HDFS-8860. Remove unused Replica copyOnWrite code (Lei (Eddy) Xu via Colin P. McCabe)

(cherry picked from commit a153b9601a)

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

@@ -555,6 +555,8 @@ Release 2.8.0 - UNRELEASED
     HDFS-9019. Adding informative message to sticky bit permission denied
     exception. (xyao)
 
+    HDFS-8860. Remove unused Replica copyOnWrite code (Lei (Eddy) Xu via Colin P. McCabe)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FinalizedReplica.java

@@ -27,7 +27,6 @@ import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeSpi;
  * This class describes a replica that has been finalized.
  */
 public class FinalizedReplica extends ReplicaInfo {
-  private boolean unlinked;      // copy-on-write done for block
 
   /**
    * Constructor
@@ -58,7 +57,6 @@ public class FinalizedReplica extends ReplicaInfo {
    */
   public FinalizedReplica(FinalizedReplica from) {
     super(from);
-    this.unlinked = from.isUnlinked();
   }
 
   @Override  // ReplicaInfo
@@ -66,16 +64,6 @@ public class FinalizedReplica extends ReplicaInfo {
     return ReplicaState.FINALIZED;
   }
   
-  @Override // ReplicaInfo
-  public boolean isUnlinked() {
-    return unlinked;
-  }
-
-  @Override  // ReplicaInfo
-  public void setUnlinked() {
-    unlinked = true;
-  }
-  
   @Override
   public long getVisibleLength() {
     return getNumBytes();       // all bytes are visible
@@ -98,7 +86,6 @@ public class FinalizedReplica extends ReplicaInfo {
   
   @Override
   public String toString() {
-    return super.toString()
+    return super.toString();
-        + "\n  unlinked          =" + unlinked;
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/ReplicaInfo.java

@@ -196,22 +196,6 @@ abstract public class ReplicaInfo extends Block implements Replica {
     return new ReplicaDirInfo(currentDir.getAbsolutePath(), hasSubdirs);
   }
 
-  /**
-   * check if this replica has already been unlinked.
-   * @return true if the replica has already been unlinked 
-   *         or no need to be detached; false otherwise
-   */
-  public boolean isUnlinked() {
-    return true;                // no need to be unlinked
-  }
-
-  /**
-   * set that this replica is unlinked
-   */
-  public void setUnlinked() {
-    // no need to be unlinked
-  }
-
   /**
    * Number of bytes reserved for this replica on disk.
    */
@@ -229,72 +213,6 @@ abstract public class ReplicaInfo extends Block implements Replica {
     return 0;
   }
 
-   /**
-   * Copy specified file into a temporary file. Then rename the
-   * temporary file to the original name. This will cause any
-   * hardlinks to the original file to be removed. The temporary
-   * files are created in the same directory. The temporary files will
-   * be recovered (especially on Windows) on datanode restart.
-   */
-  private void unlinkFile(File file, Block b) throws IOException {
-    File tmpFile = DatanodeUtil.createTmpFile(b, DatanodeUtil.getUnlinkTmpFile(file));
-    try {
-      FileInputStream in = new FileInputStream(file);
-      try {
-        FileOutputStream out = new FileOutputStream(tmpFile);
-        try {
-          IOUtils.copyBytes(in, out, 16*1024);
-        } finally {
-          out.close();
-        }
-      } finally {
-        in.close();
-      }
-      if (file.length() != tmpFile.length()) {
-        throw new IOException("Copy of file " + file + " size " + file.length()+
-                              " into file " + tmpFile +
-                              " resulted in a size of " + tmpFile.length());
-      }
-      FileUtil.replaceFile(tmpFile, file);
-    } catch (IOException e) {
-      boolean done = tmpFile.delete();
-      if (!done) {
-        DataNode.LOG.info("detachFile failed to delete temporary file " +
-                          tmpFile);
-      }
-      throw e;
-    }
-  }
-
-  /**
-   * Remove a hard link by copying the block to a temporary place and 
-   * then moving it back
-   * @param numLinks number of hard links
-   * @return true if copy is successful; 
-   *         false if it is already detached or no need to be detached
-   * @throws IOException if there is any copy error
-   */
-  public boolean unlinkBlock(int numLinks) throws IOException {
-    if (isUnlinked()) {
-      return false;
-    }
-    File file = getBlockFile();
-    if (file == null || getVolume() == null) {
-      throw new IOException("detachBlock:Block not found. " + this);
-    }
-    File meta = getMetaFile();
-
-    if (HardLink.getLinkCount(file) > numLinks) {
-      DataNode.LOG.info("CopyOnWrite for block " + this);
-      unlinkFile(file, this);
-    }
-    if (HardLink.getLinkCount(meta) > numLinks) {
-      unlinkFile(meta, this);
-    }
-    setUnlinked();
-    return true;
-  }
-
   @Override  //Object
   public String toString() {
     return getClass().getSimpleName()

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/ReplicaUnderRecovery.java

@@ -86,16 +86,6 @@ public class ReplicaUnderRecovery extends ReplicaInfo {
     return original;
   }
   
-  @Override //ReplicaInfo
-  public boolean isUnlinked() {
-    return original.isUnlinked();
-  }
-
-  @Override //ReplicaInfo
-  public void setUnlinked() {
-    original.setUnlinked();
-  }
-  
   @Override //ReplicaInfo
   public ReplicaState getState() {
     return ReplicaState.RUR;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/ReplicaWaitingToBeRecovered.java

@@ -33,7 +33,6 @@ import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeSpi;
  * lease recovery.
  */
 public class ReplicaWaitingToBeRecovered extends ReplicaInfo {
-  private boolean unlinked;      // copy-on-write done for block
 
   /**
    * Constructor
@@ -64,7 +63,6 @@ public class ReplicaWaitingToBeRecovered extends ReplicaInfo {
    */
   public ReplicaWaitingToBeRecovered(ReplicaWaitingToBeRecovered from) {
     super(from);
-    this.unlinked = from.isUnlinked();
   }
 
   @Override //ReplicaInfo
@@ -72,16 +70,6 @@ public class ReplicaWaitingToBeRecovered extends ReplicaInfo {
     return ReplicaState.RWR;
   }
   
-  @Override //ReplicaInfo
-  public boolean isUnlinked() {
-    return unlinked;
-  }
-
-  @Override //ReplicaInfo
-  public void setUnlinked() {
-    unlinked = true;
-  }
-  
   @Override //ReplicaInfo
   public long getVisibleLength() {
     return -1;  //no bytes are visible
@@ -104,7 +92,6 @@ public class ReplicaWaitingToBeRecovered extends ReplicaInfo {
 
   @Override
   public String toString() {
-    return super.toString()
+    return super.toString();
-        + "\n  unlinked=" + unlinked;
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java

@@ -1114,8 +1114,6 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
       throws IOException {
     // If the block is cached, start uncaching it.
     cacheManager.uncacheBlock(bpid, replicaInfo.getBlockId());
-    // unlink the finalized replica
-    replicaInfo.unlinkBlock(1);
     
     // construct a RBW replica with the new GS
     File blkfile = replicaInfo.getBlockFile();
@@ -2485,7 +2483,6 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
           + ", rur=" + rur);
     }
     if (rur.getNumBytes() > newlength) {
-      rur.unlinkBlock(1);
       truncateBlock(blockFile, metaFile, rur.getNumBytes(), newlength);
       if(!copyOnTruncate) {
         // update RUR with the new length

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileAppend.java

@@ -109,78 +109,6 @@ public class TestFileAppend{
         expected, "Read 1", false);
   }
 
-  /**
-   * Test that copy on write for blocks works correctly
-   * @throws IOException an exception might be thrown
-   */
-  @Test
-  public void testCopyOnWrite() throws IOException {
-    Configuration conf = new HdfsConfiguration();
-    if (simulatedStorage) {
-      SimulatedFSDataset.setFactory(conf);
-    }
-    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).build();
-    FileSystem fs = cluster.getFileSystem();
-    InetSocketAddress addr = new InetSocketAddress("localhost",
-                                                   cluster.getNameNodePort());
-    DFSClient client = new DFSClient(addr, conf);
-    try {
-
-      // create a new file, write to it and close it.
-      //
-      Path file1 = new Path("/filestatus.dat");
-      FSDataOutputStream stm = AppendTestUtil.createFile(fs, file1, 1);
-      writeFile(stm);
-      stm.close();
-
-      // Get a handle to the datanode
-      DataNode[] dn = cluster.listDataNodes();
-      assertTrue("There should be only one datanode but found " + dn.length,
-                  dn.length == 1);
-
-      LocatedBlocks locations = client.getNamenode().getBlockLocations(
-                                  file1.toString(), 0, Long.MAX_VALUE);
-      List<LocatedBlock> blocks = locations.getLocatedBlocks();
-
-      //
-      // Create hard links for a few of the blocks
-      //
-      for (int i = 0; i < blocks.size(); i = i + 2) {
-        ExtendedBlock b = blocks.get(i).getBlock();
-        final File f = DataNodeTestUtils.getFile(dn[0],
-            b.getBlockPoolId(), b.getLocalBlock().getBlockId());
-        File link = new File(f.toString() + ".link");
-        System.out.println("Creating hardlink for File " + f + " to " + link);
-        HardLink.createHardLink(f, link);
-      }
-
-      //
-      // Detach all blocks. This should remove hardlinks (if any)
-      //
-      for (int i = 0; i < blocks.size(); i++) {
-        ExtendedBlock b = blocks.get(i).getBlock();
-        System.out.println("testCopyOnWrite detaching block " + b);
-        assertTrue("Detaching block " + b + " should have returned true",
-            DataNodeTestUtils.unlinkBlock(dn[0], b, 1));
-      }
-
-      // Since the blocks were already detached earlier, these calls should
-      // return false
-      //
-      for (int i = 0; i < blocks.size(); i++) {
-        ExtendedBlock b = blocks.get(i).getBlock();
-        System.out.println("testCopyOnWrite detaching block " + b);
-        assertTrue("Detaching block " + b + " should have returned false",
-            !DataNodeTestUtils.unlinkBlock(dn[0], b, 1));
-      }
-
-    } finally {
-      client.close();
-      fs.close();
-      cluster.shutdown();
-    }
-  }
-
   /**
    * Test a simple flush on a simple HDFS file.
    * @throws IOException an exception might be thrown

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/DataNodeTestUtils.java

@@ -152,11 +152,6 @@ public class DataNodeTestUtils {
     return FsDatasetTestUtil.getMetaFile(dn.getFSDataset(), bpid, b);
   }
 
-  public static boolean unlinkBlock(DataNode dn, ExtendedBlock bk, int numLinks
-      ) throws IOException {
-    return FsDatasetTestUtil.unlinkBlock(dn.getFSDataset(), bk, numLinks);
-  }
-
   public static long getPendingAsyncDeletions(DataNode dn) {
     return FsDatasetTestUtil.getPendingAsyncDeletions(dn.getFSDataset());
   }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetTestUtil.java

@@ -55,12 +55,6 @@ public class FsDatasetTestUtil {
         .getGenerationStamp());
   }
 
-  public static boolean unlinkBlock(FsDatasetSpi<?> fsd,
-      ExtendedBlock block, int numLinks) throws IOException {
-    final ReplicaInfo info = ((FsDatasetImpl)fsd).getReplicaInfo(block);
-    return info.unlinkBlock(numLinks);
-  }
-
   public static ReplicaInfo fetchReplicaInfo (final FsDatasetSpi<?> fsd,
       final String bpid, final long blockId) {
     return ((FsDatasetImpl)fsd).fetchReplicaInfo(bpid, blockId);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/TestDatanodeRestart.java

@@ -143,79 +143,7 @@ public class TestDatanodeRestart {
     }      
   }
 
-  // test recovering unlinked tmp replicas
-  @Test public void testRecoverReplicas() throws Exception {
-    Configuration conf = new HdfsConfiguration();
-    conf.setLong(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, 1024L);
-    conf.setInt(HdfsClientConfigKeys.DFS_CLIENT_WRITE_PACKET_SIZE_KEY, 512);
-    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).build();
-    cluster.waitActive();
-    try {
-      FileSystem fs = cluster.getFileSystem();
-      for (int i=0; i<4; i++) {
-        Path fileName = new Path("/test"+i);
-        DFSTestUtil.createFile(fs, fileName, 1, (short)1, 0L);
-        DFSTestUtil.waitReplication(fs, fileName, (short)1);
-      }
-      String bpid = cluster.getNamesystem().getBlockPoolId();
-      DataNode dn = cluster.getDataNodes().get(0);
-      Iterator<ReplicaInfo> replicasItor = 
-          dataset(dn).volumeMap.replicas(bpid).iterator();
-      ReplicaInfo replica = replicasItor.next();
-      createUnlinkTmpFile(replica, true, true); // rename block file
-      createUnlinkTmpFile(replica, false, true); // rename meta file
-      replica = replicasItor.next();
-      createUnlinkTmpFile(replica, true, false); // copy block file
-      createUnlinkTmpFile(replica, false, false); // copy meta file
-      replica = replicasItor.next();
-      createUnlinkTmpFile(replica, true, true); // rename block file
-      createUnlinkTmpFile(replica, false, false); // copy meta file
-
-      cluster.restartDataNodes();
-      cluster.waitActive();
-      dn = cluster.getDataNodes().get(0);
-
-      // check volumeMap: 4 finalized replica
-      Collection<ReplicaInfo> replicas = dataset(dn).volumeMap.replicas(bpid);
-      Assert.assertEquals(4, replicas.size());
-      replicasItor = replicas.iterator();
-      while (replicasItor.hasNext()) {
-        Assert.assertEquals(ReplicaState.FINALIZED, 
-            replicasItor.next().getState());
-      }
-    } finally {
-      cluster.shutdown();
-    }
-  }
-
   private static FsDatasetImpl dataset(DataNode dn) {
     return (FsDatasetImpl)DataNodeTestUtils.getFSDataset(dn);
   }
-
-  private static void createUnlinkTmpFile(ReplicaInfo replicaInfo, 
-      boolean changeBlockFile, 
-      boolean isRename) throws IOException {
-    File src;
-    if (changeBlockFile) {
-      src = replicaInfo.getBlockFile();
-    } else {
-      src = replicaInfo.getMetaFile();
-    }
-    File dst = DatanodeUtil.getUnlinkTmpFile(src);
-    if (isRename) {
-      src.renameTo(dst);
-    } else {
-      FileInputStream in = new FileInputStream(src);
-      try {
-        FileOutputStream out = new FileOutputStream(dst);
-        try {
-          IOUtils.copyBytes(in, out, 1);
-        } finally {
-          out.close();
-        }
-      } finally {
-        in.close();
-      }
-    }
-  }
 }