org.apache.hadoop.hbase.client

Class ClientAsyncPrefetchScanner

java.lang.Object

org.apache.hadoop.hbase.client.AbstractClientScanner

org.apache.hadoop.hbase.client.ClientScanner

org.apache.hadoop.hbase.client.ClientSimpleScanner

org.apache.hadoop.hbase.client.ClientAsyncPrefetchScanner

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<Result>, ResultScanner

@InterfaceAudience.Private
public class ClientAsyncPrefetchScanner
extends ClientSimpleScanner

ClientAsyncPrefetchScanner implements async scanner behaviour. Specifically, the cache used by this scanner is a concurrent queue which allows both the producer (hbase client) and consumer (application) to access the queue in parallel. The number of rows returned in a prefetch is defined by the caching factor and the result size factor. This class allocates a buffer cache, whose size is a function of both factors. The prefetch is invoked when the cache is half­filled, instead of waiting for it to be empty. This is defined in the method prefetchCondition().

Field Summary

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

cache, caching, callable, caller, closed, conf, currentRegion, lastNext, lastResult, maxScannerResultSize, pool, primaryOperationTimeout, rpcControllerFactory, scan, scanMetricsPublished, scannerTimeout, tableName

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

scanMetrics

Constructor Summary

Constructors

Constructor and Description
ClientAsyncPrefetchScanner(org.apache.hadoop.conf.Configuration configuration, Scan scan, TableName name, ClusterConnection connection, RpcRetryingCallerFactory rpcCallerFactory, RpcControllerFactory rpcControllerFactory, ExecutorService pool, int replicaCallTimeoutMicroSecondScan)

Method Summary

Modifier and Type	Method and Description
protected void	addEstimatedSize(long estimatedSize)
void	close() Closes the scanner and releases any resources it has allocated
protected void	initCache()
Result	next() Grab the next row's worth of values.

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

createScannerCallable, setNewStartKey

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

getCacheCount, getCacheSize, getCaching, getConf, getConnection, getMaxResultSize, getPool, getPrimaryOperationTimeout, getRetries, getScan, getScannerTimeout, getTable, getTimestamp, initSyncCache, loadCache, moveToNextRegion, nextWithSyncCache, renewLease, writeScanMetrics

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

getScanMetrics, initScanMetrics

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.hbase.client.ResultScanner

iterator, next

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

ClientAsyncPrefetchScanner

public ClientAsyncPrefetchScanner(org.apache.hadoop.conf.Configuration configuration,
                                  Scan scan,
                                  TableName name,
                                  ClusterConnection connection,
                                  RpcRetryingCallerFactory rpcCallerFactory,
                                  RpcControllerFactory rpcControllerFactory,
                                  ExecutorService pool,
                                  int replicaCallTimeoutMicroSecondScan)
                           throws IOException

Throws:

IOException

Method Detail

initCache

protected void initCache()

Overrides:

initCache in class ClientScanner

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

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

addEstimatedSize

protected void addEstimatedSize(long estimatedSize)

Overrides:

addEstimatedSize in class ClientScanner