From 978701183e91899baa7896167f4f638a72741293 Mon Sep 17 00:00:00 2001
From: Duo Zhang <zhangduo@apache.org>
Date: Tue, 30 Apr 2019 16:33:58 +0800
Subject: [PATCH] HBASE-22328 NPE in RegionReplicaReplicationEndpoint

---
 .../RegionReplicaReplicationEndpoint.java          | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/RegionReplicaReplicationEndpoint.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/RegionReplicaReplicationEndpoint.java
index 65cf9a887e5d..cc2650f803f2 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/RegionReplicaReplicationEndpoint.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/RegionReplicaReplicationEndpoint.java
@@ -151,21 +151,23 @@ private boolean requiresReplication(Optional<TableDescriptor> tableDesc, Entry e
   private void getRegionLocations(CompletableFuture<RegionLocations> future,
       TableDescriptor tableDesc, byte[] encodedRegionName, byte[] row, boolean reload) {
     FutureUtils.addListener(connection.getRegionLocations(tableDesc.getTableName(), row, reload),
-      (r, e) -> {
+      (locs, e) -> {
         if (e != null) {
           future.completeExceptionally(e);
           return;
         }
         // if we are not loading from cache, just return
         if (reload) {
-          future.complete(r);
+          future.complete(locs);
           return;
         }
         // check if the number of region replicas is correct, and also the primary region name
-        // matches
-        if (r.size() == tableDesc.getRegionReplication() && Bytes.equals(
-          r.getDefaultRegionLocation().getRegion().getEncodedNameAsBytes(), encodedRegionName)) {
-          future.complete(r);
+        // matches, and also there is no null elements in the returned RegionLocations
+        if (locs.size() == tableDesc.getRegionReplication() &&
+          locs.size() == locs.numNonNullElements() &&
+          Bytes.equals(locs.getDefaultRegionLocation().getRegion().getEncodedNameAsBytes(),
+            encodedRegionName)) {
+          future.complete(locs);
         } else {
           // reload again as the information in cache maybe stale
           getRegionLocations(future, tableDesc, encodedRegionName, row, true);