in flink-connector-kafka/src/main/java/org/apache/flink/streaming/connectors/kafka/FlinkKafkaConsumerBase.java [1010:1061]
public final void snapshotState(FunctionSnapshotContext context) throws Exception {
if (!running) {
LOG.debug("snapshotState() called on closed source");
} else {
unionOffsetStates.clear();
final AbstractFetcher<?, ?> fetcher = this.kafkaFetcher;
if (fetcher == null) {
// the fetcher has not yet been initialized, which means we need to return the
// originally restored offsets or the assigned partitions
for (Map.Entry<KafkaTopicPartition, Long> subscribedPartition :
subscribedPartitionsToStartOffsets.entrySet()) {
unionOffsetStates.add(
Tuple2.of(
subscribedPartition.getKey(), subscribedPartition.getValue()));
}
if (offsetCommitMode == OffsetCommitMode.ON_CHECKPOINTS) {
// the map cannot be asynchronously updated, because only one checkpoint call
// can happen
// on this function at a time: either snapshotState() or
// notifyCheckpointComplete()
pendingOffsetsToCommit.put(context.getCheckpointId(), restoredState);
}
} else {
HashMap<KafkaTopicPartition, Long> currentOffsets = fetcher.snapshotCurrentState();
if (offsetCommitMode == OffsetCommitMode.ON_CHECKPOINTS) {
// the map cannot be asynchronously updated, because only one checkpoint call
// can happen
// on this function at a time: either snapshotState() or
// notifyCheckpointComplete()
pendingOffsetsToCommit.put(context.getCheckpointId(), currentOffsets);
}
for (Map.Entry<KafkaTopicPartition, Long> kafkaTopicPartitionLongEntry :
currentOffsets.entrySet()) {
unionOffsetStates.add(
Tuple2.of(
kafkaTopicPartitionLongEntry.getKey(),
kafkaTopicPartitionLongEntry.getValue()));
}
}
if (offsetCommitMode == OffsetCommitMode.ON_CHECKPOINTS) {
// truncate the map of pending offsets to commit, to prevent infinite growth
while (pendingOffsetsToCommit.size() > MAX_NUM_PENDING_CHECKPOINTS) {
pendingOffsetsToCommit.remove(0);
}
}
}
}