/**
* 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();
}