| /** |
| * 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.offlineEditsViewer; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| import org.apache.hadoop.hdfs.DeprecatedUTF8; |
| |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.ByteToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.ShortToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.IntToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.VIntToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.LongToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.VLongToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.StringUTF8Token; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.StringTextToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.BlobToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.BytesWritableToken; |
| import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.EmptyToken; |
| |
| /** |
| * An implementation of EditsVisitor can traverse the structure of an |
| * Hadoop edits log and respond to each of the structures within the file. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| abstract public class EditsVisitor { |
| |
| private Tokenizer tokenizer; |
| |
| public EditsVisitor(Tokenizer tokenizer) { |
| this.tokenizer = tokenizer; |
| } |
| |
| /** |
| * Begin visiting the edits log structure. Opportunity to perform |
| * any initialization necessary for the implementing visitor. |
| */ |
| abstract void start() throws IOException; |
| |
| /** |
| * Finish visiting the edits log structure. Opportunity to perform any |
| * clean up necessary for the implementing visitor. |
| */ |
| abstract void finish() throws IOException; |
| |
| /** |
| * Finish visiting the edits log 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 edits log with specified value. |
| * |
| * @param value a token to visit |
| */ |
| abstract Tokenizer.Token visit(Tokenizer.Token value) throws IOException; |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public ByteToken visitByte(EditsElement e) throws IOException { |
| return (ByteToken)visit(tokenizer.read(new ByteToken(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public ShortToken visitShort(EditsElement e) throws IOException { |
| return (ShortToken)visit(tokenizer.read(new ShortToken(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public IntToken visitInt(EditsElement e) throws IOException { |
| return (IntToken)visit(tokenizer.read(new IntToken(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public VIntToken visitVInt(EditsElement e) throws IOException { |
| return (VIntToken)visit(tokenizer.read(new VIntToken(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public LongToken visitLong(EditsElement e) throws IOException { |
| return (LongToken)visit(tokenizer.read(new LongToken(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public VLongToken visitVLong(EditsElement e) throws IOException { |
| return (VLongToken)visit(tokenizer.read(new VLongToken(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public StringUTF8Token visitStringUTF8(EditsElement e) throws IOException { |
| return (StringUTF8Token)visit(tokenizer.read(new StringUTF8Token(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public StringTextToken visitStringText(EditsElement e) throws IOException { |
| return (StringTextToken)visit(tokenizer.read(new StringTextToken(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public BlobToken visitBlob(EditsElement e, int length) throws IOException { |
| return (BlobToken)visit(tokenizer.read(new BlobToken(e, length))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public BytesWritableToken visitBytesWritable(EditsElement e) throws IOException { |
| return (BytesWritableToken)visit(tokenizer.read(new BytesWritableToken(e))); |
| } |
| |
| /** |
| * Convenience shortcut method to parse a specific token type |
| */ |
| public EmptyToken visitEmpty(EditsElement e) throws IOException { |
| return (EmptyToken)visit(tokenizer.read(new EmptyToken(e))); |
| } |
| |
| /** |
| * Begin visiting an element that encloses another element, such as |
| * the beginning of the list of blocks that comprise a file. |
| * |
| * @param value Token being visited |
| */ |
| abstract void visitEnclosingElement(Tokenizer.Token value) |
| throws IOException; |
| |
| /** |
| * Convenience shortcut method (it virutally always uses EmptyToken) |
| */ |
| void visitEnclosingElement(EditsElement e) throws IOException { |
| visitEnclosingElement(tokenizer.read(new EmptyToken(e))); |
| } |
| |
| /** |
| * Leave current enclosing element. Called, for instance, at the end of |
| * processing the blocks that compromise a file. |
| */ |
| abstract void leaveEnclosingElement() throws IOException; |
| } |