nishantmonu51 commented on a change in pull request #5958: Part 2 of changes for SQL Compatible Null Handling URL: https://github.com/apache/incubator-druid/pull/5958#discussion_r205572759
########## File path: processing/src/main/java/io/druid/query/aggregation/NullableAggregatorFactory.java ########## @@ -0,0 +1,114 @@ +/* + * Licensed to Metamarkets Group Inc. (Metamarkets) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. Metamarkets licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +package io.druid.query.aggregation; + + +import io.druid.common.config.NullHandling; +import io.druid.guice.annotations.ExtensionPoint; +import io.druid.segment.BaseNullableColumnValueSelector; +import io.druid.segment.ColumnSelectorFactory; +import io.druid.segment.ColumnValueSelector; + +/** + * Abstract class with functionality to wrap {@link Aggregator}, {@link BufferAggregator} and {@link AggregateCombiner} + * to support nullable aggregations for SQL compatibility. Implementations of {@link AggregatorFactory} which need to + * Support Nullable Aggregations are encouraged to extend this class. + */ +@ExtensionPoint +public abstract class NullableAggregatorFactory<T extends BaseNullableColumnValueSelector> extends AggregatorFactory +{ + @Override + public final Aggregator factorize(ColumnSelectorFactory metricFactory) + { + T selector = selector(metricFactory); + Aggregator aggregator = factorize(metricFactory, selector); + return NullHandling.replaceWithDefault() ? aggregator : new NullableAggregator(aggregator, selector); + } + + @Override + public final BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory) + { + T selector = selector(metricFactory); + BufferAggregator aggregator = factorizeBuffered(metricFactory, selector); + return NullHandling.replaceWithDefault() ? aggregator : new NullableBufferAggregator(aggregator, selector); + } + + @Override + public final AggregateCombiner makeAggregateCombiner() + { + AggregateCombiner combiner = makeAggregateCombiner2(); + return NullHandling.replaceWithDefault() ? combiner : new NullableAggregateCombiner(combiner); + } + + @Override + public final int getMaxIntermediateSize() + { + return getMaxIntermediateSize2() + (NullHandling.replaceWithDefault() ? 0 : Byte.BYTES); + } + + // ---- ABSTRACT METHODS BELOW ------ + + /** + * Creates a {@link ColumnValueSelector} for the aggregated column. + * + * @see ColumnValueSelector + */ + protected abstract T selector(ColumnSelectorFactory metricFactory); + + /** + * Creates an {@link Aggregator} to aggregate values from several rows, by using the provided selector. + * @param metricFactory metricFactory + * @param selector {@link ColumnValueSelector} for the column to aggregate. + * + * @see Aggregator + */ + protected abstract Aggregator factorize(ColumnSelectorFactory metricFactory, T selector); + + /** + * Creates an {@link BufferAggregator} to aggregate values from several rows into a ByteBuffer. + * @param metricFactory metricFactory + * @param selector {@link ColumnValueSelector} for the column to aggregate. + * + * @see BufferAggregator + */ + protected abstract BufferAggregator factorizeBuffered( + ColumnSelectorFactory metricFactory, + T selector + ); + + /** + * Creates an {@link AggregateCombiner} to fold rollup aggregation results from serveral "rows" of different indexes + * during index merging. AggregateCombiner implements the same logic as {@link #combine}, with the difference that it + * uses {@link ColumnValueSelector} and it's subinterfaces to get inputs and implements {@code ColumnValueSelector} + * to provide output. + * + * @see AggregateCombiner + * @see io.druid.segment.IndexMerger + */ + protected abstract AggregateCombiner makeAggregateCombiner2(); Review comment: do you have any suggestions for a better name ? the original method is final in this class and adds nullability support for the combiner. subclasses will implement this method instead of original one. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@druid.apache.org For additional commands, e-mail: commits-h...@druid.apache.org
