org.apache.hadoop.hbase.regionserver

Class HRegion.RegionScannerImpl

java.lang.Object

org.apache.hadoop.hbase.regionserver.HRegion.RegionScannerImpl

All Implemented Interfaces:

Closeable, AutoCloseable, RpcCallback, InternalScanner, RegionScanner, Shipper

Direct Known Subclasses:

ReversedRegionScannerImpl

Enclosing class:

HRegion

class HRegion.RegionScannerImpl
extends Object
implements RegionScanner, Shipper, RpcCallback

RegionScannerImpl is used to combine scanners from multiple Stores (aka column families).

Field Summary

Fields

Modifier and Type	Field and Description
protected CellComparator	comparator
private ScannerContext	defaultScannerContext
private FilterWrapper	filter
private boolean	filterClosed
protected boolean	includeStopRow
protected Cell	joinedContinuationRow If the joined heap data gathering is interrupted due to scan limits, this will contain the row for which we are populating the values.
(package private) KeyValueHeap	joinedHeap Heap of key-values that are not essential for the provided filters and are thus read on demand, if on-demand column family loading is enabled.
private long	maxResultSize
private long	readPt
protected HRegion	region
protected byte[]	stopRow
(package private) KeyValueHeap	storeHeap

Constructor Summary

Constructors

Constructor and Description
RegionScannerImpl(Scan scan, List<KeyValueScanner> additionalScanners, HRegion region)
RegionScannerImpl(Scan scan, List<KeyValueScanner> additionalScanners, HRegion region, long nonceGroup, long nonce)

Method Summary

Modifier and Type	Method and Description
void	close() Closes the scanner and releases any resources it has allocated
private boolean	filterRow() This function is to maintain backward compatibility for 0.94 filters.
private boolean	filterRowKey(Cell current)
int	getBatch()
long	getMaxResultSize()
long	getMvccReadPoint()
RegionInfo	getRegionInfo()
(package private) KeyValueHeap	getStoreHeapForTesting()
private IOException	handleException(List<KeyValueScanner> instantiatedScanners, Throwable t)
protected void	incrementCountOfRowsFilteredMetric(ScannerContext scannerContext)
protected void	incrementCountOfRowsScannedMetric(ScannerContext scannerContext)
protected void	initializeKVHeap(List<KeyValueScanner> scanners, List<KeyValueScanner> joinedScanners, HRegion region)
protected void	initializeScanners(Scan scan, List<KeyValueScanner> additionalScanners)
boolean	isFilterDone()
private boolean	isFilterDoneInternal()
private boolean	joinedHeapMayHaveData(Cell currentRowCell)
private boolean	moreCellsInRow(Cell nextKv, Cell currentRowCell) Based on the nextKv in the heap, and the current row, decide whether or not there are more cells to be read in the heap.
boolean	next(List<Cell> outResults) Grab the next row's worth of values.
boolean	next(List<Cell> outResults, ScannerContext scannerContext) Grab the next row's worth of values.
private boolean	nextInternal(List<Cell> results, ScannerContext scannerContext)
boolean	nextRaw(List<Cell> outResults) Grab the next row's worth of values.
boolean	nextRaw(List<Cell> outResults, ScannerContext scannerContext) Grab the next row's worth of values.
protected boolean	nextRow(ScannerContext scannerContext, Cell curRowCell)
private boolean	populateFromJoinedHeap(List<Cell> results, ScannerContext scannerContext)
private boolean	populateResult(List<Cell> results, KeyValueHeap heap, ScannerContext scannerContext, Cell currentRowCell) Fetches records with currentRow into results list, until next row, batchLimit (if not -1) is reached, or remainingResultSize (if not -1) is reaced
boolean	reseek(byte[] row) Do a reseek to the required row.
protected void	resetFilters() Reset both the filter and the old filter.
void	run() Called at the end of an Rpc Call RpcCallContext
void	shipped() Called after a batch of rows scanned and set to be returned to client.
protected boolean	shouldStop(Cell currentRowCell)

Methods inherited from class java.lang.Object

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

Field Detail

storeHeap

KeyValueHeap storeHeap

joinedHeap

KeyValueHeap joinedHeap

Heap of key-values that are not essential for the provided filters and are thus read on demand, if on-demand column family loading is enabled.

joinedContinuationRow

protected Cell joinedContinuationRow

If the joined heap data gathering is interrupted due to scan limits, this will contain the row for which we are populating the values.

filterClosed

private boolean filterClosed

stopRow

protected final byte[] stopRow

includeStopRow

protected final boolean includeStopRow

region

protected final HRegion region

comparator

protected final CellComparator comparator

readPt

private final long readPt

maxResultSize

private final long maxResultSize

defaultScannerContext

private final ScannerContext defaultScannerContext

filter

private final FilterWrapper filter

Constructor Detail

RegionScannerImpl

RegionScannerImpl(Scan scan,
                  List<KeyValueScanner> additionalScanners,
                  HRegion region)
           throws IOException

Throws:

IOException

RegionScannerImpl

RegionScannerImpl(Scan scan,
                  List<KeyValueScanner> additionalScanners,
                  HRegion region,
                  long nonceGroup,
                  long nonce)
           throws IOException

Throws:

IOException

Method Detail

getRegionInfo

public RegionInfo getRegionInfo()

Specified by:

getRegionInfo in interface RegionScanner

Returns:

The RegionInfo for this scanner.

initializeScanners

protected void initializeScanners(Scan scan,
                                  List<KeyValueScanner> additionalScanners)
                           throws IOException

Throws:

IOException

initializeKVHeap

protected void initializeKVHeap(List<KeyValueScanner> scanners,
                                List<KeyValueScanner> joinedScanners,
                                HRegion region)
                         throws IOException

Throws:

IOException

handleException

private IOException handleException(List<KeyValueScanner> instantiatedScanners,
                                    Throwable t)

getMaxResultSize

public long getMaxResultSize()

Specified by:

getMaxResultSize in interface RegionScanner

Returns:

The preferred max buffersize. See Scan.setMaxResultSize(long)

getMvccReadPoint

public long getMvccReadPoint()

Specified by:

getMvccReadPoint in interface RegionScanner

Returns:

The Scanner's MVCC readPt see MultiVersionConcurrencyControl

getBatch

public int getBatch()

Specified by:

getBatch in interface RegionScanner

Returns:

The limit on the number of cells to retrieve on each call to next(). See Scan.setBatch(int)

resetFilters

protected void resetFilters()
                     throws IOException

Reset both the filter and the old filter.

Throws:

IOException - in case a filter raises an I/O exception.

next

public boolean next(List<Cell> outResults)
             throws IOException

Description copied from interface: InternalScanner

Grab the next row's worth of values.

Specified by:

next in interface InternalScanner

Parameters:

outResults - return output array

Returns:

true if more rows exist after this one, false if scanner is done

Throws:

IOException - e

next

public boolean next(List<Cell> outResults,
                    ScannerContext scannerContext)
             throws IOException

Description copied from interface: InternalScanner

Grab the next row's worth of values.

Specified by:

next in interface InternalScanner

Parameters:

outResults - return output array

Returns:

true if more rows exist after this one, false if scanner is done

Throws:

IOException - e

nextRaw

public boolean nextRaw(List<Cell> outResults)
                throws IOException

Description copied from interface: RegionScanner

Grab the next row's worth of values. This is a special internal method to be called from coprocessor hooks to avoid expensive setup. Caller must set the thread's readpoint, start and close a region operation, an synchronize on the scanner object. Caller should maintain and update metrics. See RegionScanner.nextRaw(List, ScannerContext)

Specified by:

nextRaw in interface RegionScanner

Parameters:

outResults - return output array

Returns:

true if more rows exist after this one, false if scanner is done

Throws:

IOException - e

nextRaw

public boolean nextRaw(List<Cell> outResults,
                       ScannerContext scannerContext)
                throws IOException

Description copied from interface: RegionScanner

Grab the next row's worth of values. The ScannerContext is used to enforce and track any limits associated with this call. Any progress that exists in the ScannerContext prior to calling this method will be LOST if ScannerContext.getKeepProgress() is false. Upon returning from this method, the ScannerContext will contain information about the progress made towards the limits. This is a special internal method to be called from coprocessor hooks to avoid expensive setup. Caller must set the thread's readpoint, start and close a region operation, an synchronize on the scanner object. Example: HRegion region = ...; RegionScanner scanner = ... MultiVersionConcurrencyControl.setThreadReadPoint(scanner.getMvccReadPoint()); region.startRegionOperation(); try { synchronized(scanner) { ... boolean moreRows = scanner.nextRaw(values); ... } } finally { region.closeRegionOperation(); }

Specified by:

nextRaw in interface RegionScanner

Parameters:

outResults - return output array

scannerContext - The ScannerContext instance encapsulating all limits that should be tracked during calls to this method. The progress towards these limits can be tracked within this instance.

Returns:

true if more rows exist after this one, false if scanner is done

Throws:

IOException - e

populateFromJoinedHeap

private boolean populateFromJoinedHeap(List<Cell> results,
                                       ScannerContext scannerContext)
                                throws IOException

Returns:

true if more cells exist after this batch, false if scanner is done

Throws:

IOException

populateResult

private boolean populateResult(List<Cell> results,
                               KeyValueHeap heap,
                               ScannerContext scannerContext,
                               Cell currentRowCell)
                        throws IOException

Fetches records with currentRow into results list, until next row, batchLimit (if not -1) is reached, or remainingResultSize (if not -1) is reaced

Parameters:

heap - KeyValueHeap to fetch data from.It must be positioned on correct row before call.

scannerContext -

currentRowCell -

Returns:

state of last call to KeyValueHeap.next()

Throws:

IOException

moreCellsInRow

private boolean moreCellsInRow(Cell nextKv,
                               Cell currentRowCell)

Based on the nextKv in the heap, and the current row, decide whether or not there are more cells to be read in the heap. If the row of the nextKv in the heap matches the current row then there are more cells to be read in the row.

Parameters:

nextKv -

currentRowCell -

Returns:

true When there are more cells in the row to be read

isFilterDone

public boolean isFilterDone()
                     throws IOException

Specified by:

isFilterDone in interface RegionScanner

Returns:

True if a filter indicates that this scanner will return no further rows.

Throws:

IOException - in case of I/O failure on a filter.

isFilterDoneInternal

private boolean isFilterDoneInternal()
                              throws IOException

Throws:

IOException

nextInternal

private boolean nextInternal(List<Cell> results,
                             ScannerContext scannerContext)
                      throws IOException

Throws:

IOException

incrementCountOfRowsFilteredMetric

protected void incrementCountOfRowsFilteredMetric(ScannerContext scannerContext)

incrementCountOfRowsScannedMetric

protected void incrementCountOfRowsScannedMetric(ScannerContext scannerContext)

joinedHeapMayHaveData

private boolean joinedHeapMayHaveData(Cell currentRowCell)
                               throws IOException

Parameters:

currentRowCell -

Returns:

true when the joined heap may have data for the current row

Throws:

IOException

filterRow

private boolean filterRow()
                   throws IOException

This function is to maintain backward compatibility for 0.94 filters. HBASE-6429 combines both filterRow & filterRow(List<KeyValue> kvs) functions. While 0.94 code or older, it may not implement hasFilterRow as HBase-6429 expects because 0.94 hasFilterRow() only returns true when filterRow(List<KeyValue> kvs) is overridden not the filterRow(). Therefore, the filterRow() will be skipped.

Throws:

IOException

filterRowKey

private boolean filterRowKey(Cell current)
                      throws IOException

Throws:

IOException

nextRow

protected boolean nextRow(ScannerContext scannerContext,
                          Cell curRowCell)
                   throws IOException

Throws:

IOException

shouldStop

protected boolean shouldStop(Cell currentRowCell)

close

public void close()

Description copied from interface: InternalScanner

Closes the scanner and releases any resources it has allocated

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface InternalScanner

getStoreHeapForTesting

KeyValueHeap getStoreHeapForTesting()

reseek

public boolean reseek(byte[] row)
               throws IOException

Description copied from interface: RegionScanner

Do a reseek to the required row. Should not be used to seek to a key which may come before the current position. Always seeks to the beginning of a row boundary.

Specified by:

reseek in interface RegionScanner

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

Throws:

IOException

run

public void run()
         throws IOException

Description copied from interface: RpcCallback

Called at the end of an Rpc Call RpcCallContext

Specified by:

run in interface RpcCallback

Throws:

IOException