| /** |
| * 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.server.namenode; |
| |
| /** |
| * A generic interface for journal input and output streams. |
| */ |
| interface JournalStream { |
| /** |
| * Type of the underlying persistent storage type the stream is based upon. |
| * <ul> |
| * <li>{@link JournalType#FILE} - streams edits into a local file, see |
| * {@link FSEditLog.EditLogFileOutputStream} and |
| * {@link FSEditLog.EditLogFileInputStream}</li> |
| * <li>{@link JournalType#BACKUP} - streams edits to a backup node, see |
| * {@link EditLogBackupOutputStream} and {@link EditLogBackupInputStream}</li> |
| * </ul> |
| */ |
| static enum JournalType { |
| FILE, |
| BACKUP; |
| boolean isOfType(JournalType other) { |
| return other == null || this == other; |
| } |
| }; |
| |
| /** |
| * Get this stream name. |
| * |
| * @return name of the stream |
| */ |
| String getName(); |
| |
| /** |
| * Get the type of the stream. |
| * Determines the underlying persistent storage type. |
| * @see JournalType |
| * @return type |
| */ |
| JournalType getType(); |
| } |