ObjectResource.java
/*
** Module : ObjectResource.java
** Abstract : synthetic resource which helps with legacy object management.
**
** Copyright (c) 2019-2024, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description----------------------------------------
** 001 CA 20190122 First version.
** 002 CA 20200304 A 4GL object instance must delay its delete if is still on stack.
** 003 CA 20200324 For H002, use 'nestedSilent', to preserve any already set silent processing.
** 004 CA 20200827 A destructor may invalidate an in-process-of-being-deleted instance.
** CA 20210221 Allow an initializing instance to survive decrement even if it reaches 0. Its reference
** can be passed to arguments/definitions without affecting its lifecycle, unless is
** explicitly deleted.
** CA 20210305 The object fields have a Long representation at the SQL table field.
** CA 20220120 The destructors must be called from delete(), as resourceDelete() can be called multiple
** times. Fixed decrement when there is a pending assignment.
** CA 20220203 Fixed javadoc for resourceDelete().
** CA 20221006 Improved context-local lookup. Refs #6824
** CA 20220524 Fixed destructor execution.
** CA 20220526 If there are subscriptions for a legacy OO instance, do not delete (implicitly).
** Progress.Lang.Class instances can't be deleted.
** CA 20220918 Mark an object as pending delete before executing the destructors.
** CA 20221123 Progress.Lang.Class instances are not reported in the SESSION:FIRST-OBJECT chain.
** CA 20230110 Cache the helper for ProcedureManager, ObjectOps and others (as needed), to reduce
** context-local lookup.
** 005 CA 20230731 Do not delete (implicitly) an instance which is being returned by a function or method
** call.
** 006 CA 20230724 Further reduce context-local usage.
** 007 CA 20240105 The 'inScopeFinished' flag must be reset/restored while executing destructors.
*/
/*
** 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 com.goldencode.p2j.oo.lang.*;
/**
* A pseudo-resource to help management for the legacy class instances.
* <p>
* This will allow the object chaining to work naturally as with other legacy resources, help
* with reference management and resource delete.
*/
@LegacyResource(resource = LegacyResource.OBJECT)
public class ObjectResource
extends HandleChain
{
/** The contained object instance. <code>null</code> is unknown value. */
private _BaseObject_ ref;
/** The reference counter. */
private long references = 0;
/** The destructors to be executed on delete. */
private Deque<InternalEntry> destructors = new ArrayDeque<>(3);
/** Flag indicating if this resource is being deleted. */
private boolean pendingDelete = false;
/**
* Initialize this object with the given reference.
*
* @param reference
* The reference.
*/
public ObjectResource(_BaseObject_ reference)
{
super(false, !(reference instanceof LegacyClass));
this.ref = reference;
// resolve the internal resource ID now.
handle.resourceId(this);
}
/**
* Check if this resource is unknown.
*/
@Override
public boolean unknown()
{
return ref == null;
}
/**
* Check if this pseudo-resource is valid.
*
* @return <code>true</code> if {@link #ref} is not <code>null</code>.
*/
@Override
public boolean valid()
{
return ref != null;
}
/**
* Return the wrapped reference.
*
* @return The contained reference.
*/
public _BaseObject_ ref()
{
return ref;
}
/**
* Check if this resource must be processed via {@link ProcedureManager#processResource}, once
* it has been instantiated.
*
* @return Always <code>false</code>.
*/
protected boolean processResource()
{
return false;
}
/**
* Increment the reference counter.
*/
public void increment()
{
if (references == 0)
{
// remove it from the pending assignments
pm.oh.instanceAssigned(ref);
}
references = references + 1;
}
/**
* Decrement the reference counter. When it reaches zero, delete this object.
*/
public void decrement()
{
if (references > 0)
{
// there are cases where the reference was never assigned.
references = references - 1;
}
if (references == 0 &&
pm.oh.isValid(ref) &&
!pm.oh.isInitializing(ref) &&
!pm.oh.isPendingAssigned(ref) &&
!pm.oh.instanceReturned(ref) &&
!pm.hasSubscriptions(ref))
{
// if there are subscriptions for this instance, do not delete (implicitly)
pm.oh.delete(ref);
}
}
/**
* Perform actual delete of an resource. At the time of this call, it is assumed the resource
* is valid for deletion (the handle and the resource are both valid).
*/
@Override
public void delete()
{
// call resource-specific delete
if (!resourceDelete())
{
// if the resource-specific delete was not possible, exit
return;
}
pendingDelete = true;
boolean inScopeFinished = pm.oh.inScopeFinished();
// call the destructor from all loaded super-classes, in reverse order.
while (!destructors.isEmpty())
{
InternalEntry dtor = destructors.pop();
pm.oh.setInScopeFinished(false);
ControlFlowOps.executeDestructor(ref, dtor);
}
pm.oh.setInScopeFinished(inScopeFinished);
super.delete();
if (valid())
{
// may have been invalidated by the destructor calls.
// finally, delete the resource
ExternalProgramWrapper extProg = new ExternalProgramWrapper(ref);
extProg.delete();
ref = null;
}
}
/**
* Check if the resource can be deleted (is not
* {@link ProcedureManager$ProcedureHelper#isDelayedDelete(Object) delayed}).
*
* @return Always <code>true</code>
*/
@Override
protected boolean resourceDelete()
{
// do not delete a progress.lang.class
if (pm.isDelayedDelete(ref) || ref instanceof LegacyClass)
{
return false;
}
return true;
}
/**
* Checks whether the object has any destructor pushed on stack ready to be executed when the
* lifetime of the object ends.
*
* @return {@code true} if when the object is deleted at least one destructor will be
* executed.
*/
boolean hasActiveDestructors()
{
return !destructors.isEmpty();
}
/**
* Add a new destructor on the stack. These will be invoked, in the inverse order, on object
* deletion.
*
* @param mthd
* The destructor method.
*/
void pushDestructor(InternalEntry mthd)
{
if (destructors.isEmpty() || !mthd.equals(destructors.peek()))
{
destructors.push(mthd);
}
}
/**
* Get the current reference counter.
*
* @return The {@link #references}.
*/
long getReferences()
{
return references;
}
/**
* Silently delete this object, by ignoring all conditions.
*/
void deleteSilent()
{
if (pm.hasSubscriptions(ref))
{
// if there are subscriptions for this instance, do not delete (implicitly)
return;
}
ErrorManager.nestedSilent(() ->
{
try
{
// save the reference, before the delete
_BaseObject_ ref = this.ref;
delete();
if (this.ref == null)
{
// if it was actually deleted, remove the reference
pm.oh.deregisterObject(ref);
}
}
catch (Throwable t)
{
// ignore
}
});
}
/**
* Check if this resource is being deleted.
*
* @return The {@link #pendingDelete} state.
*/
boolean isPendingDelete()
{
return pendingDelete;
}
}