| /** |
| * 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.tools.offlineImageViewer; |
| |
| import java.io.IOException; |
| |
| /** |
| * An implementation of ImageVisitor can traverse the structure of an |
| * Hadoop fsimage and respond to each of the structures within the file. |
| */ |
| abstract class ImageVisitor { |
| |
| /** |
| * Structural elements of an FSImage that may be encountered within the |
| * file. ImageVisitors are able to handle processing any of these elements. |
| */ |
| public enum ImageElement { |
| FS_IMAGE, |
| IMAGE_VERSION, |
| NAMESPACE_ID, |
| IS_COMPRESSED, |
| COMPRESS_CODEC, |
| LAYOUT_VERSION, |
| NUM_INODES, |
| GENERATION_STAMP, |
| INODES, |
| INODE, |
| INODE_PATH, |
| REPLICATION, |
| MODIFICATION_TIME, |
| ACCESS_TIME, |
| BLOCK_SIZE, |
| NUM_BLOCKS, |
| BLOCKS, |
| BLOCK, |
| BLOCK_ID, |
| NUM_BYTES, |
| NS_QUOTA, |
| DS_QUOTA, |
| PERMISSIONS, |
| SYMLINK, |
| NUM_INODES_UNDER_CONSTRUCTION, |
| INODES_UNDER_CONSTRUCTION, |
| INODE_UNDER_CONSTRUCTION, |
| PREFERRED_BLOCK_SIZE, |
| CLIENT_NAME, |
| CLIENT_MACHINE, |
| USER_NAME, |
| GROUP_NAME, |
| PERMISSION_STRING, |
| CURRENT_DELEGATION_KEY_ID, |
| NUM_DELEGATION_KEYS, |
| DELEGATION_KEYS, |
| DELEGATION_KEY, |
| DELEGATION_TOKEN_SEQUENCE_NUMBER, |
| NUM_DELEGATION_TOKENS, |
| DELEGATION_TOKENS, |
| DELEGATION_TOKEN_IDENTIFIER, |
| DELEGATION_TOKEN_IDENTIFIER_KIND, |
| DELEGATION_TOKEN_IDENTIFIER_SEQNO, |
| DELEGATION_TOKEN_IDENTIFIER_OWNER, |
| DELEGATION_TOKEN_IDENTIFIER_RENEWER, |
| DELEGATION_TOKEN_IDENTIFIER_REALUSER, |
| DELEGATION_TOKEN_IDENTIFIER_ISSUE_DATE, |
| DELEGATION_TOKEN_IDENTIFIER_MAX_DATE, |
| DELEGATION_TOKEN_IDENTIFIER_EXPIRY_TIME, |
| DELEGATION_TOKEN_IDENTIFIER_MASTER_KEY_ID, |
| TRANSACTION_ID |
| } |
| |
| /** |
| * Begin visiting the fsimage structure. Opportunity to perform |
| * any initialization necessary for the implementing visitor. |
| */ |
| abstract void start() throws IOException; |
| |
| /** |
| * Finish visiting the fsimage structure. Opportunity to perform any |
| * clean up necessary for the implementing visitor. |
| */ |
| abstract void finish() throws IOException; |
| |
| /** |
| * Finish visiting the fsimage structure after an error has occurred |
| * during the processing. Opportunity to perform any clean up necessary |
| * for the implementing visitor. |
| */ |
| abstract void finishAbnormally() throws IOException; |
| |
| /** |
| * Visit non enclosing element of fsimage with specified value. |
| * |
| * @param element FSImage element |
| * @param value Element's value |
| */ |
| abstract void visit(ImageElement element, String value) throws IOException; |
| |
| // Convenience methods to automatically convert numeric value types to strings |
| void visit(ImageElement element, int value) throws IOException { |
| visit(element, Integer.toString(value)); |
| } |
| |
| void visit(ImageElement element, long value) throws IOException { |
| visit(element, Long.toString(value)); |
| } |
| |
| /** |
| * Begin visiting an element that encloses another element, such as |
| * the beginning of the list of blocks that comprise a file. |
| * |
| * @param element Element being visited |
| */ |
| abstract void visitEnclosingElement(ImageElement element) |
| throws IOException; |
| |
| /** |
| * Begin visiting an element that encloses another element, such as |
| * the beginning of the list of blocks that comprise a file. |
| * |
| * Also provide an additional key and value for the element, such as the |
| * number items within the element. |
| * |
| * @param element Element being visited |
| * @param key Key describing the element being visited |
| * @param value Value associated with element being visited |
| */ |
| abstract void visitEnclosingElement(ImageElement element, |
| ImageElement key, String value) throws IOException; |
| |
| // Convenience methods to automatically convert value types to strings |
| void visitEnclosingElement(ImageElement element, |
| ImageElement key, int value) |
| throws IOException { |
| visitEnclosingElement(element, key, Integer.toString(value)); |
| } |
| |
| void visitEnclosingElement(ImageElement element, |
| ImageElement key, long value) |
| throws IOException { |
| visitEnclosingElement(element, key, Long.toString(value)); |
| } |
| |
| /** |
| * Leave current enclosing element. Called, for instance, at the end of |
| * processing the blocks that compromise a file. |
| */ |
| abstract void leaveEnclosingElement() throws IOException; |
| } |