/**
* 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;
import java.io.IOException;
import java.util.Collection;
/**
* Interface used to abstract over classes which manage edit logs that may need
* to be purged.
*/
interface LogsPurgeable {
/**
* Remove all edit logs with transaction IDs lower than the given transaction
* ID.
*
* @param minTxIdToKeep the lowest transaction ID that should be retained
* @throws IOException in the event of error
*/
public void purgeLogsOlderThan(long minTxIdToKeep) throws IOException;
/**
* Get a list of edit log input streams. The list will start with the
* stream that contains fromTxnId, and continue until the end of the journal
* being managed.
*
* @param fromTxId the first transaction id we want to read
* @param inProgressOk whether or not in-progress streams should be returned
* @param forReading whether or not the caller intends to read from the edit logs
*
* @return a list of streams
* @throws IOException if the underlying storage has an error or is otherwise
* inaccessible
*/
void selectInputStreams(Collection<EditLogInputStream> streams,
long fromTxId, boolean inProgressOk, boolean forReading) throws IOException;
}