HDFS-4096. Merge change r1523091 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1523092 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -34,6 +34,9 @@ Release 2.3.0 - UNRELEASED
     HDFS-4879. Add "blocked ArrayList" collection to avoid CMS full GCs
     (Todd Lipcon via Colin Patrick McCabe)
 
+    HDFS-4096. Add snapshot information to namenode WebUI. (Haohui Mai via 
+    jing9)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -4182,6 +4182,15 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     return this.snapshotManager.getNumSnapshots();
   }
 
+  @Override
+  public String getSnapshotStats() {
+    Map<String, Object> info = new HashMap<String, Object>();
+    info.put("SnapshottableDirectories", this.getNumSnapshottableDirs());
+    info.put("Snapshots", this.getNumSnapshots());
+    return JSON.toString(info);
+  }
+
+
   int getNumberOfDatanodes(DatanodeReportType type) {
     readLock();
     try {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NamenodeJspHelper.java

@@ -203,6 +203,17 @@ class NamenodeJspHelper {
     return "";
   }
 
+  static void generateSnapshotReport(JspWriter out, FSNamesystem fsn)
+      throws IOException {
+    out.println("<div id=\"snapshotstats\"><div class=\"dfstable\">"
+        + "<table class=\"storage\" title=\"Snapshot Summary\">\n"
+        + "<thead><tr><td><b>Snapshottable directories</b></td>"
+        + "<td><b>Snapshotted directories</b></td></tr></thead>");
+
+    out.println(String.format("<td>%d</td><td>%d</td>", fsn.getNumSnapshottableDirs(), fsn.getNumSnapshots()));
+    out.println("</table></div></div>");
+  }
+
   static class HealthJsp {
     private int rowNum = 0;
     private int colNum = 0;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/metrics/FSNamesystemMBean.java

@@ -130,4 +130,9 @@ public interface FSNamesystemMBean {
    * @return number of decommissioned dead data nodes
    */
   public int getNumDecomDeadDataNodes();
+
+  /**
+   * The statistics of snapshots
+   */
+  public String getSnapshotStats();
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/webapps/hdfs/dfshealth.jsp

@@ -73,7 +73,10 @@
 <% healthjsp.generateJournalReport(out, nn, request); %>
 <hr/>
 <% healthjsp.generateConfReport(out, nn, request); %>
-<hr>
+<hr/>
+<h3>Snapshot Summary</h3>
+<% NamenodeJspHelper.generateSnapshotReport(out, fsn); %>
+<hr/>
 <h3>Startup Progress</h3>
 <% healthjsp.generateStartupProgress(out, nn.getStartupProgress()); %>
 <%

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

@@ -0,0 +1,72 @@
+/**
+ * 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.namenode;
+
+import static org.junit.Assert.assertTrue;
+
+import java.lang.management.ManagementFactory;
+import java.util.Map;
+
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.junit.Test;
+import org.mortbay.util.ajax.JSON;
+
+/**
+ * Class for testing {@link NameNodeMXBean} implementation
+ */
+public class TestFSNamesystemMBean {
+
+  @Test
+  public void test() throws Exception {
+    Configuration conf = new Configuration();
+    MiniDFSCluster cluster = null;
+
+    try {
+      cluster = new MiniDFSCluster.Builder(conf).build();
+      cluster.waitActive();
+
+      FSNamesystem fsn = cluster.getNameNode().namesystem;
+
+      MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
+      ObjectName mxbeanName = new ObjectName(
+          "Hadoop:service=NameNode,name=FSNamesystemState");
+
+      String snapshotStats = (String) (mbs.getAttribute(mxbeanName,
+          "SnapshotStats"));
+
+      @SuppressWarnings("unchecked")
+      Map<String, Object> stat = (Map<String, Object>) JSON
+          .parse(snapshotStats);
+
+      assertTrue(stat.containsKey("SnapshottableDirectories")
+          && (Long) stat.get("SnapshottableDirectories") == fsn
+              .getNumSnapshottableDirs());
+      assertTrue(stat.containsKey("Snapshots")
+          && (Long) stat.get("Snapshots") == fsn.getNumSnapshots());
+
+    } finally {
+      if (cluster != null) {
+        cluster.shutdown();
+      }
+    }
+  }
+}