| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF 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 org.apache.druid.query.topn; |
| |
| import org.apache.druid.query.ColumnSelectorPlus; |
| import org.apache.druid.query.Result; |
| import org.apache.druid.query.topn.types.TopNColumnAggregatesProcessor; |
| import org.apache.druid.query.topn.types.TopNColumnAggregatesProcessorFactory; |
| import org.apache.druid.segment.Cursor; |
| import org.apache.druid.segment.DimensionHandlerUtils; |
| |
| import javax.annotation.Nullable; |
| |
| public class TopNMapFn |
| { |
| private final TopNQuery query; |
| private final TopNAlgorithm topNAlgorithm; |
| |
| public TopNMapFn( |
| TopNQuery query, |
| TopNAlgorithm topNAlgorithm |
| ) |
| { |
| this.query = query; |
| this.topNAlgorithm = topNAlgorithm; |
| } |
| |
| @SuppressWarnings("unchecked") |
| @Nullable |
| public Result<TopNResultValue> apply(final Cursor cursor, final @Nullable TopNQueryMetrics queryMetrics) |
| { |
| final ColumnSelectorPlus<TopNColumnAggregatesProcessor<?>> selectorPlus = |
| DimensionHandlerUtils.createColumnSelectorPlus( |
| new TopNColumnAggregatesProcessorFactory(query.getDimensionSpec().getOutputType()), |
| query.getDimensionSpec(), |
| cursor.getColumnSelectorFactory() |
| ); |
| |
| if (selectorPlus.getSelector() == null) { |
| return null; |
| } |
| |
| TopNParams params = null; |
| try { |
| params = topNAlgorithm.makeInitParams(selectorPlus, cursor); |
| if (queryMetrics != null) { |
| queryMetrics.columnValueSelector(selectorPlus.getSelector()); |
| queryMetrics.numValuesPerPass(params); |
| } |
| |
| TopNResultBuilder resultBuilder = BaseTopNAlgorithm.makeResultBuilder(params, query); |
| |
| topNAlgorithm.run(params, resultBuilder, null, queryMetrics); |
| |
| return resultBuilder.build(); |
| } |
| finally { |
| topNAlgorithm.cleanup(params); |
| } |
| } |
| } |