Package org.apache.hadoop.hbase.regionserver

Class ReversedMobStoreScanner

java.lang.Object

org.apache.hadoop.hbase.regionserver.NonLazyKeyValueScanner

org.apache.hadoop.hbase.regionserver.NonReversedNonLazyKeyValueScanner

org.apache.hadoop.hbase.regionserver.StoreScanner

org.apache.hadoop.hbase.regionserver.ReversedStoreScanner

org.apache.hadoop.hbase.regionserver.ReversedMobStoreScanner

All Implemented Interfaces:

Closeable, AutoCloseable, ChangedReadersObserver, InternalScanner, KeyValueScanner, Shipper

@Private
public class ReversedMobStoreScanner
extends ReversedStoreScanner

ReversedMobStoreScanner extends from ReversedStoreScanner, and is used to support reversed scanning in both the memstore and the MOB store.

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	cacheMobBlocks
private static final org.slf4j.Logger	LOG
private final HMobStore	mobStore
private boolean	rawMobScan
private boolean	readEmptyValueOnMobCellMiss
private final List<MobCell>	referencedMobCells

Fields inherited from class org.apache.hadoop.hbase.regionserver.StoreScanner

currentScanners, DEFAULT_HBASE_CELLS_SCANNED_PER_HEARTBEAT_CHECK, HBASE_CELLS_SCANNED_PER_HEARTBEAT_CHECK, heap, LAZY_SEEK_ENABLED_BY_DEFAULT, memstoreOnlyReads, mixedReads, readPt, store, STORESCANNER_PARALLEL_SEEK_ENABLE, STORESCANNER_PREAD_MAX_BYTES

Fields inherited from interface org.apache.hadoop.hbase.regionserver.KeyValueScanner

NO_NEXT_INDEXED_KEY

Constructor Summary

Constructors

Constructor	Description
ReversedMobStoreScanner(HStore store, ScanInfo scanInfo, Scan scan, NavigableSet<byte[]> columns, long readPt)

Method Summary

Modifier and Type	Method	Description
void	close()	Close the KeyValue scanner.
private void	freeAllReferencedMobCells()
boolean	next(List<? super ExtendedCell> outResult, ScannerContext ctx)	Firstly reads the cells from the HBase.
void	shipped()	Called after a batch of rows scanned and set to be returned to client.

Methods inherited from class org.apache.hadoop.hbase.regionserver.ReversedStoreScanner

backwardSeek, checkScanOrder, newKVHeap, reseek, seek, seekAsDirection, seekScanners, seekToNextRow, seekToPreviousRow

Methods inherited from class org.apache.hadoop.hbase.regionserver.StoreScanner

checkFlushed, enableLazySeekGlobally, getAllScannersForTesting, getEstimatedNumberOfKvsScanned, getNextIndexedKey, getReadPoint, hasSwitchedToStreamRead, hasUpdatedReaders, instrument, isScanUsePread, next, peek, reopenAfterFlush, resetHasSwitchedToStreamRead, resetHasUpdatedReaders, resetKVHeap, selectScannersFrom, trySkipToNextColumn, trySkipToNextRow, trySwitchToStreamRead, updateReaders

Methods inherited from class org.apache.hadoop.hbase.regionserver.NonReversedNonLazyKeyValueScanner

seekToLastRow

Methods inherited from class org.apache.hadoop.hbase.regionserver.NonLazyKeyValueScanner

doRealSeek, enforceSeek, getFilePath, isFileScanner, realSeekDone, recordBlockSize, requestSeek, shouldUseScanner

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.hbase.regionserver.InternalScanner

next

Methods inherited from interface org.apache.hadoop.hbase.regionserver.KeyValueScanner

enforceSeek, getFilePath, getNextIndexedKey, getScannerOrder, isFileScanner, next, peek, realSeekDone, recordBlockSize, requestSeek, seekToLastRow, shouldUseScanner

Field Details

LOG

private static final org.slf4j.Logger LOG

cacheMobBlocks

private boolean cacheMobBlocks

rawMobScan

private boolean rawMobScan

readEmptyValueOnMobCellMiss

private boolean readEmptyValueOnMobCellMiss

mobStore

private final HMobStore mobStore

referencedMobCells

private final List<MobCell> referencedMobCells

Constructor Details

ReversedMobStoreScanner

ReversedMobStoreScanner(HStore store,
 ScanInfo scanInfo,
 Scan scan,
 NavigableSet<byte[]> columns,
 long readPt)
                 throws IOException

Throws:

IOException

Method Details

next

public boolean next(List<? super ExtendedCell> outResult,
 ScannerContext ctx)
             throws IOException

Firstly reads the cells from the HBase. If the cell is a reference cell (which has the reference tag), the scanner need seek this cell from the mob file, and use the cell found from the mob file as the result.

Specified by:

next in interface InternalScanner

Overrides:

next in class StoreScanner

Parameters:

outResult - return output array. We will only add ExtendedCell to this list, but for CP users, you'd better just use RawCell as ExtendedCell is IA.Private.

Returns:

true if there are more rows, false if scanner is done

Throws:

IOException

freeAllReferencedMobCells

private void freeAllReferencedMobCells()
                                throws IOException

Throws:

IOException

shipped

public void shipped()
             throws IOException

Description copied from interface: Shipper

Called after a batch of rows scanned and set to be returned to client. Any in between cleanup can be done here.

Specified by:

shipped in interface Shipper

Overrides:

shipped in class StoreScanner

Throws:

IOException

close

public void close()

Description copied from interface: KeyValueScanner

Close the KeyValue scanner.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in interface InternalScanner

Specified by:

close in interface KeyValueScanner

Overrides:

close in class StoreScanner