tweise commented on a change in pull request #15924: URL: https://github.com/apache/flink/pull/15924#discussion_r640180553
########## File path: flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/source/hybrid/HybridSourceReader.java ########## @@ -0,0 +1,213 @@ +/* + * 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 source reader. + * + * <p>This reader is setup with a sequence of underlying source readers. At a given point in time, + * one of these readers is active. Underlying readers are opened and closed on demand as determined + * by the enumerator, which selects the active reader via {@link SwitchSourceEvent}. + * + * <p>When the underlying reader has consumed all input, {@link HybridSourceReader} sends {@link + * SourceReaderFinishedEvent} to the coordinator and waits for the {@link SwitchSourceEvent}. + */ +public class HybridSourceReader<T, SplitT extends SourceSplit> + implements SourceReader<T, HybridSourceSplit<SplitT>> { + private static final Logger LOG = LoggerFactory.getLogger(HybridSourceReader.class); + // Controls the interval at which to indicate to the coordinator that the current reader + // has consumed all input and the next source can be activated. This is necessary to not flood + // the coordinator with duplicate events. + 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( Review comment: It's related to the jitter question. Please take a look at the comment that I added. The important part is that this repeats in a tight loop. -- 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
