RemoteLegacyJavaAppserverClient.java

/*
** Module   : RemoteLegacyJavaAppserverClient.java
** Abstract : Implementation for remote Java clients connecting to a FWD server (running in separate JVM).
**
** Copyright (c) 2022-2025, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description----------------------------------------
** 001 CA  20221031 Created initial version.
** 002 GBB 20240610 LegacyAppServerWork replaced by Consumer<LegacyServiceWorker>. 
** 003 CA  20250324 Improvements for remote FWD OpenClient connections: ensure that the remote side uses a
**                  single connection to the FWD server, and also use a client-side pool of worker threads to
**                  send the requests (the pool size is in sync with the maximum agents available to process
**                  requests).
*/

/*
** 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.util;

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

import com.goldencode.p2j.main.*;

/**
 * A Java client which connected to a remote FWD server. 
 */
class RemoteLegacyJavaAppserverClient
extends LegacyJavaAppserverClient
{
   /** Flag indicating if this client has disconnected. */
   private boolean disconnected = false;

   /**
    * Initialize this client with the given worker pool.
    * 
    * @param    pool
    *           The pool of workers where tasks will be forwarded, to be executed on the remote appserver.
    */
   public RemoteLegacyJavaAppserverClient(RemoteAppServerConnectionPool pool)
   {
      super(pool);
   }
   
   /**
    * Connect to the remote FWD server.
    * 
    * @return   <code>true</code> if it connected.
    */
   @Override
   public boolean connect()
   {
      if (disconnected)
      {
         String appserver = pool.getAppserver();
         LOG.log(Level.SEVERE, "FWD '" + appserver + "' appserver client is disconnect, can not reconnect.");
         return false;
      }
      
      return super.connect();
   }
   
   /**
    * Terminate all sessions on this client.
    */
   @Override
   public void disconnect()
   {
      this.disconnected = true;
      cancelAllRequests();
      
      CountDownLatch disc = new CountDownLatch(pool.size());

      LegacyAppServerWork work = (worker) ->
      {
         try
         {
            Set<ProxyProcedureWrapper> procedures = worker.getProcedures(sessionID);
            for (ProxyProcedureWrapper proc : procedures)
            {
               worker.getHelper().deleteProcedure(proc);
               worker.removeProcedure(sessionID, proc);
            }
            
            worker.removeProcedures(sessionID);
            worker.getHelper().disconnect();
         }
         finally
         {
            disc.countDown();
         }
      };
      
      pool.broadcast(work);
      
      try
      {
         disc.await();
      }
      catch (InterruptedException e)
      {
         // ignore
      }
      finally
      {
         pool.terminateWorkers();
         connectionID = null;
      }
   }
   
   /**
    * Cancel all the requests active on this client.
    */
   @Override
   public void cancelAllRequests()
   {
      if (connectionID == null)
      {
         return;
      }
      
      LegacyAppServerWork work = (worker) ->
      {
         worker.getHelper().sendStop();
      };
      
      pool.broadcast(work);
   }
   
   /**
    * Send the given task to be executed by one of the workers in the {@link #pool}.
    * 
    * @param    work
    *           The work to be executed.
    *           
    * @throws   RuntimeException
    *           If the request was not posted to any worker or the time allowed to execute has elapsed.
    */
   @Override
   protected boolean execute(LegacyAppServerWork work)
   {
      if (disconnected)
      {
         String appserver = pool.getAppserver();
         LOG.log(Level.SEVERE, "FWD '" + appserver + "' appserver client is not connected.");
         return false;
      }
      
      return super.execute(work);
   }
}