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Server functionality for HBase
/*
* 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.hbase.wal;
import java.io.Closeable;
import java.io.IOException;
import org.apache.yetus.audience.InterfaceAudience;
/**
* A one way WAL reader, without reset and seek support.
*
* In most cases you should use this interface to read WAL file, as the implementation is simple and
* robust. For replication, where we want to tail the WAL file which is currently being written, you
* should use {@link WALTailingReader} instead.
* @see WALTailingReader
*/
@InterfaceAudience.Private
public interface WALStreamReader extends Closeable {
/**
* Read the next entry in WAL.
*
* In most cases you should just use this method, especially when reading a closed wal file for
* splitting or printing.
*/
default WAL.Entry next() throws IOException {
return next(null);
}
/**
* Read the next entry in WAL, use the given {@link WAL.Entry} if not {@code null} to hold the
* data.
*
* Mainly used in MR.
* @param reuse the entry to be used for reading, can be {@code null}
*/
WAL.Entry next(WAL.Entry reuse) throws IOException;
/**
* Get the current reading position.
*/
long getPosition() throws IOException;
/**
* Override to remove the 'throws IOException' as we are just a reader.
*/
@Override
void close();
}