Deep `Context` refinements

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Spanning from the pub API, to instance `repr()` customization (for
logging/REPL content), to the impl details around the notion of a "final
outcome" and surrounding IPC msg draining mechanics during teardown.

A few API and field updates:

- new `.cancel_acked: bool` to replace what we were mostly using
  `.cancelled_caught: bool` for but, for purposes of better mapping the
  semantics of remote cancellation of parallel executing tasks; it's set
  only when `.cancel_called` is set and a ctxc arrives with
  a `.canceller` field set to the current actor uid indicating we
  requested and received acknowledgement from the other side's task
  that is cancelled gracefully.

- strongly document and delegate (and prolly eventually remove as a pub
  attr) the `.cancelled_caught` property entirely to the underlying
  `._scope: trio.CancelScope`; the `trio` semantics don't really map
  well to the "parallel with IPC msging"  case in the sense that for
  us it breaks the concept of the ctx/scope closure having "caught"
  something instead of having "received" a msg that the other side has
  "acknowledged" (i.e. which for us is the completion of cancellation).

- new `.__repr__()`/`.__str__()` format that tries to tersely yet
  comprehensively as possible display everything you need to know about
  the 3 main layers of an SC-linked-IPC-context:
  * ipc: the transport + runtime layers net-addressing and prot info.
  * rpc: the specific linked caller-callee task signature details
    including task and msg-stream instances.
  * state: current execution and final outcome state of the task pair.
  * a teensie extra `.repr_rpc` for a condensed rpc signature.

- new `.dst_maddr` to get a `libp2p` style "multi-address" (though right
  now it's just showing the transport layers so maybe we should move to
  to our `Channel`?)

- new public instance-var fields supporting more granular remote
  cancellation/result/error state:
  * `.maybe_error: Exception|None` for any final (remote) error/ctxc
    which computes logic on the values of `._remote_error`/`._local_error`
    to determine the "final error" (if any) on termination.
  * `.outcome` to the final error or result (or `None` if un-terminated)
  * `.repr_outcome()` for a console/logging friendly version of the
    final result or error as needed for the `.__str__()`.

- new private interface bits to support all of ^:
  * a new "no result yet" sentinel value, `Unresolved`, using a module
    level class singleton that `._result` is set too (instead of
    `id(self)`) to both determine if and present when no final result
    from the callee has-yet-been/was delivered (ever).
    => really we should get rid of `.result()` and change it to
    `.wait_for_result()` (or something)u
  * `_final_result_is_set()` predicate to avoid waiting for an already
    delivered result.
  * `._maybe_raise()` proto-impl that we should use to replace all the
    `if re:` blocks it can XD
  * new `._stream: MsgStream|None` for when a stream is opened to aid
    with the state repr mentioned above.

Tweaks to the termination drain loop `_drain_to_final_msg()`:

- obviously (obvi) use all the changes above when determining whether or
  not a "final outcome" has arrived and thus breaking from the loop ;)
  * like the `.outcome` `.maybe_error`  and `._final_ctx_is_set()` in
    the `while` pred expression.

- drop the `_recv_chan.receive_nowait()` + guard logic since it seems
  with all the surrounding (and coming soon) changes to
  `Portal.open_context()` using all the new API stuff (mentioned in
  first bullet set above) we never hit the case of inf-block?

Oh right and obviously a ton of (hopefully improved) logging msg content
changes, commented code removal and detailed comment-docs strewn about!

modden_spawn_from_client_req

Tyler Goodlet 2024-03-01 22:37:32 -05:00

parent 28fefe4ffe

commit 299429a278

1 changed files with 675 additions and 373 deletions

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