| /** |
| * 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; |
| |
| import java.util.EnumSet; |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| |
| /** |
| * This class tracks changes in the layout version of HDFS. |
| * |
| * Layout version is changed for following reasons: |
| * <ol> |
| * <li>The layout of how namenode or datanode stores information |
| * on disk changes.</li> |
| * <li>A new operation code is added to the editlog.</li> |
| * <li>Modification such as format of a record, content of a record |
| * in editlog or fsimage.</li> |
| * </ol> |
| * <br> |
| * <b>How to update layout version:<br></b> |
| * When a change requires new layout version, please add an entry into |
| * {@link Feature} with a short enum name, new layout version and description |
| * of the change. Please see {@link Feature} for further details. |
| * <br> |
| */ |
| @InterfaceAudience.Private |
| public class LayoutVersion { |
| |
| /** |
| * Version in which HDFS-2991 was fixed. This bug caused OP_ADD to |
| * sometimes be skipped for append() calls. If we see such a case when |
| * loading the edits, but the version is known to have that bug, we |
| * workaround the issue. Otherwise we should consider it a corruption |
| * and bail. |
| */ |
| public static final int BUGFIX_HDFS_2991_VERSION = -40; |
| |
| /** |
| * Enums for features that change the layout version. |
| * <br><br> |
| * To add a new layout version: |
| * <ul> |
| * <li>Define a new enum constant with a short enum name, the new layout version |
| * and description of the added feature.</li> |
| * <li>When adding a layout version with an ancestor that is not same as |
| * its immediate predecessor, use the constructor where a spacific ancestor |
| * can be passed. |
| * </li> |
| * </ul> |
| */ |
| public static enum Feature { |
| NAMESPACE_QUOTA(-16, "Support for namespace quotas"), |
| FILE_ACCESS_TIME(-17, "Support for access time on files"), |
| DISKSPACE_QUOTA(-18, "Support for disk space quotas"), |
| STICKY_BIT(-19, "Support for sticky bits"), |
| APPEND_RBW_DIR(-20, "Datanode has \"rbw\" subdirectory for append"), |
| ATOMIC_RENAME(-21, "Support for atomic rename"), |
| CONCAT(-22, "Support for concat operation"), |
| SYMLINKS(-23, "Support for symbolic links"), |
| DELEGATION_TOKEN(-24, "Support for delegation tokens for security"), |
| FSIMAGE_COMPRESSION(-25, "Support for fsimage compression"), |
| FSIMAGE_CHECKSUM(-26, "Support checksum for fsimage"), |
| REMOVE_REL13_DISK_LAYOUT_SUPPORT(-27, "Remove support for 0.13 disk layout"), |
| EDITS_CHESKUM(-28, "Support checksum for editlog"), |
| UNUSED(-29, "Skipped version"), |
| FSIMAGE_NAME_OPTIMIZATION(-30, "Store only last part of path in fsimage"), |
| RESERVED_REL20_203(-31, -19, "Reserved for release 0.20.203", true, |
| DELEGATION_TOKEN), |
| RESERVED_REL20_204(-32, -31, "Reserved for release 0.20.204", true), |
| RESERVED_REL22(-33, -27, "Reserved for release 0.22", true), |
| RESERVED_REL23(-34, -30, "Reserved for release 0.23", true), |
| FEDERATION(-35, "Support for namenode federation"), |
| LEASE_REASSIGNMENT(-36, "Support for persisting lease holder reassignment"), |
| STORED_TXIDS(-37, "Transaction IDs are stored in edits log and image files"), |
| TXID_BASED_LAYOUT(-38, "File names in NN Storage are based on transaction IDs"), |
| EDITLOG_OP_OPTIMIZATION(-39, |
| "Use LongWritable and ShortWritable directly instead of ArrayWritable of UTF8"), |
| OPTIMIZE_PERSIST_BLOCKS(-40, |
| "Serialize block lists with delta-encoded variable length ints, " + |
| "add OP_UPDATE_BLOCKS"), |
| RESERVED_REL1_2_0(-41, -32, "Reserved for release 1.2.0", true, CONCAT), |
| ADD_INODE_ID(-42, -40, "Assign a unique inode id for each inode", false), |
| SNAPSHOT(-43, "Support for snapshot feature"); |
| |
| final int lv; |
| final int ancestorLV; |
| final String description; |
| final boolean reserved; |
| final Feature[] specialFeatures; |
| |
| /** |
| * Feature that is added at layout version {@code lv} - 1. |
| * @param lv new layout version with the addition of this feature |
| * @param description description of the feature |
| */ |
| Feature(final int lv, final String description) { |
| this(lv, lv + 1, description, false); |
| } |
| |
| /** |
| * Feature that is added at layout version {@code ancestoryLV}. |
| * @param lv new layout version with the addition of this feature |
| * @param ancestorLV layout version from which the new lv is derived from. |
| * @param description description of the feature |
| * @param reserved true when this is a layout version reserved for previous |
| * verions |
| * @param features set of features that are to be enabled for this version |
| */ |
| Feature(final int lv, final int ancestorLV, final String description, |
| boolean reserved, Feature... features) { |
| this.lv = lv; |
| this.ancestorLV = ancestorLV; |
| this.description = description; |
| this.reserved = reserved; |
| specialFeatures = features; |
| } |
| |
| /** |
| * Accessor method for feature layout version |
| * @return int lv value |
| */ |
| public int getLayoutVersion() { |
| return lv; |
| } |
| |
| /** |
| * Accessor method for feature ancestor layout version |
| * @return int ancestor LV value |
| */ |
| public int getAncestorLayoutVersion() { |
| return ancestorLV; |
| } |
| |
| /** |
| * Accessor method for feature description |
| * @return String feature description |
| */ |
| public String getDescription() { |
| return description; |
| } |
| |
| public boolean isReservedForOldRelease() { |
| return reserved; |
| } |
| } |
| |
| // Build layout version and corresponding feature matrix |
| static final Map<Integer, EnumSet<Feature>>map = |
| new HashMap<Integer, EnumSet<Feature>>(); |
| |
| // Static initialization |
| static { |
| initMap(); |
| } |
| |
| /** |
| * Initialize the map of a layout version and EnumSet of {@link Feature}s |
| * supported. |
| */ |
| private static void initMap() { |
| // Go through all the enum constants and build a map of |
| // LayoutVersion <-> EnumSet of all supported features in that LayoutVersion |
| for (Feature f : Feature.values()) { |
| EnumSet<Feature> ancestorSet = map.get(f.ancestorLV); |
| if (ancestorSet == null) { |
| ancestorSet = EnumSet.noneOf(Feature.class); // Empty enum set |
| map.put(f.ancestorLV, ancestorSet); |
| } |
| EnumSet<Feature> featureSet = EnumSet.copyOf(ancestorSet); |
| if (f.specialFeatures != null) { |
| for (Feature specialFeature : f.specialFeatures) { |
| featureSet.add(specialFeature); |
| } |
| } |
| featureSet.add(f); |
| map.put(f.lv, featureSet); |
| } |
| } |
| |
| /** |
| * Gets formatted string that describes {@link LayoutVersion} information. |
| */ |
| public static String getString() { |
| final StringBuilder buf = new StringBuilder(); |
| buf.append("Feature List:\n"); |
| for (Feature f : Feature.values()) { |
| buf.append(f).append(" introduced in layout version ") |
| .append(f.lv).append(" ("). |
| append(f.description).append(")\n"); |
| } |
| |
| buf.append("\n\nLayoutVersion and supported features:\n"); |
| for (Feature f : Feature.values()) { |
| buf.append(f.lv).append(": ").append(map.get(f.lv)) |
| .append("\n"); |
| } |
| return buf.toString(); |
| } |
| |
| /** |
| * Returns true if a given feature is supported in the given layout version |
| * @param f Feature |
| * @param lv LayoutVersion |
| * @return true if {@code f} is supported in layout version {@code lv} |
| */ |
| public static boolean supports(final Feature f, final int lv) { |
| final EnumSet<Feature> set = map.get(lv); |
| return set != null && set.contains(f); |
| } |
| |
| /** |
| * Get the current layout version |
| */ |
| public static int getCurrentLayoutVersion() { |
| Feature[] values = Feature.values(); |
| for (int i = values.length -1; i >= 0; i--) { |
| if (!values[i].isReservedForOldRelease()) { |
| return values[i].lv; |
| } |
| } |
| throw new AssertionError("All layout versions are reserved."); |
| } |
| } |