stevenzwu commented on a change in pull request #2105: URL: https://github.com/apache/iceberg/pull/2105#discussion_r632186271
########## File path: flink/src/main/java/org/apache/iceberg/flink/source/enumerator/AbstractIcebergEnumerator.java ########## @@ -0,0 +1,177 @@ +/* + * 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.enumerator; + +import java.io.IOException; +import java.util.Iterator; +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.atomic.AtomicReference; +import javax.annotation.Nullable; +import org.apache.flink.api.connector.source.SourceEvent; +import org.apache.flink.api.connector.source.SplitEnumerator; +import org.apache.flink.api.connector.source.SplitEnumeratorContext; +import org.apache.iceberg.flink.source.IcebergSourceEvents; +import org.apache.iceberg.flink.source.assigner.GetSplitResult; +import org.apache.iceberg.flink.source.assigner.SplitAssigner; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * TODO: publish enumerator monitor metrics like number of pending metrics + * after FLINK-21000 is resolved + */ +abstract class AbstractIcebergEnumerator implements + SplitEnumerator<IcebergSourceSplit, IcebergEnumeratorState> { + + private static final Logger LOG = LoggerFactory.getLogger(AbstractIcebergEnumerator.class); + + private final SplitEnumeratorContext<IcebergSourceSplit> enumeratorContext; + private final SplitAssigner assigner; + private final IcebergEnumeratorConfig enumeratorConfig; + private final Map<Integer, String> readersAwaitingSplit; + private final AtomicReference<CompletableFuture<Void>> availableFuture; + + AbstractIcebergEnumerator( + SplitEnumeratorContext<IcebergSourceSplit> enumeratorContext, + SplitAssigner assigner, + IcebergEnumeratorConfig enumeratorConfig) { + this.enumeratorContext = enumeratorContext; + this.assigner = assigner; + this.enumeratorConfig = enumeratorConfig; + this.readersAwaitingSplit = new LinkedHashMap<>(); + this.availableFuture = new AtomicReference<>(); + } + + @Override + public void start() { + assigner.start(); + } + + @Override + public void close() throws IOException { + assigner.close(); + } + + /** + * Iceberg source uses a custom event inside handleSourceEvent + * so that we can piggyback the finishedSplitIds in SplitRequestEvent. + * We can move the logic back into this method once FLINK-21364 is resolved. + */ + @Override + public void handleSplitRequest(int subtaskId, @Nullable String requesterHostname) { + throw new UnsupportedOperationException("Iceberg source uses its own SplitRequestEvent"); + } + + @Override + public void handleSourceEvent(int subtaskId, SourceEvent sourceEvent) { + if (sourceEvent instanceof IcebergSourceEvents.SplitRequestEvent) { + final IcebergSourceEvents.SplitRequestEvent splitRequestEvent = + (IcebergSourceEvents.SplitRequestEvent) sourceEvent; + LOG.info("Received request split event from subtask {}", subtaskId); + assigner.onCompletedSplits(splitRequestEvent.finishedSplitIds()); + readersAwaitingSplit.put(subtaskId, splitRequestEvent.requesterHostname()); + assignSplits(); + } else { + throw new IllegalArgumentException(String.format( + "Received unknown event %s from subtask %d", sourceEvent, subtaskId)); + } + } + + @Override + public void addSplitsBack(List<IcebergSourceSplit> splits, int subtaskId) { + LOG.info("Add {} splits back to the pool for failed subtask {}: {}", + splits.size(), subtaskId, splits); + assigner.onUnassignedSplits(splits); + assignSplits(); + } + + @Override + public void addReader(int subtaskId) { + LOG.info("Added reader: {}", subtaskId); + } + + private void assignSplits() { + LOG.info("Assigning splits for {} awaiting readers", readersAwaitingSplit.size()); + final Iterator<Map.Entry<Integer, String>> awaitingReader = + readersAwaitingSplit.entrySet().iterator(); + while (awaitingReader.hasNext()) { + final Map.Entry<Integer, String> nextAwaiting = awaitingReader.next(); + // if the reader that requested another split has failed in the meantime, remove + // it from the list of waiting readers + if (!enumeratorContext.registeredReaders().containsKey(nextAwaiting.getKey())) { + awaitingReader.remove(); + continue; + } + + final int awaitingSubtask = nextAwaiting.getKey(); + final String hostname = nextAwaiting.getValue(); + final GetSplitResult getResult = assigner.getNext(hostname); + if (getResult.status() == GetSplitResult.Status.AVAILABLE) { + LOG.info("Assign split to subtask {}: {}", awaitingSubtask, getResult.split()); + enumeratorContext.assignSplit(getResult.split(), awaitingSubtask); + awaitingReader.remove(); + } else if (getResult.status() == GetSplitResult.Status.CONSTRAINED) { + getAvailableFutureIfNeeded(); + break; + } else if (getResult.status() == GetSplitResult.Status.UNAVAILABLE) { + if (shouldWaitForMoreSplits()) { + getAvailableFutureIfNeeded(); + break; + } else { + LOG.info("No more splits available for subtask {}", awaitingSubtask); + enumeratorContext.signalNoMoreSplits(awaitingSubtask); + awaitingReader.remove(); + } + } else { + throw new IllegalArgumentException("Unsupported status: " + getResult.status()); + } + } + } + + /** + * @return true if enumerator should wait for splits + * like in the continuous enumerator case + */ + protected abstract boolean shouldWaitForMoreSplits(); + + private synchronized void getAvailableFutureIfNeeded() { + if (availableFuture.get() != null) { + return; + } + CompletableFuture<Void> future = assigner.isAvailable(); + future.thenAccept(ignore -> + // Must run assignSplits in coordinator thread + // because the future may be completed from other threads. + // E.g., in event time alignment assigner, + // watermark advancement from another source may + // cause the available future to be completed + enumeratorContext.runInCoordinatorThread(() -> { + LOG.debug("Executing callback of assignSplits"); + availableFuture.set(null); + assignSplits(); + })); + availableFuture.set(future); + LOG.debug("Registered callback for future available splits"); + } Review comment: I will email you a few keynote presentation slides. let's see if the animation helps understanding the interactions. -- 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: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
