stevenzwu commented on code in PR #8553: URL: https://github.com/apache/iceberg/pull/8553#discussion_r1338815111
########## flink/v1.17/flink/src/main/java/org/apache/iceberg/flink/source/eventtimeextractor/EventTimeExtractorRecordEmitter.java: ########## @@ -0,0 +1,76 @@ +/* + * 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.eventtimeextractor; + +import org.apache.flink.api.common.eventtime.Watermark; +import org.apache.flink.api.connector.source.SourceOutput; +import org.apache.iceberg.flink.source.reader.RecordAndPosition; +import org.apache.iceberg.flink.source.reader.SerializableRecordEmitter; +import org.apache.iceberg.flink.source.split.IcebergSourceSplit; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Emitter which emits the record with event time and updates the split position. + * + * <p>The Emitter also emits watermarks at the beginning of every split, and sets the event + * timestamp based on the provided {@link IcebergEventTimeExtractor}. + */ +public final class EventTimeExtractorRecordEmitter<T> implements SerializableRecordEmitter<T> { + private static final Logger LOG = LoggerFactory.getLogger(EventTimeExtractorRecordEmitter.class); + private final IcebergEventTimeExtractor timeExtractor; + private String lastSplit = null; + private long watermark; + + public EventTimeExtractorRecordEmitter(IcebergEventTimeExtractor timeExtractor) { + this.timeExtractor = timeExtractor; + } + + @Override + public void emitRecord( + RecordAndPosition<T> element, SourceOutput<T> output, IcebergSourceSplit split) { + if (!split.splitId().equals(lastSplit)) { + long newWatermark = timeExtractor.extractWatermark(split); + if (newWatermark < watermark) { + LOG.warn( + "Watermark decreased. PreviousWM {}, currentWM {}, previousSplit {}, currentSplit {}.", + watermark, + newWatermark, + lastSplit, + split.splitId()); + } + watermark = newWatermark; + output.emitWatermark(new Watermark(watermark)); + lastSplit = split.splitId(); + } + + long eventTime = timeExtractor.extractEventTime(element.record()); + if (eventTime <= watermark) { + LOG.warn( + "Late event arrived. PreviousWM {}, split {}, eventTime {}, record {}.", + watermark, + split, + eventTime, + element.record()); + } + + output.collect(element.record(), eventTime); Review Comment: > Are you suggesting, that we should use output.collect(element.record()); instead of output.collect(element.record(), eventTime);? Yes, that is what I am suggesting. Looking at the Javadoc, `collect(T record, long timestamp)` is mainly for ` Kafka or Kinesis, which store a timestamp with each event.` In Kafka case, the timestamp is extracted from Kafka `ConsumerRecord` metadata field, which can be set by producer or broker. But we don't have such equivalent per-record timestamp metadata in Iceberg. https://github.com/stevenzwu/flink-connector-kafka/blob/main/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/source/reader/KafkaRecordEmitter.java#L52 Regarding the exception, this is sth I don't fully understand. The emitter already emits watermark, that is not enough for source watermark alignment? The exception was throw from tumbling window operator, which requires the event timestamp per record. watermark strategy can be [set and overridden after the source](https://nightlies.apache.org/flink/flink-docs-release-1.17/docs/dev/datastream/event-time/generating_watermarks/#using-watermark-strategies) or can be [passed into the source directly](https://nightlies.apache.org/flink/flink-docs-release-1.17/docs/dev/datastream/event-time/generating_watermarks/#watermark-strategies-and-the-kafka-connector). -- 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]
