Interface Loggable
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- All Superinterfaces:
java.io.Externalizable
,Formatable
,java.io.Serializable
,TypedFormat
- All Known Subinterfaces:
Compensation
,LogicalUndoable
,Undoable
- All Known Implementing Classes:
AllocPageOperation
,BeginXact
,ChainAllocPageOperation
,CheckpointOperation
,ChecksumOperation
,CompressSpacePageOperation
,CompressSpacePageOperation10_2
,ContainerBasicOperation
,ContainerOperation
,ContainerUndoOperation
,CopyRowsOperation
,DeleteOperation
,EncryptContainerOperation
,EncryptContainerUndoOperation
,EndXact
,InitPageOperation
,InsertOperation
,InvalidatePageOperation
,LogicalPageOperation
,LogicalUndoOperation
,PageBasicOperation
,PhysicalPageOperation
,PhysicalUndoOperation
,PurgeOperation
,RemoveFileOperation
,SetReservedSpaceOperation
,UpdateFieldOperation
,UpdateOperation
public interface Loggable extends Formatable
A Loggable is a record of a change of state or an event that happened in the RawStore in the context of a transaction. All changes in the RawStore must be logged. This is the root class for all log operations.
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Field Summary
Fields Modifier and Type Field Description static int
ABORT
static int
BI_LOG
static int
CHECKSUM
static int
COMMIT
static int
COMPENSATION
static int
FILE_RESOURCE
static int
FIRST
Each loggable belongs to one or more groups of similar functionality.static int
LAST
static int
PREPARE
static int
RAWSTORE
static int
XA_NEEDLOCK
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
doMe(Transaction xact, LogInstant instant, LimitObjectInput in)
Apply the change indicated by this operation and optional data.ByteArray
getPreparedLog()
The log operations are responsible to create the ByteArray, and the log operations should write out any optional data for the change to the ByteArray.int
group()
Get the loggable's group valueboolean
needsRedo(Transaction xact)
Determine if the operation should be reapplied in recovery redo.void
releaseResource(Transaction xact)
Release any resource that was acquired for doMe for rollback or recovery redo.-
Methods inherited from interface org.apache.derby.iapi.services.io.TypedFormat
getTypeFormatId
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Field Detail
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FIRST
static final int FIRST
Each loggable belongs to one or more groups of similar functionality. Grouping is a way to quickly sort out log records that are interesting to different modules or different implementations. When a module makes loggable and sent it to the log file, it must mark this loggable with one or more of the following group. If none fit, or if the loggable encompasses functionality that is not described in existing groups, then a new group should be introduced. Grouping has no effect on how the record is logged or how it is treated in rollback or recovery. The following groups are defined. This list serves as the registry of all loggable groups.- See Also:
- Constant Field Values
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LAST
static final int LAST
- See Also:
- Constant Field Values
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COMPENSATION
static final int COMPENSATION
- See Also:
- Constant Field Values
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BI_LOG
static final int BI_LOG
- See Also:
- Constant Field Values
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COMMIT
static final int COMMIT
- See Also:
- Constant Field Values
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ABORT
static final int ABORT
- See Also:
- Constant Field Values
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PREPARE
static final int PREPARE
- See Also:
- Constant Field Values
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XA_NEEDLOCK
static final int XA_NEEDLOCK
- See Also:
- Constant Field Values
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RAWSTORE
static final int RAWSTORE
- See Also:
- Constant Field Values
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FILE_RESOURCE
static final int FILE_RESOURCE
- See Also:
- Constant Field Values
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CHECKSUM
static final int CHECKSUM
- See Also:
- Constant Field Values
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Method Detail
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doMe
void doMe(Transaction xact, LogInstant instant, LimitObjectInput in) throws StandardException, java.io.IOException
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.
- Parameters:
xact
- the Transactioninstant
- the log instant of this operationin
- optional data- Throws:
java.io.IOException
- Can be thrown by any of the methods of in.StandardException
- Standard Derby policy.
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getPreparedLog
ByteArray getPreparedLog() throws StandardException
The log operations are responsible to create the ByteArray, and the log operations should write out any optional data for the change to the ByteArray. The ByteArray can be prepared when the log operation is constructed, or it can be prepared when getPreparedLog() is called. Called by the log manager to allow the log operation to pass the buffer which contains optional data that will be available in to doMe() methods.- Throws:
StandardException
- Standard Derby policy.
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needsRedo
boolean needsRedo(Transaction xact) throws StandardException
Determine if the operation should be reapplied in recovery redo. If redo is needed, acquire any resource that is necessary for the loggable's doMe method. These need to be released in the releaseResource method.The sequence of events in recovery redo of a Loggable operation is:
- Get the loggable operation. If loggable.needsRedo is false, then no need to redo this operation.
- If loggable.needsRedo is true, all the resources necessary for applying the doMe is acquired in needsRedo.
- If the loggable is actually a compensation operation, then the logging system will find the undoable operation that needs to be undone, call compensation.setUndoOp with the undoable operation.
- The recovery system then calls loggable.doMe, which re-applies the loggable operation, or re-applies the compensation operation
- The recovery system then calls loggable.releaseResource.
- Parameters:
xact
- The transaction trying to redo this operation- Returns:
- true if operation needs redoing, false if not.
- Throws:
StandardException
- Standard Derby policy.- See Also:
releaseResource(org.apache.derby.iapi.store.raw.Transaction)
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releaseResource
void releaseResource(Transaction xact)
Release any resource that was acquired for doMe for rollback or recovery redo. This resource is acquired in either generateUndo (if this is a compensation operation during run time rollback or recovery rollback) or in needsRedo (if this is during recovery redo). The run time transaction context should have all the resource already acquird for run time roll forward, so there is no need to releaseResource during run time roll forward. This method must be safe to be called multiple times.
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group
int group()
Get the loggable's group value
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