+package de.juplo.kafka;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.common.TopicPartition;
+
+import java.time.Clock;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Collection;
+import java.util.Map;
+
+
+@RequiredArgsConstructor
+@Slf4j
+public class SumRebalanceListener implements PollIntervalAwareConsumerRebalanceListener
+{
+ private final SumRecordHandler handler;
+ private final PartitionStatisticsRepository repository;
+ private final String id;
+ private final String topic;
+ private final Clock clock;
+ private final Duration commitInterval;
+ private final Consumer<String, String> consumer;
+
+ private Instant lastCommit = Instant.EPOCH;
+
+ @Override
+ public void onPartitionsAssigned(Collection<TopicPartition> partitions)
+ {
+ partitions.forEach(tp ->
+ {
+ Integer partition = tp.partition();
+ Long offset = consumer.position(tp);
+ log.info("{} - adding partition: {}, offset={}", id, partition, offset);
+ StatisticsDocument document =
+ repository
+ .findById(Integer.toString(partition))
+ .orElse(new StatisticsDocument(partition));
+ if (document.offset >= 0)
+ {
+ // Only seek, if a stored offset was found
+ // Otherwise: Use initial offset, generated by Kafka
+ consumer.seek(tp, document.offset);
+ }
+ handler.addPartition(partition, document.statistics);
+ });
+ }
+
+ @Override
+ public void onPartitionsRevoked(Collection<TopicPartition> partitions)
+ {
+ partitions.forEach(tp ->
+ {
+ Integer partition = tp.partition();
+ Long newOffset = consumer.position(tp);
+ log.info(
+ "{} - removing partition: {}, offset of next message {})",
+ id,
+ partition,
+ newOffset);
+ Map<String, Map<String, Long>> removed = handler.removePartition(partition);
+ repository.save(new StatisticsDocument(partition, removed, consumer.position(tp)));
+ });
+ }
+
+
+ @Override
+ public void beforeNextPoll()
+ {
+ if (lastCommit.plus(commitInterval).isBefore(clock.instant()))
+ {
+ log.debug("Storing data and offsets, last commit: {}", lastCommit);
+ handler.getSeen().forEach((partiton, statistics) -> repository.save(
+ new StatisticsDocument(
+ partiton,
+ statistics,
+ consumer.position(new TopicPartition(topic, partiton)))));
+ lastCommit = clock.instant();
+ }
+ }
+}