poll

Waits up to timeout for at least one record, then returns it and any records already available. Returns empty only when this tail has reached the partition's tip and nothing arrived before timeout.

An empty return is therefore a claim about position rather than about quiet. EmptyPollMeansTheTipWasReached (allium/log-processor-lifecycle.allium) makes that a safety requirement: leadership is claimed on this observation, so an implementation MUST NOT report empty for any other reason — not on a fetch failure, a dropped subscription, or a timer of its own. A tail that can no longer read has to throw, because a reader that has stopped reading must not be able to conclude that nobody has written.

A timeout of zero or less returns what is already buffered without waiting, and Duration.INFINITE waits until a record arrives or the caller is cancelled. Calls on one tail must not overlap.