hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/LayoutVersion.java - hadoop - Git at Google

 /**
  * 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"),
     RESERVED_REL1_3_0(-44, -41,
         "Reserved for release 1.3.0", true, ADD_INODE_ID, SNAPSHOT),
     OPTIMIZE_SNAPSHOT_INODES(-45, -43,
         "Reduce snapshot inode memory footprint", false),
     SEQUENTIAL_BLOCK_ID(-46, "Allocate block IDs sequentially and store " +
         "block IDs in the edits log and image files"),
     EDITLOG_SUPPORT_RETRYCACHE(-47, "Record ClientId and CallId in editlog to "
         + "enable rebuilding retry cache in case of HA failover"),
     EDITLOG_ADD_BLOCK(-48, "Add new editlog that only records allocation of "
         + "the new block instead of the entire block list"),
     ADD_DATANODE_AND_STORAGE_UUIDS(-49, "Replace StorageID with DatanodeUuid."
         + " Use distinct StorageUuid per storage directory."),
     ADD_LAYOUT_FLAGS(-50, "Add support for layout flags."),
     CACHING(-51, "Support for cache pools and path-based caching");

     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.");
   }
 }
	/**
	* 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"),
	RESERVED_REL1_3_0(-44, -41,
	"Reserved for release 1.3.0", true, ADD_INODE_ID, SNAPSHOT),
	OPTIMIZE_SNAPSHOT_INODES(-45, -43,
	"Reduce snapshot inode memory footprint", false),
	SEQUENTIAL_BLOCK_ID(-46, "Allocate block IDs sequentially and store " +
	"block IDs in the edits log and image files"),
	EDITLOG_SUPPORT_RETRYCACHE(-47, "Record ClientId and CallId in editlog to "
	+ "enable rebuilding retry cache in case of HA failover"),
	EDITLOG_ADD_BLOCK(-48, "Add new editlog that only records allocation of "
	+ "the new block instead of the entire block list"),
	ADD_DATANODE_AND_STORAGE_UUIDS(-49, "Replace StorageID with DatanodeUuid."
	+ " Use distinct StorageUuid per storage directory."),
	ADD_LAYOUT_FLAGS(-50, "Add support for layout flags."),
	CACHING(-51, "Support for cache pools and path-based caching");

	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.");
	}
	}