# IdentityManagerMultiplexerImpl.java

    /*
    ** Module   : IdentityManagerMultiplexerImpl.java
    ** Abstract : Handles server-to-server requests for record identity management
    **
    ** Copyright (c) 2004-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --JPRM-- -----------------------------------Description-----------------------------------
    ** 001 SVL 20080111  @36794  Created initial version. Handles server to server requests for record
    **                           identity management.
    ** 002 SVL 20080901  @39650  Added reclaimKeys() function.
    ** 003 ECF 20200906          New ORM implementation.
    ** 004 OM  20241128          Multi-tenant runtime support: selected the proper persistence context, eventually
    **                           based on [sharedDb] parameter.
    */

    /*
    ** 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.
    **
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    **     work or Appropriate Legal Notices displayed by works containing the covered
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    **
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    **
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    */

    package com.goldencode.p2j.persist.remote;

    import com.goldencode.p2j.persist.id.*;
    import com.goldencode.p2j.persist.*;
    import com.goldencode.p2j.net.*;

    /**
     * A singleton instance of this class services server-to-server requests for
     * database identity management.  This instance is registered as a remote
     * object and serves identity management requests for one or more databases
     * which the server authoritatively manages.
     * <p>
     * Service requests may originate from more than one external server, so this
     * implementation is threadsafe.
     *
     * @author SVL
     */
    public final class IdentityManagerMultiplexerImpl
    extends DatabaseMultiplexer<IdentityManager>
    implements IdentityManagerMultiplexer
    {
       /** Singleton instance of this class */
       private static IdentityManagerMultiplexer instance = null;

       /**
        * Initialize the identity multiplexer for this server instance. This
        * method is to be called during server bootstrap, but not before the local
        * database manager has been initialized.
        * <p>
        * This method enforces the singleton pattern.
        *
        * @throws  IllegalStateException
        *          if this method is invoked more than once.
        */
       public static synchronized void initialize()
       {
          if (instance != null)
          {
             throw new IllegalStateException(
                "Identity multiplexer already initialized for this process");
          }

          instance = new IdentityManagerMultiplexerImpl();
          RemoteObject.registerNetworkServer(IdentityManagerMultiplexer.class,
                                             instance);
       }

       /**
        * Default constructor which initializes the resources needed for this
        * multiplexer to service identity manager requests.
        */
       private IdentityManagerMultiplexerImpl()
       {
          super();
       }

       /**
        * Return the next primary key for the specified table.
        *
        * @param   database
        *          Value that uniquely identifies the target database on the
        *          remote server.
        *
        * @param   table
        *          Table for which the next primary key will be returned.
        *
        * @return  The next primary key for the given table.
        *
        * @throws  PersistenceException
        *          if there is an error determining the next primary key ID.
        */
       public Long nextPrimaryKey(int database, String table)
       throws PersistenceException
       {
          return lookupWorker(database).nextPrimaryKey(table);
       }

       /**
        * Inform the identity manager that the given primary keys can be reused.
        *
        * @param database
        *        Value that uniquely identifies the target database on the
        *        remote server.
        *
        * @param keys
        *        Keys for reuse.
        */
       public void reclaimKeys(int database, Long[] keys)
       {
          lookupWorker(database).reclaimKeys(keys);
       }

       /**
        * Get the identity manager which is associated with the given database.
        *
        * @param   database
        *          Physical database with which the returned worker is associated.
        *
        * @return  Worker object to which service requests associated with the
        *          given database must be delegated.
        */
       protected IdentityManager getWorker(Database database)
       {
          Persistence p = PersistenceFactory.getInstance(database);

          return p.getIdentityManager(!database.isTenant());
       }
    }