com.orientechnologies.orient.core.storage.impl.local.paginated.wal

Interface OWriteAheadLog

All Known Implementing Classes:

CASDiskWriteAheadLog, OAbstractWriteAheadLog, OMemoryWriteAheadLog

public interface OWriteAheadLog

Since:

6/25/14

Author:

Andrey Lomakin (a.lomakin-at-orientdb.com)

Field Summary

Fields

Modifier and Type	Field and Description
static String	MASTER_RECORD_EXTENSION
static String	WAL_SEGMENT_EXTENSION

Method Summary

Modifier and Type	Method and Description
long	activeSegment()
void	addCheckpointListener(OCheckpointRequestListener listener)
void	addCutTillLimit(OLogSequenceNumber lsn) Adds LSN after which WAL log should be preserved.
void	addEventAt(OLogSequenceNumber lsn, Runnable event) Adds the event to fire when this write ahead log instances reaches the given LSN.
boolean	appendNewSegment() Adds new segment so all subsequent log entries will be added to this new segment.
OLogSequenceNumber	begin()
OLogSequenceNumber	begin(long segmentId)
void	close()
void	close(boolean flush)
boolean	cutAllSegmentsSmallerThan(long segmentId)
boolean	cutTill(OLogSequenceNumber lsn) Cut WAL content till passed in value of LSN at maximum in many cases smaller portion of WAL may be cut.
void	delete()
OLogSequenceNumber	end()
void	flush()
OLogSequenceNumber	getFlushedLsn()
OLogSequenceNumber	log(WriteableWALRecord record)
OLogSequenceNumber	logAtomicOperationEndRecord(long operationUnitId, boolean rollback, OLogSequenceNumber startLsn, Map<String,OAtomicOperationMetadata<?>> atomicOperationMetadata)
OLogSequenceNumber	logAtomicOperationStartRecord(boolean isRollbackSupported, long unitId)
OLogSequenceNumber	logAtomicOperationStartRecord(boolean isRollbackSupported, long unitId, byte[] metadata)
void	moveLsnAfter(OLogSequenceNumber lsn) Next LSN generated by WAL will be bigger than passed in value.
List<WriteableWALRecord>	next(OLogSequenceNumber lsn, int limit)
long[]	nonActiveSegments()
File[]	nonActiveSegments(long fromSegment)
List<WriteableWALRecord>	read(OLogSequenceNumber lsn, int limit)
void	removeCheckpointListener(OCheckpointRequestListener listener)
void	removeCutTillLimit(OLogSequenceNumber lsn) Removes LSN after which WAL log should be preserved.

Field Detail

MASTER_RECORD_EXTENSION

static final String MASTER_RECORD_EXTENSION

See Also:

Constant Field Values

WAL_SEGMENT_EXTENSION

static final String WAL_SEGMENT_EXTENSION

See Also:

Constant Field Values

Method Detail

begin

OLogSequenceNumber begin()

begin

OLogSequenceNumber begin(long segmentId)
                  throws IOException

Throws:

IOException

end

OLogSequenceNumber end()

flush

void flush()

logAtomicOperationStartRecord

OLogSequenceNumber logAtomicOperationStartRecord(boolean isRollbackSupported,
                                                 long unitId,
                                                 byte[] metadata)

logAtomicOperationStartRecord

OLogSequenceNumber logAtomicOperationStartRecord(boolean isRollbackSupported,
                                                 long unitId)
                                          throws IOException

Throws:

IOException

logAtomicOperationEndRecord

OLogSequenceNumber logAtomicOperationEndRecord(long operationUnitId,
                                               boolean rollback,
                                               OLogSequenceNumber startLsn,
                                               Map<String,OAtomicOperationMetadata<?>> atomicOperationMetadata)
                                        throws IOException

Throws:

IOException

log

OLogSequenceNumber log(WriteableWALRecord record)
                throws IOException

Throws:

IOException

close

void close()
    throws IOException

Throws:

IOException

close

void close(boolean flush)
    throws IOException

Throws:

IOException

delete

void delete()
     throws IOException

Throws:

IOException

read

List<WriteableWALRecord> read(OLogSequenceNumber lsn,
                              int limit)
                       throws IOException

Throws:

IOException

next

List<WriteableWALRecord> next(OLogSequenceNumber lsn,
                              int limit)
                       throws IOException

Throws:

IOException

getFlushedLsn

OLogSequenceNumber getFlushedLsn()

cutTill

boolean cutTill(OLogSequenceNumber lsn)
         throws IOException

Cut WAL content till passed in value of LSN at maximum in many cases smaller portion of WAL may be cut. If value of LSN is bigger than values provided in addCutTillLimit(OLogSequenceNumber) then "protected" part of WAL will be preserved for sure.

Parameters:

lsn - Maximum value of LSN till WAL will be cut.

Returns:

true if some portion of WAL will be cut and false if WAL left untouched.

Throws:

IOException

cutAllSegmentsSmallerThan

boolean cutAllSegmentsSmallerThan(long segmentId)
                           throws IOException

Throws:

IOException

addCheckpointListener

void addCheckpointListener(OCheckpointRequestListener listener)

removeCheckpointListener

void removeCheckpointListener(OCheckpointRequestListener listener)

moveLsnAfter

void moveLsnAfter(OLogSequenceNumber lsn)
           throws IOException

Next LSN generated by WAL will be bigger than passed in value. DO NOT REMOVE IT, USED IN ENTERPRISE STORAGE.

Throws:

IOException

addCutTillLimit

void addCutTillLimit(OLogSequenceNumber lsn)

Adds LSN after which WAL log should be preserved. It is possible to add many such LSNs smallest value among them will be used to limit value of LSN after which WAL may be cut.

Parameters:

lsn - LSN after which cut of the WAL is not allowed.

See Also:

removeCutTillLimit(OLogSequenceNumber), cutTill(OLogSequenceNumber)

removeCutTillLimit

void removeCutTillLimit(OLogSequenceNumber lsn)

Removes LSN after which WAL log should be preserved. It is possible to add many such LSNs smallest value among them will be used to limit value of LSN after which WAL may be cut.

Parameters:

lsn - LSN after which cut of the WAL is not allowed.

See Also:

removeCutTillLimit(OLogSequenceNumber), cutTill(OLogSequenceNumber)

nonActiveSegments

File[] nonActiveSegments(long fromSegment)

nonActiveSegments

long[] nonActiveSegments()

activeSegment

long activeSegment()

addEventAt

void addEventAt(OLogSequenceNumber lsn,
                Runnable event)

Adds the event to fire when this write ahead log instances reaches the given LSN. The thread on which the event will be fired is unspecified, the event may be even fired synchronously before this method returns. Avoid running long tasks in the event handler since this may degrade the performance of this write ahead log and/or its event managing component. The exact LSN, up to which this write ahead log is actually grown, may differ from the event's LSN at the moment of invocation. But it's guarantied that the write ahead log's LSN will be larger than or equal to the event's LSN. In other words, the event invocation may be postponed, exact timings depend on implementation details of this write ahead log.

Parameters:

lsn - the LSN to fire at.

event - the event to fire.

appendNewSegment

boolean appendNewSegment()

Adds new segment so all subsequent log entries will be added to this new segment. New segment can not be appended if:

1. WAL is empty
2. There last segment in WAL is empty.

Despite of the fact that WAL segment will not be appended, method call still will reach its main target, all subsequent log records will have segment number higher than previously logged records. But to inform user that segment is not added result of success of failure of this method will be returned.

Returns:

true if new segment is added, and false otherwise.