/**
* 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,
GENERATION_STAMP_V2,
GENERATION_STAMP_V1_LIMIT,
LAST_ALLOCATED_BLOCK_ID,
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,
LAST_INODE_ID,
INODE_ID,
SNAPSHOT_COUNTER,
NUM_SNAPSHOTS_TOTAL,
NUM_SNAPSHOTS,
SNAPSHOTS,
SNAPSHOT,
SNAPSHOT_ID,
SNAPSHOT_ROOT,
SNAPSHOT_QUOTA,
NUM_SNAPSHOT_DIR_DIFF,
SNAPSHOT_DIR_DIFFS,
SNAPSHOT_DIR_DIFF,
SNAPSHOT_DIFF_SNAPSHOTID,
SNAPSHOT_DIR_DIFF_CHILDREN_SIZE,
SNAPSHOT_INODE_FILE_ATTRIBUTES,
SNAPSHOT_INODE_DIRECTORY_ATTRIBUTES,
SNAPSHOT_DIR_DIFF_CREATEDLIST,
SNAPSHOT_DIR_DIFF_CREATEDLIST_SIZE,
SNAPSHOT_DIR_DIFF_CREATED_INODE,
SNAPSHOT_DIR_DIFF_DELETEDLIST,
SNAPSHOT_DIR_DIFF_DELETEDLIST_SIZE,
SNAPSHOT_DIR_DIFF_DELETED_INODE,
IS_SNAPSHOTTABLE_DIR,
IS_WITHSNAPSHOT_DIR,
SNAPSHOT_FILE_DIFFS,
SNAPSHOT_FILE_DIFF,
NUM_SNAPSHOT_FILE_DIFF,
SNAPSHOT_FILE_SIZE,
SNAPSHOT_DST_SNAPSHOT_ID,
SNAPSHOT_LAST_SNAPSHOT_ID,
SNAPSHOT_REF_INODE_ID,
SNAPSHOT_REF_INODE,
CACHE_NEXT_ENTRY_ID,
CACHE_NUM_POOLS,
CACHE_POOL_NAME,
CACHE_POOL_OWNER_NAME,
CACHE_POOL_GROUP_NAME,
CACHE_POOL_PERMISSION_STRING,
CACHE_POOL_WEIGHT,
CACHE_NUM_ENTRIES,
CACHE_ENTRY_PATH,
CACHE_ENTRY_REPLICATION,
CACHE_ENTRY_POOL_NAME
}
/**
* 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;
}