Call it `test_lock_not_corrupted_on_fast_cancel()` and includes
a detailed doc string to explain. Implemented it "cleverly" by having
the target `@acm` cancel its parent nursery after a peer, cache-hitting
task, is already waiting on the task mutex release.
Here I was thinking the bcaster (usage) maybe required a rework but,
NOPE it's just bc a checkpoint was needed in the parent task owning the
`tn` which spawns `get_sub_and_pull()` tasks to ensure the bg allocated
`an`/portal is eventually cancel-called..
Ah well, at least i started a patch for `MsgStream.subscribe()` to make
it multicast revertible.. XD
Anyway, I tossed in some checks & notes related to all that unnecessary
effort since I do think i'll move forward implementing it:
- for the `cache_hit` case always verify that the `bcast` clone is
unregistered from the common state subs after
`.subscribe().__aexit__()`.
- do a light check that the implicit `MsgStream._broadcaster` is always
the only bcrx instance left-leaked into that state.. that is until
i get the proper de-allocation/reversion from multicast -> unicast
working.
- put in mega detailed note about the required parent-task checkpoint.
Since I recently discovered a very subtle race-case that can sometimes
cause the suite to hang, seemingly due to the `an: ActorNursery`
allocated *behind* the `.trionics.maybe_open_context()` usage; this can
result in never cancelling the 'streamer' subactor despite the `main()`
timeout-guard?
This led me to dig in and find that the underlying issue was 2-fold,
- our `BroadcastReceiver` termination-mgmt semantics in
`MsgStream.subscribe()` can result in the first subscribing task to
always keep the `MsgStream._broadcaster` instance allocated; it's
never `.aclose()`ed, which makes it tough to determine (and thus
trace) when all subscriber-tasks are actually complete and
exited-from-`.subscribe()`..
- i was shield waiting `.ipc._server.Server.wait_for_no_more_peers()` in
`._runtime.async_main()`'s shutdown sequence which would then compound
the issue resulting in a SIGINT-shielded hang.. the worst kind XD
Actual changes here are just styling, printing, and some mucking with
passing the `an`-ref up to the parent task in the root-actor where i was
doing a conditional `ActorNursery.cancel()` to mk sure that was actually
the problem. Presuming this is fixed the `.pause()` i left unmasked
should never hit.
Namely while what I was actually trying to solve was why
`TransportClosed` was getting raised from `Portal.cancel_actor()` but
still useful edge case auditing either way. Also opts into the
`debug_mode` fixture with apprope timeout adjustment B)
Tyler Goodlet