stevenzwu commented on a change in pull request #4269: URL: https://github.com/apache/iceberg/pull/4269#discussion_r835437929
########## File path: flink/v1.14/flink/src/main/java/org/apache/iceberg/flink/source/reader/IcebergSourceSplitReader.java ########## @@ -0,0 +1,134 @@ +/* + * 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.UncheckedIOException; +import java.util.ArrayDeque; +import java.util.Queue; +import org.apache.flink.api.connector.source.SourceReaderContext; +import org.apache.flink.connector.base.source.reader.RecordsWithSplitIds; +import org.apache.flink.connector.base.source.reader.splitreader.SplitReader; +import org.apache.flink.connector.base.source.reader.splitreader.SplitsChange; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.apache.iceberg.io.CloseableIterator; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +class IcebergSourceSplitReader<T> implements SplitReader<RecordAndPosition<T>, IcebergSourceSplit> { + private static final Logger LOG = LoggerFactory.getLogger(IcebergSourceSplitReader.class); + + private final ReaderFunction<T> readerFunction; + private final int indexOfSubtask; + private final IcebergSourceReaderMetrics metrics; + private final Queue<IcebergSourceSplit> splits; + + private CloseableIterator<RecordsWithSplitIds<RecordAndPosition<T>>> currentReader; + private IcebergSourceSplit currentSplit; + private String currentSplitId; + + IcebergSourceSplitReader(ReaderFunction<T> readerFunction, + SourceReaderContext context, + IcebergSourceReaderMetrics metrics) { + this.readerFunction = readerFunction; + this.indexOfSubtask = context.getIndexOfSubtask(); + this.metrics = metrics; + this.splits = new ArrayDeque<>(); + } + + @Override + public RecordsWithSplitIds<RecordAndPosition<T>> fetch() throws IOException { + metrics.incrementSplitReaderFetchCalls(); + checkSplitOrStartNext(); + + if (currentReader.hasNext()) { + // Because Iterator#next() doesn't support checked exception, + // we need to wrap and unwrap the checked IOException with UncheckedIOException + try { + return currentReader.next(); + } catch (UncheckedIOException e) { + throw e.getCause(); + } + } else { + return finishSplit(); + } + } + + @Override + public void handleSplitsChanges(SplitsChange<IcebergSourceSplit> splitsChanges) { + LOG.info("Add splits to reader: {}", splitsChanges.splits()); + splits.addAll(splitsChanges.splits()); + metrics.incrementAssignedSplits(splitsChanges.splits().size()); + metrics.incrementAssignedBytes(calculateBytes(splitsChanges)); + } + + @Override + public void wakeUp() { + } + + @Override + public void close() throws Exception { + currentSplitId = null; + if (currentReader != null) { + currentReader.close(); + } + } + + private long calculateBytes(IcebergSourceSplit split) { + return split.task().files().stream() + .map(fileScanTask -> fileScanTask.length()) + .reduce(0L, Long::sum); + } + + private long calculateBytes(SplitsChange<IcebergSourceSplit> splitsChanges) { + return splitsChanges.splits().stream() + .map(split -> calculateBytes(split)) + .reduce(0L, Long::sum); + } + + private void checkSplitOrStartNext() throws IOException { + if (currentReader != null) { + return; + } + + IcebergSourceSplit nextSplit = splits.poll(); + if (nextSplit == null) { + throw new IOException("No split remaining"); Review comment: @yittg that is a good question. In theory, I agree it is a good behavior. I haven't figured a good way to implement the wakeUp behavior Say there is no split available from the queue. if fetch() method doesn't return, it would need to poll the `splits` queue to check for new split in some loop with sleep. if the wakerUp is called and set the wakeUp flag for the fetch method to break out of the loop and return an empty `RecordsWithSplitIds` with no records and no finished splits. We can't use wait-notify to signal btw wakeUp and fetch. Otherwise, fetch method won't do a splits queue polling and discover new splits during wait. That is also undesirable. Maybe there is other way I haven't thought about. -- 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. 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