Package org.apache.druid.query.topn

Class HistoricalSingleValueDimSelector1SimpleDoubleAggPooledTopNScannerPrototype

java.lang.Object

org.apache.druid.query.topn.HistoricalSingleValueDimSelector1SimpleDoubleAggPooledTopNScannerPrototype

All Implemented Interfaces:

Historical1AggPooledTopNScanner<SingleValueHistoricalDimensionSelector,HistoricalColumnSelector,SimpleDoubleBufferAggregator>

public class HistoricalSingleValueDimSelector1SimpleDoubleAggPooledTopNScannerPrototype
extends Object
implements Historical1AggPooledTopNScanner<SingleValueHistoricalDimensionSelector,HistoricalColumnSelector,SimpleDoubleBufferAggregator>

Constructor Summary

Constructors

Constructor	Description
HistoricalSingleValueDimSelector1SimpleDoubleAggPooledTopNScannerPrototype()

Method Summary

Modifier and Type	Method	Description
long	scanAndAggregate(SingleValueHistoricalDimensionSelector dimensionSelector, HistoricalColumnSelector metricSelector, SimpleDoubleBufferAggregator aggregator, int aggregatorSize, HistoricalCursor cursor, int[] positions, ByteBuffer resultsBuffer)	Any changes to this method should be coordinated with TopNUtils, PooledTopNAlgorithm.computeSpecializedScanAndAggregateImplementations() and downstream methods.

Methods inherited from class java.lang.Object

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

Constructor Detail

HistoricalSingleValueDimSelector1SimpleDoubleAggPooledTopNScannerPrototype

public HistoricalSingleValueDimSelector1SimpleDoubleAggPooledTopNScannerPrototype()

Method Detail

scanAndAggregate

public long scanAndAggregate(SingleValueHistoricalDimensionSelector dimensionSelector,
                             HistoricalColumnSelector metricSelector,
                             SimpleDoubleBufferAggregator aggregator,
                             int aggregatorSize,
                             HistoricalCursor cursor,
                             int[] positions,
                             ByteBuffer resultsBuffer)

Any changes to this method should be coordinated with TopNUtils, PooledTopNAlgorithm.computeSpecializedScanAndAggregateImplementations() and downstream methods. It should be checked with a tool like https://github.com/AdoptOpenJDK/jitwatch that C2 compiler output for this method doesn't have any method calls in the while loop, i. e. all method calls are inlined. To be able to see assembly of this method in JITWatch and other similar tools, PooledTopNAlgorithm.SPECIALIZE_HISTORICAL_SINGLE_VALUE_DIM_SELECTOR_ONE_SIMPLE_DOUBLE_AGG_POOLED_TOPN should be turned off. Note that in this case the benchmark should be "naturally monomorphic", i. e. execute this method always with the same runtime shape. If the while loop contains not inlined method calls, it should be considered as a performance bug.

Specified by:

scanAndAggregate in interface Historical1AggPooledTopNScanner<SingleValueHistoricalDimensionSelector,HistoricalColumnSelector,SimpleDoubleBufferAggregator>

aggregatorSize - number of bytes required by aggregator for a single aggregation

positions - a cache for positions in resultsBuffer, where specific (indexed) dimension values are aggregated

Returns:

number of scanned rows, i. e. number of steps made with the given cursor