HDFS-2412. Add backwards-compatibility layer for renamed FSConstants class. Contributed by Todd Lipcon.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1180203 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -1029,6 +1029,9 @@ Release 0.23.0 - Unreleased
     HDFS-2345. TestLeaseRecovery2 fails on 0.23 branch (Uma Maheswara Rao G
                via atm)
 
+    HDFS-2412. Add backwards-compatibility layer for renamed FSConstants
+               class (todd)
+
   BREAKDOWN OF HDFS-1073 SUBTASKS
 
     HDFS-1521. Persist transaction ID on disk between NN restarts.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/FSConstants.java

@@ -0,0 +1,27 @@
+/**
+ * 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.protocol;
+
+/**
+ * @deprecated Please use {@link HdfsConstants}. This class
+ * is left only for other ecosystem projects which depended on
+ * it for SafemodeAction and DatanodeReport types.
+ */
+@Deprecated
+public abstract class FSConstants extends HdfsConstants {
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/HdfsConstants.java

@@ -26,9 +26,9 @@ import org.apache.hadoop.hdfs.HdfsConfiguration;
  * 
  ************************************/
 @InterfaceAudience.Private
-public final class HdfsConstants {
+public class HdfsConstants {
   /* Hidden constructor */
-  private HdfsConstants() {
+  protected HdfsConstants() {
   }
 
   public static int MIN_BLOCKS_FOR_WRITE = 5;
@@ -63,7 +63,7 @@ public final class HdfsConstants {
   public static final int BYTES_IN_INTEGER = Integer.SIZE / Byte.SIZE;
 
   // SafeMode actions
-  public enum SafeModeAction {
+  public static enum SafeModeAction {
     SAFEMODE_LEAVE, SAFEMODE_ENTER, SAFEMODE_GET;
   }