[skywalking] branch master updated: fix NPE when fetch empty readHeatMap metrics. (#4891)

[wusheng]

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wusheng pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/skywalking.git


The following commit(s) were added to refs/heads/master by this push:
     new 202d571  fix NPE when fetch empty readHeatMap metrics. (#4891)
202d571 is described below

commit 202d5711d43de6f634cf906ccbb4af200b598c95
Author: Jared Tan <jian....@daocloud.io>
AuthorDate: Tue Jun 9 21:22:12 2020 +0800

    fix NPE when fetch empty readHeatMap metrics. (#4891)
---
 .../org/apache/skywalking/oap/server/core/query/type/HeatMap.java    | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git 
a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/HeatMap.java
 
b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/HeatMap.java
index 8483e19..d8b11c1 100644
--- 
a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/HeatMap.java
+++ 
b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/query/type/HeatMap.java
@@ -34,7 +34,7 @@ import 
org.apache.skywalking.oap.server.core.analysis.metrics.DataTable;
 @Getter
 public class HeatMap {
     private List<HeatMapColumn> values = new ArrayList<>(10);
-    private List<Bucket> buckets = null;
+    private List<Bucket> buckets = new ArrayList<>();
 
     public void addBucket(Bucket bucket) {
         this.buckets.add(bucket);
@@ -50,8 +50,7 @@ public class HeatMap {
         DataTable dataset = new DataTable(rawdata);
 
         final List<String> sortedKeys = dataset.sortedKeys(new 
KeyComparator(true));
-        if (buckets == null) {
-            buckets = new ArrayList<>(dataset.size());
+        if (buckets.isEmpty()) {
             for (int i = 0; i < sortedKeys.size(); i++) {
                 final Bucket bucket = new Bucket();
                 final String minValue = sortedKeys.get(i);