timeStamp, TimerNotification notification) {

        if (TIMER_LOGGER.isLoggable(Level.TRACE)) {
            StringBuilder strb = new StringBuilder()
            .append("sending timer notification:")
            .append("\n\tNotification source = ")
            .append(notification.getSource())
            .append("\n\tNotification type = ")
            .append(notification.getType())
            .append("\n\tNotification ID = ")
            .append(notification.getNotificationID())
            .append("\n\tNotification date = ")
            .append(timeStamp);
            TIMER_LOGGER.log(Level.TRACE, strb::toString);
        }
        long curSeqNumber;
        synchronized(this) {
            sequenceNumber = sequenceNumber + 1;
            curSeqNumber = sequenceNumber;
        }
        synchronized (notification) {
            notification.setTimeStamp(timeStamp.getTime());
            notification.setSequenceNumber(curSeqNumber);
            this.sendNotification((TimerNotification)notification.cloneTimerNotification());
        }

        TIMER_LOGGER.log(Level.TRACE, "timer notification sent");
    }
}