HDFS-9008. Balancer#Parameters class could use a builder pattern. (Chris Trezzo via mingma)

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

@@ -915,6 +915,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-9065. Include commas on # of files, blocks, total filesystem objects
     in NN Web UI. (Daniel Templeton via wheat9)
 
+    HDFS-9008. Balancer#Parameters class could use a builder pattern.
+    (Chris Trezzo via mingma)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java

@@ -243,7 +243,8 @@ public class Balancer {
    * namenode as a client and a secondary namenode and retry proxies
    * when connection fails.
    */
-  Balancer(NameNodeConnector theblockpool, Parameters p, Configuration conf) {
+  Balancer(NameNodeConnector theblockpool, BalancerParameters p,
+      Configuration conf) {
     final long movedWinWidth = getLong(conf,
         DFSConfigKeys.DFS_BALANCER_MOVEDWINWIDTH_KEY,
         DFSConfigKeys.DFS_BALANCER_MOVEDWINWIDTH_DEFAULT);
@@ -265,13 +266,15 @@ public class Balancer {
         DFSConfigKeys.DFS_BALANCER_GETBLOCKS_MIN_BLOCK_SIZE_DEFAULT);
 
     this.nnc = theblockpool;
-    this.dispatcher = new Dispatcher(theblockpool, p.includedNodes,
+    this.dispatcher =
-        p.excludedNodes, movedWinWidth, moverThreads, dispatcherThreads,
+        new Dispatcher(theblockpool, p.getIncludedNodes(),
-        maxConcurrentMovesPerNode, getBlocksSize, getBlocksMinBlockSize, conf);
+            p.getExcludedNodes(), movedWinWidth, moverThreads,
-    this.threshold = p.threshold;
+            dispatcherThreads, maxConcurrentMovesPerNode, getBlocksSize,
-    this.policy = p.policy;
+            getBlocksMinBlockSize, conf);
-    this.sourceNodes = p.sourceNodes;
+    this.threshold = p.getThreshold();
-    this.runDuringUpgrade = p.runDuringUpgrade;
+    this.policy = p.getBalancingPolicy();
+    this.sourceNodes = p.getSourceNodes();
+    this.runDuringUpgrade = p.getRunDuringUpgrade();
 
     this.maxSizeToMove = getLong(conf,
         DFSConfigKeys.DFS_BALANCER_MAX_SIZE_TO_MOVE_KEY,
@@ -629,7 +632,7 @@ public class Balancer {
    * for each namenode,
    * execute a {@link Balancer} to work through all datanodes once.  
    */
-  static int run(Collection<URI> namenodes, final Parameters p,
+  static int run(Collection<URI> namenodes, final BalancerParameters p,
       Configuration conf) throws IOException, InterruptedException {
     final long sleeptime =
         conf.getLong(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY,
@@ -638,24 +641,25 @@ public class Balancer {
             DFSConfigKeys.DFS_NAMENODE_REPLICATION_INTERVAL_DEFAULT) * 1000;
     LOG.info("namenodes  = " + namenodes);
     LOG.info("parameters = " + p);
-    LOG.info("included nodes = " + p.includedNodes);
+    LOG.info("included nodes = " + p.getIncludedNodes());
-    LOG.info("excluded nodes = " + p.excludedNodes);
+    LOG.info("excluded nodes = " + p.getExcludedNodes());
-    LOG.info("source nodes = " + p.sourceNodes);
+    LOG.info("source nodes = " + p.getSourceNodes());
 
     System.out.println("Time Stamp               Iteration#  Bytes Already Moved  Bytes Left To Move  Bytes Being Moved");
     
     List<NameNodeConnector> connectors = Collections.emptyList();
     try {
       connectors = NameNodeConnector.newNameNodeConnectors(namenodes, 
-            Balancer.class.getSimpleName(), BALANCER_ID_PATH, conf, p.maxIdleIteration);
+              Balancer.class.getSimpleName(), BALANCER_ID_PATH, conf,
+              p.getMaxIdleIteration());
 
       boolean done = false;
       for(int iteration = 0; !done; iteration++) {
         done = true;
         Collections.shuffle(connectors);
         for(NameNodeConnector nnc : connectors) {
-          if (p.blockpools.size() == 0
+          if (p.getBlockPools().size() == 0
-              || p.blockpools.contains(nnc.getBlockpoolID())) {
+              || p.getBlockPools().contains(nnc.getBlockpoolID())) {
             final Balancer b = new Balancer(nnc, p, conf);
             final Result r = b.runOneIteration();
             r.print(iteration, System.out);
@@ -705,65 +709,6 @@ public class Balancer {
     return time+" "+unit;
   }
 
-  static class Parameters {
-    static final Parameters DEFAULT =
-        new Parameters(BalancingPolicy.Node.INSTANCE, 10.0,
-            NameNodeConnector.DEFAULT_MAX_IDLE_ITERATIONS,
-            Collections.<String> emptySet(), Collections.<String> emptySet(),
-            Collections.<String> emptySet(), Collections.<String> emptySet(),
-            false);
-
-    final BalancingPolicy policy;
-    final double threshold;
-    final int maxIdleIteration;
-    /** Exclude the nodes in this set. */
-    final Set<String> excludedNodes;
-    /** If empty, include any node; otherwise, include only these nodes. */
-    final Set<String> includedNodes;
-    /** If empty, any node can be a source;
-     *  otherwise, use only these nodes as source nodes.
-     */
-    final Set<String> sourceNodes;
-    /**
-     * A set of block pools to run the balancer on.
-     */
-    final Set<String> blockpools;
-    /**
-     * Whether to run the balancer during upgrade.
-     */
-    final boolean runDuringUpgrade;
-
-    Parameters(BalancingPolicy policy, double threshold, int maxIdleIteration,
-        Set<String> excludedNodes, Set<String> includedNodes,
-        Set<String> sourceNodes, Set<String> blockpools,
-        boolean runDuringUpgrade) {
-      this.policy = policy;
-      this.threshold = threshold;
-      this.maxIdleIteration = maxIdleIteration;
-      this.excludedNodes = excludedNodes;
-      this.includedNodes = includedNodes;
-      this.sourceNodes = sourceNodes;
-      this.blockpools = blockpools;
-      this.runDuringUpgrade = runDuringUpgrade;
-    }
-
-    @Override
-    public String toString() {
-      return String.format("%s.%s [%s,"
-              + " threshold = %s,"
-              + " max idle iteration = %s,"
-              + " #excluded nodes = %s,"
-              + " #included nodes = %s,"
-              + " #source nodes = %s,"
-              + " #blockpools = %s,"
-              + " run during upgrade = %s]",
-          Balancer.class.getSimpleName(), getClass().getSimpleName(), policy,
-          threshold, maxIdleIteration, excludedNodes.size(),
-          includedNodes.size(), sourceNodes.size(), blockpools.size(),
-          runDuringUpgrade);
-    }
-  }
-
   static class Cli extends Configured implements Tool {
     /**
      * Parse arguments and then run Balancer.
@@ -796,15 +741,10 @@ public class Balancer {
     }
 
     /** parse command line arguments */
-    static Parameters parse(String[] args) {
+    static BalancerParameters parse(String[] args) {
-      BalancingPolicy policy = Parameters.DEFAULT.policy;
+      Set<String> excludedNodes = null;
-      double threshold = Parameters.DEFAULT.threshold;
+      Set<String> includedNodes = null;
-      int maxIdleIteration = Parameters.DEFAULT.maxIdleIteration;
+      BalancerParameters.Builder b = new BalancerParameters.Builder();
-      Set<String> excludedNodes = Parameters.DEFAULT.excludedNodes;
-      Set<String> includedNodes = Parameters.DEFAULT.includedNodes;
-      Set<String> sourceNodes = Parameters.DEFAULT.sourceNodes;
-      Set<String> blockpools = Parameters.DEFAULT.blockpools;
-      boolean runDuringUpgrade = Parameters.DEFAULT.runDuringUpgrade;
 
       if (args != null) {
         try {
@@ -813,12 +753,13 @@ public class Balancer {
               checkArgument(++i < args.length,
                 "Threshold value is missing: args = " + Arrays.toString(args));
               try {
-                threshold = Double.parseDouble(args[i]);
+                double threshold = Double.parseDouble(args[i]);
                 if (threshold < 1 || threshold > 100) {
                   throw new IllegalArgumentException(
                       "Number out of range: threshold = " + threshold);
                 }
                 LOG.info( "Using a threshold of " + threshold );
+                b.setThreshold(threshold);
               } catch(IllegalArgumentException e) {
                 System.err.println(
                     "Expecting a number in the range of [1.0, 100.0]: "
@@ -829,7 +770,7 @@ public class Balancer {
               checkArgument(++i < args.length,
                 "Policy value is missing: args = " + Arrays.toString(args));
               try {
-                policy = BalancingPolicy.parse(args[i]);
+                b.setBalancingPolicy(BalancingPolicy.parse(args[i]));
               } catch(IllegalArgumentException e) {
                 System.err.println("Illegal policy name: " + args[i]);
                 throw e;
@@ -837,28 +778,33 @@ public class Balancer {
             } else if ("-exclude".equalsIgnoreCase(args[i])) {
               excludedNodes = new HashSet<>();
               i = processHostList(args, i, "exclude", excludedNodes);
+              b.setExcludedNodes(excludedNodes);
             } else if ("-include".equalsIgnoreCase(args[i])) {
               includedNodes = new HashSet<>();
               i = processHostList(args, i, "include", includedNodes);
+              b.setIncludedNodes(includedNodes);
             } else if ("-source".equalsIgnoreCase(args[i])) {
-              sourceNodes = new HashSet<>();
+              Set<String> sourceNodes = new HashSet<>();
               i = processHostList(args, i, "source", sourceNodes);
+              b.setSourceNodes(sourceNodes);
             } else if ("-blockpools".equalsIgnoreCase(args[i])) {
               checkArgument(
                   ++i < args.length,
                   "blockpools value is missing: args = "
                       + Arrays.toString(args));
-              blockpools = parseBlockPoolList(args[i]);
+              Set<String> blockpools = parseBlockPoolList(args[i]);
               LOG.info("Balancer will run on the following blockpools: "
                   + blockpools.toString());
+              b.setBlockpools(blockpools);
             } else if ("-idleiterations".equalsIgnoreCase(args[i])) {
               checkArgument(++i < args.length,
                   "idleiterations value is missing: args = " + Arrays
                       .toString(args));
-              maxIdleIteration = Integer.parseInt(args[i]);
+              int maxIdleIteration = Integer.parseInt(args[i]);
               LOG.info("Using a idleiterations of " + maxIdleIteration);
+              b.setMaxIdleIteration(maxIdleIteration);
             } else if ("-runDuringUpgrade".equalsIgnoreCase(args[i])) {
-              runDuringUpgrade = true;
+              b.setRunDuringUpgrade(true);
               LOG.info("Will run the balancer even during an ongoing HDFS "
                   + "upgrade. Most users will not want to run the balancer "
                   + "during an upgrade since it will not affect used space "
@@ -868,16 +814,14 @@ public class Balancer {
                   + Arrays.toString(args));
             }
           }
-          checkArgument(excludedNodes.isEmpty() || includedNodes.isEmpty(),
+          checkArgument(excludedNodes == null || includedNodes == null,
               "-exclude and -include options cannot be specified together.");
         } catch(RuntimeException e) {
           printUsage(System.err);
           throw e;
         }
       }
-      
+      return b.build();
-      return new Parameters(policy, threshold, maxIdleIteration, excludedNodes,
-          includedNodes, sourceNodes, blockpools, runDuringUpgrade);
     }
 
     private static int processHostList(String[] args, int i, String type,

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/BalancerParameters.java

@@ -0,0 +1,168 @@
+/**
+ * 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.server.balancer;
+
+import java.util.Collections;
+import java.util.Set;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+
+@InterfaceAudience.Private
+final class BalancerParameters {
+  private final BalancingPolicy policy;
+  private final double threshold;
+  private final int maxIdleIteration;
+  /** Exclude the nodes in this set. */
+  private final Set<String> excludedNodes;
+  /** If empty, include any node; otherwise, include only these nodes. */
+  private final Set<String> includedNodes;
+  /**
+   * If empty, any node can be a source; otherwise, use only these nodes as
+   * source nodes.
+   */
+  private final Set<String> sourceNodes;
+  /**
+   * A set of block pools to run the balancer on.
+   */
+  private final Set<String> blockpools;
+  /**
+   * Whether to run the balancer during upgrade.
+   */
+  private final boolean runDuringUpgrade;
+
+  static final BalancerParameters DEFAULT = new BalancerParameters();
+
+  private BalancerParameters() {
+    this(new Builder());
+  }
+
+  private BalancerParameters(Builder builder) {
+    this.policy = builder.policy;
+    this.threshold = builder.threshold;
+    this.maxIdleIteration = builder.maxIdleIteration;
+    this.excludedNodes = builder.excludedNodes;
+    this.includedNodes = builder.includedNodes;
+    this.sourceNodes = builder.sourceNodes;
+    this.blockpools = builder.blockpools;
+    this.runDuringUpgrade = builder.runDuringUpgrade;
+  }
+
+  BalancingPolicy getBalancingPolicy() {
+    return this.policy;
+  }
+
+  double getThreshold() {
+    return this.threshold;
+  }
+
+  int getMaxIdleIteration() {
+    return this.maxIdleIteration;
+  }
+
+  Set<String> getExcludedNodes() {
+    return this.excludedNodes;
+  }
+
+  Set<String> getIncludedNodes() {
+    return this.includedNodes;
+  }
+
+  Set<String> getSourceNodes() {
+    return this.sourceNodes;
+  }
+
+  Set<String> getBlockPools() {
+    return this.blockpools;
+  }
+
+  boolean getRunDuringUpgrade() {
+    return this.runDuringUpgrade;
+  }
+
+  @Override
+  public String toString() {
+    return String.format("%s.%s [%s," + " threshold = %s,"
+        + " max idle iteration = %s," + " #excluded nodes = %s,"
+        + " #included nodes = %s," + " #source nodes = %s,"
+        + " #blockpools = %s," + " run during upgrade = %s]",
+        Balancer.class.getSimpleName(), getClass().getSimpleName(), policy,
+        threshold, maxIdleIteration, excludedNodes.size(),
+        includedNodes.size(), sourceNodes.size(), blockpools.size(),
+        runDuringUpgrade);
+  }
+
+  static class Builder {
+    // Defaults
+    private BalancingPolicy policy = BalancingPolicy.Node.INSTANCE;
+    private double threshold = 10.0;
+    private int maxIdleIteration =
+        NameNodeConnector.DEFAULT_MAX_IDLE_ITERATIONS;
+    private Set<String> excludedNodes = Collections.<String> emptySet();
+    private Set<String> includedNodes = Collections.<String> emptySet();
+    private Set<String> sourceNodes = Collections.<String> emptySet();
+    private Set<String> blockpools = Collections.<String> emptySet();
+    private boolean runDuringUpgrade = false;
+
+    Builder() {
+    }
+
+    Builder setBalancingPolicy(BalancingPolicy p) {
+      this.policy = p;
+      return this;
+    }
+
+    Builder setThreshold(double t) {
+      this.threshold = t;
+      return this;
+    }
+
+    Builder setMaxIdleIteration(int m) {
+      this.maxIdleIteration = m;
+      return this;
+    }
+
+    Builder setExcludedNodes(Set<String> nodes) {
+      this.excludedNodes = nodes;
+      return this;
+    }
+
+    Builder setIncludedNodes(Set<String> nodes) {
+      this.includedNodes = nodes;
+      return this;
+    }
+
+    Builder setSourceNodes(Set<String> nodes) {
+      this.sourceNodes = nodes;
+      return this;
+    }
+
+    Builder setBlockpools(Set<String> pools) {
+      this.blockpools = pools;
+      return this;
+    }
+
+    Builder setRunDuringUpgrade(boolean run) {
+      this.runDuringUpgrade = run;
+      return this;
+    }
+
+    BalancerParameters build() {
+      return new BalancerParameters(this);
+    }
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java

@@ -75,8 +75,8 @@ import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.server.balancer.Balancer.Cli;
-import org.apache.hadoop.hdfs.server.balancer.Balancer.Parameters;
 import org.apache.hadoop.hdfs.server.balancer.Balancer.Result;
+import org.apache.hadoop.hdfs.server.balancer.BalancerParameters;
 import org.apache.hadoop.hdfs.server.datanode.DataNode;
 import org.apache.hadoop.hdfs.server.datanode.SimulatedFSDataset;
 import org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.LazyPersistTestCase;
@@ -319,7 +319,7 @@ public class TestBalancer {
    * @throws TimeoutException
    */
   static void waitForBalancer(long totalUsedSpace, long totalCapacity,
-      ClientProtocol client, MiniDFSCluster cluster, Balancer.Parameters p)
+      ClientProtocol client, MiniDFSCluster cluster, BalancerParameters p)
   throws IOException, TimeoutException {
     waitForBalancer(totalUsedSpace, totalCapacity, client, cluster, p, 0);
   }
@@ -377,7 +377,7 @@ public class TestBalancer {
 
       // start rebalancing
       Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
-      int r = Balancer.run(namenodes, Balancer.Parameters.DEFAULT, conf);
+      int r = Balancer.run(namenodes, BalancerParameters.DEFAULT, conf);
       assertEquals(ExitStatus.NO_MOVE_PROGRESS.getExitCode(), r);
       
     } finally {
@@ -393,16 +393,16 @@ public class TestBalancer {
    * @throws TimeoutException
    */
   static void waitForBalancer(long totalUsedSpace, long totalCapacity,
-      ClientProtocol client, MiniDFSCluster cluster, Balancer.Parameters p,
+      ClientProtocol client, MiniDFSCluster cluster, BalancerParameters p,
       int expectedExcludedNodes) throws IOException, TimeoutException {
     long timeout = TIMEOUT;
     long failtime = (timeout <= 0L) ? Long.MAX_VALUE
         : Time.monotonicNow() + timeout;
-    if (!p.includedNodes.isEmpty()) {
+    if (!p.getIncludedNodes().isEmpty()) {
-      totalCapacity = p.includedNodes.size() * CAPACITY;
+      totalCapacity = p.getIncludedNodes().size() * CAPACITY;
     }
-    if (!p.excludedNodes.isEmpty()) {
+    if (!p.getExcludedNodes().isEmpty()) {
-        totalCapacity -= p.excludedNodes.size() * CAPACITY;
+      totalCapacity -= p.getExcludedNodes().size() * CAPACITY;
     }
     final double avgUtilization = ((double)totalUsedSpace) / totalCapacity;
     boolean balanced;
@@ -415,12 +415,12 @@ public class TestBalancer {
       for (DatanodeInfo datanode : datanodeReport) {
         double nodeUtilization = ((double)datanode.getDfsUsed())
             / datanode.getCapacity();
-        if (Dispatcher.Util.isExcluded(p.excludedNodes, datanode)) {
+        if (Dispatcher.Util.isExcluded(p.getExcludedNodes(), datanode)) {
           assertTrue(nodeUtilization == 0);
           actualExcludedNodeCount++;
           continue;
         }
-        if (!Dispatcher.Util.isIncluded(p.includedNodes, datanode)) {
+        if (!Dispatcher.Util.isIncluded(p.getIncludedNodes(), datanode)) {
           assertTrue(nodeUtilization == 0);
           actualExcludedNodeCount++;
           continue;
@@ -636,16 +636,14 @@ public class TestBalancer {
         }
       }
       // run balancer and validate results
-      Balancer.Parameters p = Balancer.Parameters.DEFAULT;
+      BalancerParameters.Builder pBuilder =
+          new BalancerParameters.Builder();
       if (nodes != null) {
-        p = new Balancer.Parameters(
+        pBuilder.setExcludedNodes(nodes.getNodesToBeExcluded());
-            Balancer.Parameters.DEFAULT.policy,
+        pBuilder.setIncludedNodes(nodes.getNodesToBeIncluded());
-            Balancer.Parameters.DEFAULT.threshold,
+        pBuilder.setRunDuringUpgrade(false);
-            Balancer.Parameters.DEFAULT.maxIdleIteration,
-            nodes.getNodesToBeExcluded(), nodes.getNodesToBeIncluded(),
-            Balancer.Parameters.DEFAULT.sourceNodes,
-            Balancer.Parameters.DEFAULT.blockpools, false);
       }
+      BalancerParameters p = pBuilder.build();
 
       int expectedExcludedNodes = 0;
       if (nodes != null) {
@@ -668,14 +666,15 @@ public class TestBalancer {
     }
   }
 
-  private void runBalancer(Configuration conf,
+  private void runBalancer(Configuration conf, long totalUsedSpace,
-      long totalUsedSpace, long totalCapacity) throws Exception {
+      long totalCapacity) throws Exception {
-    runBalancer(conf, totalUsedSpace, totalCapacity, Balancer.Parameters.DEFAULT, 0);
+    runBalancer(conf, totalUsedSpace, totalCapacity,
+        BalancerParameters.DEFAULT, 0);
   }
 
-  private void runBalancer(Configuration conf,
+  private void runBalancer(Configuration conf, long totalUsedSpace,
-     long totalUsedSpace, long totalCapacity, Balancer.Parameters p,
+      long totalCapacity, BalancerParameters p, int excludedNodes)
-     int excludedNodes) throws Exception {
+      throws Exception {
     waitForHeartBeat(totalUsedSpace, totalCapacity, client, cluster);
 
     // start rebalancing
@@ -693,7 +692,8 @@ public class TestBalancer {
     waitForBalancer(totalUsedSpace, totalCapacity, client, cluster, p, excludedNodes);
   }
 
-  private static int runBalancer(Collection<URI> namenodes, final Parameters p,
+  private static int runBalancer(Collection<URI> namenodes,
+      final BalancerParameters p,
       Configuration conf) throws IOException, InterruptedException {
     final long sleeptime =
         conf.getLong(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY,
@@ -710,7 +710,7 @@ public class TestBalancer {
     try {
       connectors = NameNodeConnector.newNameNodeConnectors(namenodes, 
           Balancer.class.getSimpleName(), Balancer.BALANCER_ID_PATH, conf,
-          Balancer.Parameters.DEFAULT.maxIdleIteration);
+              BalancerParameters.DEFAULT.getMaxIdleIteration());
 
       boolean done = false;
       for(int iteration = 0; !done; iteration++) {
@@ -747,45 +747,45 @@ public class TestBalancer {
     return ExitStatus.SUCCESS.getExitCode();
   }
 
-  private void runBalancerCli(Configuration conf,
+  private void runBalancerCli(Configuration conf, long totalUsedSpace,
-      long totalUsedSpace, long totalCapacity,
+      long totalCapacity, BalancerParameters p, boolean useFile,
-      Balancer.Parameters p, boolean useFile, int expectedExcludedNodes) throws Exception {
+      int expectedExcludedNodes) throws Exception {
     waitForHeartBeat(totalUsedSpace, totalCapacity, client, cluster);
     List <String> args = new ArrayList<String>();
     args.add("-policy");
     args.add("datanode");
 
     File excludeHostsFile = null;
-    if (!p.excludedNodes.isEmpty()) {
+    if (!p.getExcludedNodes().isEmpty()) {
       args.add("-exclude");
       if (useFile) {
         excludeHostsFile = new File ("exclude-hosts-file");
         PrintWriter pw = new PrintWriter(excludeHostsFile);
-        for (String host: p.excludedNodes) {
+        for (String host : p.getExcludedNodes()) {
           pw.write( host + "\n");
         }
         pw.close();
         args.add("-f");
         args.add("exclude-hosts-file");
       } else {
-        args.add(StringUtils.join(p.excludedNodes, ','));
+        args.add(StringUtils.join(p.getExcludedNodes(), ','));
       }
     }
 
     File includeHostsFile = null;
-    if (!p.includedNodes.isEmpty()) {
+    if (!p.getIncludedNodes().isEmpty()) {
       args.add("-include");
       if (useFile) {
         includeHostsFile = new File ("include-hosts-file");
         PrintWriter pw = new PrintWriter(includeHostsFile);
-        for (String host: p.includedNodes){
+        for (String host : p.getIncludedNodes()) {
           pw.write( host + "\n");
         }
         pw.close();
         args.add("-f");
         args.add("include-hosts-file");
       } else {
-        args.add(StringUtils.join(p.includedNodes, ','));
+        args.add(StringUtils.join(p.getIncludedNodes(), ','));
       }
     }
 
@@ -879,14 +879,11 @@ public class TestBalancer {
       Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
       Set<String>  datanodes = new HashSet<String>();
       datanodes.add(cluster.getDataNodes().get(0).getDatanodeId().getHostName());
-      Balancer.Parameters p = new Balancer.Parameters(
+      BalancerParameters.Builder pBuilder =
-          Balancer.Parameters.DEFAULT.policy,
+          new BalancerParameters.Builder();
-          Balancer.Parameters.DEFAULT.threshold,
+      pBuilder.setExcludedNodes(datanodes);
-          Balancer.Parameters.DEFAULT.maxIdleIteration,
+      pBuilder.setRunDuringUpgrade(false);
-          datanodes, Balancer.Parameters.DEFAULT.includedNodes,
+      final int r = Balancer.run(namenodes, pBuilder.build(), conf);
-          Balancer.Parameters.DEFAULT.sourceNodes,
-          Balancer.Parameters.DEFAULT.blockpools, false);
-      final int r = Balancer.run(namenodes, p, conf);
       assertEquals(ExitStatus.SUCCESS.getExitCode(), r);
     } finally {
       cluster.shutdown();
@@ -1081,20 +1078,20 @@ public class TestBalancer {
   @Test
   public void testBalancerCliParseBlockpools() {
     String[] parameters = new String[] { "-blockpools", "bp-1,bp-2,bp-3" };
-    Balancer.Parameters p = Balancer.Cli.parse(parameters);
+    BalancerParameters p = Balancer.Cli.parse(parameters);
-    assertEquals(3, p.blockpools.size());
+    assertEquals(3, p.getBlockPools().size());
 
     parameters = new String[] { "-blockpools", "bp-1" };
     p = Balancer.Cli.parse(parameters);
-    assertEquals(1, p.blockpools.size());
+    assertEquals(1, p.getBlockPools().size());
 
     parameters = new String[] { "-blockpools", "bp-1,,bp-2" };
     p = Balancer.Cli.parse(parameters);
-    assertEquals(3, p.blockpools.size());
+    assertEquals(3, p.getBlockPools().size());
 
     parameters = new String[] { "-blockpools", "bp-1," };
     p = Balancer.Cli.parse(parameters);
-    assertEquals(1, p.blockpools.size());
+    assertEquals(1, p.getBlockPools().size());
   }
 
   /**
@@ -1123,7 +1120,8 @@ public class TestBalancer {
     excludeHosts.add( "datanodeZ");
     doTest(conf, new long[]{CAPACITY, CAPACITY}, new String[]{RACK0, RACK1}, CAPACITY, RACK2,
         new HostNameBasedNodes(new String[] {"datanodeX", "datanodeY", "datanodeZ"},
-        excludeHosts, Parameters.DEFAULT.includedNodes), false, false);
+            excludeHosts, BalancerParameters.DEFAULT.getIncludedNodes()),
+        false, false);
   }
 
   /**
@@ -1151,9 +1149,11 @@ public class TestBalancer {
     Set<String> excludeHosts = new HashSet<String>();
     excludeHosts.add( "datanodeY");
     excludeHosts.add( "datanodeZ");
-    doTest(conf, new long[]{CAPACITY, CAPACITY}, new String[]{RACK0, RACK1}, CAPACITY, RACK2,
+    doTest(conf, new long[] { CAPACITY, CAPACITY },
-      new HostNameBasedNodes(new String[] {"datanodeX", "datanodeY", "datanodeZ"}, excludeHosts,
+        new String[] { RACK0, RACK1 }, CAPACITY, RACK2, new HostNameBasedNodes(
-      Parameters.DEFAULT.includedNodes), true, false);
+            new String[] { "datanodeX", "datanodeY", "datanodeZ" },
+            excludeHosts, BalancerParameters.DEFAULT.getIncludedNodes()), true,
+        false);
   }
 
   /**
@@ -1183,7 +1183,8 @@ public class TestBalancer {
     excludeHosts.add( "datanodeZ");
     doTest(conf, new long[]{CAPACITY, CAPACITY}, new String[]{RACK0, RACK1}, CAPACITY, RACK2,
         new HostNameBasedNodes(new String[] {"datanodeX", "datanodeY", "datanodeZ"},
-        excludeHosts, Parameters.DEFAULT.includedNodes), true, true);
+            excludeHosts, BalancerParameters.DEFAULT.getIncludedNodes()), true,
+        true);
   }
 
   /**
@@ -1212,7 +1213,8 @@ public class TestBalancer {
     includeHosts.add( "datanodeY");
     doTest(conf, new long[]{CAPACITY, CAPACITY}, new String[]{RACK0, RACK1}, CAPACITY, RACK2,
         new HostNameBasedNodes(new String[] {"datanodeX", "datanodeY", "datanodeZ"},
-        Parameters.DEFAULT.excludedNodes, includeHosts), false, false);
+            BalancerParameters.DEFAULT.getExcludedNodes(), includeHosts),
+        false, false);
   }
 
   /**
@@ -1241,7 +1243,8 @@ public class TestBalancer {
     includeHosts.add( "datanodeY");
     doTest(conf, new long[]{CAPACITY, CAPACITY}, new String[]{RACK0, RACK1}, CAPACITY, RACK2,
         new HostNameBasedNodes(new String[] {"datanodeX", "datanodeY", "datanodeZ"},
-        Parameters.DEFAULT.excludedNodes, includeHosts), true, false);
+            BalancerParameters.DEFAULT.getExcludedNodes(), includeHosts), true,
+        false);
   }
 
   /**
@@ -1270,7 +1273,8 @@ public class TestBalancer {
     includeHosts.add( "datanodeY");
     doTest(conf, new long[]{CAPACITY, CAPACITY}, new String[]{RACK0, RACK1}, CAPACITY, RACK2,
         new HostNameBasedNodes(new String[] {"datanodeX", "datanodeY", "datanodeZ"},
-        Parameters.DEFAULT.excludedNodes, includeHosts), true, true);
+            BalancerParameters.DEFAULT.getExcludedNodes(), includeHosts), true,
+        true);
   }
 
   /**
@@ -1343,7 +1347,7 @@ public class TestBalancer {
       Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
 
       // Run Balancer
-      final Balancer.Parameters p = Parameters.DEFAULT;
+      final BalancerParameters p = BalancerParameters.DEFAULT;
       final int r = Balancer.run(namenodes, p, conf);
 
       // Validate no RAM_DISK block should be moved
@@ -1395,7 +1399,7 @@ public class TestBalancer {
       Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
 
       // Run balancer
-      final Balancer.Parameters p = Parameters.DEFAULT;
+      final BalancerParameters p = BalancerParameters.DEFAULT;
 
       fs.setSafeMode(HdfsConstants.SafeModeAction.SAFEMODE_ENTER);
       fs.rollingUpgrade(HdfsConstants.RollingUpgradeAction.PREPARE);
@@ -1406,14 +1410,10 @@ public class TestBalancer {
           Balancer.run(namenodes, p, conf));
 
       // Should work with the -runDuringUpgrade flag.
-      final Balancer.Parameters runDuringUpgrade =
+      BalancerParameters.Builder b =
-          new Balancer.Parameters(Parameters.DEFAULT.policy,
+          new BalancerParameters.Builder();
-              Parameters.DEFAULT.threshold,
+      b.setRunDuringUpgrade(true);
-              Parameters.DEFAULT.maxIdleIteration,
+      final BalancerParameters runDuringUpgrade = b.build();
-              Parameters.DEFAULT.excludedNodes,
-              Parameters.DEFAULT.includedNodes,
-              Parameters.DEFAULT.sourceNodes,
-              Balancer.Parameters.DEFAULT.blockpools, true);
       assertEquals(ExitStatus.SUCCESS.getExitCode(),
           Balancer.run(namenodes, runDuringUpgrade, conf));
 
@@ -1480,7 +1480,7 @@ public class TestBalancer {
       // update space info
       cluster.triggerHeartbeats();
 
-      Balancer.Parameters p = Balancer.Parameters.DEFAULT;
+      BalancerParameters p = BalancerParameters.DEFAULT;
       Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
       final int r = Balancer.run(namenodes, p, conf);
 
@@ -1612,12 +1612,11 @@ public class TestBalancer {
       final Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
 
       { // run Balancer with min-block-size=50
-        final Parameters p = new Parameters(
+        BalancerParameters.Builder b =
-            BalancingPolicy.Node.INSTANCE, 1,
+            new BalancerParameters.Builder();
-            NameNodeConnector.DEFAULT_MAX_IDLE_ITERATIONS,
+        b.setBalancingPolicy(BalancingPolicy.Node.INSTANCE);
-            Collections.<String> emptySet(), Collections.<String> emptySet(),
+        b.setThreshold(1);
-            Collections.<String> emptySet(),
+        final BalancerParameters p = b.build();
-            Balancer.Parameters.DEFAULT.blockpools, false);
 
         conf.setLong(DFSConfigKeys.DFS_BALANCER_GETBLOCKS_MIN_BLOCK_SIZE_KEY, 50);
         final int r = Balancer.run(namenodes, p, conf);
@@ -1632,11 +1631,12 @@ public class TestBalancer {
         for(int i = capacities.length; i < datanodes.size(); i++) {
           sourceNodes.add(datanodes.get(i).getDisplayName());
         }
-        final Parameters p = new Parameters(
+        BalancerParameters.Builder b =
-          BalancingPolicy.Node.INSTANCE, 1,
+            new BalancerParameters.Builder();
-          NameNodeConnector.DEFAULT_MAX_IDLE_ITERATIONS,
+        b.setBalancingPolicy(BalancingPolicy.Node.INSTANCE);
-          Collections.<String> emptySet(), Collections.<String> emptySet(),
+        b.setThreshold(1);
-          sourceNodes, Balancer.Parameters.DEFAULT.blockpools, false);
+        b.setSourceNodes(sourceNodes);
+        final BalancerParameters p = b.build();
 
         conf.setLong(DFSConfigKeys.DFS_BALANCER_GETBLOCKS_MIN_BLOCK_SIZE_KEY, 50);
         final int r = Balancer.run(namenodes, p, conf);
@@ -1647,11 +1647,12 @@ public class TestBalancer {
         final Set<String> sourceNodes = new HashSet<>();
         final List<DataNode> datanodes = cluster.getDataNodes();
         sourceNodes.add(datanodes.get(0).getDisplayName());
-        final Parameters p = new Parameters(
+        BalancerParameters.Builder b =
-          BalancingPolicy.Node.INSTANCE, 1,
+            new BalancerParameters.Builder();
-          NameNodeConnector.DEFAULT_MAX_IDLE_ITERATIONS,
+        b.setBalancingPolicy(BalancingPolicy.Node.INSTANCE);
-          Collections.<String> emptySet(), Collections.<String> emptySet(),
+        b.setThreshold(1);
-          sourceNodes, Balancer.Parameters.DEFAULT.blockpools, false);
+        b.setSourceNodes(sourceNodes);
+        final BalancerParameters p = b.build();
 
         conf.setLong(DFSConfigKeys.DFS_BALANCER_GETBLOCKS_MIN_BLOCK_SIZE_KEY, 1);
         final int r = Balancer.run(namenodes, p, conf);
@@ -1664,11 +1665,12 @@ public class TestBalancer {
         for(int i = 0; i < capacities.length; i++) {
           sourceNodes.add(datanodes.get(i).getDisplayName());
         }
-        final Parameters p = new Parameters(
+        BalancerParameters.Builder b =
-          BalancingPolicy.Node.INSTANCE, 1,
+            new BalancerParameters.Builder();
-          NameNodeConnector.DEFAULT_MAX_IDLE_ITERATIONS,
+        b.setBalancingPolicy(BalancingPolicy.Node.INSTANCE);
-          Collections.<String> emptySet(), Collections.<String> emptySet(),
+        b.setThreshold(1);
-          sourceNodes, Balancer.Parameters.DEFAULT.blockpools, false);
+        b.setSourceNodes(sourceNodes);
+        final BalancerParameters p = b.build();
 
         conf.setLong(DFSConfigKeys.DFS_BALANCER_GETBLOCKS_MIN_BLOCK_SIZE_KEY, 1);
         final int r = Balancer.run(namenodes, p, conf);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancerWithHANameNodes.java

@@ -97,10 +97,10 @@ public class TestBalancerWithHANameNodes {
       Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
       assertEquals(1, namenodes.size());
       assertTrue(namenodes.contains(HATestUtil.getLogicalUri(cluster)));
-      final int r = Balancer.run(namenodes, Balancer.Parameters.DEFAULT, conf);
+      final int r = Balancer.run(namenodes, BalancerParameters.DEFAULT, conf);
       assertEquals(ExitStatus.SUCCESS.getExitCode(), r);
       TestBalancer.waitForBalancer(totalUsedSpace, totalCapacity, client,
-          cluster, Balancer.Parameters.DEFAULT);
+          cluster, BalancerParameters.DEFAULT);
     } finally {
       cluster.shutdown();
     }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancerWithMultipleNameNodes.java

@@ -47,6 +47,7 @@ import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.server.balancer.BalancerParameters;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeStorageReport;
 import org.apache.hadoop.hdfs.server.protocol.StorageReport;
 import org.apache.log4j.Level;
@@ -84,10 +85,10 @@ public class TestBalancerWithMultipleNameNodes {
     final MiniDFSCluster cluster;
     final ClientProtocol[] clients;
     final short replication;
-    final Balancer.Parameters parameters;
+    final BalancerParameters parameters;
 
     Suite(MiniDFSCluster cluster, final int nNameNodes, final int nDataNodes,
-        Balancer.Parameters parameters, Configuration conf) throws IOException {
+        BalancerParameters parameters, Configuration conf) throws IOException {
       this.conf = conf;
       this.cluster = cluster;
       clients = new ClientProtocol[nNameNodes];
@@ -204,7 +205,7 @@ public class TestBalancerWithMultipleNameNodes {
       balanced = true;
       for(int d = 0; d < used.length; d++) {
         final double p = used[d]*100.0/cap[d];
-        balanced = p <= avg + s.parameters.threshold;
+        balanced = p <= avg + s.parameters.getThreshold();
         if (!balanced) {
           if (i % 100 == 0) {
             LOG.warn("datanodes " + d + " is not yet balanced: "
@@ -278,13 +279,14 @@ public class TestBalancerWithMultipleNameNodes {
     DatanodeStorageReport[]> getStorageReports(Suite s) throws IOException {
     Map<Integer, DatanodeStorageReport[]> reports =
         new HashMap<Integer, DatanodeStorageReport[]>();
-    if (s.parameters.blockpools.size() == 0) {
+    if (s.parameters.getBlockPools().size() == 0) {
       // the blockpools parameter was not set, so we don't need to track any
       // blockpools.
       return Collections.emptyMap();
     }
     for (int i = 0; i < s.clients.length; i++) {
-      if (s.parameters.blockpools.contains(s.cluster.getNamesystem(i)
+      if (s.parameters.getBlockPools().contains(
+          s.cluster.getNamesystem(i)
           .getBlockPoolId())) {
         // we want to ensure that blockpools not specified by the balancer
         // parameters were left alone. Therefore, if the pool was specified,
@@ -388,14 +390,10 @@ public class TestBalancerWithMultipleNameNodes {
         for (int i = 0; i < nNameNodesToBalance; i++) {
           blockpools.add(cluster.getNamesystem(i).getBlockPoolId());
         }
-        Balancer.Parameters params =
+        BalancerParameters.Builder b =
-            new Balancer.Parameters(Balancer.Parameters.DEFAULT.policy,
+            new BalancerParameters.Builder();
-                Balancer.Parameters.DEFAULT.threshold,
+        b.setBlockpools(blockpools);
-                Balancer.Parameters.DEFAULT.maxIdleIteration,
+        BalancerParameters params = b.build();
-                Balancer.Parameters.DEFAULT.excludedNodes,
-                Balancer.Parameters.DEFAULT.includedNodes,
-                Balancer.Parameters.DEFAULT.sourceNodes, blockpools,
-                Balancer.Parameters.DEFAULT.runDuringUpgrade);
         final Suite s =
             new Suite(cluster, nNameNodes, nDataNodes, params, conf);
         for(int n = 0; n < nNameNodes; n++) {
@@ -455,7 +453,7 @@ public class TestBalancerWithMultipleNameNodes {
       LOG.info("RUN_TEST 1");
       final Suite s =
           new Suite(cluster, nNameNodes, nDataNodes,
-              Balancer.Parameters.DEFAULT, conf);
+              BalancerParameters.DEFAULT, conf);
       long totalCapacity = TestBalancer.sum(capacities);
 
       LOG.info("RUN_TEST 2");

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancerWithNodeGroup.java

@@ -175,7 +175,7 @@ public class TestBalancerWithNodeGroup {
 
     // start rebalancing
     Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
-    final int r = Balancer.run(namenodes, Balancer.Parameters.DEFAULT, conf);
+    final int r = Balancer.run(namenodes, BalancerParameters.DEFAULT, conf);
     assertEquals(ExitStatus.SUCCESS.getExitCode(), r);
 
     waitForHeartBeat(totalUsedSpace, totalCapacity);
@@ -189,7 +189,7 @@ public class TestBalancerWithNodeGroup {
 
     // start rebalancing
     Collection<URI> namenodes = DFSUtil.getNsServiceRpcUris(conf);
-    final int r = Balancer.run(namenodes, Balancer.Parameters.DEFAULT, conf);
+    final int r = Balancer.run(namenodes, BalancerParameters.DEFAULT, conf);
     Assert.assertTrue(r == ExitStatus.SUCCESS.getExitCode() ||
         (r == ExitStatus.NO_MOVE_PROGRESS.getExitCode()));
     waitForHeartBeat(totalUsedSpace, totalCapacity);