ScannerCallable (Apache HBase 1.1.7 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 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 org.apache.commons.logging.Log`	`LOG`
`static String`	`LOG_SCANNER_ACTIVITY`
`static String`	`LOG_SCANNER_LATENCY_CUTOFF`
`protected boolean`	`renew`
`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

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()`
`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)`
`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`	`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 org.apache.commons.logging.Log LOG
```
  - scannerId
```
protected long scannerId
```
  - instantiated
```
protected boolean instantiated
```
  - closed
```
protected boolean closed
```
  - renew
```
protected boolean renew
```
  - 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 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
  - 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)
```
  - 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)
```

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

cConnection

scanMetrics

id

serverHasMoreResultsContext

serverHasMoreResults

heartbeatMessage

isRegionServerRemote

controllerFactory

controller

Constructor Detail

ScannerCallable

ScannerCallable

Method Detail

prepare

checkIfRegionServerIsRemote

call

isHeartbeatMessage

setHeartbeatMessage

updateResultsMetrics

openScanner

getScan

setClose

setRenew

getHRegionInfo

getCaching

getConnection

setCaching

getScannerCallableForReplica

getServerHasMoreResults

setServerHasMoreResults

hasMoreResultsContext

setHasMoreResultsContext