If a nursery fails to cancel (some sub-actors presumably) then hard kill
the whole process tree to avoid hangs during a catastrophic failure.
This logic may get factored out (and changed) as we introduce custom
supervisor strategies.
Add a test to verify that `trio.MultiError`s are properly propagated up
a simple actor nursery tree. We don't have any exception marshalling
between processes (yet) so we can't validate much more then a simple
2-depth tree. This satisfies the final bullet in #43.
Note I've limited the number of subactors per layer to around 5 since
any more then this seems to break the `multiprocessing` forkserver;
zombie subprocesses seem to be blocking teardown somehow...
Also add a single depth fast fail test just to verify that it's the
nested spawning that triggers this forkserver bug.
`trio.MultiError` isn't an `Exception` (derived instead from
`BaseException`) so we have to specially catch it in the task
invocation machinery and ship it upwards (like regular errors)
since nurseries running in sub-actors can raise them.
Add `@tractor.stream` which must be used to denote non async generator
streaming functions which use the `tractor.Context` API to push values.
This enforces a more explicit denotation as well as allows enforcing the
declaration of the `ctx` argument in definitions.
This begins moving toward explicitly decorated "streaming functions"
instead of checking for a `ctx` arg in the signature.
- provide each context with its task's top level `trio.CancelScope`
such that tasks can cancel themselves explictly if needed via calling
`Context.cancel_scope()`
- make `Actor.cancel_task()` a private method (`_cancel_task()`) and
handle remote rpc calls specially such that the caller does not need
to provide the `chan` argument; non-primitive types can't be passed on
the wire and we don't want the client actor be require knowledge of
the channel instance the request is associated with. This also ties into
how we're tracking tasks right now (`Actor._rpc_tasks` is keyed by the
call id, a UUID, *plus* the channel).
- make `_do_handshake` a private actor method
- use UUID version 4
Can't seem to get the `capfd` fixture to capture subprocess logging to
stderr even though the console report shows the log message as being
captured? Skipping the test on the forkserver method for now.
goodboy
Tyler Goodlet
Tyler Goodlet
Christian López Barrón
tgoodlet