Such that we are able to (finally) detect when we should
`Context._scope.cancel()` specifically when the `.parent_task` is
**not** blocking on receiving from the underlying `._rx_chan`, since if
the task is blocking on `.receive()` it will call `.cancel()`
implicitly.
This is a lot to explain with very little code actually needed for the
implementation (are we like `trio` yet anyone?? XD) but the main jist is
that `Context._maybe_cancel_and_set_remote_error()` needed the
additional case of calling `._scope.cancel()` whenever we know that
a remote-error/ctxc won't be immediately handled, bc user code is doing
non `Context`-API things, and result in a similar outcome as if that
task was waiting on `Context.wait_for_result()` or `.__aexite__()`.
Impl details,
- add a new `._is_blocked_on_rx_chan()` method which predicates whether
the (new) `.parent_task` is blocking on `._rx_chan.receive()`.
* see various stipulations about the current impl and how we might
need to adjust for the future given `trio`'s commitment to the
`Task.custom_sleep_data` attr..
- add `.parent_task`, a pub wrapper for `._task`.
- check for `not ._is_blocked_on_rx_chan()` before manually cancelling
the local `.parent_task`
- minimize the surrounding branch case expressions.
Other,
- tweak a couple logs.
- add a new `.cancel()` pre-started msg.
- mask the `.cancel_called` setter, it's only (been) used for tracing.
- todos around maybe moving the `._nursery` allocation "around" the
`.start_remote_task()` call and various subsequent tweaks therein.
While working on a fix to the hang case found from
`test_cancel_ctx_with_parent_side_entered_in_bg_task` an initial
solution caused this test to hang indefinitely; solve it with a small
wrapping `_main()` + `trio.fail_after()` entrypoint.
Further suite refinements,
- move the top-most `try:`->`else:` block
- toss in a masked base-exc block for tracing unexpected
`ctx.wait_for_result()` outcomes.
- tweak the `raise_sub_spawn_error_after` to be an optional `float`
which scales the `rng_seed: int = 50` msg counter to
`tell_little_bro()` so that the abs value to the `range()` can be
changed.
Such that when `maybe_context.cancel()` is not called (explicitly) and
only the subactor is cancelled by its parent we expect to see a ctxc
raised both from any call to `Context.wait_for_result()` and out of
the `Portal.open_context()` scope, up to the `trio.run()`.
Deats,
- obvi call-n-catch the ctxc (in scope) for the oob-only
subactor-cancelled case.
- add branches around `trio.run()` entry to match.
Discovered while writing a `@context` sanity test to verify unmasker
ignore-cases support. Masked code is due to the process of finding the
minimal example causing the original hang discovered in the original
examples script. Details are in the test-fn doc strings and surrounding
comments; more refinement and cleanup coming obviously.
Also moved over the self-cancel todos from the inter-peer tests module.
Tyler Goodlet