TransactionImpl.java

/*
** Module   : TransactionImpl.java
** Abstract : Implementation of the TRANSACTION resource. 
**
** Copyright (c) 2018-2023, Golden Code Development Corporation.

**
** -#- -I- --Date-- --------------------------------Description-----------------------------------
** 001 CA  20181112 Created initial version.
** 002 GBB 20230512 Logging methods replaced by CentralLogger/ConversionStatus.
** 003 CA  20230607 TRANSACTION-MODE AUTO must preserve the tx in the root appserver block - this is required
**                  because in modes other than State-free, requests can be executed on the same agent who had
**                  TRANSACTION-MODE AUTO, and this must see as active the tx initially set.
*/
/*
** 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.
** 
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**     name Golden Code, FWD, or the names of any author or contributor, for
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*/

package com.goldencode.p2j.util;

import java.util.logging.Level;

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

/**
 * Implements the TRANSACTION resources and all associated APIs.
 */
public class TransactionImpl
extends HandleResource
implements TransactionResource,
           Deletable
{
   /** Logger */
   private static final CentralLogger LOG = CentralLogger.get(TransactionImpl.class.getName());

   /** Context local state for the TRANSACTION handle. */
   private static final ContextLocal<WorkArea> work = new ContextLocal<WorkArea>()
   {
      /**
       * Initializes the work area, the first time it is requested within a new context.
       * 
       * @return   The newly instantiated work area.
       */
      @Override
      protected WorkArea initialValue()
      {
         return new WorkArea();
      }
   };
   
   /** The current value of the TRANS-INIT-PROCEDURE attribute. */
   private handle txInitProcedure = new handle();
   
   /** The current value of the DEFAULT-COMMIT attribute. */
   private boolean defaultCommit = false;
   
   /** Flag turned on when a pending rollback is active, via {@link #setRollback()}. */
   private boolean pendingRollback = false;
   
   /** Flag turned on when a pending commit is active, via {@link #setCommit()}. */
   private boolean pendingCommit = false;

   /** Flag indicating the current tx was open by TRANS-INIT-PROCEDURE. */
   private boolean openByTxInitProc = false;
   
   /**
    * Private c'tor, to allow a singleton instance of this resource, per each context.
    */
   private TransactionImpl()
   {
      // singleton instance, per each context
   }
   
   /**
    * Get the TRANSACTION resource for this context.
    * 
    * @return   See above.
    */
   static TransactionImpl get()
   {
      WorkArea wa = work.get();
      
      if (wa.tx == null)
      {
         wa.tx = new TransactionImpl();
      }
      
      return wa.tx;
   }
   
   /**
    * Implementation for the {@link WrappedResource#valid()} API.
    * 
    * @return   Always true.
    */
   @Override
   public boolean valid()
   {
      return true;
   }
   
   @Override
   public void delete()
   {
      if (!SessionUtils._isRemote() && LOG.isLoggable(Level.WARNING))
      {
         LOG.warning("Trying to delete the TRANSACTION-OBJECT from a non-appserver client!");
      }
      
      // when accessed from a appserver agent (SESSION:REMOTE is true), this can not be deleted
      // if accessed from normal clients, it can be deleted and the behavior is indeterminate
      // we always assume this can't be deleted.
   }
   
   /**
    * Getter for the INSTANTIATING-PROCEDURE attribute.
    * 
    * @return   Always an unknown handle.
    */
   @Override
   public handle instantiatingProcedure()
   {
      return new handle();
   }

   /**
    * Getter of IS-OPEN attribute - it will return the value of the 
    * {@link TransactionManager#isTransactionActive()} call.
    *
    * @return   See above.
    */
   @Override
   public logical isOpen()
   {
      return TransactionManager.isTransactionActive();
   }

   /**
    * Check the value of the DEFAULT-COMMIT attribute.
    * 
    * @return   The value of the DEFAULT-COMMIT attribute.
    */
   @Override
   public logical isDefaultCommit()
   {
      return new logical(defaultCommit);
   }

   /**
    * Set the value of the DEFAULT-COMMIT attribute.
    * 
    * @param    l
    *           The value of the DEFAULT-COMMIT attribute.
    */
   @Override
   public void setDefaultCommit(logical l)
   {
      if (l.isUnknown())
      {
         ErrorManager.recordOrShowError(4083, 
                                        "**Unable to assign UNKNOWN value to attribute " +
                                        "DEFAULT-COMMIT on TRANSACTION-CONTEXT widget.",
                                        false, false, false, true);
         return;
      }
      
      setDefaultCommit(l.booleanValue());
   }

   /**
    * Set the value of the DEFAULT-COMMIT attribute.
    * 
    * @param    l
    *           The value of the DEFAULT-COMMIT attribute.
    */
   @Override
   public void setDefaultCommit(boolean l)
   {
      defaultCommit = l;
   }

   /**
    * Get the TRANS-INIT-PROCEDURE attribute.
    * 
    * @return   See above.
    */
   @Override
   public handle getTxInitProcedure()
   {
      if (ProcedureManager.hasReferent(txInitProcedure.get()))
      {
         return new handle(txInitProcedure);
      }
      else
      {
         txInitProcedure.setUnknown();
         
         return new handle();
      }
   }

   /**
    * If we are in a TRANSACTION-MODE AUTOMATIC state and a tx is open, mark a pending commit for 
    * the current top-level block.
    * 
    * @return   <code>true</code> if the pending commit was set or a tx is not open.
    */
   @Override
   public logical setCommit()
   {
      if (txInitProcedure.isUnknown() || pendingRollback)
      {
         ErrorManager.recordOrShowError(7355, 
                                        "SET-COMMIT requires a TRANSACTION-MODE AUTOMATIC .p " +
                                        "to be running with no prior SET-ROLLBACK", 
                                        false, false, false);
         return new logical(false);
      }
      
      if (TransactionManager.isTransaction())
      {
         // this just marks the commit to be performed when appserver request is finished
         pendingCommit = true;
      }
      
      return new logical(true);
   }

   /**
    * If we are in a TRANSACTION-MODE AUTOMATIC state and a tx is open, mark a pending rollback for 
    * the current top-level block.
    * 
    * @return   <code>true</code> if the pending rollback was set or a tx is not open.
    */
   @Override
   public logical setRollback()
   {
      if (txInitProcedure.isUnknown())
      {
         ErrorManager.recordOrShowError(7356,
                                        "SET-ROLLBACK requires a TRANSACTION-MODE AUTOMATIC .p " +
                                        "to be running persistently",
                                        false, false, false);
         return new logical(false);
      }

      // if pending commit, then deactivate it and activate the pending rollback
      pendingCommit = false;

      // this just marks the rollback to be performed when appserver request is finished
      pendingRollback = true;
      
      return new logical(true);
   }

   /**
    * Explicitly assign the {@link #txInitProcedure TRANS-INIT-PROCEDURE} attribute.
    * 
    * @param    referent
    *           The new procedure having a TRANSACTION-MODE AUTOMATIC statement, or <code>null</code>
    *           to clear this attribute and the pending flags.
    */
   static void setTxInitProcedure(Object referent)
   {
      TransactionImpl tx = get();
      
      if (referent != null)
      {
         tx.defaultCommit = true;
         tx.txInitProcedure.assign(new ExternalProgramWrapper(referent));
      }
      else
      {
         tx.txInitProcedure.setUnknown();
         
         tx.pendingCommit = false;
         tx.pendingRollback = false;
         tx.defaultCommit = false;
      }
   }
   
   /**
    * Check if the given external program instance is the 
    * {@link #txInitProcedure TRANS-INIT-PROCEDURE} attribute.
    * 
    * @param    referent
    *           The external program instance to check.
    *           
    * @return   <code>true</code> if the refernet is the same as the {@link #txInitProcedure}.
    */
   static boolean isTxInitProcedure(Object referent)
   {
      TransactionImpl tx = get();
      
      return !tx.txInitProcedure.isUnknown() && tx.txInitProcedure.get() == referent;
   }
   
   /**
    * Get the {@link #openByTxInitProc} flag.
    * 
    * @return   The state of the {@link #openByTxInitProc}.
    */
   static boolean isOpenByTxInitProc()
   {
      return get().openByTxInitProc && TransactionManager.isTransaction();
   }
   
   /**
    * Set the {@link #openByTxInitProc} flag.
    * 
    * @param    l
    *           The new state of the {@link #openByTxInitProc}.
    */
   static void setOpenByTxInitProc(boolean l)
   {
      get().openByTxInitProc = l;
   }

   /**
    * Notification that a top-level request has been finished, in the context of a top-level block 
    * belonging to the TRANS-INIT-PROCEDURE external program.
    * 
    * @param    chained
    *           Flag indicating a new tx will be opened.
    * @param    implicit
    *           Flag indicating if this call is for the implicit end of a request, not the delete of the tx 
    *           procedure.
    *           
    * @return   <code>true</code> if there is either a pending {@link #pendingCommit commit} or 
    *           {@link #pendingRollback rollback}.
    */
   static boolean requestFinished(boolean chained, boolean implicit)
   {
      TransactionImpl tx = get();
      
      if (implicit && !(tx.pendingCommit || tx.pendingRollback))
      {
         return false;
      }
      
      try
      {
         if (tx.pendingCommit || (tx.defaultCommit && !tx.pendingRollback))
         {
            TransactionManager.commitTx(chained);
            return true;
         }
         else
         {
            // otherwise, rollback always
            TransactionManager.rollbackTx(chained);
            return true;
         }
      }
      finally
      {
         // this includes lock releases
         TransactionManager.notifyMasterFinish();
         
         tx.pendingCommit = false;
         tx.pendingRollback = false;
      }
   }
   
   /**
    * Context-local state.
    */
   private static class WorkArea
   {
      /** The context-local global instance for the TRANSACTION resource. */
      private TransactionImpl tx = null;
   }
}