TempLock.java
/*
** Module : TempLock.java
** Abstract : An object which encapsulates a resettable lock on a specific DMO
**
** Copyright (c) 2004-2024, Golden Code Development Corporation.
**
** -#- -I- --Date-- --JPRM-- -----------------------------------Description-----------------------------------
** 001 ECF 20061112 @31143 Created initial version. An object which encapsulates a resettable
** lock on a specific DMO.
** 002 ECF 20070412 @32991 Retrofit to use RecordLockContext for record locking. Minor
** implementation change.
** 003 ECF 20131029 Import change. Removed unused instance variable.
** 004 ECF 20200906 New ORM implementation.
** 005 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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**
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*/
package com.goldencode.p2j.persist;
import com.goldencode.p2j.persist.lock.*;
/**
* Object which encapsulates a resettable lock on a specific DMO. Successful
* construction of an instance of this class indicates that the requested
* lock type was obtained from the appropriate lock manager or was already
* available to this session. The old lock type is restored by invoking
* {@link #reset}.
*/
public final class TempLock
{
/** Unique record identifier */
private final RecordIdentifier<String> ident;
/** Previous lock type of DMO */
private final LockType originalLockType;
/** Object which services lock requests */
private final Persistence persistence;
/** In case of multi-tenant environment: is the buffer shared or private? */
private final boolean sharedDb;
/**
* Constructor which acquires a record lock of the specified type. This
* constructor may block indefinitely if the lock is unavailable and the
* requested lock type is not a NO_WAIT variant.
*
* @param persistence
* Object which services lock requests.
* @param lockType
* Type of lock to be acquired.
* @param table
* Table containing target DMO.
* @param recordID
* Primary key ID of DMO being locked.
* @param sharedDb
* In case of multi-tenant environment: is the buffer shared or private?
*/
TempLock(Persistence persistence, LockType lockType, String table, Long recordID, boolean sharedDb)
throws LockUnavailableException
{
this.persistence = persistence;
this.sharedDb = sharedDb;
this.ident = new RecordIdentifier<>(table, recordID);
LockType currentType = persistence.queryLock(ident, sharedDb);
if (lockType.compareTo(currentType) > 0)
{
originalLockType = currentType;
RecordLockContext lockCtx = persistence.getRecordLockContext(sharedDb);
lockCtx.lock(ident, lockType);
}
else
{
originalLockType = null;
}
}
/**
* Reset the record lock back to its original type. This is a no-op if
* the old and new types are the same or if the lock type was never
* changed by this object.
*/
void reset()
{
if (originalLockType == null)
{
// Lock type was never changed; nothing to do.
return;
}
LockType currentType = persistence.queryLock(ident, sharedDb);
if (currentType.compareTo(originalLockType) > 0)
{
try
{
RecordLockContext lockCtx = persistence.getRecordLockContext(sharedDb);
lockCtx.lock(ident, originalLockType);
}
catch (LockUnavailableException exc)
{
// Not thrown when requesting non-NO_WAIT lock type variants.
}
}
}
}