| /* |
| * 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.tephra.persist; |
| |
| import com.google.common.base.Supplier; |
| import org.apache.hadoop.io.SequenceFile; |
| import org.apache.hadoop.io.Text; |
| import org.apache.tephra.TxConstants; |
| |
| /** |
| * Provides the correct version of {@link TransactionLogReader}, based on the log's version metadata, |
| * to read HDFS Transaction Logs. |
| */ |
| public class HDFSTransactionLogReaderSupplier implements Supplier<TransactionLogReader> { |
| private final SequenceFile.Reader reader; |
| private final byte version; |
| private TransactionLogReader logReader; |
| |
| public HDFSTransactionLogReaderSupplier(SequenceFile.Reader reader) { |
| this.reader = reader; |
| Text versionInfo = reader.getMetadata().get(new Text(TxConstants.TransactionLog.VERSION_KEY)); |
| this.version = versionInfo == null ? 1 : Byte.parseByte(versionInfo.toString()); |
| } |
| |
| @Override |
| public TransactionLogReader get() { |
| if (logReader != null) { |
| return logReader; |
| } |
| |
| switch (version) { |
| case 3: |
| logReader = new HDFSTransactionLogReaderV3(reader); |
| return logReader; |
| case 2: |
| logReader = new HDFSTransactionLogReaderV2(reader); |
| return logReader; |
| case 1: |
| logReader = new HDFSTransactionLogReaderV1(reader); |
| return logReader; |
| default: |
| throw new IllegalArgumentException(String.format("Invalid version %s found in the Transaction Log", version)); |
| } |
| } |
| } |