org.apache.hadoop.hbase.client

Class AsyncReversedClientScanner

java.lang.Object

org.apache.hadoop.hbase.client.AsyncClientScanner

org.apache.hadoop.hbase.client.AsyncReversedClientScanner

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, AsyncResultScanner

Direct Known Subclasses:

AsyncClientSmallReversedScanner

@InterfaceAudience.Public
@InterfaceStability.Evolving
public class AsyncReversedClientScanner
extends AsyncClientScanner

A reversed client scanner which support backward scanning

Field Summary

Fields inherited from class org.apache.hadoop.hbase.client.AsyncClientScanner

caching, callable, caller, closed, currentRegion, lastNext, lastResult, maxScannerResultSize, scan, scanMetrics, scanMetricsPublished, scannerTimeout

Constructor Summary

Constructors

Constructor and Description
AsyncReversedClientScanner(AsyncRpcClient client, org.apache.hadoop.hbase.client.Scan scan, org.apache.hadoop.hbase.TableName tableName) Create a new ReversibleClientScanner for the specified table Note that the passed Scan's start row maybe changed.

Method Summary

Methods

Modifier and Type	Method and Description
protected boolean	checkScanStopRow(byte[] startKey)
protected byte[]	createClosestRowBefore(byte[] row) Create the closest row before the specified row
protected AsyncScannerCallable	getScannerCallable(byte[] localStartKey, int nbRows, byte[] locateStartRow) Get scanner callable
protected void	nextScanner(int nbRows, boolean done, ResponseHandler<java.lang.Boolean> handler) Gets a scanner for the next region.

Methods inherited from class org.apache.hadoop.hbase.client.AsyncClientScanner

close, getScan, getScanMetrics, getScannerCallable, getTable, getTimestamp, initScanMetrics, isScanDone, nextBatch, setScanDone, writeScanMetrics

Methods inherited from class java.lang.Object

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

Constructor Detail

AsyncReversedClientScanner

public AsyncReversedClientScanner(AsyncRpcClient client,
                          org.apache.hadoop.hbase.client.Scan scan,
                          org.apache.hadoop.hbase.TableName tableName)

Create a new ReversibleClientScanner for the specified table Note that the passed Scan's start row maybe changed.

Parameters:

client - The AsyncRpcClient to use.

scan - Scan to use in this scanner

tableName - The table that we wish to scan

Method Detail

nextScanner

protected void nextScanner(int nbRows,
               boolean done,
               ResponseHandler<java.lang.Boolean> handler)

Description copied from class: AsyncClientScanner

Gets a scanner for the next region. If this.currentRegion != null, then we will move to the endrow of this.currentRegion. Else we will get scanner at the scan.getStartRow(). We will go no further, just tidy up outstanding scanners, if currentRegion != null and done is true.

Overrides:

nextScanner in class AsyncClientScanner

Parameters:

nbRows - number of rows to scan

done - Server-side says we're done scanning.

handler - for the next scanner

getScannerCallable

protected AsyncScannerCallable getScannerCallable(byte[] localStartKey,
                                      int nbRows,
                                      byte[] locateStartRow)

Get scanner callable

Parameters:

localStartKey - start key to start

nbRows - rows to scan

locateStartRow - start row

Returns:

AsyncScannerCallable

checkScanStopRow

protected boolean checkScanStopRow(byte[] startKey)

Overrides:

checkScanStopRow in class AsyncClientScanner

Parameters:

startKey - to check

Returns:

returns true if the passed region endKey

createClosestRowBefore

protected byte[] createClosestRowBefore(byte[] row)

Create the closest row before the specified row

Parameters:

row - to create row before

Returns:

a new byte array which is the closest front row of the specified one