HDDS-1139 : Fix findbugs issues caused by HDDS-1085. Contributed by Aravindan Vijayan.

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/RDBCheckpointManager.java

@@ -93,7 +93,7 @@ public class RDBCheckpointManager {
     return null;
   }
 
-  class RocksDBCheckpointSnapshot implements DBCheckpointSnapshot {
+  static class RocksDBCheckpointSnapshot implements DBCheckpointSnapshot {
 
     private Path checkpointLocation;
     private long checkpointTimestamp;

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/db/RDBStore.java

@@ -119,7 +119,10 @@ public class RDBStore implements DBStore {
           OM_DB_CHECKPOINTS_DIR_NAME).toString();
       File checkpointsDir = new File(checkpointsParentDir);
       if (!checkpointsDir.exists()) {
-        checkpointsDir.mkdir();
+        boolean success = checkpointsDir.mkdir();
+        if (!success) {
+          LOG.warn("Unable to create RocksDB checkpoint directory");
+        }
       }
 
       //Initialize checkpoint manager

hadoop-hdds/common/src/main/resources/ozone-default.xml

@@ -1881,4 +1881,13 @@
       jar and false for the ozone-filesystem-lib.jar
     </description>
   </property>
+  <property>
+    <name>ozone.manager.db.snapshot.transfer.bandwidthPerSec</name>
+    <value>0</value>
+    <tag>OZONE</tag>
+    <description>
+      Maximum bandwidth used for Ozone Manager DB checkpoint download through
+      the servlet.
+    </description>
+  </property>
 </configuration>

hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/OmUtils.java

@@ -315,8 +315,10 @@ public final class OmUtils {
       tarOs = new TarArchiveOutputStream(gzipOutputStream);
       File folder = new File(sourceDir);
       File[] filesInDir = folder.listFiles();
-      for (File file : filesInDir) {
-        addFilesToArchive(file.getName(), file, tarOs);
+      if (filesInDir != null) {
+        for (File file : filesInDir) {
+          addFilesToArchive(file.getName(), file, tarOs);
+        }
       }
       return new File(fileName);
     } finally {
@@ -343,8 +345,12 @@ public final class OmUtils {
       fileInputStream.close();
     } else if (file.isDirectory()) {
       tarFileOutputStream.closeArchiveEntry();
-      for (File cFile : file.listFiles()) {
-        addFilesToArchive(cFile.getAbsolutePath(), cFile, tarFileOutputStream);
+      File[] filesInDir = file.listFiles();
+      if (filesInDir != null) {
+        for (File cFile : filesInDir) {
+          addFilesToArchive(cFile.getAbsolutePath(), cFile,
+              tarFileOutputStream);
+        }
       }
     }
   }

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OMDbSnapshotServlet.java

@@ -50,9 +50,10 @@ public class OMDbSnapshotServlet extends HttpServlet {
 
   private static final Logger LOG =
       LoggerFactory.getLogger(OMDbSnapshotServlet.class);
+  private static final long serialVersionUID = 1L;
 
   private transient DBStore omDbStore;
-  private DataTransferThrottler throttler = null;
+  private transient DataTransferThrottler throttler = null;
 
   @Override
   public void init() throws ServletException {
@@ -111,7 +112,6 @@ public class OMDbSnapshotServlet extends HttpServlet {
         response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
         return;
       }
-      LOG.info("Tar location = " + checkPointTarFile.getAbsolutePath());
       checkPointTarFile = OmUtils.createTarFile(
           checkpoint.getCheckpointLocation());
       LOG.info("Tar location = " + checkPointTarFile.getAbsolutePath());