tweise commented on a change in pull request #15924: URL: https://github.com/apache/flink/pull/15924#discussion_r634044007
########## File path: flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/source/hybrid/HybridSourceReader.java ########## @@ -0,0 +1,201 @@ +/* + * 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.flink.connector.base.source.hybrid; + +import org.apache.flink.api.connector.source.ReaderOutput; +import org.apache.flink.api.connector.source.SourceEvent; +import org.apache.flink.api.connector.source.SourceReader; +import org.apache.flink.api.connector.source.SourceReaderContext; +import org.apache.flink.api.connector.source.SourceSplit; +import org.apache.flink.core.io.InputStatus; +import org.apache.flink.util.Preconditions; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.CompletableFuture; + +/** Hybrid source reader that delegates to the actual current source reader. */ +public class HybridSourceReader<T, SplitT extends SourceSplit> + implements SourceReader<T, HybridSourceSplit<SplitT>> { + private static final Logger LOG = LoggerFactory.getLogger(HybridSourceReader.class); + private static final int SOURCE_READER_FINISHED_EVENT_DELAY = 250; + private SourceReaderContext readerContext; + private List<SourceReader<?, SplitT>> realReaders; + private int currentSourceIndex = -1; + private long lastCheckpointId = -1; + private SourceReader<?, SplitT> currentReader; + private long lastReaderFinishedMs; + + public HybridSourceReader( + SourceReaderContext readerContext, List<SourceReader<?, SplitT>> readers) { + this.readerContext = readerContext; + this.realReaders = readers; + } + + @Override + public void start() { + setCurrentReader(0); + } + + @Override + public InputStatus pollNext(ReaderOutput output) throws Exception { + InputStatus status = currentReader.pollNext(output); + if (status == InputStatus.END_OF_INPUT) { + // trap END_OF_INPUT if this wasn't the final reader + LOG.debug( + "End of input subtask={} sourceIndex={} {}", + readerContext.getIndexOfSubtask(), + currentSourceIndex, + currentReader); + if (currentSourceIndex + 1 < realReaders.size()) { + // signal coordinator to advance readers + long currentMillis = System.currentTimeMillis(); + if (lastReaderFinishedMs + SOURCE_READER_FINISHED_EVENT_DELAY < currentMillis) { + lastReaderFinishedMs = currentMillis; + readerContext.sendSourceEventToCoordinator( + new SourceReaderFinishedEvent(currentSourceIndex, lastCheckpointId)); + } + // more data will be available from the next reader + return InputStatus.MORE_AVAILABLE; + } + } + return status; + } + + @Override + public List<HybridSourceSplit<SplitT>> snapshotState(long checkpointId) { + this.lastCheckpointId = checkpointId; + List<SplitT> state = currentReader.snapshotState(checkpointId); + return wrappedSplits(currentSourceIndex, state); + } + + public static <SplitT extends SourceSplit> List<HybridSourceSplit<SplitT>> wrappedSplits( + int readerIndex, List<SplitT> state) { + List<HybridSourceSplit<SplitT>> wrappedSplits = new ArrayList<>(state.size()); + for (SplitT split : state) { + wrappedSplits.add(new HybridSourceSplit<>(readerIndex, split)); + } + return wrappedSplits; + } + + public static <SplitT extends SourceSplit> List<SplitT> unwrappedSplits( + List<HybridSourceSplit<SplitT>> splits) { + List<SplitT> unwrappedSplits = new ArrayList<>(splits.size()); + for (HybridSourceSplit<SplitT> split : splits) { + unwrappedSplits.add(split.getWrappedSplit()); + } + return unwrappedSplits; + } + + @Override + public CompletableFuture<Void> isAvailable() { + return currentReader.isAvailable(); + } + + @Override + public void addSplits(List<HybridSourceSplit<SplitT>> splits) { + LOG.info( + "### Adding splits subtask={} sourceIndex={} {} {}", + readerContext.getIndexOfSubtask(), + currentSourceIndex, + currentReader, + splits); + List<SplitT> realSplits = new ArrayList<>(splits.size()); + for (HybridSourceSplit split : splits) { + Preconditions.checkState( + split.sourceIndex() == currentSourceIndex, + "Split %s while current source is %s", + split, + currentSourceIndex); + realSplits.add((SplitT) split.getWrappedSplit()); + } + currentReader.addSplits(realSplits); + } + + @Override + public void notifyNoMoreSplits() { + currentReader.notifyNoMoreSplits(); + LOG.debug( + "No more splits for reader subtask={} sourceIndex={} {}", + readerContext.getIndexOfSubtask(), + currentSourceIndex, + currentReader); + } + + @Override + public void handleSourceEvents(SourceEvent sourceEvent) { + if (sourceEvent instanceof SwitchSourceEvent) { + SwitchSourceEvent sse = (SwitchSourceEvent) sourceEvent; + LOG.debug( + "Switch source event: subtask={} sourceIndex={}", + readerContext.getIndexOfSubtask(), + sse.sourceIndex()); + setCurrentReader(sse.sourceIndex()); Review comment: The enumerator only switches when all readers are done. Once the enumerator switches, it will send the `SwitchSourceEvent` -- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
