HDFS-9647. DiskBalancer: Add getRuntimeSettings. (Contributed by Anu Engineer)

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

@@ -183,4 +183,14 @@ void submitDiskBalancerPlan(String planID, long planVersion, long bandwidth,
    * Gets the status of an executing diskbalancer Plan.
    */
   WorkStatus queryDiskBalancerPlan() throws IOException;
+
+  /**
+   * Gets a run-time configuration value from running diskbalancer instance.
+   * For example : Disk Balancer bandwidth of a running instance.
+   *
+   * @param key runtime configuration key
+   * @return value of the key as a string.
+   * @throws IOException - Throws if there is no such key
+   */
+  String getDiskBalancerSetting(String key) throws IOException;
 }

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

@@ -56,6 +56,8 @@
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.CancelPlanRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.QueryPlanStatusRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.QueryPlanStatusResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.DiskBalancerSettingRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.DiskBalancerSettingResponseProto;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.hdfs.server.datanode.WorkStatus;
 import org.apache.hadoop.ipc.ProtobufHelper;
@@ -365,8 +367,8 @@ public void submitDiskBalancerPlan(String planID, long planVersion,
 
   /**
    * Cancels an executing disk balancer plan.
-   * @param planID - A SHA512 hash of the plan string.
    *
+   * @param planID - A SHA512 hash of the plan string.
    * @throws IOException on error
    */
   @Override
@@ -399,4 +401,17 @@ public WorkStatus queryDiskBalancerPlan() throws IOException {
       throw ProtobufHelper.getRemoteException(e);
     }
   }
+
+  @Override
+  public String getDiskBalancerSetting(String key) throws IOException {
+    try {
+      DiskBalancerSettingRequestProto request =
+          DiskBalancerSettingRequestProto.newBuilder().setKey(key).build();
+      DiskBalancerSettingResponseProto response =
+          rpcProxy.getDiskBalancerSetting(NULL_CONTROLLER, request);
+      return response.hasValue() ? response.getValue() : null;
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
 }

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

@@ -197,7 +197,21 @@ message QueryPlanStatusResponseProto {
   optional string status = 2;
   optional string planID = 3;
   optional string currentStatus = 4;
+}
 
+/**
+  * This message sends a request to data node get a specific setting
+  * that is used by disk balancer.
+  */
+message DiskBalancerSettingRequestProto {
+  required string key = 1;
+}
+
+/**
+ * Response that describes the value of requested disk balancer setting.
+ */
+message DiskBalancerSettingResponseProto {
+  required string value = 1;
 }
 
 /**
@@ -275,4 +289,9 @@ service ClientDatanodeProtocolService {
    */
   rpc queryDiskBalancerPlan(QueryPlanStatusRequestProto)
       returns (QueryPlanStatusResponseProto);
+  /**
+   *  Gets run-time settings of Disk Balancer.
+   */
+  rpc getDiskBalancerSetting(DiskBalancerSettingRequestProto)
+      returns(DiskBalancerSettingResponseProto);
 }

hadoop-hdfs-project/hadoop-hdfs/HDFS-1312_CHANGES.txt

@@ -21,3 +21,6 @@ HDFS-1312 Change Log
 
     HDFS-9645. DiskBalancer: Add Query RPC. (Anu Engineer via Arpit Agarwal)
 
+    HDFS-9647. DiskBalancer: Add getRuntimeSettings. (Anu Engineer
+    via Arpit Agarwal)
+

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

@@ -53,7 +53,8 @@
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.CancelPlanResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.QueryPlanStatusRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.QueryPlanStatusResponseProto;
-
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.DiskBalancerSettingRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.DiskBalancerSettingResponseProto;
 import com.google.protobuf.RpcController;
 import com.google.protobuf.ServiceException;
 import org.apache.hadoop.hdfs.server.datanode.WorkStatus;
@@ -279,7 +280,7 @@ public CancelPlanResponseProto cancelDiskBalancerPlan(
     try {
       impl.cancelDiskBalancePlan(request.getPlanID());
       return CancelPlanResponseProto.newBuilder().build();
-    }catch (Exception e) {
+    } catch (Exception e) {
       throw new ServiceException(e);
     }
   }
@@ -304,4 +305,21 @@ public QueryPlanStatusResponseProto queryDiskBalancerPlan(
       throw new ServiceException(e);
     }
   }
+
+  /**
+   * Returns a run-time setting from diskbalancer like Bandwidth.
+   */
+  @Override
+  public DiskBalancerSettingResponseProto getDiskBalancerSetting(
+      RpcController controller, DiskBalancerSettingRequestProto request)
+      throws ServiceException {
+    try {
+      String val = impl.getDiskBalancerSetting(request.getKey());
+      return DiskBalancerSettingResponseProto.newBuilder()
+          .setValue(val)
+          .build();
+    } catch (Exception e) {
+      throw new ServiceException(e);
+    }
+  }
 }

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

@@ -3322,4 +3322,18 @@ public WorkStatus queryDiskBalancerPlan() throws IOException {
     checkSuperuserPrivilege();
     throw new DiskbalancerException("Not Implemented", 0);
   }
+
+  /**
+   * Gets a run-time configuration value from running diskbalancer instance. For
+   * example : Disk Balancer bandwidth of a running instance.
+   *
+   * @param key - String that represents the run time key value.
+   * @return value of the key as a string.
+   * @throws IOException - Throws if there is no such key
+   */
+  @Override
+  public String getDiskBalancerSetting(String key) throws IOException {
+    checkSuperuserPrivilege();
+    throw new DiskbalancerException("Not Implemented", 0);
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/DiskBalancerConstants.java

@@ -0,0 +1,35 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.server.diskbalancer;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/**
+ * Constants used by Disk Balancer.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+public final class DiskBalancerConstants {
+  public static final String DISKBALANCER_BANDWIDTH = "DiskBalancerBandwidth";
+  public static final String DISKBALANCER_VOLUME_NAME =
+      "DiskBalancerVolumeName";
+
+  // never constructed.
+  private DiskBalancerConstants() {
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/diskbalancer/TestDiskBalancerRPC.java

@@ -60,7 +60,7 @@ public void tearDown() throws Exception {
   }
 
   @Test
-  public void TestSubmitTestRpc() throws Exception {
+  public void testSubmitTestRpc() throws Exception {
     final int dnIndex = 0;
     cluster.restartDataNode(dnIndex);
     cluster.waitActive();
@@ -91,7 +91,7 @@ public void TestSubmitTestRpc() throws Exception {
   }
 
   @Test
-  public void TestCancelTestRpc() throws Exception {
+  public void testCancelTestRpc() throws Exception {
     final int dnIndex = 0;
     cluster.restartDataNode(dnIndex);
     cluster.waitActive();
@@ -122,11 +122,10 @@ public void TestCancelTestRpc() throws Exception {
     }
     thrown.expect(DiskbalancerException.class);
     dataNode.cancelDiskBalancePlan(planHash);
-
   }
 
   @Test
-  public void TestQueryTestRpc() throws Exception {
+  public void testQueryTestRpc() throws Exception {
     final int dnIndex = 0;
     cluster.restartDataNode(dnIndex);
     cluster.waitActive();
@@ -162,4 +161,13 @@ public void TestQueryTestRpc() throws Exception {
     thrown.expect(DiskbalancerException.class);
     dataNode.queryDiskBalancerPlan();
   }
+
+  @Test
+  public void testgetDiskBalancerSetting() throws Exception {
+    final int dnIndex = 0;
+    DataNode dataNode = cluster.getDataNodes().get(dnIndex);
+    thrown.expect(DiskbalancerException.class);
+    dataNode.getDiskBalancerSetting(
+        DiskBalancerConstants.DISKBALANCER_BANDWIDTH);
+  }
 }