Removal of TopNResultMerger because it is vestigial. (#4520)

processing/src/main/java/io/druid/query/topn/TopNBinaryFn.java

@@ -38,7 +38,6 @@ import java.util.Map;
  */
 public class TopNBinaryFn implements BinaryFn<Result<TopNResultValue>, Result<TopNResultValue>, Result<TopNResultValue>>
 {
-  private final TopNResultMerger merger;
   private final DimensionSpec dimSpec;
   private final Granularity gran;
   private final String dimension;
@@ -49,7 +48,6 @@ public class TopNBinaryFn implements BinaryFn<Result<TopNResultValue>, Result<To
   private final Comparator comparator;
 
   public TopNBinaryFn(
-      final TopNResultMerger merger,
       final Granularity granularity,
       final DimensionSpec dimSpec,
       final TopNMetricSpec topNMetricSpec,
@@ -58,7 +56,6 @@ public class TopNBinaryFn implements BinaryFn<Result<TopNResultValue>, Result<To
       final List<PostAggregator> postAggregatorSpecs
   )
   {
-    this.merger = merger;
     this.dimSpec = dimSpec;
     this.gran = granularity;
     this.topNMetricSpec = topNMetricSpec;
@@ -78,10 +75,10 @@ public class TopNBinaryFn implements BinaryFn<Result<TopNResultValue>, Result<To
   public Result<TopNResultValue> apply(Result<TopNResultValue> arg1, Result<TopNResultValue> arg2)
   {
     if (arg1 == null) {
-      return merger.getResult(arg2, comparator);
+      return arg2;
     }
     if (arg2 == null) {
-      return merger.getResult(arg1, comparator);
+      return arg1;
     }
 
     Map<Object, DimensionAndMetricValueExtractor> retVals = new LinkedHashMap<>();

processing/src/main/java/io/druid/query/topn/TopNQueryQueryToolChest.java

@@ -139,7 +139,6 @@ public class TopNQueryQueryToolChest extends QueryToolChest<Result<TopNResultVal
       {
         TopNQuery query = (TopNQuery) input;
         return new TopNBinaryFn(
-            TopNResultMerger.identity,
             query.getGranularity(),
             query.getDimensionSpec(),
             query.getTopNMetricSpec(),

processing/src/main/java/io/druid/query/topn/TopNResultMerger.java

@@ -1,40 +0,0 @@
-/*
- * 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.topn;
-
-import io.druid.query.Result;
-
-import java.util.Comparator;
-
-/**
- */
-public interface TopNResultMerger
-{
-  public static TopNResultMerger identity = new TopNResultMerger()
-  {
-    @Override
-    public Result<TopNResultValue> getResult(Result<TopNResultValue> result, Comparator comparator)
-    {
-      return result;
-    }
-  };
-
-  public Result<TopNResultValue> getResult(Result<TopNResultValue> result, Comparator comparator);
-}

processing/src/test/java/io/druid/query/topn/TopNBinaryFnBenchmark.java

@@ -115,7 +115,6 @@ public class TopNBinaryFnBenchmark extends SimpleBenchmark
         new TopNResultValue(list2)
     );
     fn = new TopNBinaryFn(
-        TopNResultMerger.identity,
         Granularities.ALL,
         new DefaultDimensionSpec("testdim", null),
         new NumericTopNMetricSpec("index"),

processing/src/test/java/io/druid/query/topn/TopNBinaryFnTest.java

@@ -144,7 +144,6 @@ public class TopNBinaryFnTest
     );
 
     Result<TopNResultValue> actual = new TopNBinaryFn(
-        TopNResultMerger.identity,
         Granularities.ALL,
         new DefaultDimensionSpec("testdim", null),
         new NumericTopNMetricSpec("index"),
@@ -226,7 +225,6 @@ public class TopNBinaryFnTest
     );
 
     Result<TopNResultValue> actual = new TopNBinaryFn(
-        TopNResultMerger.identity,
         Granularities.DAY,
         new DefaultDimensionSpec("testdim", null),
         new NumericTopNMetricSpec("index"),
@@ -271,7 +269,6 @@ public class TopNBinaryFnTest
     Result<TopNResultValue> expected = result1;
 
     Result<TopNResultValue> actual = new TopNBinaryFn(
-        TopNResultMerger.identity,
         Granularities.ALL,
         new DefaultDimensionSpec("testdim", null),
         new NumericTopNMetricSpec("index"),
@@ -367,7 +364,6 @@ public class TopNBinaryFnTest
     );
 
     Result<TopNResultValue> actual = new TopNBinaryFn(
-        TopNResultMerger.identity,
         Granularities.ALL,
         new DefaultDimensionSpec("testdim", null),
         new NumericTopNMetricSpec("addrowsindexconstant"),
@@ -449,7 +445,6 @@ public class TopNBinaryFnTest
     );
 
     Result<TopNResultValue> actual = new TopNBinaryFn(
-        TopNResultMerger.identity,
         Granularities.ALL,
         new DefaultDimensionSpec("testdim", null),
         new NumericTopNMetricSpec("index"),
@@ -507,7 +502,6 @@ public class TopNBinaryFnTest
     );
 
     Result<TopNResultValue> actual = new TopNBinaryFn(
-        TopNResultMerger.identity,
         Granularities.ALL,
         new DefaultDimensionSpec("INVALID_DIM_NAME", null),
         new DimensionTopNMetricSpec(null, StringComparators.LEXICOGRAPHIC),