TriggerDefinition.java

/*
** Module   : TriggerDefinition.java
** Abstract : container for trigger metadata that allows a new instance to
**            be manufactured
**
** Copyright (c) 2008-2023, Golden Code Development Corporation.
**
** -#- -I- --Date-- --JPRM-- -----------------------------Description-----------------------------
** 001 GES 20081217   @40928 Created initial version as the container for trigger metadata that 
**                           allows a new instance to be manufactured.
** 002 CA  20140218          Expose trigger's external program instance.
** 003 CA  20151030          Report if the trigger definition was created in an external program.
** 004 GES 20161004          Enabled an alternate path that uses a single pre-instantiated
**                           Trigger instance (using lambdas).  Inner class mode is still
**                           supported and is needed when there are local variables defined for
**                           the trigger.
** 005 CA  20190328          Triggers are emitted as anon inner classes, instantiated via a lambda 
**                           expression.
** 006 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.
** 
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** 
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*/

package com.goldencode.p2j.util;

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

import java.util.function.*;

import static com.goldencode.p2j.util.BlockManager.*;

/**
 * Container for trigger metadata that allows a new instance to be
 * manufactured.
 * <p>
 * Triggers are anonymous inner classes that may have data members. The
 * initialization of those data members naturally occurs during construction.
 * This means that only after construction can one be assured that the value
 * of a trigger's data members is set to the expected default value. This
 * means that every time a trigger is executed, that execution must occur on
 * a newly constructed instance, so that the data member's default values
 * will be correct.
 * <p>
 * This class stores the data needed to delegate the construction of a
 * {@link Trigger} subclass to code that is executing that trigger. This is
 * performed via a lambda expression, which creates a new instance of the
 * trigger each time the trigger is invoked.
 * <p>
 * The complexity of the instantiation is hidden in this class. The logic
 * can be found in {@link #getTrigger}.
 */
public class TriggerDefinition
{
   /** Logger (this is JVM-wide rather than being context-local). */
   private static final CentralLogger LOG = 
      CentralLogger.get(TransactionManager.class.getName());
   
   /** The supplier for this trigger's instances. */
   private Supplier<Trigger> trigger = null;
   
   /** The external program instance where the trigger was defined. */
   private Object externalProgram = null;
   
   /** Determines if this trigger should start a full transaction. */
   private boolean fullTrans = false;
   
   /** Flag indicating the trigger definition was created in an external program. */
   private final boolean fromExternalProgram;
   
   /**
    * Constructor for lambda mode.
    *
    * @param    trigger
    *           The specific {@link Trigger} instance that implements the
    *           trigger logic.
    * @param    outer
    *           The instance of the containing class for the trigger.
    * @param    fullTrans
    *           <code>true</code> if the trigger should start a full
    *           transaction, <code>false</code> if the trigger should
    *           create a sub-transaction.
    */
   public TriggerDefinition(Supplier<Trigger> trigger, Object outer, boolean fullTrans)
   {
      this.trigger   = trigger;
      this.fullTrans = fullTrans;
      this.externalProgram = outer;
      this.fromExternalProgram = TransactionManager.isExternalBlock();
      this.fullTrans = fullTrans;
   }
   
   /**
    * Construct a new instance of the trigger class that is defined by the
    * contained metadata.
    *
    * @return   The newly instantiated trigger instance. If any failure
    *           occurs, this will return <code>null</code>.
    */
   public Trigger getTrigger()
   {
      Trigger instance = trigger.get();
      if (fullTrans)
      {
         instance.setLevel(TransactionType.FULL);
      }
      
      return instance;
   }
   
   /**
    * Get the external program instance where this trigger was defined.
    * 
    * @return    See above.
    */
   public Object getExternalProgram()
   {
      return externalProgram;
   }
   
   /**
    * Check if this trigger was created by an external program.
    * 
    * @return   The state of the {@link #fromExternalProgram} flag.
    */
   public boolean isFromExternalProgram()
   {
      return fromExternalProgram;
   }
}