fix checkstyles, update the documents

Author: tomscut

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSHAAdmin.java

@@ -247,7 +247,7 @@ private boolean checkSupportObserver(HAServiceTarget target) {
   }
 
   private int transitionToObserver(final CommandLine cmd)
-      throws IOException, ServiceFailedException {
+      throws IOException {
     String[] argv = cmd.getArgs();
     if (argv.length != 1) {
       errOut.println("transitionToObserver: incorrect number of arguments");
@@ -265,8 +265,8 @@ private int transitionToObserver(final CommandLine cmd)
     try {
       HAServiceProtocol proto = target.getProxy(getConf(), 0);
       HAServiceProtocolHelper.transitionToObserver(proto, createReqInfo());
-    } catch (IOException e) {
-      errOut.println("TransitionToObserver failed! " + e.getMessage());
+    } catch (ServiceFailedException e) {
+      errOut.println("transitionToObserver failed! " + e.getLocalizedMessage());
       return -1;
     }
     return 0;

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -3749,7 +3749,7 @@
   <name>dfs.ha.nn.not-become-active-in-safemode</name>
   <value>false</value>
   <description>
-    This will prevent safe mode namenodes to become active while other standby
+    This will prevent safe mode namenodes to become active or observer while other standby
     namenodes might be ready to serve requests when it is set to true.
   </description>
 </property>

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSHighAvailabilityWithNFS.md

@@ -83,7 +83,7 @@ To configure HA NameNodes, you must add several configuration options to your **
 
 The order in which you set these configurations is unimportant, but the values you choose for **dfs.nameservices** and **dfs.ha.namenodes.[nameservice ID]** will determine the keys of those that follow. Thus, you should decide on these values before setting the rest of the configuration options.
 
-*   **dfs.nameservices** - the logical name for this new nameservice
+* **dfs.nameservices** - the logical name for this new nameservice
 
     Choose a logical name for this nameservice, for example "mycluster", and use
     this logical name for the value of this config option. The name you choose is
@@ -97,7 +97,7 @@ The order in which you set these configurations is unimportant, but the values y
           <value>mycluster</value>
         </property>
 
-*   **dfs.ha.namenodes.[nameservice ID]** - unique identifiers for each NameNode in the nameservice
+* **dfs.ha.namenodes.[nameservice ID]** - unique identifiers for each NameNode in the nameservice
 
     Configure with a list of comma-separated NameNode IDs. This will be used by
     DataNodes to determine all the NameNodes in the cluster. For example, if you
@@ -111,7 +111,7 @@ The order in which you set these configurations is unimportant, but the values y
 
     **Note:** The minimum number of NameNodes for HA is two, but you can configure more. Its suggested to not exceed 5 - with a recommended 3 NameNodes - due to communication overheads.
 
-*   **dfs.namenode.rpc-address.[nameservice ID].[name node ID]** - the fully-qualified RPC address for each NameNode to listen on
+* **dfs.namenode.rpc-address.[nameservice ID].[name node ID]** - the fully-qualified RPC address for each NameNode to listen on
 
     For both of the previously-configured NameNode IDs, set the full address and
     IPC port of the NameNode process. Note that this results in two separate
@@ -133,7 +133,7 @@ The order in which you set these configurations is unimportant, but the values y
     **Note:** You may similarly configure the "**servicerpc-address**" setting if
     you so desire.
 
-*   **dfs.namenode.http-address.[nameservice ID].[name node ID]** - the fully-qualified HTTP address for each NameNode to listen on
+* **dfs.namenode.http-address.[nameservice ID].[name node ID]** - the fully-qualified HTTP address for each NameNode to listen on
 
     Similarly to *rpc-address* above, set the addresses for both NameNodes' HTTP
     servers to listen on. For example:
@@ -154,7 +154,7 @@ The order in which you set these configurations is unimportant, but the values y
     **Note:** If you have Hadoop's security features enabled, you should also set
     the *https-address* similarly for each NameNode.
 
-*   **dfs.namenode.shared.edits.dir** - the location of the shared storage directory
+* **dfs.namenode.shared.edits.dir** - the location of the shared storage directory
 
     This is where one configures the path to the remote shared edits directory
     which the Standby NameNodes use to stay up-to-date with all the file system
@@ -168,7 +168,7 @@ The order in which you set these configurations is unimportant, but the values y
           <value>file:///mnt/filer1/dfs/ha-name-dir-shared</value>
         </property>
 
-*   **dfs.client.failover.proxy.provider.[nameservice ID]** - the Java class that HDFS clients use to contact the Active NameNode
+* **dfs.client.failover.proxy.provider.[nameservice ID]** - the Java class that HDFS clients use to contact the Active NameNode
 
     Configure the name of the Java class which will be used by the DFS Client to
     determine which NameNode is the current Active, and therefore which NameNode is
@@ -184,7 +184,7 @@ The order in which you set these configurations is unimportant, but the values y
           <value>org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider</value>
         </property>
 
-*   **dfs.ha.fencing.methods** - a list of scripts or Java classes which will be used to fence the Active NameNode during a failover
+* **dfs.ha.fencing.methods** - a list of scripts or Java classes which will be used to fence the Active NameNode during a failover
 
     It is critical for correctness of the system that only one NameNode be in the
     Active state at any given time. Thus, during a failover, we first ensure that
@@ -316,12 +316,14 @@ The order in which you set these configurations is unimportant, but the values y
           <value>hdfs://mycluster</value>
         </property>
 
-*   **dfs.ha.nn.not-become-active-in-safemode** - if prevent safe mode namenodes to become active
+*   **dfs.ha.nn.not-become-active-in-safemode** - if prevent safe mode namenodes to become active or observer
 
-    Whether allow namenode to become active when it is in safemode, when it is
-    set to true, namenode in safemode will report SERVICE_UNHEALTHY to ZKFC if
-    auto failover is on, or will throw exception to fail the transition to
-    active if auto failover is off. For example:
+      Whether allow namenode to become active when it is in safemode, when it is
+      set to true, namenode in safemode will report SERVICE_UNHEALTHY to ZKFC if
+      auto failover is on, or will throw exception to fail the transition to
+      active if auto failover is off. If you transition namenode to observer state 
+      when it is in safemode, when this configuration is set to true, namenode will throw exception 
+      to fail the transition to observer. For example:
 
         <property>
           <name>dfs.ha.nn.not-become-active-in-safemode</name>

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSHighAvailabilityWithQJM.md

@@ -376,12 +376,14 @@ The order in which you set these configurations is unimportant, but the values y
           <value>/path/to/journal/node/local/data</value>
         </property>
 
-*   **dfs.ha.nn.not-become-active-in-safemode** - if prevent safe mode namenodes to become active
+*   **dfs.ha.nn.not-become-active-in-safemode** - if prevent safe mode namenodes to become active or observer
 
     Whether allow namenode to become active when it is in safemode, when it is
     set to true, namenode in safemode will report SERVICE_UNHEALTHY to ZKFC if
     auto failover is on, or will throw exception to fail the transition to
-    active if auto failover is off. For example:
+    active if auto failover is off. If you transition namenode to observer state
+    when it is in safemode, when this configuration is set to true, namenode will throw exception
+    to fail the transition to observer. For example:
 
         <property>
           <name>dfs.ha.nn.not-become-active-in-safemode</name>

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestHASafeMode.java

@@ -978,20 +978,15 @@ public void testTransitionToActiveWhenSafeMode() throws Exception {
     }
   }
 
-  /**
-   * Test transition to observer when namenode in safemode.
-   *
-   * @throws IOException
-   */
   @Test
   public void testTransitionToObserverWhenSafeMode() throws Exception {
     Configuration config = new Configuration();
     config.setBoolean(DFS_HA_NN_NOT_BECOME_ACTIVE_IN_SAFEMODE, true);
     try (MiniDFSCluster miniCluster = new MiniDFSCluster.Builder(config,
-            new File(GenericTestUtils.getRandomizedTempPath()))
-            .nnTopology(MiniDFSNNTopology.simpleHATopology())
-            .numDataNodes(1)
-            .build()) {
+        new File(GenericTestUtils.getRandomizedTempPath()))
+        .nnTopology(MiniDFSNNTopology.simpleHATopology())
+        .numDataNodes(1)
+        .build()) {
       miniCluster.waitActive();
       miniCluster.transitionToStandby(0);
       miniCluster.transitionToStandby(1);
@@ -1000,8 +995,8 @@ public void testTransitionToObserverWhenSafeMode() throws Exception {
       NameNodeAdapter.enterSafeMode(namenode0, false);
       NameNodeAdapter.enterSafeMode(namenode1, false);
       LambdaTestUtils.intercept(ServiceFailedException.class,
-              "NameNode still not leave safemode",
-              () -> miniCluster.transitionToObserver(0));
+          "NameNode still not leave safemode", 
+          () -> miniCluster.transitionToObserver(0));
     }
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSHAAdminMiniCluster.java

@@ -171,17 +171,17 @@ public void testObserverIllegalTransition() throws Exception {
   @Test
   public void testObserverTransitionInSafeMode() throws Exception {
     NameNodeAdapter.enterSafeMode(cluster.getNameNode(0), false);
-    DFSHAAdmin tool = new DFSHAAdmin();
-    tool.setConf(conf);
+    DFSHAAdmin admin = new DFSHAAdmin();
+    admin.setConf(conf);
     System.setIn(new ByteArrayInputStream("yes\n".getBytes()));
-    int result = tool.run(
-            new String[]{"-transitionToObserver", "-forcemanual", "nn1"});
+    int result = admin.run(
+        new String[]{"-transitionToObserver", "-forcemanual", "nn1"});
     assertEquals("State transition returned: " + result, -1, result);
 
     NameNodeAdapter.leaveSafeMode(cluster.getNameNode(0));
     System.setIn(new ByteArrayInputStream("yes\n".getBytes()));
-    int result1 = tool.run(
-            new String[]{"-transitionToObserver", "-forcemanual", "nn1"});
+    int result1 = admin.run(
+        new String[]{"-transitionToObserver", "-forcemanual", "nn1"});
     assertEquals("State transition returned: " + result1, 0, result1);
     assertFalse(cluster.getNameNode(0).isInSafeMode());
   }