001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hdfs.server.namenode;
019
020import java.util.HashMap;
021import java.util.Map;
022import java.util.SortedSet;
023
024import org.apache.hadoop.classification.InterfaceAudience;
025import org.apache.hadoop.hdfs.protocol.LayoutVersion;
026import org.apache.hadoop.hdfs.protocol.LayoutVersion.FeatureInfo;
027import org.apache.hadoop.hdfs.protocol.LayoutVersion.LayoutFeature;
028
029
030@InterfaceAudience.Private
031public class NameNodeLayoutVersion { 
032  /** Build layout version and corresponding feature matrix */
033  public final static Map<Integer, SortedSet<LayoutFeature>> FEATURES
034      = new HashMap<Integer, SortedSet<LayoutFeature>>();
035
036  public static final int CURRENT_LAYOUT_VERSION
037      = LayoutVersion.getCurrentLayoutVersion(Feature.values());
038
039  static {
040    LayoutVersion.updateMap(FEATURES, LayoutVersion.Feature.values());
041    LayoutVersion.updateMap(FEATURES, NameNodeLayoutVersion.Feature.values());
042  }
043  
044  public static SortedSet<LayoutFeature> getFeatures(int lv) {
045    return FEATURES.get(lv);
046  }
047
048  public static boolean supports(final LayoutFeature f, final int lv) {
049    return LayoutVersion.supports(FEATURES, f, lv);
050  }
051
052  /**
053   * Enums for features that change the layout version.
054   * <br><br>
055   * To add a new layout version:
056   * <ul>
057   * <li>Define a new enum constant with a short enum name, the new layout version 
058   * and description of the added feature.</li>
059   * <li>When adding a layout version with an ancestor that is not same as
060   * its immediate predecessor, use the constructor where a specific ancestor
061   * can be passed.
062   * </li>
063   * </ul>
064   */
065  public static enum Feature implements LayoutFeature {
066    ROLLING_UPGRADE(-55, -53, "Support rolling upgrade", false),
067    EDITLOG_LENGTH(-56, "Add length field to every edit log op"),
068    XATTRS(-57, "Extended attributes"),
069    CREATE_OVERWRITE(-58, "Use single editlog record for " +
070      "creating file with overwrite"),
071    XATTRS_NAMESPACE_EXT(-59, "Increase number of xattr namespaces"),
072    BLOCK_STORAGE_POLICY(-60, "Block Storage policy"),
073    TRUNCATE(-61, "Truncate"),
074    APPEND_NEW_BLOCK(-62, "Support appending to new block"),
075    QUOTA_BY_STORAGE_TYPE(-63, "Support quota for specific storage types");
076
077    private final FeatureInfo info;
078
079    /**
080     * Feature that is added at layout version {@code lv} - 1. 
081     * @param lv new layout version with the addition of this feature
082     * @param description description of the feature
083     */
084    Feature(final int lv, final String description) {
085      this(lv, lv + 1, description, false);
086    }
087
088    /**
089     * NameNode feature that is added at layout version {@code ancestoryLV}.
090     * @param lv new layout version with the addition of this feature
091     * @param ancestorLV layout version from which the new lv is derived from.
092     * @param description description of the feature
093     * @param reserved true when this is a layout version reserved for previous
094     *        versions
095     * @param features set of features that are to be enabled for this version
096     */
097    Feature(final int lv, final int ancestorLV, final String description,
098        boolean reserved, Feature... features) {
099      info = new FeatureInfo(lv, ancestorLV, description, reserved, features);
100    }
101    
102    @Override
103    public FeatureInfo getInfo() {
104      return info;
105    }
106  }
107}