HDDS-13586. [DiskBalancer] Refactor DiskBalancer to remove unused methods and improve naming

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/client/ScmClient.java

@@ -17,6 +17,7 @@
 
 package org.apache.hadoop.hdds.scm.client;
 
+import jakarta.annotation.Nullable;
 import java.io.Closeable;
 import java.io.IOException;
 import java.util.List;
@@ -496,34 +497,34 @@ List<HddsProtos.DatanodeDiskBalancerInfoProto> getDiskBalancerReport(
    * @throws IOException
    */
   List<HddsProtos.DatanodeDiskBalancerInfoProto> getDiskBalancerStatus(
-      Optional<List<String>> hosts,
-      Optional<HddsProtos.DiskBalancerRunningStatus> runningStatus)
+      @Nullable List<String> hosts,
+      @Nullable HddsProtos.DiskBalancerRunningStatus runningStatus)
       throws IOException;
 
   /**
    * Start DiskBalancer.
    */
   List<DatanodeAdminError> startDiskBalancer(
-      Optional<Double> threshold,
-      Optional<Long> bandwidthInMB,
-      Optional<Integer> parallelThread,
-      Optional<Boolean> stopAfterDiskEven,
-      Optional<List<String>> hosts) throws IOException;
+      @Nullable Double threshold,
+      @Nullable Long bandwidthInMB,
+      @Nullable Integer parallelThread,
+      @Nullable Boolean stopAfterDiskEven,
+      @Nullable List<String> hosts) throws IOException;
 
   /**
    * Stop DiskBalancer.
    */
-  List<DatanodeAdminError> stopDiskBalancer(Optional<List<String>> hosts)
+  List<DatanodeAdminError> stopDiskBalancer(@Nullable List<String> hosts)
       throws IOException;
 
 
   /**
    * Update DiskBalancer Configuration.
    */
   List<DatanodeAdminError> updateDiskBalancerConfiguration(
-      Optional<Double> threshold,
-      Optional<Long> bandwidth,
-      Optional<Integer> parallelThread,
-      Optional<Boolean> stopAfterDiskEven,
-      Optional<List<String>> hosts) throws IOException;
+      @Nullable Double threshold,
+      @Nullable Long bandwidth,
+      @Nullable Integer parallelThread,
+      @Nullable Boolean stopAfterDiskEven,
+      @Nullable List<String> hosts) throws IOException;
 }

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/protocol/StorageContainerLocationProtocol.java

@@ -17,6 +17,7 @@
 
 package org.apache.hadoop.hdds.scm.protocol;
 
+import jakarta.annotation.Nullable;
 import java.io.Closeable;
 import java.io.IOException;
 import java.util.Collections;
@@ -499,35 +500,35 @@ List<HddsProtos.DatanodeDiskBalancerInfoProto> getDiskBalancerReport(
    * Get DiskBalancer status.
    */
   List<HddsProtos.DatanodeDiskBalancerInfoProto> getDiskBalancerStatus(
-      Optional<List<String>> hosts,
-      Optional<HddsProtos.DiskBalancerRunningStatus> runningStatus,
+      @Nullable List<String> hosts,
+      @Nullable HddsProtos.DiskBalancerRunningStatus runningStatus,
       int clientVersion) throws IOException;
 
   /**
    * Start DiskBalancer.
    */
   List<DatanodeAdminError> startDiskBalancer(
-      Optional<Double> threshold,
-      Optional<Long> bandwidthInMB,
-      Optional<Integer> parallelThread,
-      Optional<Boolean> stopAfterDiskEven,
-      Optional<List<String>> hosts) throws IOException;
+      @Nullable Double threshold,
+      @Nullable Long bandwidthInMB,
+      @Nullable Integer parallelThread,
+      @Nullable Boolean stopAfterDiskEven,
+      @Nullable List<String> hosts) throws IOException;
 
   /**
    * Stop DiskBalancer.
    */
-  List<DatanodeAdminError> stopDiskBalancer(Optional<List<String>> hosts)
+  List<DatanodeAdminError> stopDiskBalancer(@Nullable List<String> hosts)
       throws IOException;
 
   /**
    * Update DiskBalancer Configuration.
    */
   List<DatanodeAdminError> updateDiskBalancerConfiguration(
-      Optional<Double> threshold,
-      Optional<Long> bandwidthInMB,
-      Optional<Integer> parallelThread,
-      Optional<Boolean> stopAfterDiskEven,
-      Optional<List<String>> hosts) throws IOException;
+      @Nullable Double threshold,
+      @Nullable Long bandwidthInMB,
+      @Nullable Integer parallelThread,
+      @Nullable Boolean stopAfterDiskEven,
+      @Nullable List<String> hosts) throws IOException;
 
   /**
    * Trigger a reconcile command to datanodes for the current container ID.

hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/storage/DiskBalancerConfiguration.java

@@ -21,7 +21,6 @@
 
 import jakarta.annotation.Nonnull;
 import java.time.Duration;
-import java.util.Optional;
 import org.apache.hadoop.hdds.conf.Config;
 import org.apache.hadoop.hdds.conf.ConfigGroup;
 import org.apache.hadoop.hdds.conf.ConfigTag;
@@ -117,13 +116,22 @@ public final class DiskBalancerConfiguration {
       description = "If true, the DiskBalancer will automatically stop once disks are balanced.")
   private boolean stopAfterDiskEven = true;
 
-  public DiskBalancerConfiguration(Optional<Double> threshold,
-      Optional<Long> bandwidthInMB,
-      Optional<Integer> parallelThread, Optional<Boolean> stopAfterDiskEven) {
-    threshold.ifPresent(aDouble -> this.threshold = aDouble);
-    bandwidthInMB.ifPresent(aLong -> this.diskBandwidthInMB = aLong);
-    parallelThread.ifPresent(integer -> this.parallelThread = integer);
-    stopAfterDiskEven.ifPresent(bool -> this.stopAfterDiskEven = bool);
+  public DiskBalancerConfiguration(Double threshold,
+      Long bandwidthInMB,
+      Integer parallelThread,
+      Boolean stopAfterDiskEven) {
+    if (threshold != null) {
+      this.threshold = threshold;
+    }
+    if (bandwidthInMB != null) {
+      this.diskBandwidthInMB = bandwidthInMB;
+    }
+    if (parallelThread != null) {
+      this.parallelThread = parallelThread;
+    }
+    if (stopAfterDiskEven != null) {
+      this.stopAfterDiskEven = stopAfterDiskEven;
+    }
   }
 
   public DiskBalancerConfiguration() {