HDFS-9414. Refactor reconfiguration of ClientDatanodeProtocol for reusability. (Contributed by Xiaobing Zhou)

hadoop-hdfs-project/hadoop-hdfs-client/pom.xml

@@ -118,6 +118,7 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
                   <include>encryption.proto</include>
                   <include>inotify.proto</include>
                   <include>erasurecoding.proto</include>
+                  <include>ReconfigurationProtocol.proto</include>
                 </includes>
               </source>
               <output>${project.build.directory}/generated-sources/java</output>

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/ReconfigurationProtocol.java

@@ -0,0 +1,36 @@
+package org.apache.hadoop.hdfs.protocol;
+
+
+import java.io.IOException;
+import java.util.List;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.conf.ReconfigurationTaskStatus;
+
+/**********************************************************************
+ * ReconfigurationProtocol is used by HDFS admin to reload configuration
+ * for NN/DN without restarting them.
+ **********************************************************************/
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public interface ReconfigurationProtocol {
+
+  long versionID = 1L;
+
+  /**
+   * Asynchronously reload configuration on disk and apply changes.
+   */
+  void startReconfiguration() throws IOException;
+
+  /**
+   * Get the status of the previously issued reconfig task.
+   * @see {@link org.apache.hadoop.conf.ReconfigurationTaskStatus}.
+   */
+  ReconfigurationTaskStatus getReconfigurationStatus() throws IOException;
+
+  /**
+   * Get a list of allowed properties for reconfiguration.
+   */
+  List<String> listReconfigurableProperties() throws IOException;
+}

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

@@ -21,17 +21,13 @@ import java.io.Closeable;
 import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.util.List;
-import java.util.Map;
 
 import javax.net.SocketFactory;
 
-import com.google.common.base.Optional;
-import com.google.common.collect.Maps;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.conf.ReconfigurationTaskStatus;
-import org.apache.hadoop.conf.ReconfigurationUtil.PropertyChange;
 import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
 import org.apache.hadoop.hdfs.client.BlockReportOptions;
 import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
@@ -48,14 +44,12 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetBlo
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetDatanodeInfoRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetDatanodeInfoResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReplicaVisibleLengthRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ListReconfigurablePropertiesRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ListReconfigurablePropertiesResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.RefreshNamenodesRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReconfigurationStatusRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReconfigurationStatusResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReconfigurationStatusConfigChangeProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ShutdownDatanodeRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.StartReconfigurationRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.StartReconfigurationRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.TriggerBlockReportRequestProto;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.ipc.ProtobufHelper;
@@ -273,39 +267,19 @@ public class ClientDatanodeProtocolTranslatorPB implements
   @Override
   public ReconfigurationTaskStatus getReconfigurationStatus()
       throws IOException {
-    GetReconfigurationStatusResponseProto response;
-    Map<PropertyChange, Optional<String>> statusMap = null;
-    long startTime;
-    long endTime = 0;
     try {
-      response = rpcProxy.getReconfigurationStatus(NULL_CONTROLLER,
-          VOID_GET_RECONFIG_STATUS);
-      startTime = response.getStartTime();
-      if (response.hasEndTime()) {
-        endTime = response.getEndTime();
-      }
-      if (response.getChangesCount() > 0) {
-        statusMap = Maps.newHashMap();
-        for (GetReconfigurationStatusConfigChangeProto change :
-            response.getChangesList()) {
-          PropertyChange pc = new PropertyChange(
-              change.getName(), change.getNewValue(), change.getOldValue());
-          String errorMessage = null;
-          if (change.hasErrorMessage()) {
-            errorMessage = change.getErrorMessage();
-          }
-          statusMap.put(pc, Optional.fromNullable(errorMessage));
-        }
-      }
+      return ReconfigurationProtocolUtils.getReconfigurationStatus(
+          rpcProxy
+          .getReconfigurationStatus(
+              NULL_CONTROLLER,
+              VOID_GET_RECONFIG_STATUS));
     } catch (ServiceException e) {
       throw ProtobufHelper.getRemoteException(e);
     }
-    return new ReconfigurationTaskStatus(startTime, endTime, statusMap);
   }
 
   @Override
-  public List<String> listReconfigurableProperties()
-      throws IOException {
+  public List<String> listReconfigurableProperties() throws IOException {
     ListReconfigurablePropertiesResponseProto response;
     try {
       response = rpcProxy.listReconfigurableProperties(NULL_CONTROLLER,

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

@@ -0,0 +1,43 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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 org.apache.hadoop.hdfs.protocolPB;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.ipc.ProtocolInfo;
+import org.apache.hadoop.security.KerberosInfo;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ReconfigurationProtocolService;
+
+@KerberosInfo(serverPrincipal =
+    CommonConfigurationKeys.HADOOP_SECURITY_SERVICE_USER_NAME_KEY)
+@ProtocolInfo(
+    protocolName = "org.apache.hadoop.hdfs.protocol.ReconfigurationProtocol",
+    protocolVersion = 1)
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+/**
+ * Protocol that clients use to communicate with the NN/DN to do
+ * reconfiguration on the fly.
+ *
+ * Note: This extends the protocolbuffer service based interface to
+ * add annotations required for security.
+ */
+public interface ReconfigurationProtocolPB extends
+    ReconfigurationProtocolService.BlockingInterface {
+}

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

@@ -0,0 +1,146 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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 org.apache.hadoop.hdfs.protocolPB;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.util.List;
+
+import javax.net.SocketFactory;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.conf.ReconfigurationTaskStatus;
+import org.apache.hadoop.hdfs.protocol.ReconfigurationProtocol;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.StartReconfigurationRequestProto;
+import org.apache.hadoop.ipc.ProtobufHelper;
+import org.apache.hadoop.ipc.ProtobufRpcEngine;
+import org.apache.hadoop.ipc.ProtocolMetaInterface;
+import org.apache.hadoop.ipc.ProtocolTranslator;
+import org.apache.hadoop.ipc.RPC;
+import org.apache.hadoop.ipc.RpcClientUtil;
+import org.apache.hadoop.security.UserGroupInformation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.protobuf.RpcController;
+import com.google.protobuf.ServiceException;
+
+/**
+ * This class is the client side translator to translate the requests made on
+ * {@link ReconfigurationProtocol} interfaces to the RPC server implementing
+ * {@link ReconfigurationProtocolPB}.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Stable
+public class ReconfigurationProtocolTranslatorPB implements
+    ProtocolMetaInterface, ReconfigurationProtocol, ProtocolTranslator,
+    Closeable {
+  public static final Logger LOG = LoggerFactory
+      .getLogger(ReconfigurationProtocolTranslatorPB.class);
+
+  private static final RpcController NULL_CONTROLLER = null;
+  private static final StartReconfigurationRequestProto VOID_START_RECONFIG =
+      StartReconfigurationRequestProto.newBuilder().build();
+
+  private static final ListReconfigurablePropertiesRequestProto
+      VOID_LIST_RECONFIGURABLE_PROPERTIES =
+      ListReconfigurablePropertiesRequestProto.newBuilder().build();
+
+  private static final GetReconfigurationStatusRequestProto
+      VOID_GET_RECONFIG_STATUS =
+      GetReconfigurationStatusRequestProto.newBuilder().build();
+
+  private final ReconfigurationProtocolPB rpcProxy;
+
+  public ReconfigurationProtocolTranslatorPB(InetSocketAddress addr,
+      UserGroupInformation ticket, Configuration conf, SocketFactory factory)
+      throws IOException {
+    rpcProxy = createReconfigurationProtocolProxy(addr, ticket, conf, factory,
+        0);
+  }
+
+  static ReconfigurationProtocolPB createReconfigurationProtocolProxy(
+      InetSocketAddress addr, UserGroupInformation ticket, Configuration conf,
+      SocketFactory factory, int socketTimeout) throws IOException {
+    RPC.setProtocolEngine(conf, ReconfigurationProtocolPB.class,
+        ProtobufRpcEngine.class);
+    return RPC.getProxy(ReconfigurationProtocolPB.class,
+        RPC.getProtocolVersion(ReconfigurationProtocolPB.class),
+        addr, ticket, conf, factory, socketTimeout);
+  }
+
+  @Override
+  public void close() throws IOException {
+    RPC.stopProxy(rpcProxy);
+  }
+
+  @Override
+  public Object getUnderlyingProxyObject() {
+    return rpcProxy;
+  }
+
+  @Override
+  public void startReconfiguration() throws IOException {
+    try {
+      rpcProxy.startReconfiguration(NULL_CONTROLLER, VOID_START_RECONFIG);
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
+  @Override
+  public ReconfigurationTaskStatus getReconfigurationStatus()
+      throws IOException {
+    try {
+      return ReconfigurationProtocolUtils.getReconfigurationStatus(
+          rpcProxy
+          .getReconfigurationStatus(
+              NULL_CONTROLLER,
+              VOID_GET_RECONFIG_STATUS));
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
+  @Override
+  public List<String> listReconfigurableProperties() throws IOException {
+    ListReconfigurablePropertiesResponseProto response;
+    try {
+      response = rpcProxy.listReconfigurableProperties(NULL_CONTROLLER,
+          VOID_LIST_RECONFIGURABLE_PROPERTIES);
+      return response.getNameList();
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
+  @Override
+  public boolean isMethodSupported(String methodName) throws IOException {
+    return RpcClientUtil.isMethodSupported(rpcProxy,
+        ReconfigurationProtocolPB.class,
+        RPC.RpcKind.RPC_PROTOCOL_BUFFER,
+        RPC.getProtocolVersion(ReconfigurationProtocolPB.class),
+        methodName);
+  }
+}

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

@@ -0,0 +1,64 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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 org.apache.hadoop.hdfs.protocolPB;
+
+import java.util.Map;
+
+import org.apache.hadoop.conf.ReconfigurationTaskStatus;
+import org.apache.hadoop.conf.ReconfigurationUtil.PropertyChange;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusConfigChangeProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusResponseProto;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.Maps;
+
+/**
+ * This is a client side utility class that handles
+ * common logic to to parameter reconfiguration.
+ */
+public class ReconfigurationProtocolUtils {
+  private ReconfigurationProtocolUtils() {
+  }
+
+  public static ReconfigurationTaskStatus getReconfigurationStatus(
+      GetReconfigurationStatusResponseProto response) {
+    Map<PropertyChange, Optional<String>> statusMap = null;
+    long startTime;
+    long endTime = 0;
+
+    startTime = response.getStartTime();
+    if (response.hasEndTime()) {
+      endTime = response.getEndTime();
+    }
+    if (response.getChangesCount() > 0) {
+      statusMap = Maps.newHashMap();
+      for (GetReconfigurationStatusConfigChangeProto change : response
+          .getChangesList()) {
+        PropertyChange pc = new PropertyChange(change.getName(),
+            change.getNewValue(), change.getOldValue());
+        String errorMessage = null;
+        if (change.hasErrorMessage()) {
+          errorMessage = change.getErrorMessage();
+        }
+        statusMap.put(pc, Optional.fromNullable(errorMessage));
+      }
+    }
+    return new ReconfigurationTaskStatus(startTime, endTime, statusMap);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs-client/src/main/proto/ClientDatanodeProtocol.proto

@@ -33,6 +33,7 @@ package hadoop.hdfs;
 
 import "Security.proto";
 import "hdfs.proto";
+import "ReconfigurationProtocol.proto";
 
 /**
  * block - block for which visible length is requested
@@ -123,12 +124,6 @@ message GetDatanodeInfoResponseProto {
   required DatanodeLocalInfoProto localInfo = 1;
 }
 
-/** Asks DataNode to reload configuration file. */
-message StartReconfigurationRequestProto {
-}
-
-message StartReconfigurationResponseProto {
-}
 
 message TriggerBlockReportRequestProto {
   required bool incremental = 1;
@@ -137,31 +132,6 @@ message TriggerBlockReportRequestProto {
 message TriggerBlockReportResponseProto {
 }
 
-/** Query the running status of reconfiguration process */
-message GetReconfigurationStatusRequestProto {
-}
-
-message GetReconfigurationStatusConfigChangeProto {
-  required string name = 1;
-  required string oldValue = 2;
-  optional string newValue = 3;
-  optional string errorMessage = 4;  // It is empty if success.
-}
-
-message GetReconfigurationStatusResponseProto {
-  required int64 startTime = 1;
-  optional int64 endTime = 2;
-  repeated GetReconfigurationStatusConfigChangeProto changes = 3;
-}
-
-message ListReconfigurablePropertiesRequestProto {
-}
-
-/** Query the reconfigurable properties on DataNode. */
-message ListReconfigurablePropertiesResponseProto {
-  repeated string name = 1;
-}
-
 message GetBalancerBandwidthRequestProto {
 }
 

hadoop-hdfs-project/hadoop-hdfs-client/src/main/proto/ReconfigurationProtocol.proto

@@ -0,0 +1,74 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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.
+ */
+
+ // This file contains protocol buffers that are used to reconfigure NameNode
+ // and DataNode by HDFS admin.
+
+option java_package = "org.apache.hadoop.hdfs.protocol.proto";
+option java_outer_classname = "ReconfigurationProtocolProtos";
+option java_generic_services = true;
+option java_generate_equals_and_hash = true;
+package hadoop.hdfs;
+
+/** Asks NN/DN to reload configuration file. */
+message StartReconfigurationRequestProto {
+}
+
+message StartReconfigurationResponseProto {
+}
+
+/** Query the running status of reconfiguration process */
+message GetReconfigurationStatusRequestProto {
+}
+
+message GetReconfigurationStatusConfigChangeProto {
+  required string name = 1;
+  required string oldValue = 2;
+  optional string newValue = 3;
+  optional string errorMessage = 4;  // It is empty if success.
+}
+
+message GetReconfigurationStatusResponseProto {
+  required int64 startTime = 1;
+  optional int64 endTime = 2;
+  repeated GetReconfigurationStatusConfigChangeProto changes = 3;
+}
+
+/** Query the reconfigurable properties on NN/DN. */
+message ListReconfigurablePropertiesRequestProto {
+}
+
+message ListReconfigurablePropertiesResponseProto {
+  repeated string name = 1;
+}
+
+/**
+ * Protocol used from client to the NN/DN.
+ * See the request and response for details of rpc call.
+ */
+service ReconfigurationProtocolService {
+  rpc getReconfigurationStatus(GetReconfigurationStatusRequestProto)
+      returns(GetReconfigurationStatusResponseProto);
+
+  rpc startReconfiguration(StartReconfigurationRequestProto)
+      returns(StartReconfigurationResponseProto);
+
+  rpc listReconfigurableProperties(
+      ListReconfigurablePropertiesRequestProto)
+      returns(ListReconfigurablePropertiesResponseProto);
+}

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

@@ -883,11 +883,15 @@ Release 2.9.0 - UNRELEASED
   NEW FEATURES
 
   IMPROVEMENTS
-      HDFS-9267. TestDiskError should get stored replicas through
-      FsDatasetTestUtils. (Lei (Eddy) Xu via Colin P. McCabe)
 
-      HDFS-9491. Tests should get the number of pending async delets via
-      FsDatasetTestUtils. (Tony Wu via lei)
+    HDFS-9267. TestDiskError should get stored replicas through
+    FsDatasetTestUtils. (Lei (Eddy) Xu via Colin P. McCabe)
+
+    HDFS-9491. Tests should get the number of pending async delets via
+    FsDatasetTestUtils. (Tony Wu via lei)
+
+    HDFS-9414. Refactor reconfiguration of ClientDatanodeProtocol for
+    reusability. (Xiaobing Zhou via Arpit Agarwal)
 
   OPTIMIZATIONS
 

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

@@ -18,12 +18,8 @@
 package org.apache.hadoop.hdfs.protocolPB;
 
 import java.io.IOException;
-import java.util.Map;
 
-import com.google.common.base.Optional;
 import org.apache.hadoop.classification.InterfaceAudience;
-import org.apache.hadoop.conf.ReconfigurationTaskStatus;
-import org.apache.hadoop.conf.ReconfigurationUtil.PropertyChange;
 import org.apache.hadoop.hdfs.client.BlockReportOptions;
 import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
 import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
@@ -35,19 +31,18 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetBlo
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetBlockLocalPathInfoResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetDatanodeInfoRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetDatanodeInfoResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReconfigurationStatusConfigChangeProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReconfigurationStatusRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReconfigurationStatusResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReplicaVisibleLengthRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReplicaVisibleLengthResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ListReconfigurablePropertiesRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ListReconfigurablePropertiesResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.RefreshNamenodesRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.RefreshNamenodesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ShutdownDatanodeRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ShutdownDatanodeResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.StartReconfigurationRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.StartReconfigurationResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.StartReconfigurationRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.StartReconfigurationResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.TriggerBlockReportRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.TriggerBlockReportResponseProto;
 
@@ -162,7 +157,7 @@ public class ClientDatanodeProtocolServerSideTranslatorPB implements
   @Override
   public StartReconfigurationResponseProto startReconfiguration(
       RpcController unused, StartReconfigurationRequestProto request)
-    throws ServiceException {
+      throws ServiceException {
     try {
       impl.startReconfiguration();
     } catch (IOException e) {
@@ -173,54 +168,27 @@ public class ClientDatanodeProtocolServerSideTranslatorPB implements
 
   @Override
   public ListReconfigurablePropertiesResponseProto listReconfigurableProperties(
-        RpcController controller,
-        ListReconfigurablePropertiesRequestProto request)
+      RpcController controller,
+      ListReconfigurablePropertiesRequestProto request)
       throws ServiceException {
-    ListReconfigurablePropertiesResponseProto.Builder builder =
-        ListReconfigurablePropertiesResponseProto.newBuilder();
     try {
-      for (String name : impl.listReconfigurableProperties()) {
-        builder.addName(name);
-      }
+      return ReconfigurationProtocolServerSideUtils
+          .listReconfigurableProperties(impl.listReconfigurableProperties());
     } catch (IOException e) {
       throw new ServiceException(e);
     }
-    return builder.build();
   }
 
   @Override
   public GetReconfigurationStatusResponseProto getReconfigurationStatus(
       RpcController unused, GetReconfigurationStatusRequestProto request)
       throws ServiceException {
-    GetReconfigurationStatusResponseProto.Builder builder =
-        GetReconfigurationStatusResponseProto.newBuilder();
     try {
-      ReconfigurationTaskStatus status = impl.getReconfigurationStatus();
-      builder.setStartTime(status.getStartTime());
-      if (status.stopped()) {
-        builder.setEndTime(status.getEndTime());
-        assert status.getStatus() != null;
-        for (Map.Entry<PropertyChange, Optional<String>> result :
-            status.getStatus().entrySet()) {
-          GetReconfigurationStatusConfigChangeProto.Builder changeBuilder =
-              GetReconfigurationStatusConfigChangeProto.newBuilder();
-          PropertyChange change = result.getKey();
-          changeBuilder.setName(change.prop);
-          changeBuilder.setOldValue(change.oldVal != null ? change.oldVal : "");
-          if (change.newVal != null) {
-            changeBuilder.setNewValue(change.newVal);
-          }
-          if (result.getValue().isPresent()) {
-            // Get full stack trace.
-            changeBuilder.setErrorMessage(result.getValue().get());
-          }
-          builder.addChanges(changeBuilder);
-        }
-      }
+      return ReconfigurationProtocolServerSideUtils
+          .getReconfigurationStatus(impl.getReconfigurationStatus());
     } catch (IOException e) {
       throw new ServiceException(e);
     }
-    return builder.build();
   }
 
   @Override

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

@@ -0,0 +1,89 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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 org.apache.hadoop.hdfs.protocolPB;
+
+import java.io.IOException;
+
+import org.apache.hadoop.hdfs.protocol.ReconfigurationProtocol;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.StartReconfigurationRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.StartReconfigurationResponseProto;
+
+import com.google.protobuf.RpcController;
+import com.google.protobuf.ServiceException;
+
+/**
+ * This class is used on the server side. Calls come across the wire for the
+ * for protocol {@link ReconfigurationProtocolPB}.
+ * This class translates the PB data types
+ * to the native data types used inside the NN/DN as specified in the generic
+ * ReconfigurationProtocol.
+ */
+public class ReconfigurationProtocolServerSideTranslatorPB implements
+    ReconfigurationProtocolPB {
+
+  private final ReconfigurationProtocol impl;
+
+  private static final StartReconfigurationResponseProto START_RECONFIG_RESP =
+      StartReconfigurationResponseProto.newBuilder().build();
+
+  public ReconfigurationProtocolServerSideTranslatorPB(
+      ReconfigurationProtocol impl) {
+    this.impl = impl;
+  }
+
+  @Override
+  public StartReconfigurationResponseProto startReconfiguration(
+      RpcController controller, StartReconfigurationRequestProto request)
+      throws ServiceException {
+    try {
+      impl.startReconfiguration();
+    } catch (IOException e) {
+      throw new ServiceException(e);
+    }
+    return START_RECONFIG_RESP;
+  }
+
+  @Override
+  public ListReconfigurablePropertiesResponseProto listReconfigurableProperties(
+      RpcController controller,
+      ListReconfigurablePropertiesRequestProto request)
+      throws ServiceException {
+    try {
+      return ReconfigurationProtocolServerSideUtils
+          .listReconfigurableProperties(impl.listReconfigurableProperties());
+    } catch (IOException e) {
+      throw new ServiceException(e);
+    }
+  }
+
+  @Override
+  public GetReconfigurationStatusResponseProto getReconfigurationStatus(
+      RpcController unused, GetReconfigurationStatusRequestProto request)
+      throws ServiceException {
+    try {
+      return ReconfigurationProtocolServerSideUtils
+          .getReconfigurationStatus(impl.getReconfigurationStatus());
+    } catch (IOException e) {
+      throw new ServiceException(e);
+    }
+  }
+}

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

@@ -0,0 +1,78 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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 org.apache.hadoop.hdfs.protocolPB;
+
+import java.util.List;
+import java.util.Map;
+
+import org.apache.hadoop.conf.ReconfigurationTaskStatus;
+import org.apache.hadoop.conf.ReconfigurationUtil.PropertyChange;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusConfigChangeProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.GetReconfigurationStatusResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ListReconfigurablePropertiesResponseProto;
+
+import com.google.common.base.Optional;
+
+/**
+ * This is a server side utility class that handles
+ * common logic to to parameter reconfiguration.
+ */
+public class ReconfigurationProtocolServerSideUtils {
+  private ReconfigurationProtocolServerSideUtils() {
+  }
+
+  public static ListReconfigurablePropertiesResponseProto
+      listReconfigurableProperties(
+          List<String> reconfigurableProperties) {
+    ListReconfigurablePropertiesResponseProto.Builder builder =
+        ListReconfigurablePropertiesResponseProto.newBuilder();
+    for (String name : reconfigurableProperties) {
+      builder.addName(name);
+    }
+    return builder.build();
+  }
+
+  public static GetReconfigurationStatusResponseProto getReconfigurationStatus(
+      ReconfigurationTaskStatus status) {
+    GetReconfigurationStatusResponseProto.Builder builder =
+        GetReconfigurationStatusResponseProto.newBuilder();
+
+    builder.setStartTime(status.getStartTime());
+    if (status.stopped()) {
+      builder.setEndTime(status.getEndTime());
+      assert status.getStatus() != null;
+      for (Map.Entry<PropertyChange, Optional<String>> result : status
+          .getStatus().entrySet()) {
+        GetReconfigurationStatusConfigChangeProto.Builder changeBuilder =
+            GetReconfigurationStatusConfigChangeProto.newBuilder();
+        PropertyChange change = result.getKey();
+        changeBuilder.setName(change.prop);
+        changeBuilder.setOldValue(change.oldVal != null ? change.oldVal : "");
+        if (change.newVal != null) {
+          changeBuilder.setNewValue(change.newVal);
+        }
+        if (result.getValue().isPresent()) {
+          // Get full stack trace.
+          changeBuilder.setErrorMessage(result.getValue().get());
+        }
+        builder.addChanges(changeBuilder);
+      }
+    }
+    return builder.build();
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java

@@ -49,6 +49,7 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_MAX_NUM_BLOCKS_TO_LOG_KEY
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_METRICS_LOGGER_PERIOD_SECONDS_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_METRICS_LOGGER_PERIOD_SECONDS_KEY;
 import static org.apache.hadoop.util.ExitUtil.terminate;
+import org.apache.hadoop.hdfs.protocol.proto.ReconfigurationProtocolProtos.ReconfigurationProtocolService;
 
 import java.io.BufferedOutputStream;
 import java.io.ByteArrayInputStream;
@@ -124,6 +125,7 @@ import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.DatanodeLocalInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
+import org.apache.hadoop.hdfs.protocol.ReconfigurationProtocol;
 import org.apache.hadoop.hdfs.protocol.datatransfer.BlockConstructionStage;
 import org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtocol;
 import org.apache.hadoop.hdfs.protocol.datatransfer.IOStreamPair;
@@ -143,6 +145,8 @@ import org.apache.hadoop.hdfs.protocolPB.InterDatanodeProtocolPB;
 import org.apache.hadoop.hdfs.protocolPB.InterDatanodeProtocolServerSideTranslatorPB;
 import org.apache.hadoop.hdfs.protocolPB.InterDatanodeProtocolTranslatorPB;
 import org.apache.hadoop.hdfs.protocolPB.PBHelperClient;
+import org.apache.hadoop.hdfs.protocolPB.ReconfigurationProtocolPB;
+import org.apache.hadoop.hdfs.protocolPB.ReconfigurationProtocolServerSideTranslatorPB;
 import org.apache.hadoop.hdfs.security.token.block.BlockPoolTokenSecretManager;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier.AccessMode;
@@ -251,7 +255,7 @@ import org.slf4j.LoggerFactory;
 @InterfaceAudience.Private
 public class DataNode extends ReconfigurableBase
     implements InterDatanodeProtocol, ClientDatanodeProtocol,
-        TraceAdminProtocol, DataNodeMXBean {
+        TraceAdminProtocol, DataNodeMXBean, ReconfigurationProtocol {
   public static final Logger LOG = LoggerFactory.getLogger(DataNode.class);
   
   static{
@@ -914,7 +918,14 @@ public class DataNode extends ReconfigurableBase
             conf.getInt(DFS_DATANODE_HANDLER_COUNT_KEY,
                 DFS_DATANODE_HANDLER_COUNT_DEFAULT)).setVerbose(false)
         .setSecretManager(blockPoolTokenSecretManager).build();
-    
+
+    ReconfigurationProtocolServerSideTranslatorPB reconfigurationProtocolXlator
+      = new ReconfigurationProtocolServerSideTranslatorPB(this);
+    service = ReconfigurationProtocolService
+        .newReflectiveBlockingService(reconfigurationProtocolXlator);
+    DFSUtil.addPBProtocol(conf, ReconfigurationProtocolPB.class, service,
+        ipcServer);
+
     InterDatanodeProtocolServerSideTranslatorPB interDatanodeProtocolXlator = 
         new InterDatanodeProtocolServerSideTranslatorPB(this);
     service = InterDatanodeProtocolService
@@ -2918,19 +2929,19 @@ public class DataNode extends ReconfigurableBase
         confVersion, uptime);
   }
 
-  @Override // ClientDatanodeProtocol
+  @Override // ClientDatanodeProtocol & ReconfigurationProtocol
   public void startReconfiguration() throws IOException {
     checkSuperuserPrivilege();
     startReconfigurationTask();
   }
 
-  @Override // ClientDatanodeProtocol
+  @Override // ClientDatanodeProtocol & ReconfigurationProtocol
   public ReconfigurationTaskStatus getReconfigurationStatus() throws IOException {
     checkSuperuserPrivilege();
     return getReconfigurationTaskStatus();
   }
 
-  @Override // ClientDatanodeProtocol
+  @Override // ClientDatanodeProtocol & ReconfigurationProtocol
   public List<String> listReconfigurableProperties()
       throws IOException {
     return RECONFIGURABLE_PROPERTIES;