d 🔹 6dbdd4674f

fix: guarantee END sentinel delivery when stream bridge queue is full (#1695) ...

When MemoryStreamBridge queue reaches capacity, publish_end() previously
used the same 30s timeout + drop strategy as regular events. If the END
sentinel was dropped, subscribe() would loop forever waiting for it,
causing the SSE connection to hang indefinitely and leaking _queues and
_counters resources for that run_id.

Changes:
- publish_end() now evicts oldest regular events when queue is full to
  guarantee END sentinel delivery — the sentinel is the only signal that
  allows subscribers to terminate
- Added per-run drop counters (_dropped_counts) with dropped_count() and
  dropped_total properties for observability
- cleanup() and close() now clear drop counters
- publish() logs total dropped count per run for easier debugging

Tests:
- test_end_sentinel_delivered_when_queue_full: verifies END arrives even
  with a completely full queue
- test_end_sentinel_evicts_oldest_events: verifies eviction behavior
- test_end_sentinel_no_eviction_when_space_available: no side effects
  when queue has room
- test_concurrent_tasks_end_sentinel: 4 concurrent producer/consumer
  pairs all terminate properly
- test_dropped_count_tracking, test_dropped_total,
  test_cleanup_clears_dropped_counts, test_close_clears_dropped_counts:
  drop counter coverage

Closes #1689

Co-authored-by: voidborne-d <voidborne-d@users.noreply.github.com>

2026-04-03 20:12:30 +08:00

..

harness

fix: guarantee END sentinel delivery when stream bridge queue is full (#1695)

2026-04-03 20:12:30 +08:00