--- /dev/null
+package de.juplo.kafka;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+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 ApplicationRebalanceListener implements PollIntervalAwareConsumerRebalanceListener
+{
+ private final ApplicationRecordHandler recordHandler;
+ private final StateRepository stateRepository;
+ private final String id;
+ private final Clock clock;
+ private final Duration commitInterval;
+
+ private Instant lastCommit = Instant.EPOCH;
+
+ @Override
+ public void onPartitionsAssigned(Collection<TopicPartition> partitions)
+ {
+ partitions.forEach(tp ->
+ {
+ Integer partition = tp.partition();
+ log.info("{} - adding partition: {}", id, partition);
+ StateDocument document =
+ stateRepository
+ .findById(Integer.toString(partition))
+ .orElse(new StateDocument(partition));
+ recordHandler.addPartition(partition, document.state);
+ });
+ }
+
+ @Override
+ public void onPartitionsRevoked(Collection<TopicPartition> partitions)
+ {
+ partitions.forEach(tp ->
+ {
+ Integer partition = tp.partition();
+ log.info("{} - removing partition: {}", id, partition);
+ Map<String, Long> removed = recordHandler.removePartition(partition);
+ for (String key : removed.keySet())
+ {
+ log.info(
+ "{} - Seen {} messages for partition={}|key={}",
+ id,
+ removed.get(key),
+ partition,
+ key);
+ }
+ stateRepository.save(new StateDocument(partition, removed));
+ });
+ }
+
+
+ @Override
+ public void beforeNextPoll()
+ {
+ if (lastCommit.plus(commitInterval).isBefore(clock.instant()))
+ {
+ log.debug("Storing data, last commit: {}", lastCommit);
+ recordHandler.getState().forEach((partiton, statistics) -> stateRepository.save(
+ new StateDocument(
+ partiton,
+ statistics)));
+ lastCommit = clock.instant();
+ }
+ }
+}