HDFS-4429. When the latest snapshot exists, INodeFileUnderConstruction should be replaced with INodeFileWithSnapshot but not INodeFile.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2802@1438304 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-2802.txt

@@ -120,3 +120,7 @@ Branch-2802 Snapshot (Unreleased)
   HDFS-4436. Change INode.recordModification(..) to return only the current
   inode and remove the updateCircularList parameter from some methods in
   INodeDirectoryWithSnapshot.Diff.  (szetszwo)
+
+  HDFS-4429. When the latest snapshot exists, INodeFileUnderConstruction should
+  be replaced with INodeFileWithSnapshot but not INodeFile.  (Jing Zhao
+  via szetszwo)

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

@@ -178,6 +178,7 @@ import org.apache.hadoop.hdfs.server.namenode.ha.StandbyCheckpointer;
 import org.apache.hadoop.hdfs.server.namenode.metrics.FSNamesystemMBean;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable;
+import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeFileUnderConstructionWithSnapshot;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeFileWithSnapshot;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.Snapshot;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager;
@@ -3294,6 +3295,21 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     assert hasWriteLock();
     leaseManager.removeLease(pendingFile.getClientName(), src);
     
+    if (latestSnapshot != null) {
+      if (!(pendingFile instanceof INodeFileUnderConstructionWithSnapshot)) {
+        // replace INodeFileUnderConstruction with
+        // INodeFileUnderConstructionWithSnapshot. This replacement does not
+        // need to be recorded in snapshot.
+        INodeFileUnderConstructionWithSnapshot pendingFileWithSnaphsot = 
+            new INodeFileUnderConstructionWithSnapshot(pendingFile);
+        dir.replaceINodeFile(src, pendingFile,
+            pendingFileWithSnaphsot, null);
+        pendingFile = pendingFileWithSnaphsot;
+      }
+      pendingFile = (INodeFileUnderConstruction) pendingFile
+          .recordModification(latestSnapshot);
+    }
+
     // The file is no longer pending.
     // Create permanent INode, update blocks
     final INodeFile newFile = pendingFile.toINodeFile(now());

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

@@ -39,6 +39,7 @@ import org.apache.hadoop.hdfs.server.namenode.snapshot.FileWithSnapshot;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectoryWithSnapshot;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeFileSnapshot;
+import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeFileUnderConstructionSnapshot;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeFileWithSnapshot;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.Snapshot;
 import org.apache.hadoop.hdfs.util.ReadOnlyList;
@@ -431,8 +432,8 @@ public abstract class INode implements Comparable<byte[]> {
 
   @VisibleForTesting
   public String getObjectString() {
-    final String s = super.toString();
-    return s.substring(s.lastIndexOf(getClass().getSimpleName()));
+    return getClass().getSimpleName() + "@"
+        + Integer.toHexString(super.hashCode());
   }
 
   @VisibleForTesting
@@ -693,15 +694,21 @@ public abstract class INode implements Comparable<byte[]> {
         String blocksInfo = ((INodeFile) this).printBlocksInfo();
         out.print(", blocks=[" + blocksInfo + "]");
       }
-      if (this instanceof INodeFileWithSnapshot) {
-        INodeFileWithSnapshot nodeWithLink = (INodeFileWithSnapshot) this;
-        FileWithSnapshot next = nodeWithLink.getNext();
-        out.print(", next="
-            + (next != null ? next.asINodeFile().getObjectString() : "null"));
-        if (this instanceof INodeFileSnapshot) {
+      if (this instanceof FileWithSnapshot) {
+        if (this instanceof INodeFileSnapshot
+            || this instanceof INodeFileUnderConstructionSnapshot) {
           out.print(", computedSize="
               + ((INodeFileSnapshot) this).computeFileSize(true));
         }
+        FileWithSnapshot nodeWithLink = (FileWithSnapshot) this;
+        FileWithSnapshot next = nodeWithLink.getNext();
+        // An INodeFileWithSnapshot whose next link pointing to itself should be
+        // equivalent with a normal INodeFile 
+        if (!(this instanceof INodeFileWithSnapshot && 
+            ((INodeFileWithSnapshot) this).getNext() == this)) {
+          out.print(", next="
+              + (next != null ? next.asINodeFile().getObjectString() : "null"));
+        }
       }
       out.println();
     } else {

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

@@ -528,7 +528,7 @@ public class INodeDirectoryWithSnapshot extends INodeDirectoryWithQuota {
       diff.deleted = deletedList;
     }
     
-    public Diff getDiff() {
+    Diff getDiff() {
       return diff;
     }
 

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

@@ -39,6 +39,20 @@ public class INodeFileUnderConstructionWithSnapshot
     super(f.asINodeFile(), clientName, clientMachine, clientNode);
   }
 
+  /**
+   * The constructor that creates an
+   * {@link INodeFileUnderConstructionWithSnapshot} based on an
+   * {@link INodeFileUnderConstruction}
+   * 
+   * @param child The given {@link INodeFileUnderConstruction} instance
+   */
+  public INodeFileUnderConstructionWithSnapshot(
+      INodeFileUnderConstruction child) {
+    super(child, child.getClientName(), child.getClientMachine(), child
+        .getClientNode());
+    next = this;
+  }
+  
   @Override
   protected INodeFileWithSnapshot toINodeFile(final long mtime) {
     assertAllBlocksComplete();
@@ -46,7 +60,8 @@ public class INodeFileUnderConstructionWithSnapshot
     final INodeFileWithSnapshot f = new INodeFileWithSnapshot(this);
     f.setModificationTime(mtime, null);
     f.setAccessTime(atime, null);
-    Util.replace(this, f);
+    // link f with this
+    this.insertBefore(f);
     return f;
   }
 

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

@@ -43,7 +43,7 @@ public class INodeFileWithSnapshot extends INodeFile
     final INodeFileUnderConstructionWithSnapshot f
         = new INodeFileUnderConstructionWithSnapshot(this,
             clientName, clientMachine, clientNode);
-    Util.replace(this, f);
+    this.insertBefore(f);
     return f;
   }
 

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

@@ -0,0 +1,240 @@
+/**
+ * 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.snapshot;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+import java.util.EnumSet;
+import java.util.Random;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataOutputStream;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.DFSTestUtil;
+import org.apache.hadoop.hdfs.DistributedFileSystem;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.client.HdfsDataOutputStream;
+import org.apache.hadoop.hdfs.client.HdfsDataOutputStream.SyncFlag;
+import org.apache.hadoop.hdfs.server.namenode.FSDirectory;
+import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
+import org.apache.hadoop.hdfs.server.namenode.INode;
+import org.apache.hadoop.hdfs.server.namenode.INodeFile;
+import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectoryWithSnapshot.Diff;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * Test snapshot functionalities while file appending.
+ */
+public class TestINodeFileUnderConstructionWithSnapshot {
+
+  static final long seed = 0;
+  static final short REPLICATION = 3;
+  static final int BLOCKSIZE = 1024;
+
+  private final Path dir = new Path("/TestSnapshot");
+  
+  Configuration conf;
+  MiniDFSCluster cluster;
+  FSNamesystem fsn;
+  DistributedFileSystem hdfs;
+  FSDirectory fsdir;
+  
+  @Before
+  public void setUp() throws Exception {
+    conf = new Configuration();
+    conf.setLong(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, BLOCKSIZE);
+    cluster = new MiniDFSCluster.Builder(conf).numDataNodes(REPLICATION)
+        .build();
+    cluster.waitActive();
+    fsn = cluster.getNamesystem();
+    fsdir = fsn.getFSDirectory();
+    hdfs = cluster.getFileSystem();
+    hdfs.mkdirs(dir);
+  }
+
+  @After
+  public void tearDown() throws Exception {
+    if (cluster != null) {
+      cluster.shutdown();
+    }
+  }
+  
+  /**
+   * Check if the given nodes can form a circular list
+   */
+  private void checkCircularList(FileWithSnapshot... nodes) {
+    for (int i = 0; i < nodes.length; i++) {
+      FileWithSnapshot next = nodes[i].getNext();
+      FileWithSnapshot expectedNext = nodes[(i + 1) % nodes.length];
+      Assert.assertTrue(next == expectedNext);
+    }
+  }
+  
+  /**
+   * Test snapshot after file appending
+   */
+  @Test
+  public void testSnapshotAfterAppending() throws Exception {
+    Path file = new Path(dir, "file");
+    // 1. create snapshot --> create file --> append
+    SnapshotTestHelper.createSnapshot(hdfs, dir, "s0");
+    DFSTestUtil.createFile(hdfs, file, BLOCKSIZE, REPLICATION, seed);
+    DFSTestUtil.appendFile(hdfs, file, BLOCKSIZE);
+    
+    // check the circular list and corresponding inodes: there should only be a
+    // reference of the current node in the created list
+    INodeFile fileNode = (INodeFile) fsdir.getINode(file.toString());
+    INodeDirectorySnapshottable dirNode = (INodeDirectorySnapshottable) fsdir
+        .getINode(dir.toString());
+    Diff diff = dirNode.getLastSnapshotDiff().getDiff();
+    INode nodeInCreated = diff.searchCreated(fileNode.getLocalNameBytes());
+    assertTrue(fileNode == nodeInCreated);
+    INode nodeInDeleted = diff.searchDeleted(fileNode.getLocalNameBytes());
+    assertNull(nodeInDeleted);
+    
+    // 2. create snapshot --> modify the file --> append
+    hdfs.createSnapshot(dir, "s1");
+    hdfs.setReplication(file, (short) (REPLICATION - 1));
+    DFSTestUtil.appendFile(hdfs, file, BLOCKSIZE);
+    
+    // check the circular list and corresponding inodes
+    diff = dirNode.getLastSnapshotDiff().getDiff();
+    fileNode = (INodeFile) fsdir.getINode(file.toString());
+    nodeInCreated = diff.searchCreated(fileNode.getLocalNameBytes());
+    assertTrue(fileNode == nodeInCreated);
+    assertEquals(REPLICATION - 1,
+        ((INodeFile) nodeInCreated).getFileReplication());
+    assertEquals(BLOCKSIZE * 3, ((INodeFile) fileNode).computeFileSize(true));
+    nodeInDeleted = diff.searchDeleted(fileNode.getLocalNameBytes());
+    assertEquals(REPLICATION,
+        ((INodeFile) nodeInDeleted).getFileReplication());
+    assertEquals(BLOCKSIZE * 2,
+        ((INodeFile) nodeInDeleted).computeFileSize(true));
+    checkCircularList((INodeFileWithSnapshot) fileNode,
+        (INodeFileSnapshot) nodeInDeleted);
+    
+    // 3. create snapshot --> append
+    hdfs.createSnapshot(dir, "s2");
+    DFSTestUtil.appendFile(hdfs, file, BLOCKSIZE);
+    
+    // check the circular list and corresponding inodes
+    diff = dirNode.getLastSnapshotDiff().getDiff();
+    fileNode = (INodeFile) fsdir.getINode(file.toString());
+    nodeInCreated = diff.searchCreated(fileNode.getLocalNameBytes());
+    assertTrue(fileNode == nodeInCreated);
+    assertEquals(REPLICATION - 1,
+        ((INodeFile) nodeInCreated).getFileReplication());
+    assertEquals(BLOCKSIZE * 4, ((INodeFile) fileNode).computeFileSize(true));
+    INode nodeInDeleted2 = diff.searchDeleted(fileNode.getLocalNameBytes());
+    assertEquals(REPLICATION - 1,
+        ((INodeFile) nodeInDeleted2).getFileReplication());
+    assertEquals(BLOCKSIZE * 3,
+        ((INodeFile) nodeInDeleted2).computeFileSize(true));
+    checkCircularList((INodeFileWithSnapshot) fileNode,
+        (INodeFileSnapshot) nodeInDeleted2, (INodeFileSnapshot) nodeInDeleted);
+  }
+  
+  private HdfsDataOutputStream appendFileWithoutClosing(Path file, int length)
+      throws IOException {
+    byte[] toAppend = new byte[length];
+    Random random = new Random();
+    random.nextBytes(toAppend);
+    HdfsDataOutputStream out = (HdfsDataOutputStream) hdfs.append(file);
+    out.write(toAppend);
+    return out;
+  }
+  
+  /**
+   * Test snapshot during file appending, before the corresponding
+   * {@link FSDataOutputStream} instance closes.
+   */
+  @Test
+  public void testSnapshotWhileAppending() throws Exception {
+    Path file = new Path(dir, "file");
+    DFSTestUtil.createFile(hdfs, file, BLOCKSIZE, REPLICATION, seed);
+    
+    // 1. append without closing stream --> create snapshot
+    HdfsDataOutputStream out = appendFileWithoutClosing(file, BLOCKSIZE);
+    out.hsync(EnumSet.of(SyncFlag.UPDATE_LENGTH));
+    SnapshotTestHelper.createSnapshot(hdfs, dir, "s0");
+    out.close();
+    
+    // check: an INodeFileUnderConstructionSnapshot should be stored into s0's
+    // deleted list, with size BLOCKSIZE*2
+    INodeFile fileNode = (INodeFile) fsdir.getINode(file.toString());
+    assertEquals(BLOCKSIZE * 2, ((INodeFile) fileNode).computeFileSize(true));
+    INodeDirectorySnapshottable dirNode = (INodeDirectorySnapshottable) fsdir
+        .getINode(dir.toString());
+    Diff diff = dirNode.getLastSnapshotDiff().getDiff();
+    INode nodeInDeleted_S0 = diff.searchDeleted(fileNode.getLocalNameBytes());
+    assertTrue(nodeInDeleted_S0 instanceof INodeFileUnderConstructionSnapshot);
+    assertEquals(BLOCKSIZE * 2,
+        ((INodeFile) nodeInDeleted_S0).computeFileSize(true));
+    
+    // 2. append without closing stream
+    out = appendFileWithoutClosing(file, BLOCKSIZE);
+    out.hsync(EnumSet.of(SyncFlag.UPDATE_LENGTH));
+    
+    // re-check nodeInDeleted_S0
+    dirNode = (INodeDirectorySnapshottable) fsdir.getINode(dir.toString());
+    diff = dirNode.getLastSnapshotDiff().getDiff();
+    nodeInDeleted_S0 = diff.searchDeleted(fileNode.getLocalNameBytes());
+    assertTrue(nodeInDeleted_S0 instanceof INodeFileUnderConstructionSnapshot);
+    assertEquals(BLOCKSIZE * 2,
+        ((INodeFile) nodeInDeleted_S0).computeFileSize(true));
+    
+    // 3. take snapshot --> close stream
+    hdfs.createSnapshot(dir, "s1");
+    out.close();
+    
+    // check: an INodeFileUnderConstructionSnapshot with size BLOCKSIZE*3 should
+    // have been stored in s1's deleted list
+    fileNode = (INodeFile) fsdir.getINode(file.toString());
+    dirNode = (INodeDirectorySnapshottable) fsdir.getINode(dir.toString());
+    diff = dirNode.getLastSnapshotDiff().getDiff();
+    INode nodeInCreated_S1 = diff.searchCreated(fileNode.getLocalNameBytes());
+    assertTrue(fileNode == nodeInCreated_S1);
+    assertTrue(fileNode instanceof INodeFileWithSnapshot);
+    INode nodeInDeleted_S1 = diff.searchDeleted(fileNode.getLocalNameBytes());
+    assertTrue(nodeInDeleted_S1 instanceof INodeFileUnderConstructionSnapshot);
+    assertEquals(BLOCKSIZE * 3,
+        ((INodeFile) nodeInDeleted_S1).computeFileSize(true));
+    // also check the circular linked list
+    checkCircularList((INodeFileWithSnapshot) fileNode,
+        (INodeFileUnderConstructionSnapshot) nodeInDeleted_S1,
+        (INodeFileUnderConstructionSnapshot) nodeInDeleted_S0);
+    
+    // 4. modify file --> append without closing stream --> take snapshot -->
+    // close stream
+    hdfs.setReplication(file, (short) (REPLICATION - 1));
+    out = appendFileWithoutClosing(file, BLOCKSIZE);
+    hdfs.createSnapshot(dir, "s2");
+    out.close();
+    
+    // re-check the size of nodeInDeleted_S1
+    assertEquals(BLOCKSIZE * 3,
+        ((INodeFile) nodeInDeleted_S1).computeFileSize(true));
+  }  
+}

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

@@ -20,6 +20,12 @@ package org.apache.hadoop.hdfs.server.namenode.snapshot;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -42,6 +48,7 @@ import org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotTestHelper.TestDi
 import org.apache.hadoop.ipc.RemoteException;
 import org.apache.hadoop.util.Time;
 import org.junit.After;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
@@ -68,6 +75,9 @@ public class TestSnapshot {
 
   private static Random random = new Random(seed);
   
+  private static String testDir =
+      System.getProperty("test.build.data", "build/test/data");
+  
   @Rule
   public ExpectedException exception = ExpectedException.none();
   
@@ -144,13 +154,23 @@ public class TestSnapshot {
     return nodes;
   }
 
+  private File getDumpTreeFile(String dir, String suffix) {
+    return new File(dir, String.format("dumptree_%s", suffix));
+  }
+  
   /**
    * Restart the cluster to check edit log applying and fsimage saving/loading
    */
   private void checkFSImage() throws Exception {
+    File fsnBefore = getDumpTreeFile(testDir, "before");
+    File fsnMiddle = getDumpTreeFile(testDir, "middle");
+    File fsnAfter = getDumpTreeFile(testDir, "after");
+    
     String rootDir = "/";
-    StringBuffer fsnStrBefore = fsn.getFSDirectory().getINode(rootDir)
-        .dumpTreeRecursively();
+    PrintWriter out = new PrintWriter(new FileWriter(fsnBefore, false), true);
+    fsn.getFSDirectory().getINode(rootDir)
+        .dumpTreeRecursively(out, new StringBuilder(), null);
+    out.close();
     
     cluster.shutdown();
     cluster = new MiniDFSCluster.Builder(conf).format(false)
@@ -158,10 +178,12 @@ public class TestSnapshot {
     cluster.waitActive();
     fsn = cluster.getNamesystem();
     hdfs = cluster.getFileSystem();
-    // later check fsnStrMiddle to see if the edit log is recorded and applied
+    // later check fsnMiddle to see if the edit log is recorded and applied
     // correctly 
-    StringBuffer fsnStrMiddle = fsn.getFSDirectory().getINode(rootDir)
-        .dumpTreeRecursively();
+    out = new PrintWriter(new FileWriter(fsnMiddle, false), true);
+    fsn.getFSDirectory().getINode(rootDir)
+        .dumpTreeRecursively(out, new StringBuilder(), null);
+    out.close();
    
     // save namespace and restart cluster
     hdfs.setSafeMode(SafeModeAction.SAFEMODE_ENTER);
@@ -174,18 +196,38 @@ public class TestSnapshot {
     fsn = cluster.getNamesystem();
     hdfs = cluster.getFileSystem();
     // dump the namespace loaded from fsimage
-    StringBuffer fsnStrAfter = fsn.getFSDirectory().getINode(rootDir)
-        .dumpTreeRecursively();
+    out = new PrintWriter(new FileWriter(fsnAfter, false), true);
+    fsn.getFSDirectory().getINode(rootDir)
+        .dumpTreeRecursively(out, new StringBuilder(), null);
+    out.close();
     
-    System.out.println("================== Original FSDir ==================");
-    System.out.println(fsnStrBefore.toString());
-    System.out.println("================== FSDir After Applying Edit Logs ==================");
-    System.out.println(fsnStrMiddle.toString());
-    System.out.println("================ FSDir After FSImage Saving/Loading ================");
-    System.out.println(fsnStrAfter.toString());
-    System.out.println("====================================================");
-    assertEquals(fsnStrBefore.toString(), fsnStrMiddle.toString());
-    assertEquals(fsnStrBefore.toString(), fsnStrAfter.toString());
+    compareFile(fsnBefore, fsnMiddle);
+    compareFile(fsnBefore, fsnAfter);
+  }
+  
+  /** compare two file's content */
+  private void compareFile(File file1, File file2) throws IOException {
+    BufferedReader reader1 = new BufferedReader(new FileReader(file1));
+    BufferedReader reader2 = new BufferedReader(new FileReader(file2));
+    try {
+      String line1 = "";
+      String line2 = "";
+      while ((line1 = reader1.readLine()) != null
+          && (line2 = reader2.readLine()) != null) {
+        // skip the hashCode part of the object string during the comparison,
+        // also ignore the difference between INodeFile/INodeFileWithSnapshot
+        line1 = line1.replaceAll("INodeFileWithSnapshot", "INodeFile");
+        line2 = line2.replaceAll("INodeFileWithSnapshot", "INodeFile");
+        line1 = line1.replaceAll("@[\\dabcdef]+", "");
+        line2 = line2.replaceAll("@[\\dabcdef]+", "");
+        assertEquals(line1, line2);
+      }
+      Assert.assertNull(reader1.readLine());
+      Assert.assertNull(reader2.readLine());
+    } finally {
+      reader1.close();
+      reader2.close();
+    }
   }
   
   /**