From fdf7b182475050aaf67765eb53aaf342ebaebe8b Mon Sep 17 00:00:00 2001
From: Eli Collins <eli@apache.org>
Date: Thu, 26 Jan 2012 23:48:08 +0000
Subject: [PATCH] HDFS-2838. NPE in FSNamesystem when in safe mode. Contributed
 by Gregory Chanan

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-1623@1236450 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hadoop-hdfs/CHANGES.HDFS-1623.txt         |  2 ++
 .../hdfs/server/namenode/FSNamesystem.java    |  3 +--
 .../hadoop/hdfs/TestMiniDFSCluster.java       | 20 ++++++++++++++++++-
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-1623.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-1623.txt
index bf685c91cf2..c8a760336a9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-1623.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-1623.txt
@@ -131,3 +131,5 @@ HDFS-2804. Should not mark blocks under-replicated when exiting safemode (todd)
 HDFS-2807. Service level authorizartion for HAServiceProtocol. (jitendra)
 
 HDFS-2809. Add test to verify that delegation tokens are honored after failover. (jitendra and atm)
+
+HDFS-2838. NPE in FSNamesystem when in safe mode. (Gregory Chanan via eli)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
index 85ae12d4bd0..b3b3dbdaf31 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
@@ -3623,11 +3623,10 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       assert assertsOn = true; // set to true if asserts are on
       if (!assertsOn) return;
       
-      
-      int activeBlocks = blockManager.getActiveBlockCount();
       if (blockTotal == -1 && blockSafe == -1) {
         return; // manual safe mode
       }
+      int activeBlocks = blockManager.getActiveBlockCount();
       if ((blockTotal != activeBlocks) &&
           !(blockSafe >= 0 && blockSafe <= blockTotal)) {
         throw new AssertionError(
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestMiniDFSCluster.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestMiniDFSCluster.java
index 5a3524495b4..0eec0d18774 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestMiniDFSCluster.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestMiniDFSCluster.java
@@ -20,6 +20,7 @@ package org.apache.hadoop.hdfs;
 
 import junit.framework.Assert;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.protocol.FSConstants;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -37,6 +38,7 @@ public class TestMiniDFSCluster {
   private static final String CLUSTER_1 = "cluster1";
   private static final String CLUSTER_2 = "cluster2";
   private static final String CLUSTER_3 = "cluster3";
+  private static final String CLUSTER_4 = "cluster4";
   protected String testDataPath;
   protected File testDataDir;
   @Before
@@ -104,5 +106,21 @@ public class TestMiniDFSCluster {
     }
   }
 
-
+  @Test(timeout=100000)
+  public void testIsClusterUpAfterShutdown() throws Throwable {
+    Configuration conf = new HdfsConfiguration();
+    File testDataCluster4 = new File(testDataPath, CLUSTER_4);
+    String c4Path = testDataCluster4.getAbsolutePath();
+    conf.set(MiniDFSCluster.HDFS_MINIDFS_BASEDIR, c4Path);
+    MiniDFSCluster cluster4 = new MiniDFSCluster.Builder(conf).build();
+    try {
+      DistributedFileSystem dfs = (DistributedFileSystem) cluster4.getFileSystem();
+      dfs.setSafeMode(FSConstants.SafeModeAction.SAFEMODE_ENTER);
+      cluster4.shutdown();
+    } finally {
+      while(cluster4.isClusterUp()){
+        Thread.sleep(1000);
+      }  
+    }
+  }
 }