The channel server should be torn down *before* the rpc
task/service nursery. Do this explicitly even in the root's main task
to avoid a strange hang I found in the pubsub tests. Start dropping
the `warnings.warn()` usage.
Add `Actor._cancel_called` and `._cancel_complete` making it possible to
determine whether the actor has started the cancellation sequence and
whether that sequence has fully completed. This allows for blocking in
internal machinery tasks as necessary. Also, always trigger the end of
ongoing rpc tasks even if the last task errors; there's no guarantee the
trio cancellation semantics will guarantee us a nice internal "state"
without this.
For reliable remote cancellation we need to "report" `trio.Cancelled`s
(just like any other error) when exhausting a portal such that the
caller can make decisions about cancelling the respective actor if need
be.
Resolves#156
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.
Every subactor in the tree now receives the socket (or whatever the
mailbox type ends up being) during startup and can call the new
`tractor._discovery.get_root()` function to get a portal to the current
root actor in their tree. The main reason for adding this atm is to
support nested child actors gaining access to the root's tty lock for
debugging.
Also, when a channel disconnects from a message loop, might as well kill
all its rpc tasks.
It's not like any of this code is really being used anyway since we
aren't indefinitely blocking for cancelled subactors to terminate (yet).
Drop the `do_hard_kill()` bit for now and just rely on the underlying
process api. Oh, and mark the nursery as cancelled asap.
Tyler Goodlet
goodboy