The (rare) condition is heavily detailed in new comments in
the `cancel_trio()` callback but, more or less the idea here is to be
extra pedantic in raising an `Exceptiongroup` of errors from each task
(both `asyncio` and `trio`) whenever the 2 tasks raise "independently"
- in the sense that it's not obviously one side's task causing an error
(or cancellation) in the other. In this case we set the error for each
side on the `LinkedTaskChannel` (via new attrs described later).
As a synopsis, most of this work was refined out of supporting
`infected_aio=True` mode in the **root actor** and in particular as part
of getting that to work inside the `modden` daemon which at the time of
writing was still using the `i3ipc` lib and thus `asyncio`.
Impl deats,
- extend the `LinkedTaskChannel` field/API set (and type it),
- `._trio_task: trio.Task` for test/user introspection.
- also "stage" some ideas for a more refined interface,
- `.started()` to deliver the value yielded to the `trio.Task` parent.
|_ also includes some todos for how to implement this design
underneath.
- `._aio_first: Any|None = None` to hold that value ^.
- `.wait_aio_complete()` for syncing to the asyncio task.
- some detailed logging around "asyncio cancelled trio" case.
- Move `AsyncioCancelled` in this module.
Styling changes,
- generally more explicit var naming.
- some todos for getting modern and fancy with typing..
NB, Let it be known this commit msg was written on a friday with the
help of various "mr. white" solns.
85c60095ba