From 193f11a7ab539c360ecd9f2015c0f46cd070a875 Mon Sep 17 00:00:00 2001
From: Chris Nauroth <cnauroth@apache.org>
Date: Sat, 12 Apr 2014 21:38:35 +0000
Subject: [PATCH] HDFS-6236. ImageServlet should use Time#monotonicNow to
 measure latency. Contributed by Chris Nauroth.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1586902 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt        |  3 +++
 .../hadoop/hdfs/server/namenode/ImageServlet.java  | 14 +++++++-------
 .../hdfs/server/namenode/TestCheckpoint.java       |  7 ++++++-
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 04feab0801f..2bd7abd3b11 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -387,6 +387,9 @@ Release 2.4.1 - UNRELEASED
     HDFS-6232. OfflineEditsViewer throws a NPE on edits containing ACL
     modifications (ajisakaa via cmccabe)
 
+    HDFS-6236. ImageServlet should use Time#monotonicNow to measure latency.
+    (cnauroth)
+
 Release 2.4.0 - 2014-04-07 
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ImageServlet.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ImageServlet.java
index fb765680f5c..d406a15118a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ImageServlet.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ImageServlet.java
@@ -17,7 +17,7 @@
  */
 package org.apache.hadoop.hdfs.server.namenode;
 
-import static org.apache.hadoop.util.Time.now;
+import static org.apache.hadoop.util.Time.monotonicNow;
 
 import java.net.HttpURLConnection;
 import java.security.PrivilegedExceptionAction;
@@ -116,11 +116,11 @@ public class ImageServlet extends HttpServlet {
               throw new IOException(errorMessage);
             }
             CheckpointFaultInjector.getInstance().beforeGetImageSetsHeaders();
-            long start = now();
+            long start = monotonicNow();
             serveFile(imageFile);
 
             if (metrics != null) { // Metrics non-null only when used inside name node
-              long elapsed = now() - start;
+              long elapsed = monotonicNow() - start;
               metrics.addGetImage(elapsed);
             }
           } else if (parsedParams.isGetEdit()) {
@@ -129,11 +129,11 @@ public class ImageServlet extends HttpServlet {
             
             File editFile = nnImage.getStorage()
                 .findFinalizedEditsFile(startTxId, endTxId);
-            long start = now();
+            long start = monotonicNow();
             serveFile(editFile);
 
             if (metrics != null) { // Metrics non-null only when used inside name node
-              long elapsed = now() - start;
+              long elapsed = monotonicNow() - start;
               metrics.addGetEdit(elapsed);
             }
           }
@@ -469,7 +469,7 @@ public class ImageServlet extends HttpServlet {
 
                 InputStream stream = request.getInputStream();
                 try {
-                  long start = now();
+                  long start = monotonicNow();
                   MD5Hash downloadImageDigest = TransferFsImage
                       .handleUploadImageRequest(request, txid,
                           nnImage.getStorage(), stream,
@@ -478,7 +478,7 @@ public class ImageServlet extends HttpServlet {
                       downloadImageDigest);
                   // Metrics non-null only when used inside name node
                   if (metrics != null) {
-                    long elapsed = now() - start;
+                    long elapsed = monotonicNow() - start;
                     metrics.addPutImage(elapsed);
                   }
                   // Now that we have a new checkpoint, we might be able to
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java
index 73e837734a4..14d8edf2027 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java
@@ -1897,7 +1897,12 @@ public class TestCheckpoint {
           .format(true).build();
       int origPort = cluster.getNameNodePort();
       int origHttpPort = cluster.getNameNode().getHttpAddress().getPort();
-      secondary = startSecondaryNameNode(conf);
+      Configuration snnConf = new Configuration(conf);
+      File checkpointDir = new File(MiniDFSCluster.getBaseDirectory(),
+        "namesecondary");
+      snnConf.set(DFSConfigKeys.DFS_NAMENODE_CHECKPOINT_DIR_KEY,
+        checkpointDir.getAbsolutePath());
+      secondary = startSecondaryNameNode(snnConf);
 
       // secondary checkpoints once
       secondary.doCheckpoint();