HDFS-13842. RBF: Exceptions are conflicting when creating the same mount entry twice. Contributed by Ranith Sardar.

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/tools/federation/RouterAdmin.java

@@ -530,6 +530,7 @@ public class RouterAdmin extends Configured implements Tool {
       for (String nsId : nss) {
         if (!existingEntry.addDestination(nsId, dest)) {
           System.err.println("Cannot add destination at " + nsId + " " + dest);
+          return false;
         }
       }
       if (readonly) {

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterAdminCLI.java

@@ -159,6 +159,8 @@ public class TestRouterAdminCLI {
     String dest = "/addmounttable";
     String[] argv = new String[] {"-add", src, nsId, dest};
     assertEquals(0, ToolRunner.run(admin, argv));
+    assertEquals(-1, ToolRunner.run(admin, argv));
+
 
     stateStore.loadCache(MountTableStoreImpl.class, true);
     GetMountTableEntriesRequest getRequest = GetMountTableEntriesRequest
@@ -744,9 +746,7 @@ public class TestRouterAdminCLI {
 
     // verify multi args ClrQuota
     String dest1 = "/QuotaMounttable1";
-    // Add mount table entries.
-    argv = new String[] {"-add", src, nsId, dest};
-    assertEquals(0, ToolRunner.run(admin, argv));
+    // Add one more mount table entry.
     argv = new String[] {"-add", src1, nsId, dest1};
     assertEquals(0, ToolRunner.run(admin, argv));