ClientSmallScanner (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.client.AbstractClientScanner
- - org.apache.hadoop.hbase.client.ClientScanner
  - - org.apache.hadoop.hbase.client.ClientSmallScanner

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<Result>, ResultScanner
```
@InterfaceAudience.Private
public class ClientSmallScanner
extends ClientScanner
```
Client scanner for small scan. Generally, only one RPC is called to fetch the scan results, unless the results cross multiple regions or the row count of results excess the caching. For small scan, it will get better performance than ClientScanner

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`(package private) static class`	`ClientSmallScanner.SmallScannerCallable`
`protected static class`	`ClientSmallScanner.SmallScannerCallableFactory`

Field Summary

Fields
Modifier and Type	Field and Description
`private ClientSmallScanner.SmallScannerCallableFactory`	`callableFactory`
`private static org.apache.commons.logging.Log`	`LOG`
`private ScannerCallableWithReplicas`	`smallScanCallable`

Fields inherited from class org.apache.hadoop.hbase.client.ClientScanner
cache, caching, callable, caller, closed, conf, currentRegion, lastCellLoadedToCache, lastNext, lastResult, MAX_BYTE_ARRAY, maxScannerResultSize, partialResults, partialResultsRow, pool, primaryOperationTimeout, rpcControllerFactory, scan, scanMetricsPublished, scannerTimeout

Fields inherited from class org.apache.hadoop.hbase.client.AbstractClientScanner
scanMetrics

Constructor Summary

Constructors
Constructor and Description
`ClientSmallScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, ClusterConnection connection, RpcRetryingCallerFactory rpcFactory, RpcControllerFactory controllerFactory, ExecutorService pool, int primaryOperationTimeout)` Create a new ShortClientScanner for the specified table.
`ClientSmallScanner(org.apache.hadoop.conf.Configuration conf, Scan scan, TableName tableName, ClusterConnection connection, RpcRetryingCallerFactory rpcFactory, RpcControllerFactory controllerFactory, ExecutorService pool, int primaryOperationTimeout, ClientSmallScanner.SmallScannerCallableFactory callableFactory)` Create a new ShortClientScanner for the specified table.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`close()` Closes the scanner and releases any resources it has allocated
`protected void`	`initializeScannerInConstruction()`
`protected void`	`loadCache()` Contact the servers to load more `Result`s in the cache.
`Result`	`next()` Grab the next row's worth of values.
`private boolean`	`nextScanner(int nbRows, boolean done, boolean currentRegionDone)` Gets a scanner for following scan.
`protected void`	`setScannerCallableFactory(ClientSmallScanner.SmallScannerCallableFactory callableFactory)`

Methods inherited from class org.apache.hadoop.hbase.client.ClientScanner
call, checkScanStopRow, createClosestRowBefore, getCacheSize, getCaching, getConf, getConnection, getMaxResultSize, getPool, getPrimaryOperationTimeout, getResultsToAddToCache, getRetries, getScan, getScannerCallable, getScannerTimeout, getTable, getTableName, getTimestamp, isAnyRPCcancelled, nextScanner, renewLease, updateLastCellLoadedToCache, writeScanMetrics

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
  - LOG
```
private static final org.apache.commons.logging.Log LOG
```
  - smallScanCallable
```
private ScannerCallableWithReplicas smallScanCallable
```
  - callableFactory
```
private ClientSmallScanner.SmallScannerCallableFactory callableFactory
```
- Constructor Detail
  - ClientSmallScanner
```
public ClientSmallScanner(org.apache.hadoop.conf.Configuration conf,
                  Scan scan,
                  TableName tableName,
                  ClusterConnection connection,
                  RpcRetryingCallerFactory rpcFactory,
                  RpcControllerFactory controllerFactory,
                  ExecutorService pool,
                  int primaryOperationTimeout)
                   throws IOException
```
    Create a new ShortClientScanner for the specified table. Take 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 rangeGet
    connection - Connection identifying the cluster
    rpcFactory - Factory used to create the RpcRetryingCaller
    controllerFactory - Factory used to access RPC payloads
    pool - Threadpool for RPC threads
    primaryOperationTimeout - Call timeout
    
    Throws:
    
    IOException - If the remote call fails
  - ClientSmallScanner
```
ClientSmallScanner(org.apache.hadoop.conf.Configuration conf,
                  Scan scan,
                  TableName tableName,
                  ClusterConnection connection,
                  RpcRetryingCallerFactory rpcFactory,
                  RpcControllerFactory controllerFactory,
                  ExecutorService pool,
                  int primaryOperationTimeout,
                  ClientSmallScanner.SmallScannerCallableFactory callableFactory)
             throws IOException
```
    Create a new ShortClientScanner for the specified table. Take note that the passed Scan 's start row maybe changed changed. Intended for unit tests to provide their own ClientSmallScanner.SmallScannerCallableFactory implementation/mock.
    
    Parameters:
    conf - The Configuration to use.
    scan - Scan to use in this scanner
    tableName - The table that we wish to rangeGet
    connection - Connection identifying the cluster
    rpcFactory - Factory used to create the RpcRetryingCaller
    controllerFactory - Factory used to access RPC payloads
    pool - Threadpool for RPC threads
    primaryOperationTimeout - Call timeout
    callableFactory - Factory used to create the ClientSmallScanner.SmallScannerCallable
    
    Throws:
    
    IOException
- Method Detail
  - initializeScannerInConstruction
```
protected void initializeScannerInConstruction()
                                        throws IOException
```
    Overrides:
    
    initializeScannerInConstruction in class ClientScanner
    
    Throws:
    
    IOException
  - nextScanner
```
private boolean nextScanner(int nbRows,
                  boolean done,
                  boolean currentRegionDone)
                     throws IOException
```
    Gets a scanner for following scan. Move to next region or continue from the last result or start from the start row.
    
    Parameters:
    nbRows -
    done - true if Server-side says we're done scanning.
    currentRegionDone - true if scan is over on current region
    
    Returns:
    true if has next scanner
    
    Throws:
    
    IOException
  - 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.
    
    Specified by:
    
    next in interface ResultScanner
    
    Overrides:
    
    next in class ClientScanner
    
    Returns:
    Result object if there is another row, null if the scanner is exhausted.
    
    Throws:
    
    IOException - e
  - loadCache
```
protected void loadCache()
                  throws IOException
```
    Description copied from class: ClientScanner
    
    Contact the servers to load more Results in the cache.
    
    Overrides:
    
    loadCache in class ClientScanner
    
    Throws:
    
    IOException
  - close
```
public void close()
```
    Description copied from interface: ResultScanner
    
    Closes the scanner and releases any resources it has allocated
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface ResultScanner
    
    Overrides:
    
    close in class ClientScanner
  - setScannerCallableFactory
```
protected void setScannerCallableFactory(ClientSmallScanner.SmallScannerCallableFactory callableFactory)
```

Class ClientSmallScanner

Nested Class Summary

Field Summary

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

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

Constructor Summary

Method Summary

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

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

Methods inherited from class java.lang.Object

Field Detail

LOG

smallScanCallable

callableFactory

Constructor Detail

ClientSmallScanner

ClientSmallScanner

Method Detail

initializeScannerInConstruction

nextScanner

next

loadCache

close

setScannerCallableFactory