stevenzwu commented on a change in pull request #2305: URL: https://github.com/apache/iceberg/pull/2305#discussion_r666431755
########## File path: flink/src/main/java/org/apache/iceberg/flink/source/reader/ReaderFactory.java ########## @@ -0,0 +1,102 @@ +/* + * 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.iceberg.flink.source.reader; + +import java.io.IOException; +import java.io.Serializable; +import javax.annotation.Nullable; +import org.apache.flink.configuration.Configuration; +import org.apache.flink.connector.file.src.util.MutableRecordAndPosition; +import org.apache.flink.connector.file.src.util.RecordAndPosition; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; + +public interface ReaderFactory<T> extends Serializable { + + /** + * An iterator over records with their position in the file. The iterator is closeable to + * support clean resource release and recycling. + * + * @param <T> The type of the record. + */ + interface RecordIterator<T> { + + /** + * Gets the next record from the file, together with its position. + * + * <p>The position information returned with the record point to the record AFTER the + * returned record, because it defines the point where the reading should resume once the + * current record is emitted. The position information is put in the source's state when the + * record is emitted. If a checkpoint is taken directly after the record is emitted, the + * checkpoint must to describe where to resume the source reading from after that record. + * + * <p>Objects returned by this method may be reused by the iterator. By the time that this + * method is called again, no object returned from the previous call will be referenced any + * more. That makes it possible to have a single {@link MutableRecordAndPosition} object and + * return the same instance (with updated record and position) on every call. + */ + @Nullable + RecordAndPosition<T> next(); + + /** + * Releases the batch that this iterator iterated over. This is not supposed to close the + * reader and its resources, but is simply a signal that this iterator is no used any more. + * This method can be used as a hook to recycle/reuse heavyweight object structures. + */ + void releaseBatch(); + } + + /** + * A batch reader for a {@link IcebergSourceSplit} + * + * @param <T> output record type + */ + interface Reader<T> { + + /** + * Reads one batch. The method should return null when reaching the end of the input. The + * returned batch will be handed over to the processing threads as one. + * + * <p>The returned iterator object and any contained objects may be held onto by the + * source for some time, so it should not be immediately reused by the reader. + * + * <p>To implement reuse and to save object allocation, consider using a {@link + * org.apache.flink.connector.file.src.util.Pool} and recycle objects into the Pool in the + * the {@link RecordIterator#releaseBatch()} method. + */ + @Nullable + RecordIterator<T> readBatch() throws IOException; + + /** + * Closes the reader and release all resources + */ + void close() throws IOException; + } + + + /** + * Create a batch reader for the input split + * + * @param config Flink configuration + * @param split Iceberg source split + * @return a batch reader + */ + Reader<T> create(Configuration config, IcebergSourceSplit split); Review comment: make sense. will change -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
