stevenzwu commented on a change in pull request #13574: URL: https://github.com/apache/flink/pull/13574#discussion_r502831204
########## File path: flink-connectors/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/source/reader/KafkaPartitionSplitReader.java ########## @@ -0,0 +1,398 @@ +/* + 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.kafka.source.reader; + +import org.apache.flink.api.java.tuple.Tuple3; +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.SplitsAddition; +import org.apache.flink.connector.base.source.reader.splitreader.SplitsChange; +import org.apache.flink.connector.kafka.source.KafkaSourceOptions; +import org.apache.flink.connector.kafka.source.reader.deserializer.KafkaRecordDeserializer; +import org.apache.flink.connector.kafka.source.split.KafkaPartitionSplit; +import org.apache.flink.util.Collector; +import org.apache.flink.util.FlinkRuntimeException; +import org.apache.flink.util.Preconditions; + +import org.apache.kafka.clients.consumer.ConsumerConfig; +import org.apache.kafka.clients.consumer.ConsumerRecord; +import org.apache.kafka.clients.consumer.ConsumerRecords; +import org.apache.kafka.clients.consumer.KafkaConsumer; +import org.apache.kafka.common.TopicPartition; +import org.apache.kafka.common.errors.WakeupException; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nullable; + +import java.io.IOException; +import java.time.Duration; +import java.util.ArrayList; +import java.util.Collection; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import java.util.Properties; +import java.util.Random; +import java.util.Set; +import java.util.StringJoiner; + +/** + * A {@link SplitReader} implementation that reads records from Kafka partitions. + * + * <p>The returned type are in the format of {@code tuple3(record, offset and timestamp}. + * + * @param <T> the type of the record to be emitted from the Source. + */ +public class KafkaPartitionSplitReader<T> implements SplitReader<Tuple3<T, Long, Long>, KafkaPartitionSplit> { + private static final Logger LOG = LoggerFactory.getLogger(KafkaPartitionSplitReader.class); + private static final long POLL_TIMEOUT = 10000L; + + private final KafkaConsumer<byte[], byte[]> consumer; + private final KafkaRecordDeserializer<T> deserializationSchema; + private final Map<TopicPartition, Long> stoppingOffsets; + private final SimpleCollector<T> collector; + private final String groupId; + + public KafkaPartitionSplitReader( + Properties props, + KafkaRecordDeserializer<T> deserializationSchema) { + Properties consumerProps = new Properties(); + consumerProps.putAll(props); + consumerProps.setProperty(ConsumerConfig.CLIENT_ID_CONFIG, createConsumerClientId(props)); + this.consumer = new KafkaConsumer<>(consumerProps); + this.stoppingOffsets = new HashMap<>(); + this.deserializationSchema = deserializationSchema; + this.collector = new SimpleCollector<>(); + this.groupId = consumerProps.getProperty(ConsumerConfig.GROUP_ID_CONFIG); + } + + @Override + public RecordsWithSplitIds<Tuple3<T, Long, Long>> fetch() throws IOException { + KafkaPartitionSplitRecords<Tuple3<T, Long, Long>> recordsBySplits = new KafkaPartitionSplitRecords<>(); + ConsumerRecords<byte[], byte[]> consumerRecords; + try { + consumerRecords = consumer.poll(Duration.ofMillis(POLL_TIMEOUT)); + } catch (WakeupException we) { + return recordsBySplits; + } + + List<TopicPartition> finishedPartitions = new ArrayList<>(); + for (TopicPartition tp : consumerRecords.partitions()) { + long stoppingOffset = getStoppingOffset(tp); + String splitId = tp.toString(); + Collection<Tuple3<T, Long, Long>> recordsForSplit = recordsBySplits.recordsForSplit(splitId); + for (ConsumerRecord<byte[], byte[]> consumerRecord : consumerRecords.records(tp)) { + // Stop consuming from this partition if the offsets has reached the stopping offset. + // Note that there are two cases, either case finishes a split: + // 1. After processing a record with offset of "stoppingOffset - 1". The split reader + // should not continue fetching because the record with stoppingOffset may not exist. + // 2. Before processing a record whose offset is greater than or equals to the stopping + // offset. This should only happens when case 1 was not met due to log compaction or + // log retention. + // Case 2 is handled here. Case 1 is handled after the record is processed. + if (consumerRecord.offset() >= stoppingOffset) { + finishSplitAtRecord(tp, stoppingOffset, consumerRecord.offset(), + finishedPartitions, recordsBySplits); + break; + } + // Add the record to the partition collector. + try { + deserializationSchema.deserialize(consumerRecord, collector); + collector.getRecords().forEach(r -> + recordsForSplit.add(new Tuple3<>(r, + consumerRecord.offset(), + consumerRecord.timestamp()))); + // Finish the split because there might not be any message after this point. Keep polling + // will just block forever. + if (consumerRecord.offset() == stoppingOffset - 1) { + finishSplitAtRecord(tp, stoppingOffset, consumerRecord.offset(), + finishedPartitions, recordsBySplits); + } + } catch (Exception e) { + throw new IOException("Failed to deserialize consumer record due to", e); + } finally { + collector.reset(); + } + } + } + // Unassign the partitions that has finished. + if (!finishedPartitions.isEmpty()) { + unassignPartitions(finishedPartitions); + } + recordsBySplits.prepareForRead(); + return recordsBySplits; + } + + @Override + public void handleSplitsChanges(SplitsChange<KafkaPartitionSplit> splitsChange) { + // Get all the partition assignments and stopping offsets. + if (!(splitsChange instanceof SplitsAddition)) { + throw new UnsupportedOperationException(String.format( + "The SplitChange type of %s is not supported.", splitsChange.getClass())); + } + + // Assignment. + List<TopicPartition> newPartitionAssignments = new ArrayList<>(); + // Starting offsets. + Map<TopicPartition, Long> partitionsStartingFromSpecifiedOffsets = new HashMap<>(); + List<TopicPartition> partitionsStartingFromEarliest = new ArrayList<>(); + List<TopicPartition> partitionsStartingFromLatest = new ArrayList<>(); + // Stopping offsets. + List<TopicPartition> partitionsStoppingAtLatest = new ArrayList<>(); + Set<TopicPartition> partitionsStoppingAtCommitted = new HashSet<>(); + + // Parse the starting and stopping offsets. + splitsChange.splits().forEach(s -> { + newPartitionAssignments.add(s.getTopicPartition()); + parseStartingOffsets(s, partitionsStartingFromEarliest, partitionsStartingFromLatest, partitionsStartingFromSpecifiedOffsets); + parseStoppingOffsets(s, partitionsStoppingAtLatest, partitionsStoppingAtCommitted); + }); + + // Assign new partitions. + newPartitionAssignments.addAll(consumer.assignment()); + consumer.assign(newPartitionAssignments); + + // Seek on the newly assigned partitions to their stating offsets. + seekToStartingOffsets(partitionsStartingFromEarliest, partitionsStartingFromLatest, partitionsStartingFromSpecifiedOffsets); + // Setup the stopping offsets. + acquireAndSetStoppingOffsets(partitionsStoppingAtLatest, partitionsStoppingAtCommitted); + + // After acquiring the starting and stopping offsets, remove the empty splits if necessary. + removeEmptySplits(); + + maybeLogSplitChangesHandlingResult(splitsChange); + } + + @Override + public void wakeUp() { + consumer.wakeup(); + } + + // --------------- private helper method ---------------------- + + private void parseStartingOffsets( + KafkaPartitionSplit split, + List<TopicPartition> partitionsStartingFromEarliest, + List<TopicPartition> partitionsStartingFromLatest, + Map<TopicPartition, Long> partitionsStartingFromSpecifiedOffsets) { + TopicPartition tp = split.getTopicPartition(); + // Parse starting offsets. + if (split.getStartingOffset() == KafkaPartitionSplit.EARLIEST_OFFSET) { + partitionsStartingFromEarliest.add(tp); + } else if (split.getStartingOffset() == KafkaPartitionSplit.LATEST_OFFSET) { + partitionsStartingFromLatest.add(tp); + } else if (split.getStartingOffset() == KafkaPartitionSplit.COMMITTED_OFFSET) { + // Do nothing here, the consumer will first try to get the committed offsets of + // these partitions by default. + } else { + partitionsStartingFromSpecifiedOffsets.put(tp, split.getStartingOffset()); + } + } + + private void parseStoppingOffsets( + KafkaPartitionSplit split, + List<TopicPartition> partitionsStoppingAtLatest, + Set<TopicPartition> partitionsStoppingAtCommitted) { + TopicPartition tp = split.getTopicPartition(); + split.getStoppingOffset().ifPresent(stoppingOffset -> { + if (stoppingOffset >= 0) { + stoppingOffsets.put(tp, stoppingOffset); + } else if (stoppingOffset == KafkaPartitionSplit.LATEST_OFFSET) { + partitionsStoppingAtLatest.add(tp); + } else if (stoppingOffset == KafkaPartitionSplit.COMMITTED_OFFSET) { + partitionsStoppingAtCommitted.add(tp); + } else { + // This should not happen. + throw new FlinkRuntimeException(String.format( + "Invalid stopping offset %d for partition %s", stoppingOffset, tp)); + } + }); + } + + private void seekToStartingOffsets( + List<TopicPartition> partitionsStartingFromEarliest, + List<TopicPartition> partitionsStartingFromLatest, + Map<TopicPartition, Long> partitionsStartingFromSpecifiedOffsets) { + + if (!partitionsStartingFromEarliest.isEmpty()) { + LOG.trace("Seeking starting offsets to beginning: {}", partitionsStartingFromEarliest); + consumer.seekToBeginning(partitionsStartingFromEarliest); + } + + if (!partitionsStartingFromLatest.isEmpty()) { + LOG.trace("Seeking starting offsets to end: {}", partitionsStartingFromLatest); + consumer.seekToEnd(partitionsStartingFromLatest); + } + + if (!partitionsStartingFromSpecifiedOffsets.isEmpty()) { + LOG.trace("Seeking starting offsets to specified offsets: {}", partitionsStartingFromSpecifiedOffsets); + partitionsStartingFromSpecifiedOffsets.forEach(consumer::seek); + } + } + + private void acquireAndSetStoppingOffsets( + List<TopicPartition> partitionsStoppingAtLatest, + Set<TopicPartition> partitionsStoppingAtCommitted) { + Map<TopicPartition, Long> endOffset = consumer.endOffsets(partitionsStoppingAtLatest); + stoppingOffsets.putAll(endOffset); + consumer.committed(partitionsStoppingAtCommitted).forEach((tp, offsetAndMetadata) -> { + Preconditions.checkNotNull(offsetAndMetadata, String.format( + "Partition %s should stop at committed offset. " + + "But there is no committed offset of this partition for group %s", tp, groupId)); + stoppingOffsets.put(tp, offsetAndMetadata.offset()); + }); + } + + private void removeEmptySplits() { + List<TopicPartition> emptySplits = new ArrayList<>(); + // If none of the partitions have any records, + for (TopicPartition tp : consumer.assignment()) { + if (consumer.position(tp) >= getStoppingOffset(tp)) { + emptySplits.add(tp); + } + } + if (!emptySplits.isEmpty()) { + unassignPartitions(emptySplits); + } + } + + private void maybeLogSplitChangesHandlingResult(SplitsChange<KafkaPartitionSplit> splitsChange) { + if (LOG.isDebugEnabled()) { + StringJoiner splitsInfo = new StringJoiner(","); + for (KafkaPartitionSplit split : splitsChange.splits()) { + long startingOffset = consumer.position(split.getTopicPartition()); + long stoppingOffset = getStoppingOffset(split.getTopicPartition()); + splitsInfo.add(String.format("[%s, start:%d, stop: %d]", + split.getTopicPartition(), startingOffset, stoppingOffset)); + } + LOG.debug("SplitsChange handling result: {}", splitsInfo.toString()); + } + } + + private void unassignPartitions(Collection<TopicPartition> partitionsToUnassign) { + Collection<TopicPartition> newAssignment = new HashSet<>(consumer.assignment()); + newAssignment.removeAll(partitionsToUnassign); + consumer.assign(newAssignment); + } + + private String createConsumerClientId(Properties props) { + String prefix = props.getProperty(KafkaSourceOptions.CLIENT_ID_PREFIX.key()); + return prefix + "-" + new Random().nextLong(); Review comment: can we pass in subtaskId and append subtaskId as suffix? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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