org.apache.hadoop.hbase.client

Class ClientScanner

java.lang.Object

org.apache.hadoop.hbase.client.AbstractClientScanner

org.apache.hadoop.hbase.client.ClientScanner

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<Result>, ResultScanner

Direct Known Subclasses:

ClientSimpleScanner, ReversedClientScanner

@InterfaceAudience.Private
public abstract class ClientScanner
extends AbstractClientScanner

Implements the scanner interface for the HBase client. If there are multiple regions in a table, this scanner will iterate through them all.

Field Summary

Fields

Modifier and Type	Field and Description
protected LinkedList<Result>	cache
protected int	caching
protected org.apache.hadoop.hbase.client.ScannerCallableWithReplicas	callable
protected RpcRetryingCaller<Result[]>	caller
protected boolean	closed
protected org.apache.hadoop.conf.Configuration	conf
protected HRegionInfo	currentRegion
protected long	lastNext
protected Result	lastResult
protected long	maxScannerResultSize
protected ExecutorService	pool
protected int	primaryOperationTimeout
protected RpcControllerFactory	rpcControllerFactory
protected Scan	scan
protected boolean	scanMetricsPublished
protected int	scannerTimeout

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

scanMetrics

Constructor Summary

Constructors

Constructor and Description
ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, ClusterConnection connection, RpcRetryingCallerFactory rpcFactory, RpcControllerFactory controllerFactory, ExecutorService pool, int primaryOperationTimeout) Create a new ClientScanner for the specified table Note that the passed Scan's start row maybe changed changed.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the scanner and releases any resources it has allocated
protected abstract ScannerCallable	createScannerCallable() Will be called in moveToNextRegion to create ScannerCallable.
int	getCacheSize()
protected int	getCaching()
protected org.apache.hadoop.conf.Configuration	getConf()
protected ClusterConnection	getConnection()
protected long	getMaxResultSize()
protected ExecutorService	getPool()
protected int	getPrimaryOperationTimeout()
protected int	getRetries()
protected Scan	getScan()
protected int	getScannerTimeout()
protected TableName	getTable()
protected byte[]	getTableName() Deprecated. As of release 0.96 (HBASE-9508). This will be removed in HBase 2.0.0. Use getTable().
protected long	getTimestamp()
protected void	loadCache() Contact the servers to load more Results in the cache.
protected boolean	moveToNextRegion() Close the previous scanner and create a new ScannerCallable for the next scanner.
Result	next() Grab the next row's worth of values.
boolean	renewLease() Allow the client to renew the scanner's lease on the server.
protected abstract boolean	setNewStartKey() Will be called in moveToNextRegion when currentRegion is null.
protected void	writeScanMetrics() Publish the scan metrics.

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

getScanMetrics, initScanMetrics, iterator, next

Methods inherited from class java.lang.Object

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

Field Detail

scan

protected final Scan scan

closed

protected boolean closed

currentRegion

protected HRegionInfo currentRegion

callable

protected org.apache.hadoop.hbase.client.ScannerCallableWithReplicas callable

cache

protected final LinkedList<Result> cache

caching

protected final int caching

lastNext

protected long lastNext

lastResult

protected Result lastResult

maxScannerResultSize

protected final long maxScannerResultSize

scannerTimeout

protected final int scannerTimeout

scanMetricsPublished

protected boolean scanMetricsPublished

caller

protected RpcRetryingCaller<Result[]> caller

rpcControllerFactory

protected RpcControllerFactory rpcControllerFactory

conf

protected org.apache.hadoop.conf.Configuration conf

primaryOperationTimeout

protected final int primaryOperationTimeout

pool

protected final ExecutorService pool

Constructor Detail

ClientScanner

public ClientScanner(org.apache.hadoop.conf.Configuration conf,
             Scan scan,
             TableName tableName,
             ClusterConnection connection,
             RpcRetryingCallerFactory rpcFactory,
             RpcControllerFactory controllerFactory,
             ExecutorService pool,
             int primaryOperationTimeout)
              throws IOException

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

Parameters:

conf - The Configuration to use.

scan - Scan to use in this scanner

tableName - The table that we wish to scan

connection - Connection identifying the cluster

Throws:

IOException

Method Detail

getConnection

protected ClusterConnection getConnection()

getTableName

@Deprecated
protected byte[] getTableName()

Deprecated. As of release 0.96 (HBASE-9508). This will be removed in HBase 2.0.0. Use getTable().

Returns:

Table name

getTable

protected TableName getTable()

getRetries

protected int getRetries()

getScannerTimeout

protected int getScannerTimeout()

getConf

protected org.apache.hadoop.conf.Configuration getConf()

getScan

protected Scan getScan()

getPool

protected ExecutorService getPool()

getPrimaryOperationTimeout

protected int getPrimaryOperationTimeout()

getCaching

protected int getCaching()

getTimestamp

protected long getTimestamp()

getMaxResultSize

protected long getMaxResultSize()

setNewStartKey

protected abstract boolean setNewStartKey()

Will be called in moveToNextRegion when currentRegion is null. Abstract because for normal scan, we will start next scan from the endKey of the currentRegion, and for reversed scan, we will start next scan from the startKey of the currentRegion.

Returns:

false if we have reached the stop row. Otherwise true.

createScannerCallable

protected abstract ScannerCallable createScannerCallable()

Will be called in moveToNextRegion to create ScannerCallable. Abstract because for reversed scan we need to create a ReversedScannerCallable.

moveToNextRegion

protected boolean moveToNextRegion()

Close the previous scanner and create a new ScannerCallable for the next scanner.

Marked as protected only because TestClientScanner need to override this method.

Returns:

false if we should terminate the scan. Otherwise

writeScanMetrics

protected void writeScanMetrics()

Publish the scan metrics. For now, we use scan.setAttribute to pass the metrics back to the application or TableInputFormat.Later, we could push it to other systems. We don't use metrics framework because it doesn't support multi-instances of the same metrics on the same machine; for scan/map reduce scenarios, we will have multiple scans running at the same time. By default, scan metrics are disabled; if the application wants to collect them, this behavior can be turned on by calling calling Scan.setScanMetricsEnabled(boolean)

next

public Result next()
            throws IOException

Description copied from interface: ResultScanner

Grab the next row's worth of values. The scanner will return a Result.

Returns:

Result object if there is another row, null if the scanner is exhausted.

Throws:

IOException - e

getCacheSize

public int getCacheSize()

loadCache

protected void loadCache()
                  throws IOException

Contact the servers to load more Results in the cache.

Throws:

IOException

close

public void close()

Description copied from interface: ResultScanner

Closes the scanner and releases any resources it has allocated

renewLease

public boolean renewLease()

Description copied from interface: ResultScanner

Allow the client to renew the scanner's lease on the server.

Returns:

true if the lease was successfully renewed, false otherwise.