Even moar bitty `Context` refinements

- set `._state._ctxvar_Context` just after `StartAck` inside
  `open_context_from_portal()` so that `current_ipc_ctx()` always
  works on the 'parent' side.
- always set `.canceller` to any `MsgTypeError.src_uid` and otherwise to
  any maybe-detected `.src_uid` (i.e. for RAEs).
- always set `.canceller` to us when we rx a ctxc which reports us as
  its canceller; this is a sanity check on definite "self cancellation".
- adjust `._is_self_cancelled()` logic to only be `True` when
  `._remote_error` is both a ctxc with a `.canceller` set to us AND
  when `Context.canceller` is also set to us (since the change above)
  as a little bit of extra rigor.
- fill-in/fix some `.repr_state` edge cases:
  - merge self-vs.-peer ctxc cases to one block and distinguish via
    nested `._is_self_cancelled()` check.
  - set 'errored' for all exception matched cases despite `.canceller`.
  - add pre-`Return` phase statuses:
   |_'pre-started' and 'syncing-to-child' depending on side and when
     `._stream` has not (yet) been set.
   |_'streaming' and 'streaming-finished' depending on side when
     `._stream` is set and whether it was stopped/closed.
- tweak drainage log-message to use "outcome" instead of "result".
- use new `.devx.pformat.pformat_cs()` inside `_maybe_cancel_and_set_remote_error()`
  but, IFF the log level is at least 'cancel'.

tractor/_context.py

@@ -37,8 +37,9 @@ import inspect
 from pprint import pformat
 from typing import (
     Any,
-    Callable,
     AsyncGenerator,
+    Callable,
+    Mapping,
     Type,
     TYPE_CHECKING,
     Union,
@@ -59,7 +60,10 @@ from ._exceptions import (
     pack_from_raise,
     unpack_error,
 )
-from .log import get_logger
+from .log import (
+    get_logger,
+    at_least_level,
+)
 from .msg import (
     Error,
     MsgType,
@@ -83,6 +87,7 @@ from ._streaming import MsgStream
 from ._state import (
     current_actor,
     debug_mode,
+    _ctxvar_Context,
 )
 
 if TYPE_CHECKING:
@@ -384,8 +389,12 @@ class Context:
 
         re: BaseException|None = (
             remote_error
-            or self._remote_error
+            or
+            self._remote_error
         )
+        # XXX we only report "this context" as self-cancelled
+        # once we've received a ctxc from our direct-peer task
+        # (aka we're `.cancel_acked`).
         if not re:
             return False
 
@@ -396,10 +405,10 @@ class Context:
         our_canceller = self.canceller
 
         return bool(
-            isinstance(re, ContextCancelled)
+            isinstance((ctxc := re), ContextCancelled)
             and from_uid == self.chan.uid
-            and re.canceller == our_uid
+            and ctxc.canceller == our_uid
-            and our_canceller == from_uid
+            and our_canceller == our_uid
         )
 
     @property
@@ -619,15 +628,27 @@ class Context:
         )
         self._remote_error: BaseException = error
 
+        msgerr: bool = False
+
         # self-cancel (ack) or,
         # peer propagated remote cancellation.
-        msgerr: bool = False
         if isinstance(error, ContextCancelled):
+            # NOTE in the case error is a ctxc the canceller will
+            # either be another peer or us. in the case where it's us
+            # we mark ourself as the canceller of ourselves (a ctx
+            # "self cancel" from this side's perspective), if instead
+            # the far end was cancelled by some other (inter-) peer,
+            # we want to mark our canceller as the actor that was
+            # cancelled, NOT their reported canceller. IOW in the
+            # latter case we're cancelled by someone else getting
+            # cancelled.
+            if (canc := error.canceller) == self._actor.uid:
+                whom: str = 'us'
+                self._canceller = canc
+            else:
+                whom = 'a remote peer (not us)'
+                self._canceller = error.src_uid
 
-            whom: str = (
-                'us' if error.canceller == self._actor.uid
-                else 'a remote peer (not us)'
-            )
             log.cancel(
                 f'IPC context was cancelled by {whom}!\n\n'
                 f'{error}'
@@ -635,6 +656,7 @@ class Context:
 
         elif isinstance(error, MsgTypeError):
             msgerr = True
+            self._canceller = error.src_uid
             log.error(
                 f'IPC dialog error due to msg-type caused by {self.peer_side!r} side\n\n'
                 f'{error}\n'
@@ -642,28 +664,25 @@ class Context:
             )
 
         else:
+            # always record the cancelling actor's uid since its
+            # cancellation state is linked and we want to know
+            # which process was the cause / requester of the
+            # cancellation.
+            maybe_error_src_uid: tuple = getattr(
+                error,
+                'src_uid',
+                None,
+            )
+            # we mark the source actor as our canceller
+            self._canceller = maybe_error_src_uid
             log.error(
                 f'Remote context error:\n\n'
                 # f'{pformat(self)}\n'
                 f'{error}\n'
             )
 
-        # always record the cancelling actor's uid since its
+        if self._canceller is None:
-        # cancellation state is linked and we want to know
+            log.error('Ctx has no canceller set!?')
-        # which process was the cause / requester of the
-        # cancellation.
-        maybe_error_src: tuple = getattr(
-            error,
-            'src_uid',
-            None,
-        )
-        self._canceller = (
-            maybe_error_src
-            or
-            # XXX: in the case we get a non-boxed error?
-            # -> wait but this should never happen right?
-            self.chan.uid
-        )
 
         # Cancel the local `._scope`, catch that
         # `._scope.cancelled_caught` and re-raise any remote error
@@ -707,27 +726,34 @@ class Context:
             message: str = 'NOT cancelling `Context._scope` !\n\n'
 
         fmt_str: str = 'No `self._scope: CancelScope` was set/used ?'
-        if cs:
+        if (
+            cs
+            and
+            at_least_level(log=log, level='cancel')
+        ):
             fmt_str: str = self.pformat(
                 extra_fields={
                     '._is_self_cancelled()': self._is_self_cancelled(),
                     '._cancel_on_msgerr': self._cancel_on_msgerr,
-
-                    '._scope': cs,
-                    '._scope.cancel_called': cs.cancel_called,
-                    '._scope.cancelled_caught': cs.cancelled_caught,
-                    '._scope._cancel_status': cs._cancel_status,
                 }
             )
+            from .devx.pformat import pformat_cs
+            cs_fmt: str = pformat_cs(
+                cs,
+                var_name='Context._scope',
+            )
+            fmt_str += (
+                '\n'
+                +
+                cs_fmt
+            )
         log.cancel(
             message
             +
             fmt_str
         )
-        # TODO: maybe we should also call `._res_scope.cancel()` if it
-        # exists to support cancelling any drain loop hangs?
 
-    # TODO: add to `Channel`?
+    # TODO: also add to `Channel`?
     @property
     def dst_maddr(self) -> str:
         chan: Channel = self.chan
@@ -1100,7 +1126,8 @@ class Context:
                             f'ctx id: {self.cid}'
                         )
 
-    # TODO: replace all the instances of this!! XD
+    # TODO: replace all the `._maybe_raise_remote_err()` usage
+    # with instances of this!!
     def maybe_raise(
         self,
         hide_tb: bool = True,
@@ -1111,6 +1138,7 @@ class Context:
         if re := self._remote_error:
             return self._maybe_raise_remote_err(
                 re,
+                hide_tb=hide_tb,
                 **kwargs,
             )
 
@@ -1212,7 +1240,6 @@ class Context:
         #       runtime frames from the tb explicitly?
         # https://docs.python.org/3/reference/simple_stmts.html#the-raise-statement
         # https://stackoverflow.com/a/24752607
-        __tracebackhide__: bool = True
         raise remote_error # from None
 
     # TODO: change  to `.wait_for_result()`?
@@ -1263,8 +1290,15 @@ class Context:
             # wait for a final context result/error by "draining"
             # (by more or less ignoring) any bi-dir-stream "yield"
             # msgs still in transit from the far end.
+            #
+            # XXX NOTE XXX: this call shouldn't really ever raise
+            # (other then internal error), instead delivering an
+            # `Error`-msg  and that being `.maybe_raise()`-ed below
+            # since every message should be delivered via the normal
+            # `._deliver_msg()` route which will appropriately set
+            # any `.maybe_error`.
             (
-                return_msg,
+                outcome_msg,
                 drained_msgs,
             ) = await msgops.drain_to_final_msg(
                 ctx=self,
@@ -1282,14 +1316,19 @@ class Context:
                         f'{msg}\n'
                     )
 
-            log.cancel(
+            drained_status: str = (
-                'Ctx drained to final result msgs\n'
+                'Ctx drained to final outcome msg\n\n'
-                f'{return_msg}\n\n'
+                f'{outcome_msg}\n'
-
+            )
-                f'pre-result drained msgs:\n'
+            if drained_msgs:
+                drained_status += (
+                    '\n'
+                    f'The pre-drained msgs are\n'
                     f'{pformat(drained_msgs)}\n'
                 )
 
+            log.cancel(drained_status)
+
         self.maybe_raise(
             # NOTE: obvi we don't care if we
             # overran the far end if we're already
@@ -1319,7 +1358,7 @@ class Context:
 
     @property
     def maybe_error(self) -> BaseException|None:
-        le: Exception|None = self._local_error
+        le: BaseException|None = self._local_error
         re: RemoteActorError|ContextCancelled|None = self._remote_error
 
         match (le, re):
@@ -1347,7 +1386,7 @@ class Context:
             #     ContextCancelled(canceller=),
             # ):
 
-        error: Exception|None = le or re
+        error: BaseException|None = le or re
         if error:
             return error
 
@@ -1462,52 +1501,63 @@ class Context:
         '''
         merr: Exception|None = self.maybe_error
         outcome: Unresolved|Exception|Any = self.outcome
-
+        status: str|None = None
         match (
             outcome,
             merr,
         ):
+            # "graceful" ctx cancellation
             case (
                 Unresolved,
                 ContextCancelled(),
-            ) if self.cancel_acked:
+            ):
+                if self._is_self_cancelled():
                     status = 'self-cancelled'
-
+                elif (
-            case (
-                Unresolved,
-                ContextCancelled(),
-            ) if (
                     self.canceller
                     and not self._cancel_called
                 ):
                     status = 'peer-cancelled'
 
+            # (remote) error condition
             case (
                 Unresolved,
-                BaseException(),
+                BaseException(),  # any error-type
-            ) if self.canceller:
+            ):
                 status = 'errored'
 
+            # result already returned
             case (
                 _,  # any non-unresolved value
                 None,
             ) if self._final_result_is_set():
                 status = 'returned'
 
+            # normal operation but still in a pre-`Return`-result
+            # dialog phase
             case (
-                Unresolved,  # noqa (weird.. ruff)
+                Unresolved,  # noqa (ruff, you so weird..)
-                None,
+                None,  # no (remote) error set
             ):
                 if stream := self._stream:
                     if stream.closed:
                         status = 'streaming-finished'
                     else:
                         status = 'streaming'
+
                 elif self._started_called:
                     status = 'started'
 
-            case _:
+                else:
-                status = 'unknown!?'
+                    if self.side == 'child':
+                        status = 'pre-started'
+                    else:
+                        status = 'syncing-to-child'
+
+        if status is None:
+            status = '??unknown??'
+            # from tractor.devx import mk_pdb
+            # mk_pdb().set_trace()
 
         return status
 
@@ -1738,7 +1788,6 @@ class Context:
                 f'Delivering IPC ctx error from {self.peer_side!r} to {side!r} task\n\n'
 
                 f'{flow_body}'
-
                 f'{pformat(re)}\n'
             )
             self._cancel_msg: dict = msg
@@ -2003,6 +2052,7 @@ async def open_context_from_portal(
     )
     assert ctx._remote_func_type == 'context'
     assert ctx._caller_info
+    _ctxvar_Context.set(ctx)
 
     # XXX NOTE since `._scope` is NOT set BEFORE we retreive the
     # `Started`-msg any cancellation triggered
@@ -2156,7 +2206,7 @@ async def open_context_from_portal(
 
         # CASE 2: context was cancelled by local task calling
         # `.cancel()`, we don't raise and the exit block should
-        # exit silently.
+        # finish silently.
         if (
             ctx._cancel_called
             and
@@ -2281,6 +2331,11 @@ async def open_context_from_portal(
             try:
                 result_or_err: Exception|Any = await ctx.result()
             except BaseException as berr:
+                # cancelled before (or maybe during?) final result capture
+                # if isinstance(trio.Cancelled, berr):
+                #     from .devx import mk_pdb
+                #     mk_pdb.set_trace()
+
                 # on normal teardown, if we get some error
                 # raised in `Context.result()` we still want to
                 # save that error on the ctx's state to
@@ -2476,12 +2531,12 @@ def mk_context(
         _caller_info=caller_info,
         **kwargs,
     )
-    # TODO: we can drop the old placeholder yah?
-    # ctx._result: int | Any = id(ctx)
     ctx._result = Unresolved
     return ctx
 
 
+# TODO: use the new type-parameters to annotate this in 3.13?
+# -[ ] https://peps.python.org/pep-0718/#unknown-types
 def context(func: Callable) -> Callable:
     '''
     Mark an (async) function as an SC-supervised, inter-`Actor`,
@@ -2495,8 +2550,8 @@ def context(func: Callable) -> Callable:
     # https://github.com/python/mypy/issues/2087#issuecomment-769266912
     func._tractor_context_function = True  # type: ignore
 
-    sig = inspect.signature(func)
+    sig: inspect.Signature = inspect.signature(func)
-    params = sig.parameters
+    params: Mapping = sig.parameters
     if 'ctx' not in params:
         raise TypeError(
             "The first argument to the context function "