HDFS-4079. Add SnapshotManager which maintains a list for all the snapshottable directories and supports snapshot methods such as setting a directory to snapshottable and creating a snapshot.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2802@1400728 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -14,3 +14,7 @@ Branch-2802 Snapshot (Unreleased)
 
   HDFS-4087. Protocol changes for listSnapshots functionality.
   (Brandon Li via suresh)
+
+  HDFS-4079. Add SnapshotManager which maintains a list for all the
+  snapshottable directories and supports snapshot methods such as setting a
+  directory to snapshottable and creating a snapshot.  (szetszwo)

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

@@ -1304,7 +1304,7 @@ public class FSDirectory implements Closeable {
   /**
    * Get {@link INode} associated with the file / directory.
    */
-  INode getINode(String src) throws UnresolvedLinkException {
+  public INode getINode(String src) throws UnresolvedLinkException {
     readLock();
     try {
       INode iNode = rootDir.getNode(src, true);

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

@@ -169,7 +169,7 @@ import org.apache.hadoop.hdfs.server.namenode.ha.StandbyCheckpointer;
 import org.apache.hadoop.hdfs.server.namenode.ha.StandbyState;
 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.SnapshotManager;
 import org.apache.hadoop.hdfs.server.namenode.web.resources.NamenodeWebHdfsMethods;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeCommand;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
@@ -307,6 +307,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
   /** The namespace tree. */
   FSDirectory dir;
   private final BlockManager blockManager;
+  private final SnapshotManager snapshotManager;
   private final DatanodeStatistics datanodeStatistics;
 
   // Block pool ID used by this namenode
@@ -464,6 +465,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
           DFS_NAMENODE_RESOURCE_CHECK_INTERVAL_DEFAULT);
 
       this.blockManager = new BlockManager(this, this, conf);
+      this.snapshotManager = new SnapshotManager(this);
       this.datanodeStatistics = blockManager.getDatanodeManager().getDatanodeStatistics();
 
       this.fsOwner = UserGroupInformation.getCurrentUser();
@@ -2963,29 +2965,6 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     getEditLog().logSync();
   }
 
-  /**
-   * Set the given directory as a snapshottable directory.
-   * If the path is already a snapshottable directory, this is a no-op.
-   * Otherwise, the {@link INodeDirectory} of the path is replaced by an 
-   * {@link INodeDirectorySnapshottable}.
-   */
-  void setSnapshottable(final String path) throws IOException {
-    writeLock();
-    try {
-      final INodeDirectory d = INodeDirectory.valueOf(dir.getINode(path), path);
-      if (d.isSnapshottable()) {
-        //The directory is already a snapshottable directory. 
-        return;
-      }
-
-      final INodeDirectorySnapshottable s
-          = INodeDirectorySnapshottable.newInstance(d);
-      dir.replaceINodeDirectory(path, d, s);
-    } finally {
-      writeUnlock();
-    }
-  }
-
   /** Persist all metadata about this file.
    * @param src The string representation of the path
    * @param clientName The string representation of the client

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

@@ -38,7 +38,7 @@ import com.google.common.primitives.SignedBytes;
  * directory inodes.
  */
 @InterfaceAudience.Private
-abstract class INode implements Comparable<byte[]> {
+public abstract class INode implements Comparable<byte[]> {
   /*
    *  The inode name is in java UTF8 encoding; 
    *  The name in HdfsFileStatus should keep the same encoding as this.
@@ -135,7 +135,7 @@ abstract class INode implements Comparable<byte[]> {
     setPermission(ps.getPermission());
   }
   /** Get the {@link PermissionStatus} */
-  protected PermissionStatus getPermissionStatus() {
+  public PermissionStatus getPermissionStatus() {
     return new PermissionStatus(getUserName(),getGroupName(),getFsPermission());
   }
   private void updatePermissionStatus(PermissionStatusFormat f, long n) {
@@ -246,7 +246,7 @@ abstract class INode implements Comparable<byte[]> {
   /**
    * Set local file name
    */
-  void setLocalName(String name) {
+  protected void setLocalName(String name) {
     this.name = DFSUtil.string2Bytes(name);
   }
 
@@ -288,7 +288,7 @@ abstract class INode implements Comparable<byte[]> {
   /**
    * Set last modification time of inode.
    */
-  void setModificationTime(long modtime) {
+  public void setModificationTime(long modtime) {
     assert isDirectory();
     if (this.modificationTime <= modtime) {
       this.modificationTime = modtime;

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

@@ -50,7 +50,7 @@ public class INodeDirectory extends INode {
 
   private List<INode> children;
 
-  INodeDirectory(String name, PermissionStatus permissions) {
+  protected INodeDirectory(String name, PermissionStatus permissions) {
     super(name, permissions);
     this.children = null;
   }

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

@@ -0,0 +1,29 @@
+/**
+ * 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 org.apache.hadoop.hdfs.server.namenode.INodeDirectory;
+
+/** The root directory of a snapshot. */
+public class INodeDirectorySnapshotRoot extends INodeDirectory {
+  INodeDirectorySnapshotRoot(String name, INodeDirectory dir) {
+    super(name, dir.getPermissionStatus());
+    setLocalName(name);
+    parent = dir;
+  }
+}

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

@@ -17,9 +17,15 @@
  */
 package org.apache.hadoop.hdfs.server.namenode.snapshot;
 
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
 import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.hdfs.server.namenode.INode;
 import org.apache.hadoop.hdfs.server.namenode.INodeDirectory;
 import org.apache.hadoop.hdfs.server.namenode.INodeDirectoryWithQuota;
+import org.apache.hadoop.util.Time;
 
 /** Directories where taking snapshots is allowed. */
 @InterfaceAudience.Private
@@ -36,6 +42,20 @@ public class INodeDirectorySnapshottable extends INodeDirectoryWithQuota {
     return new INodeDirectorySnapshottable(nsq, dsq, dir);
   }
 
+  /** Cast INode to INodeDirectorySnapshottable. */
+  static public INodeDirectorySnapshottable valueOf(
+      INode inode, String src) throws IOException {
+    final INodeDirectory dir = INodeDirectory.valueOf(inode, src);
+    if (!dir.isSnapshottable()) {
+      throw new SnapshotException(src + " is not a snapshottable directory.");
+    }
+    return (INodeDirectorySnapshottable)dir;
+  }
+
+  /** A list of snapshots of this directory. */
+  private final List<INodeDirectorySnapshotRoot> snapshots
+      = new ArrayList<INodeDirectorySnapshotRoot>();
+
   private INodeDirectorySnapshottable(long nsQuota, long dsQuota,
       INodeDirectory dir) {
     super(nsQuota, dsQuota, dir);
@@ -45,4 +65,16 @@ public class INodeDirectorySnapshottable extends INodeDirectoryWithQuota {
   public boolean isSnapshottable() {
     return true;
   }
+
+  /** Add a snapshot root under this directory. */
+  INodeDirectorySnapshotRoot addSnapshotRoot(final String name) {
+    final INodeDirectorySnapshotRoot r = new INodeDirectorySnapshotRoot(name, this);
+    snapshots.add(r);
+
+    //set modification time
+    final long timestamp = Time.now();
+    r.setModificationTime(timestamp);
+    setModificationTime(timestamp);
+    return r;
+  }
 }

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

@@ -0,0 +1,33 @@
+/**
+ * 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 java.io.IOException;
+
+/** Snapshot related exception. */
+public class SnapshotException extends IOException {
+  private static final long serialVersionUID = 1L;
+
+  SnapshotException(final String message) {
+    super(message);
+  }
+
+  SnapshotException(final Throwable cause) {
+    super(cause);
+  }
+}

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

@@ -0,0 +1,77 @@
+/**
+ * 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 java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.hadoop.hdfs.server.namenode.FSDirectory;
+import org.apache.hadoop.hdfs.server.namenode.INodeDirectory;
+import org.apache.hadoop.hdfs.server.namenode.Namesystem;
+
+/** Manage snapshottable directories and their snapshots. */
+public class SnapshotManager {
+  private final Namesystem namesystem;
+
+  /** All snapshottable directories in the namesystem. */
+  private final List<INodeDirectorySnapshottable> snapshottables
+      = new ArrayList<INodeDirectorySnapshottable>();
+
+  public SnapshotManager(final Namesystem namesystem) {
+    this.namesystem = namesystem;
+  }
+
+  /**
+   * Set the given directory as a snapshottable directory.
+   * If the path is already a snapshottable directory, this is a no-op.
+   * Otherwise, the {@link INodeDirectory} of the path is replaced by an 
+   * {@link INodeDirectorySnapshottable}.
+   */
+  public void setSnapshottable(final String path,
+      final FSDirectory fsdir) throws IOException {
+    namesystem.writeLock();
+    try {
+      final INodeDirectory d = INodeDirectory.valueOf(fsdir.getINode(path), path);
+      if (d.isSnapshottable()) {
+        //The directory is already a snapshottable directory. 
+        return;
+      }
+
+      final INodeDirectorySnapshottable s
+          = INodeDirectorySnapshottable.newInstance(d);
+      fsdir.replaceINodeDirectory(path, d, s);
+      snapshottables.add(s);
+    } finally {
+      namesystem.writeUnlock();
+    }
+  }
+
+  /** Create a snapshot of given path. */
+  public void createSnapshot(final String snapshotName, final String path,
+      final FSDirectory fsdir) throws IOException {
+    final INodeDirectorySnapshottable d = INodeDirectorySnapshottable.valueOf(
+        fsdir.getINode(path), path);
+
+    //TODO: check ns quota
+    
+    final INodeDirectorySnapshotRoot root = d.addSnapshotRoot(snapshotName);
+    
+    //TODO: create the remaining subtree
+  }
+}