svn merge -c 1293716 from branch-1 for HDFS-2978.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0@1300347 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -7,6 +7,8 @@ Release 1.0.2 - unreleased
     HADOOP-7206. Support Snappy compression. (Issei Yoshida and
     Alejandro Abdelnur via vinodkv).
 
+    HDFS-2978. The NameNode should expose name dir statuses via JMX. (atm)
+
   IMPROVEMENTS
 
     MAPREDUCE-3773. Add queue metrics with buckets for job run times. (omalley

src/hdfs/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -83,6 +83,8 @@ import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSecretMan
 import org.apache.hadoop.hdfs.server.common.GenerationStamp;
 import org.apache.hadoop.hdfs.server.common.HdfsConstants;
 import org.apache.hadoop.hdfs.server.common.HdfsConstants.StartupOption;
+import org.apache.hadoop.hdfs.server.common.Storage.StorageDirType;
+import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.UpgradeStatusReport;
 import org.apache.hadoop.hdfs.server.namenode.BlocksMap.BlockInfo;
@@ -5794,6 +5796,30 @@ public class FSNamesystem implements FSConstants, FSNamesystemMBean,
     return JSON.toString(info);
   }
 
+  @Override  // NameNodeMXBean
+  public String getNameDirStatuses() {
+    Map<String, Map<File, StorageDirType>> statusMap =
+      new HashMap<String, Map<File, StorageDirType>>();
+    
+    Map<File, StorageDirType> activeDirs = new HashMap<File, StorageDirType>();
+    for (Iterator<StorageDirectory> it
+        = getFSImage().dirIterator(); it.hasNext();) {
+      StorageDirectory st = it.next();
+      activeDirs.put(st.getRoot(), st.getStorageDirType());
+    }
+    statusMap.put("active", activeDirs);
+    
+    List<Storage.StorageDirectory> removedStorageDirs
+        = getFSImage().getRemovedStorageDirs();
+    Map<File, StorageDirType> failedDirs = new HashMap<File, StorageDirType>();
+    for (StorageDirectory st : removedStorageDirs) {
+      failedDirs.put(st.getRoot(), st.getStorageDirType());
+    }
+    statusMap.put("failed", failedDirs);
+    
+    return JSON.toString(statusMap);
+  }
+
   private long getLastContact(DatanodeDescriptor alivenode) {
     return (System.currentTimeMillis() - alivenode.getLastUpdate())/1000;
   }

src/hdfs/org/apache/hadoop/hdfs/server/namenode/NameNodeMXBean.java

@@ -135,4 +135,12 @@ public interface NameNodeMXBean {
    * @return the decommissioning node information
    */
   public String getDecomNodes();
+
+  /**
+   * Get status information about the directories storing image and edits logs
+   * of the NN.
+   * 
+   * @return the name dir status information, as a JSON string.
+   */
+  public String getNameDirStatuses();
 }

src/test/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMXBean.java

@@ -17,23 +17,32 @@
  */
 package org.apache.hadoop.hdfs.server.namenode;
 
+import static org.junit.Assert.*;
+
+import java.io.File;
 import java.lang.management.ManagementFactory;
+import java.util.Collection;
+import java.util.Map;
 
 import javax.management.MBeanServer;
 import javax.management.ObjectName;
 
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
 import org.apache.hadoop.util.VersionInfo;
 
 import org.junit.Test;
+import org.mortbay.util.ajax.JSON;
+
 import junit.framework.Assert;
 
 /**
  * Class for testing {@link NameNodeMXBean} implementation
  */
 public class TestNameNodeMXBean {
+  @SuppressWarnings({ "unchecked", "deprecation" })
   @Test
   public void testNameNodeMXBeanInfo() throws Exception {
     Configuration conf = new Configuration();
@@ -84,8 +93,44 @@ public class TestNameNodeMXBean {
       String deadnodeinfo = (String) (mbs.getAttribute(mxbeanName,
           "DeadNodes"));
       Assert.assertEquals(fsn.getDeadNodes(), deadnodeinfo);
+      // get attribute NameDirStatuses
+      String nameDirStatuses = (String) (mbs.getAttribute(mxbeanName,
+          "NameDirStatuses"));
+      Assert.assertEquals(fsn.getNameDirStatuses(), nameDirStatuses);
+      Map<String, Map<String, String>> statusMap =
+        (Map<String, Map<String, String>>) JSON.parse(nameDirStatuses);
+      Collection<File> nameDirs = cluster.getNameDirs();
+      for (File nameDir : nameDirs) {
+        System.out.println("Checking for the presence of " + nameDir +
+            " in active name dirs.");
+        assertTrue(statusMap.get("active").containsKey(nameDir.getAbsolutePath()));
+      }
+      assertEquals(2, statusMap.get("active").size());
+      assertEquals(0, statusMap.get("failed").size());
+      
+      // This will cause the first dir to fail.
+      File failedNameDir = nameDirs.toArray(new File[0])[0];
+      assertEquals(0, FileUtil.chmod(failedNameDir.getAbsolutePath(), "000"));
+      cluster.getNameNode().rollEditLog();
+      
+      nameDirStatuses = (String) (mbs.getAttribute(mxbeanName,
+          "NameDirStatuses"));
+      statusMap = (Map<String, Map<String, String>>) JSON.parse(nameDirStatuses);
+      for (File nameDir : nameDirs) {
+        String expectedStatus =
+            nameDir.equals(failedNameDir) ? "failed" : "active";
+        System.out.println("Checking for the presence of " + nameDir +
+            " in " + expectedStatus + " name dirs.");
+        assertTrue(statusMap.get(expectedStatus).containsKey(
+            nameDir.getAbsolutePath()));
+      }
+      assertEquals(1, statusMap.get("active").size());
+      assertEquals(1, statusMap.get("failed").size());
     } finally {
       if (cluster != null) {
+        for (File dir : cluster.getNameDirs()) {
+          FileUtil.chmod(dir.toString(), "700");
+        }
         cluster.shutdown();
       }
     }