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, Iterable<Result>, ResultScanner

Direct Known Subclasses:

ClientSmallScanner, ReversedClientScanner

@InterfaceAudience.Public
@InterfaceStability.Stable
public 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

protected LinkedList<Result>	cache
protected int	caching
protected ScannerCallable	callable
protected RpcRetryingCaller<Result[]>	caller
protected boolean	closed
protected HRegionInfo	currentRegion
protected long	lastNext
protected Result	lastResult
protected long	maxScannerResultSize
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

ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, byte[] tableName)
Deprecated. Use ClientScanner(Configuration, Scan, TableName)

ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, byte[] tableName, HConnection connection)
Deprecated. Use ClientScanner(Configuration, Scan, TableName, HConnection)

ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName)
Deprecated.

ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, HConnection connection)
Create a new ClientScanner for the specified table Note that the passed Scan's start row maybe changed changed.

ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, HConnection connection, RpcRetryingCallerFactory rpcFactory)
Deprecated. Use ClientScanner(Configuration, Scan, TableName, HConnection, RpcRetryingCallerFactory, RpcControllerFactory) instead

ClientScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, HConnection connection, RpcRetryingCallerFactory rpcFactory, RpcControllerFactory controllerFactory)
Create a new ClientScanner for the specified table Note that the passed Scan's start row maybe changed changed.

Method Summary

protected boolean	checkScanStopRow(byte[] endKey)
void	close() Closes the scanner and releases any resources it has allocated
int	getCacheSize()
protected HConnection	getConnection()
protected long	getMaxResultSize()
protected Scan	getScan()
protected ScannerCallable	getScannerCallable(byte[] localStartKey, int nbRows)
protected TableName	getTable()
protected byte[]	getTableName() Deprecated. Since 0.96.0; use getTable()
protected long	getTimestamp()
protected void	initializeScannerInConstruction()
protected void	loadCache() Contact the servers to load more Results in the cache.
Result	next() Grab the next row's worth of values.
protected boolean	nextScanner(int nbRows, boolean done)
boolean	renewLease() Allow the client to renew the scanner's lease on the server.
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 Scan scan

closed

protected boolean closed

currentRegion

protected HRegionInfo currentRegion

callable

protected ScannerCallable 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

Constructor Detail

ClientScanner

@Deprecated
public ClientScanner(org.apache.hadoop.conf.Configuration conf,
                                Scan scan,
                                TableName tableName)
              throws IOException

Deprecated.

Create a new ClientScanner for the specified table. An HConnection will be retrieved using the passed Configuration. 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

Throws:

IOException

ClientScanner

@Deprecated
public ClientScanner(org.apache.hadoop.conf.Configuration conf,
                                Scan scan,
                                byte[] tableName)
              throws IOException

Deprecated. Use ClientScanner(Configuration, Scan, TableName)

Throws:

IOException

ClientScanner

public ClientScanner(org.apache.hadoop.conf.Configuration conf,
                     Scan scan,
                     TableName tableName,
                     HConnection connection)
              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

ClientScanner

@Deprecated
public ClientScanner(org.apache.hadoop.conf.Configuration conf,
                                Scan scan,
                                byte[] tableName,
                                HConnection connection)
              throws IOException

Deprecated. Use ClientScanner(Configuration, Scan, TableName, HConnection)

Throws:

IOException

ClientScanner

@Deprecated
public ClientScanner(org.apache.hadoop.conf.Configuration conf,
                                Scan scan,
                                TableName tableName,
                                HConnection connection,
                                RpcRetryingCallerFactory rpcFactory)
              throws IOException

Deprecated. Use ClientScanner(Configuration, Scan, TableName, HConnection, RpcRetryingCallerFactory, RpcControllerFactory) instead

Throws:

IOException

ClientScanner

public ClientScanner(org.apache.hadoop.conf.Configuration conf,
                     Scan scan,
                     TableName tableName,
                     HConnection connection,
                     RpcRetryingCallerFactory rpcFactory,
                     RpcControllerFactory controllerFactory)
              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

initializeScannerInConstruction

protected void initializeScannerInConstruction()
                                        throws IOException

Throws:

IOException

getConnection

protected HConnection getConnection()

getTableName

@Deprecated
protected byte[] getTableName()

Deprecated. Since 0.96.0; use getTable()

Returns:

Table name

getTable

protected TableName getTable()

getScan

protected Scan getScan()

getTimestamp

protected long getTimestamp()

getMaxResultSize

protected long getMaxResultSize()

checkScanStopRow

protected boolean checkScanStopRow(byte[] endKey)

nextScanner

protected boolean nextScanner(int nbRows,
                              boolean done)
                       throws IOException

Throws:

IOException

getScannerCallable

@InterfaceAudience.Private
protected ScannerCallable getScannerCallable(byte[] localStartKey,
                                                                       int nbRows)

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.setAttribute(SCAN_ATTRIBUTES_METRICS_ENABLE, Bytes.toBytes(Boolean.TRUE))

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 class: AbstractClientScanner

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

Specified by:

renewLease in class AbstractClientScanner

Returns:

true if the lease was successfully renewed, false otherwise.