fix(worker): StaWaitHelper regression tests + full-drain contract notes; consolidate wait P/Invoke

2026-08-15 17:17:10 -04:00
parent 896d81e286
commit 7c9add3d73
10 changed files with 466 additions and 66 deletions
@@ -295,6 +295,14 @@ cache lock) so a cross-thread producer wakes the waiter immediately; in the live
 worker the update arrives on the STA from inside `pumpStep` itself, and the
 message wake is what carries it.

+`MWMO_INPUTAVAILABLE` makes the drain contract load-bearing: the wait wakes on
+input that is merely *present*, including input an earlier `PeekMessage` saw but
+did not remove. A `pumpStep` that drains only part of the queue — or a no-op one
+— therefore leaves a message that satisfies the wake condition forever, and the
+loop spins at 100% CPU until its deadline (deadline and reply shape still hold;
+it is a CPU fault, not a correctness one). Every `pumpStep` must drain to empty,
+as `StaRuntime.PumpPendingMessages` does.
+
 The wait slice is capped at 50 ms so `pumpStep` runs periodically even when
 nothing wakes the wait — a process with no STA message queue (unit tests drive
 these caches from ordinary threads, standing in for the STA by updating the