# Facultative.java

    /*
    ** Module   : Facultative.java
    ** Abstract : MBean supporting enable/disable
    **
    ** Copyright (c) 2020-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description----------------------------------
    ** 001 IAS 20200930 Created initial version.
    ** 002 IAS 20201001 Added dump of MBean state.
    ** 003 HC  20240222 Enabled JMX on FWD Client.
    */

    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program 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 Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.jmx;

    import java.lang.ref.*;
    import java.util.*;
    import java.util.concurrent.atomic.*;

    import com.goldencode.util.*;

    /**
     * MBean supporting enable/disable
     */
    public class Facultative
    implements FacultativeMBean,
               AgentRegistry<BooleanConsumer>
    {
       /** agent's set */
       private final Set<BooleanConsumer> agents = Collections.newSetFromMap(
             new WeakHashMap<BooleanConsumer, Boolean>()
       );

       /** "MBean enabled flag */
       private final AtomicBoolean enabled = new AtomicBoolean(false);

       /** MBean annotation */
       private String annotation = "Counters";

       /**
        * Check if enabled
        * @return <code>true</code> if enabled
        */
       @Override
       public boolean isEnabled()
       {
          return enabled.get();
       }

       /**
        * Enable/disable
        * @param val
        *        new value of the "enabled" flag.
        */
       @Override
       public synchronized void enable(boolean val)
       {

          if (enabled.getAndSet(val) != val)
          {
             agents.stream().forEach(c -> c.accept(val));
          }
       }

       /**
        * Register agent
        *
        * @param agent
        *        agent to be registered
        */
       @Override
       public synchronized void register(BooleanConsumer agent)
       {
          // sync the enabled state on registration for the case when
          // the simple counter gets loaded/unloaded dynamically (like a web app)
          // or the class has simply not been yet loaded by the class loader
          agent.accept(enabled.get());
          agents.add(agent);
       }

       /**
        * Get counter annotation
        * @return counter annotation
        */
       @Override
       public String getAnnotation()
       {
          return annotation;
       }

       /**
        * Set counter annotation
        * @param annotation
        *        counter annotation
        */
       @Override
       public void setAnnotation(String annotation)
       {
          this.annotation = annotation;
       }
    }