C0urante commented on code in PR #13801: URL: https://github.com/apache/kafka/pull/13801#discussion_r1417751374
########## connect/runtime/src/main/java/org/apache/kafka/connect/storage/ConnectorOffsetBackingStore.java: ########## @@ -279,15 +290,54 @@ public Future<Void> set(Map<ByteBuffer, ByteBuffer> values, Callback<Void> callb throw new IllegalStateException("At least one non-null offset store must be provided"); } - return primaryStore.set(values, (primaryWriteError, ignored) -> { + List<ByteBuffer> partitionsWithTombstoneOffsets = values.entrySet().stream() + .filter(offsetEntry -> offsetEntry.getValue() == null) + .map(Map.Entry::getKey).collect(Collectors.toList()); + + Map<ByteBuffer, ByteBuffer> tombstoneOffsets = new HashMap<>(); + for (ByteBuffer partition : partitionsWithTombstoneOffsets) { + tombstoneOffsets.put(partition, null); + } + Map<ByteBuffer, ByteBuffer> regularOffsets = values.entrySet().stream() + .filter(offsetEntry -> offsetEntry.getValue() != null) + .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)); + + // If the supplied offsets contain tombstone values, then tombstone offsets are extracted first, + // written to the secondary store in a synchronous manner and then to the primary store. + // This is because, if a tombstone offset is successfully written to the per-connector offsets topic, + // but cannot be written to the global offsets topic, then the global offsets topic will still contain that + // source offset, but the per-connector topic will not. Due to the fallback-on-global logic used by the worker, + // if a task requests offsets for one of the tombstoned partitions, the worker will provide it with the + // offsets present in the global offsets topic, instead of indicating to the task that no offsets can be found. + CompletableFuture<Void> offsetWriteFuture = CompletableFuture.completedFuture(null); + if (secondaryStore != null && !tombstoneOffsets.isEmpty()) { + offsetWriteFuture.thenAccept(v -> { Review Comment: This causes the passed-in lambda to be executed after `offsetWriteFuture` completes, but it doesn't cause `offsetWriteFuture::get` to block on the completion of that lambda, which means that if the caller of `ConnectorOffsetBackingStore::set` waits for the returned `Future` to complete right now, it'll complete immediately even though it's likely no offsets will have been written to either the primary or secondary store. Also, nit: when researching this behavior, I ran into `CompletableFuture::thenRun`, which is a slightly better fit than `CompletableFuture::thenAccept` (since we don't use the return value). ```suggestion offsetWriteFuture = offsetWriteFuture.thenRun(() -> { ``` -- 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