ScannerCallable (Apache HBase 1.4.11 API)

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 HBaseRpcController`	`controller`
`protected RpcControllerFactory`	`controllerFactory`
`protected Cursor`	`cursor`
`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 org.apache.commons.logging.Log`	`LOG`
`static String`	`LOG_SCANNER_ACTIVITY`
`static String`	`LOG_SCANNER_LATENCY_CUTOFF`
`protected boolean`	`renew`
`protected Scan`	`scan`
`protected ScanMetrics`	`scanMetrics`
`protected long`	`scannerId`

Fields inherited from class org.apache.hadoop.hbase.client.RegionServerCallable
connection, location, priority, 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

Methods
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()`
`Cursor`	`getCursor()`
`HRegionInfo`	`getHRegionInfo()`
`protected Scan`	`getScan()`
`ScannerCallable`	`getScannerCallableForReplica(int id)`
`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
`void`	`setRenew(boolean val)` Indicate whether we make a call only to renew the lease, but without affected the scanner in any other way.
`protected void`	`updateResultsMetrics(Result[] rrs)`

Methods inherited from class org.apache.hadoop.hbase.client.RegionServerCallable
getExceptionMessageAdditionalDetail, getLocation, getPriority, 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 org.apache.commons.logging.Log LOG
```
  - scannerId
```
protected long scannerId
```
  - instantiated
```
protected boolean instantiated
```
  - closed
```
protected boolean closed
```
  - renew
```
protected boolean renew
```
  - scan
```
protected final Scan scan
```
  - cConnection
```
protected final ClusterConnection cConnection
```
  - scanMetrics
```
protected ScanMetrics scanMetrics
```
  - id
```
protected final int id
```
  - 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
```
  - controllerFactory
```
protected RpcControllerFactory controllerFactory
```
  - controller
```
protected HBaseRpcController 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 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
  - getCursor
```
public Cursor getCursor()
```
  - updateResultsMetrics
```
protected void updateResultsMetrics(Result[] rrs)
```
  - 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()
```
    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)
```

Class ScannerCallable

Field Summary

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

Constructor Summary

Method Summary

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

Methods inherited from class java.lang.Object

Field Detail

LOG_SCANNER_LATENCY_CUTOFF

LOG_SCANNER_ACTIVITY

LOG

scannerId

instantiated

closed

renew

scan

cConnection

scanMetrics

id

heartbeatMessage

cursor

isRegionServerRemote

controllerFactory

controller

Constructor Detail

ScannerCallable

ScannerCallable

Method Detail

prepare

checkIfRegionServerIsRemote

call

getCursor

updateResultsMetrics

getScan

setClose

setRenew

getHRegionInfo

getCaching

getConnection

setCaching

getScannerCallableForReplica