Class CompressSpacePageOperation

java.lang.Object

org.apache.derby.impl.store.raw.data.PageBasicOperation

org.apache.derby.impl.store.raw.data.PhysicalPageOperation

org.apache.derby.impl.store.raw.data.CompressSpacePageOperation

All Implemented Interfaces:

Externalizable, Serializable, Formatable, TypedFormat, Loggable, RePreparable, Undoable

Direct Known Subclasses:

CompressSpacePageOperation10_2

public class CompressSpacePageOperation
extends PhysicalPageOperation

Log operation to implement compressing space from a container and returning it to the operating system.

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected int	newHighestPage	The new highest page on this allocation page.
protected int	num_pages_truncated	The number of allocated pages in this allocation page prior to the truncate.

Fields inherited from class PageBasicOperation

containerHdl, foundHere, page

Fields inherited from interface Loggable

ABORT, BI_LOG, CHECKSUM, COMMIT, COMPENSATION, FILE_RESOURCE, FIRST, LAST, PREPARE, RAWSTORE, XA_NEEDLOCK

Constructor Summary

Constructors

Constructor	Description
CompressSpacePageOperation()	Public Methods of Formatable interface.
CompressSpacePageOperation(AllocPage allocPage, int highest_page, int num_truncated)	Constructors for This class:

Method Summary

Modifier and Type	Method	Description
final void	doMe(Transaction tran, LogInstant instant, LimitObjectInput in)	Compress space from container.
int	getTypeFormatId()	Return my format identifier.
void	readExternal(ObjectInput in)
void	restoreMe(Transaction xact, BasePage undoPage, LogInstant CLRinstant, LimitObjectInput in)	Undo the change indicated by this log operation and optional data.
String	toString()	debug
void	undoMe(Transaction xact, BasePage undoPage, LogInstant CLRInstant, LimitObjectInput in)	Compress space undo.
void	writeExternal(ObjectOutput out)

Methods inherited from class PhysicalPageOperation

generateUndo

Methods inherited from class PageBasicOperation

findpage, getPage, getPageForRedoRecovery, getPageId, getPageVersion, getPreparedLog, group, needsRedo, reclaimPrepareLocks, releaseResource, resetPageNumber

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface Loggable

getPreparedLog, group, needsRedo, releaseResource

Field Details

newHighestPage

protected int newHighestPage

The new highest page on this allocation page. The number is the offset of the page in the array of pages maintained by this allocation page, for instance a value of 0 indicates all page except the first one are to be truncated. If all pages are truncated then the offset is set to -1.

num_pages_truncated

protected int num_pages_truncated

The number of allocated pages in this allocation page prior to the truncate. Note that all pages from NewHighestPage+1 through newHighestPage+num_pages_truncated should be FREE.

Constructor Details

CompressSpacePageOperation

CompressSpacePageOperation(AllocPage allocPage,
 int highest_page,
 int num_truncated)
                    throws StandardException

Constructors for This class:

Throws:

StandardException

CompressSpacePageOperation

public CompressSpacePageOperation()

Public Methods of Formatable interface.

Method Details

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Overrides:

writeExternal in class PageBasicOperation

Throws:

IOException

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Overrides:

readExternal in class PageBasicOperation

Throws:

IOException - error reading from log stream

ClassNotFoundException - cannot read object from input

getTypeFormatId

public int getTypeFormatId()

Return my format identifier.

Returns:

The identifier. (A UUID stuffed in an array of 16 bytes).

doMe

public final void doMe(Transaction tran,
 LogInstant instant,
 LimitObjectInput in)
                throws StandardException

Compress space from container.

Compress the indicate space from the container, returning the free pages to the OS. Update the allocation page to reflect the file change.

Parameters:

tran - transaction doing the operation.

instant - log instant for this operation.

in - unused by this log operation.

Throws:

StandardException - Standard exception policy.

undoMe

public void undoMe(Transaction xact,
 BasePage undoPage,
 LogInstant CLRInstant,
 LimitObjectInput in)
            throws StandardException

Compress space undo.

Specified by:

undoMe in class PhysicalPageOperation

Parameters:

xact - the Transaction doing the rollback

undoPage - the page to rollback changes on

CLRInstant - the log instant of this (PageUndo) operation

in - optional data for the rollback operation

Throws:

StandardException - Thrown by methods I call

See Also:

• PhysicalPageOperation.undoMe(Transaction, BasePage, LogInstant, LimitObjectInput)

restoreMe

public void restoreMe(Transaction xact,
 BasePage undoPage,
 LogInstant CLRinstant,
 LimitObjectInput in)

Description copied from class: PageBasicOperation

Undo the change indicated by this log operation and optional data. The page the undo should apply to is the latched undoPage. The undoPage must be the same page as the doMe page and the undo operation must restore the before image of the row that changed.
this can only be used under special circumstances: namely table level locking, and no internal or nested transaction, and all operations are rollec back with restoreMe instead of undoMe.
This method is here to support BeforeImageLogging

Specified by:

restoreMe in class PageBasicOperation

Parameters:

xact - the Transaction doing the rollback

undoPage - the page to rollback changes on

CLRinstant - the log instant of this (PageUndo) operation

in - optional data for the rollback operation

toString

public String toString()

debug

Overrides:

toString in class PageBasicOperation