Date: 2026-05-29
Time: 14:17
I can't read the implementation file due to permissions, but I have the full test file content. Here's the explanation based on what the tests reveal about the system.
stream-join-processor/streamjoinprocessor.py — The implementation: how buffers are indexed by key, how the watermark drives expiration, and how miss detection works for left/full outer joinsstream-join-processor/streamjoinprocessor.py:StreamJoinProcessor.advance_time — The expiration and miss-emission logic is the most complex part — it must scan for unmatched events, emit misses, and clean buffers atomicallystream-join-processor/streamjoinprocessor.py:TumblingWindowAggregator.advance_time — How window alignment and closure works, and whether it handles the edge case of events exactly on window boundariesstream-join-semantics — DDIA Ch. 11 discusses stream-stream joins vs. stream-table joins vs. table-table joins; this module implements stream-stream, worth understanding where the others differstream-join-processor/testerteststreamjoinprocessor.py — The "tester" variant likely validates these tests against an alternative implementation or stricter contractsstream-join-inner-requires-key-and-window-match — Inner join only produces a result when both key equality and |tleft - tright| <= window_duration holdstream-join-left-miss-emitted-on-expiration — Unmatched left events in a LEFT join emit a JoinResult with rightevent=None only when advancetime expires them, not eagerlystream-join-late-events-dropped-silently — Events arriving after watermark - allowedlateness are dropped and counted in stats.lateevents_dropped, never raising exceptionsstream-join-process-event-returns-immediate-matches — process_event returns matches synchronously on each call rather than batching to a flush boundarystream-join-buffers-bounded-by-window — The processor actively expires events so buffer sizes remain proportional to windowduration × eventrate, not total events processed