/*
* 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.kafka.common.record;
import java.io.IOException;
/**
* An abstraction between an underlying input stream and record iterators, a {@link LogInputStream} only returns
* the batches at one level. For magic values 0 and 1, this means that it can either handle iteration
* at the top level of the log or deep iteration within the payload of a single message, but it does not attempt
* to handle both. For magic value 2, this is only used for iterating over the top-level record batches (inner
* records do not follow the {@link RecordBatch} interface.
*
* The generic typing allows for implementations which present only a view of the log entries, which enables more
* efficient iteration when the record data is not actually needed. See for example
* {@link FileLogInputStream.FileChannelRecordBatch} in which the record is not brought into memory until needed.
*
* @param <T> Type parameter of the log entry
*/
interface LogInputStream<T extends RecordBatch> {
/**
* Get the next record batch from the underlying input stream.
*
* @return The next record batch or null if there is none
* @throws IOException for any IO errors
*/
T nextBatch() throws IOException;
}