# TemporaryAccountWorker.java

    /*
    ** Module   : TemporaryAccountWorker.java
    ** Abstract : a Runnable object used to manage user accounts.
    **
    ** Copyright (c) 2013-2023, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- -------------------------------Description------------------------------------
    ** 001 MAG 20131216 Created initial version.
    ** 002 CA  20140214 Fixed NPE at thread shutdown when the pool is never used.
    ** 003 MAG 20140217 Fixed thread termination.
    ** 004 CA  20150909 Fixed a race condition resulting in a NPE for callerLatch.
    ** 005 GBB 20230512 Logging methods replaced by CentralLogger/ConversionStatus.
    */
    /*
    ** 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.main;

    import java.util.concurrent.*;
    import java.util.logging.*;

    import com.goldencode.p2j.util.logging.*;

    /**
     * A Runnable object used to manage user accounts.
     * In order to manage user account admin rights are mandatory.
     * This object is used as Runnable target in an AssociatedThread instance
     * which run in standard server security context and inherit server admin rights.
     * This object execute the run method of another Runnable object the task to be executed.
     * The execute method is synchronized between this thread and caller.
     * The caller waits for end of execution of task that he provide as parameter.
     *
     * @author mag
     *
     */
    public class TemporaryAccountWorker
    implements Runnable
    {
       /** Logger. */
       private static final CentralLogger LOG = CentralLogger.get(TemporaryAccountWorker.class.getName());

       /**  Termination flag */
       private volatile boolean terminated = false;

       /** Thread synchronization */
       private volatile CountDownLatch workerLatch;

       /** Caller synchronization */
       private volatile CountDownLatch callerLatch;

       /** Task to be executed */
       private volatile Runnable task;

       /**
        * Constructor.
        * Initialize thread synchronization latch.
        */
       public TemporaryAccountWorker()
       {
          workerLatch = new CountDownLatch(1);
       }

       /**
        * Execute specified task.
        *
        * @param   task
        *          Task to be executed.
        */
       public void execute(Runnable task)
       {
          try
          {
             if (!terminated)
             {
                // Set task instance.
                this.task = task;
                // Arm caller latch.
                callerLatch = new CountDownLatch(1);
                // Execute task.
                workerLatch.countDown();
                // Wait for task execution to end.
                callerLatch.await();
             }
          }
          catch (InterruptedException e)
          {
             LOG.logp(Level.WARNING,
                      "TemporaryAccountWorker.execute()",
                      "",
                      "InterruptedException!",
                      e);
          }
       }

       /**
        * Task executor.
        */
       public void run()
       {
          while (!terminated)
          {
             try
             {
                // Waiting for a call
                workerLatch.await();
                // Execute task
                if (!terminated && task != null)
                {
                   task.run();
                   task = null;
                }
             }
             catch (InterruptedException e)
             {
                LOG.logp(Level.WARNING,
                         "TemporaryAccountWorker.run()",
                         "",
                         "InterruptedException!",
                         e);
             }
             finally
             {
                if (!terminated && workerLatch.getCount() == 0)
                {
                   workerLatch = new CountDownLatch(1);
                }
                if (callerLatch != null && callerLatch.getCount() == 1)
                {
                   // Notify caller
                   callerLatch.countDown();
                }
             }
          }

          LOG.logp(Level.INFO,
                   "TemporaryAccountWorker.run()",
                   "",
                   "Thread exit.");
       }

       /**
        * Terminate thread.
        */
       public void terminate()
       {
          this.terminated = true;
          if (workerLatch.getCount() == 1)
          {
             workerLatch.countDown();
          }
       }
    }