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org.apache.derby.impl.store.raw.data
Class ContainerOperation  

java.lang.Object
  org.apache.derby.impl.store.raw.data.ContainerBasicOperation
      org.apache.derby.impl.store.raw.data.ContainerOperation

All Implemented Interfaces:

java.io.Externalizable, org.apache.derby.iapi.services.io.Formatable, org.apache.derby.iapi.store.raw.Loggable, java.io.Serializable, org.apache.derby.iapi.services.io.TypedFormat, org.apache.derby.iapi.store.raw.Undoable

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public class ContainerOperation

extends ContainerBasicOperation

implements org.apache.derby.iapi.store.raw.Undoable

Log operation to create, drop or remove a container. Both the doMe or the undoMe of a create actually caused the container header to be modified and flushed before the log record is flushed. This is necessary for 2 reasons, one is that of ensuring enough disk space, and the other is because unlike any other operation, the log record create container is in the log stream before the container is in the container cache. What this mean is that if a checkpoint started after the container operation but before the container is kept or is dirtied in the container cache, then checkpoint will not know to wait for the container to be kept or cleaned. The checkpoint will erroneous assume that the operation does not need to be redone since its log instant is before the checkpoint but in fact the change has not been flushed to disk. A drop or remove container does not have this problem. The container exist and is in kept state when the operation is logged so the checkpoint will not overlook it and it doesn't need to flush the container header. In the case of remove, the stub is flushed for a different reason - that of ensuring disk space.

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Field Summary
protected static byte	CREATE
protected  org.apache.derby.iapi.util.ByteArray	createByteArray
protected static byte	DROP
protected  boolean	hasCreateByteArray
protected  byte	operation
protected static byte	REMOVE

 

Fields inherited from class org.apache.derby.impl.store.raw.data.ContainerBasicOperation

containerHdl, containerId

 

Fields inherited from interface org.apache.derby.iapi.store.raw.Loggable

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

 

Constructor Summary
	ContainerOperation()
protected	ContainerOperation(org.apache.derby.iapi.store.raw.data.RawContainerHandle hdl, byte operation)

 

Method Summary
void	doMe(org.apache.derby.iapi.store.raw.Transaction tran, org.apache.derby.iapi.store.raw.log.LogInstant instant, org.apache.derby.iapi.services.io.LimitObjectInput in)           Apply the change indicated by this operation and optional data.
protected  org.apache.derby.iapi.store.raw.data.RawContainerHandle	findContainerForLoadTran(org.apache.derby.iapi.store.raw.xact.RawTransaction xact)           Find container for load tran.
org.apache.derby.iapi.store.raw.Compensation	generateUndo(org.apache.derby.iapi.store.raw.Transaction tran, org.apache.derby.iapi.services.io.LimitObjectInput in)           Generate a loggable which will undo this change, using the optional input if necessary.
int	getTypeFormatId()           Return my format identifier.
void	readExternal(java.io.ObjectInput in)           This method restores an object's state by reading in the instance data for the object from the passed in stream.
java.lang.String	toString()           debug
void	undoMe(org.apache.derby.iapi.store.raw.Transaction tran, org.apache.derby.iapi.store.raw.data.RawContainerHandle hdl, org.apache.derby.iapi.store.raw.log.LogInstant CLRInstant, org.apache.derby.iapi.services.io.LimitObjectInput in)           Undo of create, drop or remove
void	writeExternal(java.io.ObjectOutput out)           This method is responsible for writing the instance data of an object to the passed in stream.

 

Methods inherited from class org.apache.derby.impl.store.raw.data.ContainerBasicOperation

findContainer, getPreparedLog, group, needsRedo, releaseResource

 

Methods inherited from class java.lang.Object

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

 

Methods inherited from interface org.apache.derby.iapi.store.raw.Loggable

getPreparedLog, group, needsRedo, releaseResource

 

Field Detail

operation

protected byte operation

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hasCreateByteArray

protected transient boolean hasCreateByteArray

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createByteArray

protected org.apache.derby.iapi.util.ByteArray createByteArray

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CREATE

protected static final byte CREATE

See Also:

Constant Field Values

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DROP

protected static final byte DROP

See Also:

Constant Field Values

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REMOVE

protected static final byte REMOVE

See Also:

Constant Field Values

Constructor Detail

ContainerOperation

protected ContainerOperation(org.apache.derby.iapi.store.raw.data.RawContainerHandle hdl,
                             byte operation)
                      throws org.apache.derby.iapi.error.StandardException

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ContainerOperation

public ContainerOperation()

Method Detail

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Description copied from interface: java.io.Externalizable

This method is responsible for writing the instance data of an object to the passed in stream. Note that this stream is not a subclass of OutputStream, but rather is a class that implements the ObjectOutput interface. That interface provides a number of methods for writing Java data values to a stream.

Not that the implementation of this method must be coordinated with the implementation of readExternal.

Specified by:

writeExternal in interface java.io.Externalizable

Overrides:

writeExternal in class ContainerBasicOperation

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readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Description copied from interface: java.io.Externalizable

This method restores an object's state by reading in the instance data for the object from the passed in stream. Note that this stream is not a subclass of InputStream, but rather is a class that implements the ObjectInput interface. That interface provides a mechanism for reading in Java data types from a stream.

Note that this method must be compatible with writeExternal. It must read back the exact same types that were written by that method in the exact order they were written.

If this method needs to read back an object instance, then the class for that object must be found and loaded. If that operation fails, then this method throws a ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Overrides:

readExternal in class ContainerBasicOperation

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getTypeFormatId

public int getTypeFormatId()

Return my format identifier.

Specified by:

getTypeFormatId in interface org.apache.derby.iapi.services.io.TypedFormat

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findContainerForLoadTran

protected org.apache.derby.iapi.store.raw.data.RawContainerHandle findContainerForLoadTran(org.apache.derby.iapi.store.raw.xact.RawTransaction xact)
                                                                                    throws org.apache.derby.iapi.error.StandardException

Find container for load tran.

If we are in load tran, and the operation is a create, the container may not (should not?) exist yet. We need to recreate it.

Overrides:

findContainerForLoadTran in class ContainerBasicOperation

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doMe

public final void doMe(org.apache.derby.iapi.store.raw.Transaction tran,
                       org.apache.derby.iapi.store.raw.log.LogInstant instant,
                       org.apache.derby.iapi.services.io.LimitObjectInput in)
                throws org.apache.derby.iapi.error.StandardException

Description copied from interface: org.apache.derby.iapi.store.raw.Loggable

Apply the change indicated by this operation and optional data. If this method fail, the system will be shut down because the log record has already been written to disk. Moreover, the log record will be replayed during recovery and this doMe method will be called on the same page again, so if it fails again, recovery will fail and the database cannot be started. So it is very important to make sure that every resource you need, such as disk space, has been acquired before the logAndDo method is called!
This method cannot acquire any resource (like latching of a page) since it is called underneath the logging system, ie., the log record has already been written to the log stream.

The available() method of in indicates how much data can be read, i.e. how much was originally written.

Specified by:

doMe in interface org.apache.derby.iapi.store.raw.Loggable

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undoMe

public void undoMe(org.apache.derby.iapi.store.raw.Transaction tran,
                   org.apache.derby.iapi.store.raw.data.RawContainerHandle hdl,
                   org.apache.derby.iapi.store.raw.log.LogInstant CLRInstant,
                   org.apache.derby.iapi.services.io.LimitObjectInput in)
            throws org.apache.derby.iapi.error.StandardException

Undo of create, drop or remove

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generateUndo

public org.apache.derby.iapi.store.raw.Compensation generateUndo(org.apache.derby.iapi.store.raw.Transaction tran,
                                                                 org.apache.derby.iapi.services.io.LimitObjectInput in)
                                                          throws org.apache.derby.iapi.error.StandardException

Description copied from interface: org.apache.derby.iapi.store.raw.Undoable

Generate a loggable which will undo this change, using the optional input if necessary.

NOTE
Any logical undo logic must be hidden behind generateUndo. During recovery redo, it should not depend on any logical undo logic.

There are 3 ways to implement a redo-only log record:

Make the log record a Loggable instead of an Undoable, this is the cleanest method.

If you want to extend a log operation class that is an Undoable, you can then either have generateUndo return null - this is preferred - (the log operation's undoMe should never be called, so you can put a null body there if the super class you are extending does not implement a undoMe).

Or, have undoMe do nothing - this is least preferred.

Any resource (e.g., latched page) that is needed for the undoable.undoMe() must be acquired in undoable.generateUndo(). Moreover, that resource must be identified in the compensation operation, and reacquired in the compensation.needsRedo() method during recovery redo.
If you do write your own generateUndo or needsRedo, any resource you latch or acquire, you must release them in Compensation.doMe() or in Compensation.releaseResource().

To write a generateUndo operation, find the object that needs to be rolled back. Assuming that it is a page, latch it, put together a Compensation operation with the undoOp set to this operation, and save the page number in the compensation operation, then return the Compensation operation to the logging system.

The sequence of events in a rollback of a undoable operation is

The logging system calls undoable.generateUndo. If this returns null, then there is nothing to undo.

If generateUndo returns a Compensation operation, then the logging system will log the Compensation log record and call Compenstation.doMe(). (Hopefully, this just calls the undoable's undoMe)

After the Compensation operation has been applied, the logging system will call compensation.releaseResource(). If you do overwrite a super class's releaseResource(), it would be prudent to call super.releaseResource() first.

The available() method of in indicates how much data can be read, i.e. how much was originally written.

Specified by:

generateUndo in interface org.apache.derby.iapi.store.raw.Undoable

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toString

public java.lang.String toString()

debug

Overrides:

toString in class ContainerBasicOperation

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> org >> apache >> derby >> impl >> store >> raw >> [ data overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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