lianetm commented on code in PR #16885: URL: https://github.com/apache/kafka/pull/16885#discussion_r1727373275
########## clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/ApplicationEventProcessor.java: ########## @@ -256,14 +271,176 @@ private void process(final UnsubscribeEvent event) { } } - private void process(final ResetPositionsEvent event) { - CompletableFuture<Void> future = requestManagers.offsetsRequestManager.resetPositionsIfNeeded(); - future.whenComplete(complete(event.future())); + /** + * + * Fetch committed offsets and use them to update positions in the subscription state. If no + * committed offsets available, fetch offsets from the leader. + */ + private void process(final UpdateFetchPositionsEvent updateFetchPositionsEvent) { + try { + // The event could be completed in the app thread before it got to be + // processed in the background (ex. interrupted) + if (updateFetchPositionsEvent.future().isCompletedExceptionally()) { + log.debug("UpdateFetchPositions event {} was completed exceptionally before it " + + "got time to be processed.", updateFetchPositionsEvent); + return; + } + + // Validate positions using the partition leader end offsets, to detect if any partition + // has been truncated due to a leader change. This will trigger an OffsetForLeaderEpoch + // request, retrieve the partition end offsets, and validate the current position + // against it. It will throw an exception if log truncation is detected. + requestManagers.offsetsRequestManager.validatePositionsIfNeeded(); + + boolean hasAllFetchPositions = subscriptions.hasAllFetchPositions(); + if (hasAllFetchPositions) { + updateFetchPositionsEvent.future().complete(true); + return; + } + + // Reset positions using committed offsets retrieved from the group coordinator, for any + // partitions which do not have a valid position and are not awaiting reset. This will + // trigger an OffsetFetch request and update positions with the offsets retrieved. This + // will only do a coordinator lookup if there are partitions which have missing + // positions, so a consumer with manually assigned partitions can avoid a coordinator + // dependence by always ensuring that assigned partitions have an initial position. + if (requestManagers.commitRequestManager.isPresent()) { + CompletableFuture<Void> initWithCommittedOffsetsResult = initWithCommittedOffsetsIfNeeded(updateFetchPositionsEvent); + initWithCommittedOffsetsResult.whenComplete((__, error) -> { + if (error == null) { + // Retrieve partition offsets to init positions for partitions that still + // don't have a valid position + initWithPartitionOffsetsIfNeeded(updateFetchPositionsEvent); + } else { + updateFetchPositionsEvent.future().completeExceptionally(error); + } + }); + } else { + initWithPartitionOffsetsIfNeeded(updateFetchPositionsEvent); + } + + } catch (Exception e) { + updateFetchPositionsEvent.future().completeExceptionally(maybeWrapAsKafkaException(e)); + } } - private void process(final ValidatePositionsEvent event) { - CompletableFuture<Void> future = requestManagers.offsetsRequestManager.validatePositionsIfNeeded(); - future.whenComplete(complete(event.future())); + private void initWithPartitionOffsetsIfNeeded(final UpdateFetchPositionsEvent updateFetchPositionsEvent) { + try { + // If there are partitions still needing a position and a reset policy is defined, + // request reset using the default policy. If no reset strategy is defined and there + // are partitions with a missing position, then we will raise a NoOffsetForPartitionException exception. + subscriptions.resetInitializingPositions(); + + // Reset positions using partition offsets retrieved from the leader, for any partitions + // which are awaiting reset. This will trigger a ListOffset request, retrieve the + // partition offsets according to the strategy (ex. earliest, latest), and update the + // positions. + CompletableFuture<Void> resetPositionsFuture = requestManagers.offsetsRequestManager.resetPositionsIfNeeded(); + + resetPositionsFuture.whenComplete((result, error) -> { + if (updateFetchPositionsEvent.future().isDone()) { + log.debug("UpdateFetchPositions event {} had already expired when reset " + + "positions completed.", updateFetchPositionsEvent); + return; + } + if (error == null) { + updateFetchPositionsEvent.future().complete(false); + } else { + updateFetchPositionsEvent.future().completeExceptionally(error); + } + }); + } catch (Exception e) { + updateFetchPositionsEvent.future().completeExceptionally(e); Review Comment: uhm I wasn't completely sure about this, but after checking in detail seems to make sense to wrap here. I was concerned that maybe we would mistakenly wrap something that was expected from the API, given that we know perform in the background lots of operations that were in the app thread before. But we do handle the expected errors in the updatePositions flow and requests, and use them to complete the future). So this would really be for unexpected errors in the flow I would say, and ok to wrap. Done -- 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: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org