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 */
018 package org.apache.hadoop.hdfs.protocol;
019
020 import java.util.EnumSet;
021 import java.util.HashMap;
022 import java.util.Map;
023
024 import org.apache.hadoop.classification.InterfaceAudience;
025
026 /**
027 * This class tracks changes in the layout version of HDFS.
028 *
029 * Layout version is changed for following reasons:
030 * <ol>
031 * <li>The layout of how namenode or datanode stores information
032 * on disk changes.</li>
033 * <li>A new operation code is added to the editlog.</li>
034 * <li>Modification such as format of a record, content of a record
035 * in editlog or fsimage.</li>
036 * </ol>
037 * <br>
038 * <b>How to update layout version:<br></b>
039 * When a change requires new layout version, please add an entry into
040 * {@link Feature} with a short enum name, new layout version and description
041 * of the change. Please see {@link Feature} for further details.
042 * <br>
043 */
044 @InterfaceAudience.Private
045 public class LayoutVersion {
046
047 /**
048 * Version in which HDFS-2991 was fixed. This bug caused OP_ADD to
049 * sometimes be skipped for append() calls. If we see such a case when
050 * loading the edits, but the version is known to have that bug, we
051 * workaround the issue. Otherwise we should consider it a corruption
052 * and bail.
053 */
054 public static final int BUGFIX_HDFS_2991_VERSION = -40;
055
056 /**
057 * Enums for features that change the layout version.
058 * <br><br>
059 * To add a new layout version:
060 * <ul>
061 * <li>Define a new enum constant with a short enum name, the new layout version
062 * and description of the added feature.</li>
063 * <li>When adding a layout version with an ancestor that is not same as
064 * its immediate predecessor, use the constructor where a spacific ancestor
065 * can be passed.
066 * </li>
067 * </ul>
068 */
069 public static enum Feature {
070 NAMESPACE_QUOTA(-16, "Support for namespace quotas"),
071 FILE_ACCESS_TIME(-17, "Support for access time on files"),
072 DISKSPACE_QUOTA(-18, "Support for disk space quotas"),
073 STICKY_BIT(-19, "Support for sticky bits"),
074 APPEND_RBW_DIR(-20, "Datanode has \"rbw\" subdirectory for append"),
075 ATOMIC_RENAME(-21, "Support for atomic rename"),
076 CONCAT(-22, "Support for concat operation"),
077 SYMLINKS(-23, "Support for symbolic links"),
078 DELEGATION_TOKEN(-24, "Support for delegation tokens for security"),
079 FSIMAGE_COMPRESSION(-25, "Support for fsimage compression"),
080 FSIMAGE_CHECKSUM(-26, "Support checksum for fsimage"),
081 REMOVE_REL13_DISK_LAYOUT_SUPPORT(-27, "Remove support for 0.13 disk layout"),
082 EDITS_CHESKUM(-28, "Support checksum for editlog"),
083 UNUSED(-29, "Skipped version"),
084 FSIMAGE_NAME_OPTIMIZATION(-30, "Store only last part of path in fsimage"),
085 RESERVED_REL20_203(-31, -19, "Reserved for release 0.20.203", true,
086 DELEGATION_TOKEN),
087 RESERVED_REL20_204(-32, -31, "Reserved for release 0.20.204", true),
088 RESERVED_REL22(-33, -27, "Reserved for release 0.22", true),
089 RESERVED_REL23(-34, -30, "Reserved for release 0.23", true),
090 FEDERATION(-35, "Support for namenode federation"),
091 LEASE_REASSIGNMENT(-36, "Support for persisting lease holder reassignment"),
092 STORED_TXIDS(-37, "Transaction IDs are stored in edits log and image files"),
093 TXID_BASED_LAYOUT(-38, "File names in NN Storage are based on transaction IDs"),
094 EDITLOG_OP_OPTIMIZATION(-39,
095 "Use LongWritable and ShortWritable directly instead of ArrayWritable of UTF8"),
096 OPTIMIZE_PERSIST_BLOCKS(-40,
097 "Serialize block lists with delta-encoded variable length ints, " +
098 "add OP_UPDATE_BLOCKS"),
099 RESERVED_REL1_2_0(-41, -32, "Reserved for release 1.2.0", true, CONCAT),
100 ADD_INODE_ID(-42, -40, "Assign a unique inode id for each inode", false),
101 SNAPSHOT(-43, "Support for snapshot feature"),
102 RESERVED_REL1_3_0(-44, -41,
103 "Reserved for release 1.3.0", true, ADD_INODE_ID, SNAPSHOT),
104 OPTIMIZE_SNAPSHOT_INODES(-45, -43,
105 "Reduce snapshot inode memory footprint", false),
106 SEQUENTIAL_BLOCK_ID(-46, "Allocate block IDs sequentially and store " +
107 "block IDs in the edits log and image files"),
108 EDITLOG_SUPPORT_RETRYCACHE(-47, "Record ClientId and CallId in editlog to "
109 + "enable rebuilding retry cache in case of HA failover"),
110 EDITLOG_ADD_BLOCK(-48, "Add new editlog that only records allocation of "
111 + "the new block instead of the entire block list"),
112 ADD_DATANODE_AND_STORAGE_UUIDS(-49, "Replace StorageID with DatanodeUuid."
113 + " Use distinct StorageUuid per storage directory."),
114 ADD_LAYOUT_FLAGS(-50, "Add support for layout flags."),
115 CACHING(-51, "Support for cache pools and path-based caching");
116
117 final int lv;
118 final int ancestorLV;
119 final String description;
120 final boolean reserved;
121 final Feature[] specialFeatures;
122
123 /**
124 * Feature that is added at layout version {@code lv} - 1.
125 * @param lv new layout version with the addition of this feature
126 * @param description description of the feature
127 */
128 Feature(final int lv, final String description) {
129 this(lv, lv + 1, description, false);
130 }
131
132 /**
133 * Feature that is added at layout version {@code ancestoryLV}.
134 * @param lv new layout version with the addition of this feature
135 * @param ancestorLV layout version from which the new lv is derived from.
136 * @param description description of the feature
137 * @param reserved true when this is a layout version reserved for previous
138 * verions
139 * @param features set of features that are to be enabled for this version
140 */
141 Feature(final int lv, final int ancestorLV, final String description,
142 boolean reserved, Feature... features) {
143 this.lv = lv;
144 this.ancestorLV = ancestorLV;
145 this.description = description;
146 this.reserved = reserved;
147 specialFeatures = features;
148 }
149
150 /**
151 * Accessor method for feature layout version
152 * @return int lv value
153 */
154 public int getLayoutVersion() {
155 return lv;
156 }
157
158 /**
159 * Accessor method for feature ancestor layout version
160 * @return int ancestor LV value
161 */
162 public int getAncestorLayoutVersion() {
163 return ancestorLV;
164 }
165
166 /**
167 * Accessor method for feature description
168 * @return String feature description
169 */
170 public String getDescription() {
171 return description;
172 }
173
174 public boolean isReservedForOldRelease() {
175 return reserved;
176 }
177 }
178
179 // Build layout version and corresponding feature matrix
180 static final Map<Integer, EnumSet<Feature>>map =
181 new HashMap<Integer, EnumSet<Feature>>();
182
183 // Static initialization
184 static {
185 initMap();
186 }
187
188 /**
189 * Initialize the map of a layout version and EnumSet of {@link Feature}s
190 * supported.
191 */
192 private static void initMap() {
193 // Go through all the enum constants and build a map of
194 // LayoutVersion <-> EnumSet of all supported features in that LayoutVersion
195 for (Feature f : Feature.values()) {
196 EnumSet<Feature> ancestorSet = map.get(f.ancestorLV);
197 if (ancestorSet == null) {
198 ancestorSet = EnumSet.noneOf(Feature.class); // Empty enum set
199 map.put(f.ancestorLV, ancestorSet);
200 }
201 EnumSet<Feature> featureSet = EnumSet.copyOf(ancestorSet);
202 if (f.specialFeatures != null) {
203 for (Feature specialFeature : f.specialFeatures) {
204 featureSet.add(specialFeature);
205 }
206 }
207 featureSet.add(f);
208 map.put(f.lv, featureSet);
209 }
210 }
211
212 /**
213 * Gets formatted string that describes {@link LayoutVersion} information.
214 */
215 public static String getString() {
216 final StringBuilder buf = new StringBuilder();
217 buf.append("Feature List:\n");
218 for (Feature f : Feature.values()) {
219 buf.append(f).append(" introduced in layout version ")
220 .append(f.lv).append(" (").
221 append(f.description).append(")\n");
222 }
223
224 buf.append("\n\nLayoutVersion and supported features:\n");
225 for (Feature f : Feature.values()) {
226 buf.append(f.lv).append(": ").append(map.get(f.lv))
227 .append("\n");
228 }
229 return buf.toString();
230 }
231
232 /**
233 * Returns true if a given feature is supported in the given layout version
234 * @param f Feature
235 * @param lv LayoutVersion
236 * @return true if {@code f} is supported in layout version {@code lv}
237 */
238 public static boolean supports(final Feature f, final int lv) {
239 final EnumSet<Feature> set = map.get(lv);
240 return set != null && set.contains(f);
241 }
242
243 /**
244 * Get the current layout version
245 */
246 public static int getCurrentLayoutVersion() {
247 Feature[] values = Feature.values();
248 for (int i = values.length -1; i >= 0; i--) {
249 if (!values[i].isReservedForOldRelease()) {
250 return values[i].lv;
251 }
252 }
253 throw new AssertionError("All layout versions are reserved.");
254 }
255 }
256