RegionScannerImpl (Apache HBase 2.5.0 API)

java.lang.Object
- org.apache.hadoop.hbase.regionserver.RegionScannerImpl

All Implemented Interfaces:

Closeable, AutoCloseable, RpcCallback, InternalScanner, RegionScanner, Shipper

Direct Known Subclasses:

ReversedRegionScannerImpl
```
@InterfaceAudience.Private
class 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 static org.slf4j.Logger`	`LOG`
`private long`	`maxResultSize`
`private static List<Cell>`	`MOCKED_LIST` A mocked list implementation - discards all updates.
`private String`	`operationId`
`private long`	`readPt`
`protected HRegion`	`region`
`private RegionServerServices`	`rsServices`
`private ConcurrentHashMap<RegionScanner,Long>`	`scannerReadPoints`
`protected byte[]`	`stopRow`
`(package private) KeyValueHeap`	`storeHeap`

Constructor Summary

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

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`private void`	`checkClientDisconnect(Optional<RpcCall> rpcCall)`
`void`	`close()` Closes the scanner and releases any resources it has allocated n
`private void`	`closeInternal()`
`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()` Returns The Scanner's MVCC readPt see `MultiVersionConcurrencyControl`
`String`	`getOperationId()`
`RegionInfo`	`getRegionInfo()` Returns The RegionInfo for this scanner.
`private IOException`	`handleException(List<KeyValueScanner> instantiatedScanners, Throwable t)`
`private static boolean`	`hasNonce(HRegion region, long nonce)`
`private void`	`incrementCountOfRowsFilteredMetric(ScannerContext scannerContext)`
`private void`	`incrementCountOfRowsScannedMetric(ScannerContext scannerContext)`
`protected void`	`initializeKVHeap(List<KeyValueScanner> scanners, List<KeyValueScanner> joinedScanners, HRegion region)`
`private void`	`initializeScanners(Scan scan, List<KeyValueScanner> additionalScanners)`
`boolean`	`isFilterDone()` Returns True if a filter rules the scanner is over, done.
`private boolean`	`isFilterDoneInternal()`
`private boolean`	`joinedHeapMayHaveData(Cell currentRowCell)` Returns true when the joined heap may have data for the current row
`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)` Returns true if more cells exist after this batch, false if scanner is done
`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.
`private void`	`resetProgress(ScannerContext scannerContext, int initialBatchProgress, long initialSizeProgress, long initialHeapSizeProgress)`
`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
  - LOG
```
private static final org.slf4j.Logger LOG
```
  - 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
```
  - scannerReadPoints
```
private final ConcurrentHashMap<RegionScanner,Long> scannerReadPoints
```
  - readPt
```
private final long readPt
```
  - maxResultSize
```
private final long maxResultSize
```
  - defaultScannerContext
```
private final ScannerContext defaultScannerContext
```
  - filter
```
private final FilterWrapper filter
```
  - operationId
```
private final String operationId
```
  - rsServices
```
private RegionServerServices rsServices
```
  - MOCKED_LIST
```
private static final List<Cell> MOCKED_LIST
```
    A mocked list implementation - discards all updates.
- Constructor Detail
  - RegionScannerImpl
```
RegionScannerImpl(Scan scan,
                  List<KeyValueScanner> additionalScanners,
                  HRegion region,
                  long nonceGroup,
                  long nonce)
           throws IOException
```
    Throws:
    
    IOException
- Method Detail
  - getRegionInfo
```
public RegionInfo getRegionInfo()
```
    Description copied from interface: RegionScanner
    
    Returns The RegionInfo for this scanner.
    
    Specified by:
    
    getRegionInfo in interface RegionScanner
  - hasNonce
```
private static boolean hasNonce(HRegion region,
                                long nonce)
```
  - initializeScanners
```
private 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()
```
    Description copied from interface: RegionScanner
    
    Returns The Scanner's MVCC readPt see MultiVersionConcurrencyControl
    
    Specified by:
    
    getMvccReadPoint in interface RegionScanner
  - 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)
  - getOperationId
```
public String getOperationId()
```
    Specified by:
    
    getOperationId in interface RegionScanner
    
    Returns:
    
    The Scanner's OperationWithAttributes.ID_ATRIBUTE value, or null if not set.
  - resetFilters
```
protected final 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 n * @return 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.
    
    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.
    
    Returns:
    
    true When there are more cells in the row to be read
  - isFilterDone
```
public boolean isFilterDone()
                     throws IOException
```
    Returns True if a filter rules the scanner is over, done.
    
    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
  - checkClientDisconnect
```
private void checkClientDisconnect(Optional<RpcCall> rpcCall)
                            throws CallerDisconnectedException
```
    Throws:
    
    CallerDisconnectedException
  - resetProgress
```
private void resetProgress(ScannerContext scannerContext,
                           int initialBatchProgress,
                           long initialSizeProgress,
                           long initialHeapSizeProgress)
```
  - nextInternal
```
private boolean nextInternal(List<Cell> results,
                             ScannerContext scannerContext)
                      throws IOException
```
    Throws:
    
    IOException
  - incrementCountOfRowsFilteredMetric
```
private void incrementCountOfRowsFilteredMetric(ScannerContext scannerContext)
```
  - incrementCountOfRowsScannedMetric
```
private void incrementCountOfRowsScannedMetric(ScannerContext scannerContext)
```
  - joinedHeapMayHaveData
```
private boolean joinedHeapMayHaveData(Cell currentRowCell)
                               throws IOException
```
    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)
```
  - closeInternal
```
private void closeInternal()
```
  - close
```
public void close()
```
    Description copied from interface: InternalScanner
    
    Closes the scanner and releases any resources it has allocated n
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface InternalScanner
  - 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. nn * if row is null
    
    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

Class RegionScannerImpl

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

storeHeap

joinedHeap

joinedContinuationRow

filterClosed

stopRow

includeStopRow

region

comparator

scannerReadPoints

readPt

maxResultSize

defaultScannerContext

filter

operationId

rsServices

MOCKED_LIST

Constructor Detail

RegionScannerImpl

Method Detail

getRegionInfo

hasNonce

initializeScanners

initializeKVHeap

handleException

getMaxResultSize

getMvccReadPoint

getBatch

getOperationId

resetFilters

next

next

nextRaw

nextRaw

populateFromJoinedHeap

populateResult

moreCellsInRow

isFilterDone

isFilterDoneInternal

checkClientDisconnect

resetProgress

nextInternal

incrementCountOfRowsFilteredMetric

incrementCountOfRowsScannedMetric

joinedHeapMayHaveData

filterRow

filterRowKey

nextRow

shouldStop

closeInternal

close

reseek

shipped

run