org.apache.hadoop.hbase.client

Class ScannerCallable

java.lang.Object

org.apache.hadoop.hbase.client.RegionServerCallable<Result[]>

org.apache.hadoop.hbase.client.ScannerCallable

All Implemented Interfaces:

RetryingCallable<Result[]>

Direct Known Subclasses:

ReversedScannerCallable

@InterfaceAudience.Private
public class ScannerCallable
extends RegionServerCallable<Result[]>

Scanner operations such as create, next, etc. Used by ResultScanners made by HTable. Passed to a retrying caller such as RpcRetryingCaller so fails are retried.

Field Summary

Fields

Modifier and Type	Field and Description
protected ClusterConnection	cConnection
protected boolean	closed
protected PayloadCarryingRpcController	controller
protected RpcControllerFactory	controllerFactory
protected boolean	heartbeatMessage Saves whether or not the most recent response from the server was a heartbeat message.
protected int	id
protected boolean	instantiated
protected boolean	isRegionServerRemote
static Log	LOG
static String	LOG_SCANNER_ACTIVITY
static String	LOG_SCANNER_LATENCY_CUTOFF
protected ScanMetrics	scanMetrics
protected long	scannerId
protected boolean	serverHasMoreResults
protected boolean	serverHasMoreResultsContext

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

connection, location, MIN_WAIT_DEAD_SERVER, row, tableName

Constructor Summary

Constructors

Constructor and Description
ScannerCallable(ClusterConnection connection, TableName tableName, Scan scan, ScanMetrics scanMetrics, RpcControllerFactory rpcControllerFactory)
ScannerCallable(ClusterConnection connection, TableName tableName, Scan scan, ScanMetrics scanMetrics, RpcControllerFactory rpcControllerFactory, int id)

Method Summary

Modifier and Type	Method and Description
Result[]	call(int callTimeout) Computes a result, or throws an exception if unable to do so.
protected void	checkIfRegionServerIsRemote() compare the local machine hostname with region server's hostname to decide if hbase client connects to a remote region server
int	getCaching() Get the number of rows that will be fetched on next
ClusterConnection	getConnection()
HRegionInfo	getHRegionInfo()
protected Scan	getScan()
ScannerCallable	getScannerCallableForReplica(int id)
protected boolean	getServerHasMoreResults() Should the client attempt to fetch more results from this region
protected boolean	hasMoreResultsContext() Did the server respond with information about whether more results might exist.
protected boolean	isHeartbeatMessage()
protected long	openScanner()
void	prepare(boolean reload) Prepare for connection to the server hosting region with row from tablename.
void	setCaching(int caching) Set the number of rows that will be fetched on next
void	setClose() Call this when the next invocation of call should close the scanner
protected void	setHasMoreResultsContext(boolean serverHasMoreResultsContext)
protected void	setHeartbeatMessage(boolean heartbeatMessage)
protected void	setServerHasMoreResults(boolean serverHasMoreResults)
protected void	updateResultsMetrics(Result[] rrs)

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

getExceptionMessageAdditionalDetail, getLocation, getRow, getStub, getTableName, setLocation, sleep, throwable

Methods inherited from class java.lang.Object

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

Field Detail

LOG_SCANNER_LATENCY_CUTOFF

public static final String LOG_SCANNER_LATENCY_CUTOFF

See Also:

Constant Field Values

LOG_SCANNER_ACTIVITY

public static final String LOG_SCANNER_ACTIVITY

See Also:

Constant Field Values

LOG

public static final Log LOG

scannerId

protected long scannerId

instantiated

protected boolean instantiated

closed

protected boolean closed

cConnection

protected final ClusterConnection cConnection

scanMetrics

protected ScanMetrics scanMetrics

id

protected final int id

serverHasMoreResultsContext

protected boolean serverHasMoreResultsContext

serverHasMoreResults

protected boolean serverHasMoreResults

heartbeatMessage

protected boolean heartbeatMessage

Saves whether or not the most recent response from the server was a heartbeat message. Heartbeat messages are identified by the flag ClientProtos.ScanResponse.getHeartbeatMessage()

isRegionServerRemote

protected boolean isRegionServerRemote

controllerFactory

protected RpcControllerFactory controllerFactory

controller

protected PayloadCarryingRpcController controller

Constructor Detail

ScannerCallable

public ScannerCallable(ClusterConnection connection,
                       TableName tableName,
                       Scan scan,
                       ScanMetrics scanMetrics,
                       RpcControllerFactory rpcControllerFactory)

Parameters:

connection - which connection

tableName - table callable is on

scan - the scan to execute

scanMetrics - the ScanMetrics to used, if it is null, ScannerCallable won't collect metrics

rpcControllerFactory - factory to use when creating com.google.protobuf.RpcController

ScannerCallable

public ScannerCallable(ClusterConnection connection,
                       TableName tableName,
                       Scan scan,
                       ScanMetrics scanMetrics,
                       RpcControllerFactory rpcControllerFactory,
                       int id)

Parameters:

connection -

tableName -

scan -

scanMetrics -

id - the replicaId

Method Detail

prepare

public void prepare(boolean reload)
             throws IOException

Description copied from class: RegionServerCallable

Prepare for connection to the server hosting region with row from tablename. Does lookup to find region location and hosting server.

Specified by:

prepare in interface RetryingCallable<Result[]>

Overrides:

prepare in class RegionServerCallable<Result[]>

Parameters:

reload - force reload of server location

Throws:

IOException

checkIfRegionServerIsRemote

protected void checkIfRegionServerIsRemote()

compare the local machine hostname with region server's hostname to decide if hbase client connects to a remote region server

call

public Result[] call(int callTimeout)
              throws IOException

Description copied from interface: RetryingCallable

Computes a result, or throws an exception if unable to do so.

Parameters:

callTimeout - - the time available for this call. 0 for infinite.

Returns:

computed result

Throws:

IOException

isHeartbeatMessage

protected boolean isHeartbeatMessage()

Returns:

true when the most recent RPC response indicated that the response was a heartbeat message. Heartbeat messages are sent back from the server when the processing of the scan request exceeds a certain time threshold. Heartbeats allow the server to avoid timeouts during long running scan operations.

setHeartbeatMessage

protected void setHeartbeatMessage(boolean heartbeatMessage)

updateResultsMetrics

protected void updateResultsMetrics(Result[] rrs)

openScanner

protected long openScanner()
                    throws IOException

Throws:

IOException

getScan

protected Scan getScan()

setClose

public void setClose()

Call this when the next invocation of call should close the scanner

getHRegionInfo

public HRegionInfo getHRegionInfo()

Overrides:

getHRegionInfo in class RegionServerCallable<Result[]>

Returns:

the HRegionInfo for the current region

getCaching

public int getCaching()

Get the number of rows that will be fetched on next

Returns:

the number of rows for caching

getConnection

public ClusterConnection getConnection()

Returns:

HConnection instance used by this Callable.

setCaching

public void setCaching(int caching)

Set the number of rows that will be fetched on next

Parameters:

caching - the number of rows for caching

getScannerCallableForReplica

public ScannerCallable getScannerCallableForReplica(int id)

getServerHasMoreResults

protected boolean getServerHasMoreResults()

Should the client attempt to fetch more results from this region

Returns:

True if the client should attempt to fetch more results, false otherwise.

setServerHasMoreResults

protected void setServerHasMoreResults(boolean serverHasMoreResults)

hasMoreResultsContext

protected boolean hasMoreResultsContext()

Did the server respond with information about whether more results might exist. Not guaranteed to respond with older server versions

Returns:

True if the server responded with information about more results.

setHasMoreResultsContext

protected void setHasMoreResultsContext(boolean serverHasMoreResultsContext)