Add a couple more tests to check that a parent and sub-task stream can
be lagged and recovered (depending on who's slower). Factor some of the
test machinery into a new ctx mngr to make it all happen.
The whole origin was not having an explicit open/close semantic for
streams. We have that now so this internal mechanic isn't needed and
further our streams become more correct by having `.aclose()` be
independent of cancellation.
We may get multiple re-entries to debugger by `bp_forever` sub-actor
now since the root will incrementally try to cancel it only when the tty
lock is not held.
This resolves and completes #69 allowing all RPC invocation APIs to pass
function references directly instead of explicit `str` names for the
target namespace and function (this is still done implicitly
underneath). This brings us closer to `trio`'s task running API as well
as acknowledges that any inter-host RPC system (and API) will likely
need to be implemented on top of local RPC primitives anyway. Even if
this ends up **not** being true we can always go to "function stubs" as
part of our IAC protocol or, add a new method to do explicit namespace
calls: `.run_from_module()` or whatever everyone votes on.
Resolves#69
Further, this commit drops `Actor.statespace` from the entire system
since a user can easily get this same functionality using module
level variables. Fix docs to match all these changes (luckily mostly
already done due to example scripts referencing).
Add a ``tractor._portal.StreamReceiveChannel.shield_channel()`` context
manager which allows for avoiding the closing of an IPC stream's
underlying channel for the purposes of task re-spawning. Sometimes you
might want to cancel a task consuming a stream but not tear down the IPC
between actors (the default). A common use can might be where the task's
"setup" work might need to be redone but you want to keep the
established portal / channel in tact despite the task restart.
Includes a test.
This appears to demonstrate the same bug found in #156. It looks like
cancelling a subactor with a child, while that child is running sync code,
can result in the child never getting cancelled due to some strange
condition where the internal nurseries aren't being torn down as
expected when a `trio.Cancelled` is raised.
The real issue is if the root nursery gets cancelled prior to
de-registration with the arbiter. This doesn't seem easy to
reproduce by side effect of a KBI however that is how it was
discovered in practise.
There was code from the last de-registration fix PR that I had commented
(to do with shielding arbiter dereg steps in `Actor._async_main()`) because
the block didn't seem to make a difference under infinite streaming
tests. Turns out it **for sure** is needed under certain conditions (likely
if the actor's root nursery is cancelled prior to actor nursery exit).
This was an attempt to simulate the failure mode if you manually close the
stream **before** cancelling the containing **actor**.
More tests to come I guess.
This truly reproduces #141. It turns out the problem only occurs when
we're cancelled in the middle of consuming "infinite streams".
Good news is this tests a lot of edge cases :)
Tyler Goodlet
Guillermo Rodriguez