/*
Derby - Class org.apache.derby.impl.store.raw.data.PhysicalPageOperation
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to you under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package org.apache.derby.impl.store.raw.data;
import org.apache.derby.impl.store.raw.data.BasePage;
import org.apache.derby.iapi.store.raw.Compensation;
import org.apache.derby.iapi.store.raw.log.LogInstant;
import org.apache.derby.iapi.store.raw.Transaction;
import org.apache.derby.iapi.store.raw.Undoable;
import org.apache.derby.iapi.error.StandardException;
import java.io.InputStream;
import java.io.ObjectInput;
import java.io.IOException;
import org.apache.derby.iapi.services.io.LimitObjectInput;
/**
An abstract class that is used for physical log operation. A physical log
operation is one where the undo of the operation must be applied to the
same page as the original operation, and the undo operation must store the
byte image of the row(s) changed to its before image. (If a logical page
operation happened to the page or if another transaction altered other rows
on the page, the undo of this operation will only restore the before image
of the row(s) affected).
<PRE>
@format_id no format id, an abstract class.
@purpose provide methods for physical undo
@upgrade
@disk_layout
PageBasicOperation the super class
@end_format
</PRE>
*/
public abstract class PhysicalPageOperation extends PageBasicOperation implements Undoable
{
protected PhysicalPageOperation(BasePage page)
{
super(page);
}
/*
* Formatable methods
*/
// no-arg constructor, required by Formatable
public PhysicalPageOperation() { super(); }
// no fields, therefore no writeExternal or readExternal
/**
Undoable method
*/
/**
Generate a Compensation (PageUndoOperation) that will rollback the
changes of this page operation. If this Page operation cannot or need not
be rolled back (redo only), overwrite this function to return null.
<P><B>Note</B><BR> For operation that needs logical undo, use
LogicalUndoOperation instead</B> This implementation just finds
the same page that the PageOperation was applied on - i.e., only works
for undo on the same page.
<P>During recovery redo, the logging system is page oriented and will use
the pageID stored in the PageUndoOperation to find the page. The
page will be latched and released using the default findpage and
releaseResource - this.releaseResource() will still be called so it has
to know not to release any resource it did not acquire.
@param xact the transaction doing the compensating
@param in optional input
@return the compensation operation that will rollback this change
@exception StandardException Standard Derby policy.
@see PageBasicOperation
@see Undoable#generateUndo
*/
public Compensation generateUndo(Transaction xact, LimitObjectInput in)
throws StandardException
{
// findpage will have the page latched.
// CompensationOperation.doMe must call this.releaseResource the page
// when it is done
BasePage undoPage = findpage(xact);
// Needs to pre-dirty this page so that if a checkpoint is taken any
// time after the CLR is sent to the log stream, it will wait for the
// actual undo to happen on the page. We need this to preserve the
// integrity of the redoLWM.
undoPage.preDirty();
return new PhysicalUndoOperation(undoPage, this);
}
/**
Undo the change indicated by this log operation and optional data.
The page the undo should apply to is the latched undoPage, the
recordId is the same as the roll forward operation.
<BR><B>In this RawStore implementation, should only only be called via
CompOp.doMe</B>.
<P> The available() method of in indicates how much data can be read, i.e.
how much was originally written.
@param xact the Transaction doing the rollback
@param undoPage the page to rollback changes on
@param CLRinstant the log instant of this (PageUndo) operation
@param in optional data for the rollback operation
@exception IOException Can be thrown by any of the methods of ObjectInput.
@exception StandardException Standard Derby policy.
*/
abstract public void undoMe(Transaction xact, BasePage undoPage,
LogInstant CLRinstant, LimitObjectInput in)
throws StandardException, IOException;
}