HDFS-15911 : Provide blocks moved count in Balancer iteration result (#2794)

Contributed by Viraj Jasani.

Signed-off-by: Mingliang Liu <liuml07@apache.org>
Signed-off-by: Ayush Saxena <ayushsaxena@apache.org>

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

@@ -38,6 +38,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
+import org.apache.commons.lang3.builder.ToStringBuilder;
 import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
 import org.apache.hadoop.hdfs.DFSUtilClient;
 import org.slf4j.Logger;
@@ -638,13 +639,15 @@ public class Balancer {
     private final long bytesLeftToMove;
     private final long bytesBeingMoved;
     private final long bytesAlreadyMoved;
+    private final long blocksMoved;
 
     Result(ExitStatus exitStatus, long bytesLeftToMove, long bytesBeingMoved,
-        long bytesAlreadyMoved) {
+           long bytesAlreadyMoved, long blocksMoved) {
       this.exitStatus = exitStatus;
       this.bytesLeftToMove = bytesLeftToMove;
       this.bytesBeingMoved = bytesBeingMoved;
       this.bytesAlreadyMoved = bytesAlreadyMoved;
+      this.blocksMoved = blocksMoved;
     }
 
     public ExitStatus getExitStatus() {
@@ -663,23 +666,40 @@ public class Balancer {
       return bytesAlreadyMoved;
     }
 
+    public long getBlocksMoved() {
+      return blocksMoved;
+    }
+
     void print(int iteration, NameNodeConnector nnc, PrintStream out) {
-      out.printf("%-24s %10d  %19s  %18s  %17s  %s%n",
+      out.printf("%-24s %10d  %19s  %18s  %17s  %17s  %s%n",
           DateFormat.getDateTimeInstance().format(new Date()), iteration,
           StringUtils.byteDesc(bytesAlreadyMoved),
           StringUtils.byteDesc(bytesLeftToMove),
           StringUtils.byteDesc(bytesBeingMoved),
+          blocksMoved,
           nnc.getNameNodeUri());
     }
+
+    @Override
+    public String toString() {
+      return new ToStringBuilder(this)
+          .append("exitStatus", exitStatus)
+          .append("bytesLeftToMove", bytesLeftToMove)
+          .append("bytesBeingMoved", bytesBeingMoved)
+          .append("bytesAlreadyMoved", bytesAlreadyMoved)
+          .append("blocksMoved", blocksMoved)
+          .toString();
+    }
   }
 
   Result newResult(ExitStatus exitStatus, long bytesLeftToMove, long bytesBeingMoved) {
     return new Result(exitStatus, bytesLeftToMove, bytesBeingMoved,
-        dispatcher.getBytesMoved());
+        dispatcher.getBytesMoved(), dispatcher.getBblocksMoved());
   }
 
   Result newResult(ExitStatus exitStatus) {
-    return new Result(exitStatus, -1, -1, dispatcher.getBytesMoved());
+    return new Result(exitStatus, -1, -1, dispatcher.getBytesMoved(),
+        dispatcher.getBblocksMoved());
   }
 
   /** Run an iteration for all datanodes. */

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

@@ -1658,6 +1658,7 @@ public class TestBalancer {
           // a block is moved unexpectedly, IN_PROGRESS will be reported.
           assertEquals("We expect ExitStatus.NO_MOVE_PROGRESS to be reported.",
               ExitStatus.NO_MOVE_PROGRESS, r.getExitStatus());
+          assertEquals(0, r.getBlocksMoved());
         }
       } finally {
         for (NameNodeConnector nnc : connectors) {
@@ -2309,8 +2310,11 @@ public class TestBalancer {
     // Hence, overall total blocks moved by HDFS balancer would be either of these 2 options:
     // a) 2 blocks of total size (100B + 100B)
     // b) 3 blocks of total size (50B + 100B + 100B)
-    assertTrue(balancerResult.getBytesAlreadyMoved() == 200
-        || balancerResult.getBytesAlreadyMoved() == 250);
+    assertTrue("BalancerResult is not as expected. " + balancerResult,
+        (balancerResult.getBytesAlreadyMoved() == 200
+            && balancerResult.getBlocksMoved() == 2)
+            || (balancerResult.getBytesAlreadyMoved() == 250
+            && balancerResult.getBlocksMoved() == 3));
     // 100% and 95% used nodes will be balanced, so top used will be 900
     assertEquals(900, maxUsage);
   }