DriverInstanceActor.RunWriteAsync cancelled every write with a hard-coded,
undilated 5 s CancellationTokenSource, so writeTimeout / DefaultWriteTimeout
(then 10 s) only ever served as the pessimistic abandon bound: a configured
bound above 5 s never took effect.
The write's token is now cancelled at the configured write timeout; a write
that ignores its token is abandoned WriteAbandonGrace later (half the
timeout, at most 2 s) so a token-honouring driver still gets to answer the
cancellation itself. Both bounds run on an injectable TimeProvider
(Props writeClock, System by default).
DefaultWriteTimeout is now 5 s (cancel 5 s, abandon 7 s), not 10 s: the
host's write Ask is 8 s, and a write allowed to run past it would already
have been reported as a timeout and its node reverted while the device could
still take the value - the exact failure the off-mailbox write work fixed.
Production behaviour is therefore unchanged for the cancel (5 s) and tighter
for a token-ignoring driver (abandoned at 7 s instead of 10 s, i.e. inside
the Ask). DriverHostActor's Ask comment updated to match.
Tests (DriverInstanceActorConcurrentWriteTests, manual clock copied from
Ab.Transport.Tests into Runtime.Tests/Harness/ManualTimeProvider):
- a write held past 6 s under a 10 s write timeout succeeds;
- positive control: at 10 s the token is cancelled ("write timeout");
- a token-ignoring write is still pending at 10 s and abandoned (BadTimeout)
after the grace.
Mutation checks: a fixed 5 s token on the same clock fails the first test;
dropping the grace fails the third (and the second, where the abandon then
races the cancellation).
342a825d re-check: its held-write tests were written around the undilated
5 s cap. Connect() now defaults the write timeout to the DILATED presence
budget, so a held, explicitly-released write no longer races any undilated
deadline; tests about the bound pass their own. AwaitWritesEntered keeps its
20 ms interval (doc updated).
Runtime.Tests: 946 passed / 3 skipped / 0 failed at AKKA_TEST_TIMEFACTOR 3
and 1. Solution Release build: 0 warnings.
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
Joseph Doherty