From 9afaa2b94a2ba444e30af002ed750c843e02666e Mon Sep 17 00:00:00 2001
From: jon-wei <jon.wei@imply.io>
Date: Thu, 24 Mar 2016 18:38:42 -0700
Subject: [PATCH] Fix HyperUniquesAggregatorFactory comparator

---
 .../HyperUniquesAggregatorFactory.java         | 16 ++--------------
 .../druid/query/topn/TopNQueryRunnerTest.java  | 18 +++++++++---------
 2 files changed, 11 insertions(+), 23 deletions(-)

diff --git a/processing/src/main/java/io/druid/query/aggregation/hyperloglog/HyperUniquesAggregatorFactory.java b/processing/src/main/java/io/druid/query/aggregation/hyperloglog/HyperUniquesAggregatorFactory.java
index cc8ff7ba431..852b4fa323d 100644
--- a/processing/src/main/java/io/druid/query/aggregation/hyperloglog/HyperUniquesAggregatorFactory.java
+++ b/processing/src/main/java/io/druid/query/aggregation/hyperloglog/HyperUniquesAggregatorFactory.java
@@ -21,6 +21,7 @@ package io.druid.query.aggregation.hyperloglog;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.collect.Ordering;
 import com.metamx.common.IAE;
 import com.metamx.common.StringUtils;
 import io.druid.query.aggregation.Aggregator;
@@ -106,20 +107,7 @@ public class HyperUniquesAggregatorFactory extends AggregatorFactory
   @Override
   public Comparator getComparator()
   {
-    return new Comparator<HyperLogLogCollector>()
-    {
-      @Override
-      public int compare(HyperLogLogCollector lhs, HyperLogLogCollector rhs)
-      {
-        if(lhs == null) {
-          return -1;
-        }
-        if(rhs == null) {
-          return 1;
-        }
-        return lhs.compareTo(rhs);
-      }
-    };
+    return Ordering.<HyperLogLogCollector>natural().nullsFirst();
   }
 
   @Override
diff --git a/processing/src/test/java/io/druid/query/topn/TopNQueryRunnerTest.java b/processing/src/test/java/io/druid/query/topn/TopNQueryRunnerTest.java
index f822c18ec21..4bee2f23aae 100644
--- a/processing/src/test/java/io/druid/query/topn/TopNQueryRunnerTest.java
+++ b/processing/src/test/java/io/druid/query/topn/TopNQueryRunnerTest.java
@@ -377,17 +377,17 @@ public class TopNQueryRunnerTest
             new TopNResultValue(
                 Arrays.<Map<String, Object>>asList(
                     ImmutableMap.<String, Object>builder()
-                                .put("market", "total_market")
-                                .put("uniques", 0)
-                                .build(),
+                        .put("market", "spot")
+                        .put("uniques", 0)
+                        .build(),
                     ImmutableMap.<String, Object>builder()
-                                .put("market", "spot")
-                                .put("uniques", 0)
-                                .build(),
+                        .put("market", "total_market")
+                        .put("uniques", 0)
+                        .build(),
                     ImmutableMap.<String, Object>builder()
-                                .put("market", "upfront")
-                                .put("uniques", 0)
-                                .build()
+                        .put("market", "upfront")
+                        .put("uniques", 0)
+                        .build()
                 )
             )
         )