stevenzwu commented on a change in pull request #4269: URL: https://github.com/apache/iceberg/pull/4269#discussion_r825224154
########## 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: This is a great question. I looked into Flink code again. Throwing an IOException will cause the fetcher to be closed so that we don't have to poll the fetcher again. that is not a problem, because new split later will create new fetcher. This is the `FetchTask` that calls `splitReader.fetch`. We can see that the return value can't be null. I agree that this is a little weird behavior. cc @tweise ``` public boolean run() throws IOException { try { if (!isWakenUp() && lastRecords == null) { lastRecords = splitReader.fetch(); } if (!isWakenUp()) { // The order matters here. We must first put the last records into the queue. // This ensures the handling of the fetched records is atomic to wakeup. if (elementsQueue.put(fetcherIndex, lastRecords)) { if (!lastRecords.finishedSplits().isEmpty()) { // The callback does not throw InterruptedException. splitFinishedCallback.accept(lastRecords.finishedSplits()); } lastRecords = null; } } } ``` -- 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]
