HDFS-4369. Merging change 1433206 from trunk to branch-2

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1433211 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -15,6 +15,8 @@ Release 2.0.3-alpha - Unreleased
 
     HDFS-4364. GetLinkTargetResponseProto does not handle null path. (suresh)
 
+    HDFS-4369. GetBlockKeysResponseProto does not handle null response.
+    (suresh)
 
   NEW FEATURES
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/NamenodeProtocolServerSideTranslatorPB.java

@@ -91,8 +91,12 @@ public class NamenodeProtocolServerSideTranslatorPB implements
     } catch (IOException e) {
       throw new ServiceException(e);
     }
-    return GetBlockKeysResponseProto.newBuilder()
-        .setKeys(PBHelper.convert(keys)).build();
+    GetBlockKeysResponseProto.Builder builder = 
+        GetBlockKeysResponseProto.newBuilder();
+    if (keys != null) {
+      builder.setKeys(PBHelper.convert(keys));
+    }
+    return builder.build();
   }
 
   @Override

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/NamenodeProtocolTranslatorPB.java

@@ -29,6 +29,7 @@ import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.VersionRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.NamenodeProtocolProtos.EndCheckpointRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.NamenodeProtocolProtos.ErrorReportRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.NamenodeProtocolProtos.GetBlockKeysRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.NamenodeProtocolProtos.GetBlockKeysResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.NamenodeProtocolProtos.GetBlocksRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.NamenodeProtocolProtos.GetEditLogManifestRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.NamenodeProtocolProtos.GetMostRecentCheckpointTxIdRequestProto;
@@ -104,8 +105,9 @@ public class NamenodeProtocolTranslatorPB implements NamenodeProtocol,
   @Override
   public ExportedBlockKeys getBlockKeys() throws IOException {
     try {
-      return PBHelper.convert(rpcProxy.getBlockKeys(NULL_CONTROLLER,
-          GET_BLOCKKEYS).getKeys());
+      GetBlockKeysResponseProto rsp = rpcProxy.getBlockKeys(NULL_CONTROLLER,
+          GET_BLOCKKEYS);
+      return rsp.hasKeys() ? PBHelper.convert(rsp.getKeys()) : null;
     } catch (ServiceException e) {
       throw ProtobufHelper.getRemoteException(e);
     }

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/NamenodeProtocol.proto

@@ -56,7 +56,7 @@ message GetBlockKeysRequestProto {
  * keys - Information about block keys at the active namenode
  */
 message GetBlockKeysResponseProto {
-  required ExportedBlockKeysProto keys = 1;
+  optional ExportedBlockKeysProto keys = 1;
 }
 
 /**