Package org.apache.hadoop.hbase.client

Class ScannerCallable

java.lang.Object

org.apache.hadoop.hbase.client.RegionServerCallable<T,org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ClientService.BlockingInterface>

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

org.apache.hadoop.hbase.client.ScannerCallable

All Implemented Interfaces:

RetryingCallable<Result[]>

Direct Known Subclasses:

ReversedScannerCallable

@Private
public class ScannerCallable
extends ClientServiceCallable<Result[]>

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

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static enum	ScannerCallable.MoreResults

Field Summary

Fields

Modifier and Type	Field	Description
private int	caching
protected boolean	closed
protected Cursor	cursor
protected boolean	heartbeatMessage	Saves whether or not the most recent response from the server was a heartbeat message.
protected final int	id
protected boolean	instantiated
protected boolean	isRegionServerRemote
static final org.slf4j.Logger	LOG
static final String	LOG_SCANNER_ACTIVITY
static final String	LOG_SCANNER_LATENCY_CUTOFF
private int	logCutOffLatency
private boolean	logScannerActivity
private ScannerCallable.MoreResults	moreResultsForScan
private ScannerCallable.MoreResults	moreResultsInRegion
private long	nextCallSeq
protected boolean	renew
protected final RpcControllerFactory	rpcControllerFactory
protected final Scan	scan
protected ScanMetrics	scanMetrics
protected long	scannerId

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

location, requestAttributes, rpcController, stub

Constructor Summary

Constructors

Constructor	Description
ScannerCallable(ClusterConnection connection, TableName tableName, Scan scan, ScanMetrics scanMetrics, RpcControllerFactory rpcControllerFactory, int id, Map<String,byte[]> requestAttributes)

Method Summary

Modifier and Type	Method	Description
protected void	checkIfRegionServerIsRemote()	compare the local machine hostname with region server's hostname to decide if hbase client connects to a remote region server
private void	close()
int	getCaching()	Get the number of rows that will be fetched on next
Cursor	getCursor()
HRegionInfo	getHRegionInfo()	Returns the HRegionInfo for the current region
protected final HRegionLocation	getLocationForReplica(RegionLocations locs)
protected final RegionLocations	getRegionLocationsForPrepare(byte[] row)	Fetch region locations for the row.
protected Scan	getScan()
ScannerCallable	getScannerCallableForReplica(int id)
(package private) boolean	isHeartbeatMessage()
(package private) ScannerCallable.MoreResults	moreResultsForScan()	Should the client attempt to fetch more results for the whole scan.
(package private) ScannerCallable.MoreResults	moreResultsInRegion()	Should the client attempt to fetch more results from this region
private org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ScanResponse	next()
private org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ScanResponse	openScanner()
void	prepare(boolean reload)	Prepare by setting up any connections to servers, etc., ahead of call invocation.
protected Result[]	rpcCall()	Run the RPC call.
private void	setAlreadyClosed()
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
private void	setHeartbeatMessage(boolean heartbeatMessage)
(package private) void	setMoreResultsForScan(ScannerCallable.MoreResults moreResults)
(package private) void	setMoreResultsInRegion(ScannerCallable.MoreResults moreResults)
void	setRenew(boolean val)	Indicate whether we make a call only to renew the lease, but without affected the scanner in any other way.

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

doGet, doMutate, setStubByServiceName

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

call, getConnection, getExceptionMessageAdditionalDetail, getLocation, getPriority, getRow, getRpcController, getRpcControllerCellScanner, getStub, getTableName, setLocation, setRpcControllerCellScanner, setStub, sleep, throwable

Methods inherited from class java.lang.Object

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

Field Details

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 org.slf4j.Logger LOG

scannerId

protected long scannerId

instantiated

protected boolean instantiated

closed

protected boolean closed

renew

protected boolean renew

scan

protected final Scan scan

caching

private int caching

scanMetrics

protected ScanMetrics scanMetrics

logScannerActivity

private boolean logScannerActivity

logCutOffLatency

private int logCutOffLatency

id

protected final int id

moreResultsInRegion

private ScannerCallable.MoreResults moreResultsInRegion

moreResultsForScan

private ScannerCallable.MoreResults moreResultsForScan

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()

cursor

protected Cursor cursor

isRegionServerRemote

protected boolean isRegionServerRemote

nextCallSeq

private long nextCallSeq

rpcControllerFactory

protected final RpcControllerFactory rpcControllerFactory

Constructor Details

ScannerCallable

public ScannerCallable(ClusterConnection connection,
 TableName tableName,
 Scan scan,
 ScanMetrics scanMetrics,
 RpcControllerFactory rpcControllerFactory,
 int id,
 Map<String,byte[]> requestAttributes)

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 RpcController

Method Details

getLocationForReplica

protected final HRegionLocation getLocationForReplica(RegionLocations locs)
                                               throws HBaseIOException

Throws:

HBaseIOException

getRegionLocationsForPrepare

protected final RegionLocations getRegionLocationsForPrepare(byte[] row)
                                                      throws IOException

Fetch region locations for the row. Since this is for prepare, we always useCache. This is because we can be sure that RpcRetryingCaller will have cleared the cache in error handling if this is a retry.

Parameters:

row - the row to look up region location for

Throws:

IOException

prepare

public void prepare(boolean reload)
             throws IOException

Description copied from interface: RetryingCallable

Prepare by setting up any connections to servers, etc., ahead of call invocation. TODO: We call prepare before EVERY call. Seems wrong. FIX!!!!

Specified by:

prepare in interface RetryingCallable<Result[]>

Overrides:

prepare in class RegionServerCallable<Result[],org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ClientService.BlockingInterface>

Parameters:

reload - force reload of server location

Throws:

IOException - e

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

next

private org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ScanResponse next()
                                                                                  throws IOException

Throws:

IOException

setAlreadyClosed

private void setAlreadyClosed()

rpcCall

protected Result[] rpcCall()
                    throws Exception

Description copied from class: RegionServerCallable

Run the RPC call. Implement this method. To get at the rpcController that has been created and configured to make this rpc call, use getRpcController(). We are trying to contain rpcController references so we don't pollute codebase with protobuf references; keep the protobuf references contained and only present in a few classes rather than all about the code base.

Specified by:

rpcCall in class RegionServerCallable<Result[],org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ClientService.BlockingInterface>

Throws:

Exception

isHeartbeatMessage

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.

getCursor

public Cursor getCursor()

setHeartbeatMessage

private void setHeartbeatMessage(boolean heartbeatMessage)

close

private void close()

openScanner

private org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ScanResponse 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

setRenew

public void setRenew(boolean val)

Indicate whether we make a call only to renew the lease, but without affected the scanner in any other way.

Parameters:

val - true if only the lease should be renewed

getHRegionInfo

public HRegionInfo getHRegionInfo()

Returns the HRegionInfo for the current region

Overrides:

getHRegionInfo in class RegionServerCallable<Result[],org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ClientService.BlockingInterface>

getCaching

public int getCaching()

Get the number of rows that will be fetched on next

Returns:

the number of rows for caching

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)

moreResultsInRegion

ScannerCallable.MoreResults moreResultsInRegion()

Should the client attempt to fetch more results from this region

setMoreResultsInRegion

void setMoreResultsInRegion(ScannerCallable.MoreResults moreResults)

moreResultsForScan

ScannerCallable.MoreResults moreResultsForScan()

Should the client attempt to fetch more results for the whole scan.

setMoreResultsForScan

void setMoreResultsForScan(ScannerCallable.MoreResults moreResults)