Be mega-pedantic with `ContextCancelled` semantics

As part of extremely detailed inter-peer-actor testing, add much more
granular `Context` cancellation state tracking via the following (new)
fields:
- `.canceller: tuple[str, str]` the uuid of the actor responsible for
  the cancellation condition - always set by
  `Context._maybe_cancel_and_set_remote_error()` and replaces
  `._cancelled_remote` and `.cancel_called_remote`. If set, this value
  should normally always match a value from some `ContextCancelled`
  raised or caught by one side of the context.
- `._local_error` which is always set to the locally raised (and caller
  or callee task's scope-internal) error which caused any
  eventual cancellation/error condition and thus any closure of the
  context's per-task-side-`trio.Nursery`.
- `.cancelled_caught: bool` is now always `True` whenever the local task
  catches (or "silently absorbs") a `ContextCancelled` (a `ctxc`) that
  indeed originated from one of the context's linked tasks or any other
  context which raised its own `ctxc` in the current `.open_context()` scope.
  => whenever there is a case that no `ContextCancelled` was raised
  **in** the `.open_context().__aexit__()` (eg. `ctx.result()` called
  after a call `ctx.cancel()`), we still consider the context's as
  having "caught a cancellation" since the `ctxc` was indeed silently
  handled by the cancel requester; all other error cases are already
  represented by mirroring the state of the `._scope: trio.CancelScope`
  => IOW there should be **no case** where an error is **not raised** in
  the context's scope and `.cancelled_caught: bool == False`, i.e. no
  case where `._scope.cancelled_caught == False and ._local_error is not
  None`!
- always raise any `ctxc` from `.open_stream()` if `._cancel_called ==
  True` - if the cancellation request has not already resulted in
  a `._remote_error: ContextCancelled` we raise a `RuntimeError` to
  indicate improper usage to the guilty side's task code.
- make `._maybe_raise_remote_err()` a sync func and don't raise
  any `ctxc` which is matched against a `.canceller` determined to
  be the current actor, aka a "self cancel", and always set the
  `._local_error` to any such `ctxc`.
- `.side: str` taken from inside `.cancel()` and unused as of now since
  it might be better re-written as a similar `.is_opener() -> bool`?
- drop unused `._started_received: bool`..
- TONS and TONS of detailed comments/docs to attempt to explain all the
  possible cancellation/exit cases and how they should exhibit as either
  silent closes or raises from the `Context` API!

Adjust the `._runtime._invoke()` code to match:
- use `ctx._maybe_raise_remote_err()` in `._invoke()`.
- adjust to new `.canceller` property.
- more type hints.
- better `log.cancel()` msging around self-cancels vs. peer-cancels.
- always set the `._local_error: BaseException` for the "callee" task
  just like `Portal.open_context()` now will do B)

Prior we were raising any `Context._remote_error` directly and doing
(more or less) the same `ContextCancelled` "absorbing" logic (well
kinda) in block; instead delegate to the method

tractor/_context.py

@@ -56,6 +56,7 @@ from ._state import current_actor
 
 if TYPE_CHECKING:
     from ._portal import Portal
+    from ._runtime import Actor
 
 
 log = get_logger(__name__)
@@ -64,20 +65,26 @@ log = get_logger(__name__)
 @dataclass
 class Context:
     '''
-    An inter-actor, ``trio``-task communication context.
+    An inter-actor, SC transitive, `trio.Task` communication context.
 
-    NB: This class should never be instatiated directly, it is delivered
+    NB: This class should **never be instatiated directly**, it is allocated
-    by either,
+    by the runtime in 2 ways:
-     - runtime machinery to a remotely started task or,
+     - by entering ``Portal.open_context()`` which is the primary
-     - by entering ``Portal.open_context()``.
+       public API for any "caller" task or,
+     - by the RPC machinery's `._runtime._invoke()` as a `ctx` arg
+       to a remotely scheduled "callee" function.
 
-     and is always constructed using ``mkt_context()``.
+    AND is always constructed using the below ``mk_context()``.
 
     Allows maintaining task or protocol specific state between
-    2 communicating, parallel executing actor tasks. A unique context is
+    2 cancel-scope-linked, communicating and parallel executing
-    allocated on each side of any task RPC-linked msg dialog, for
+    `trio.Task`s. Contexts are allocated on each side of any task
-    every request to a remote actor from a portal. On the "callee"
+    RPC-linked msg dialog, i.e. for every request to a remote
-    side a context is always allocated inside ``._runtime._invoke()``.
+    actor from a `Portal`. On the "callee" side a context is
+    always allocated inside ``._runtime._invoke()``.
+
+    # TODO: more detailed writeup on cancellation, error and
+    # streaming semantics..
 
     A context can be cancelled and (possibly eventually restarted) from
     either side of the underlying IPC channel, it can also open task
@@ -108,12 +115,31 @@ class Context:
     # which is exactly the primitive that allows for
     # cross-actor-task-supervision and thus SC.
     _scope: trio.CancelScope | None = None
+
+    # on a clean exit there should be a final value
+    # delivered from the far end "callee" task, so
+    # this value is only set on one side.
     _result: Any | int = None
+
+    # if the local "caller"  task errors this
+    # value is always set to the error that was
+    # captured in the `Portal.open_context().__aexit__()`
+    # teardown.
+    _local_error: BaseException | None = None
+
+    # if the either side gets an error from the other
+    # this value is set to that error unpacked from an
+    # IPC msg.
     _remote_error: BaseException | None = None
 
-    # cancellation state
+    # only set if the local task called `.cancel()`
     _cancel_called: bool = False  # did WE cancel the far end?
-    _cancelled_remote: tuple[str, str] | None = None
+
+    # TODO: do we even need this? we can assume that if we're
+    # cancelled that the other side is as well, so maybe we should
+    # instead just have a `.canceller` pulled from the
+    # `ContextCancelled`?
+    _canceller: tuple[str, str] | None = None
 
     # NOTE: we try to ensure assignment of a "cancel msg" since
     # there's always going to be an "underlying reason" that any
@@ -145,23 +171,47 @@ class Context:
         return self._cancel_called
 
     @property
-    def cancel_called_remote(self) -> tuple[str, str] | None:
+    def canceller(self) -> tuple[str, str] | None:
         '''
-        ``Actor.uid`` of the remote actor who's task was cancelled
+        ``Actor.uid: tuple[str, str]`` of the (remote)
-        causing this side of the context to also be cancelled.
+        actor-process who's task was cancelled thus causing this
+        (side of the) context to also be cancelled.
 
         '''
-        remote_uid = self._cancelled_remote
+        return self._canceller
-        if remote_uid:
-            return tuple(remote_uid)
 
     @property
     def cancelled_caught(self) -> bool:
-        return self._scope.cancelled_caught
+        return (
+            # the local scope was cancelled either by
+            # remote error or self-request
+            self._scope.cancelled_caught
+
+            # the local scope was never cancelled
+            # and instead likely we received a remote side
+            # cancellation that was raised inside `.result()`
+            or (
+                (se := self._local_error)
+                and
+                isinstance(se, ContextCancelled)
+                and (
+                    se.canceller == self.canceller
+                    or
+                    se is self._remote_error
+                )
+            )
+        )
+
+    @property
+    def side(self) -> str:
+        '''
+        Return string indicating which task this instance is wrapping.
+
+        '''
+        return 'caller' if self._portal else 'callee'
 
     # init and streaming state
     _started_called: bool = False
-    _started_received: bool = False
     _stream_opened: bool = False
 
     # overrun handling machinery
@@ -196,7 +246,7 @@ class Context:
     async def send_stop(self) -> None:
         await self.chan.send({'stop': True, 'cid': self.cid})
 
-    async def _maybe_cancel_and_set_remote_error(
+    def _maybe_cancel_and_set_remote_error(
         self,
         error: BaseException,
 
@@ -269,16 +319,19 @@ class Context:
         # that error as the reason.
         self._remote_error: BaseException = error
 
-        # always record the remote actor's uid since its cancellation
-        # state is directly linked to ours (the local one).
-        self._cancelled_remote = self.chan.uid
-
         if (
             isinstance(error, ContextCancelled)
         ):
+            # 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.
+            self._canceller = error.canceller
+
             log.cancel(
-                'Remote task-context sucessfully cancelled for '
+                'Remote task-context was cancelled for '
-                f'{self.chan.uid}:{self.cid}'
+                f'actor: {self.chan.uid}\n'
+                f'task: {self.cid}\n'
+                f'canceller: {error.canceller}\n'
             )
 
             if self._cancel_called:
@@ -289,22 +342,37 @@ class Context:
                 # and we **don't need to raise it** in local cancel
                 # scope since it will potentially override a real error.
                 return
+
         else:
             log.error(
-                f'Remote context error for {self.chan.uid}:{self.cid}:\n'
+                f'Remote context error,\n'
+                f'remote actor: {self.chan.uid}\n'
+                f'task: {self.cid}\n'
                 f'{error}'
             )
+            self._canceller = self.chan.uid
+
         # TODO: tempted to **not** do this by-reraising in a
         # nursery and instead cancel a surrounding scope, detect
         # the cancellation, then lookup the error that was set?
         # YES! this is way better and simpler!
-        if self._scope:
+        cs: trio.CancelScope = self._scope
+        if (
+            cs
+            and not cs.cancel_called
+            and not cs.cancelled_caught
+        ):
+
+            # TODO: we can for sure drop this right?
             # from trio.testing import wait_all_tasks_blocked
             # await wait_all_tasks_blocked()
-            # self._cancelled_remote = self.chan.uid
+
+            # TODO: it'd sure be handy to inject our own
+            # `trio.Cancelled` subtype here ;)
+            # https://github.com/goodboy/tractor/issues/368
             self._scope.cancel()
 
-            # this REPL usage actually works here BD
+            # NOTE: this REPL usage actually works here dawg! Bo
             # from .devx._debug import pause
             # await pause()
 
@@ -320,13 +388,19 @@ class Context:
         Timeout quickly in an attempt to sidestep 2-generals...
 
         '''
-        side: str = 'caller' if self._portal else 'callee'
+        side: str = self.side
         log.cancel(
             f'Cancelling {side} side of context to {self.chan.uid}'
         )
-
         self._cancel_called: bool = True
 
+        # caller side who entered `Portal.open_context()`
+        # NOTE: on the call side we never manually call
+        # `._scope.cancel()` since we expect the eventual
+        # `ContextCancelled` from the other side to trigger this
+        # when the runtime finally receives it during teardown
+        # (normally in `.result()` called from
+        # `Portal.open_context().__aexit__()`)
         if side == 'caller':
             if not self._portal:
                 raise RuntimeError(
@@ -349,7 +423,6 @@ class Context:
                     '_cancel_task',
                     cid=cid,
                 )
-                # print("EXITING CANCEL CALL")
 
             if cs.cancelled_caught:
                 # XXX: there's no way to know if the remote task was indeed
@@ -368,6 +441,9 @@ class Context:
                     )
 
         # callee side remote task
+        # NOTE: on this side we ALWAYS cancel the local scope since
+        # the caller expects a `ContextCancelled` to be sent from
+        # `._runtime._invoke()` back to the other side.
         else:
             # TODO: should we have an explicit cancel message
             # or is relaying the local `trio.Cancelled` as an
@@ -403,7 +479,7 @@ class Context:
             ``trio``'s cancellation system.
 
         '''
-        actor = current_actor()
+        actor: Actor = current_actor()
 
         # here we create a mem chan that corresponds to the
         # far end caller / callee.
@@ -413,12 +489,34 @@ class Context:
         # killed
 
         if self._cancel_called:
-            task = trio.lowlevel.current_task().name
+
-            raise ContextCancelled(
+            # XXX NOTE: ALWAYS RAISE any remote error here even if
-                f'Context around {actor.uid[0]}:{task} was already cancelled!'
+            # it's an expected `ContextCancelled` (after some local
+            # task having called `.cancel()` !
+            #
+            # WHY: we expect the error to always bubble up to the
+            # surrounding `Portal.open_context()` call and be
+            # absorbed there (silently) and we DO NOT want to
+            # actually try to stream - a cancel msg was already
+            # sent to the other side!
+            if re := self._remote_error:
+                raise self._remote_error
+
+            # XXX NOTE: if no `ContextCancelled` has been responded
+            # back from the other side (yet), we raise a different
+            # runtime error indicating that this task's usage of
+            # `Context.cancel()` and then `.open_stream()` is WRONG!
+            task: str = trio.lowlevel.current_task().name
+            raise RuntimeError(
+                'Stream opened after `Context.cancel()` called..?\n'
+                f'task: {actor.uid[0]}:{task}\n'
+                f'{self}'
             )
 
-        if not self._portal and not self._started_called:
+        if (
+            not self._portal
+            and not self._started_called
+        ):
             raise RuntimeError(
                 'Context.started()` must be called before opening a stream'
             )
@@ -434,7 +532,7 @@ class Context:
             msg_buffer_size=msg_buffer_size,
             allow_overruns=allow_overruns,
         )
-        ctx._allow_overruns = allow_overruns
+        ctx._allow_overruns: bool = allow_overruns
         assert ctx is self
 
         # XXX: If the underlying channel feeder receive mem chan has
@@ -444,27 +542,32 @@ class Context:
 
         if ctx._recv_chan._closed:
             raise trio.ClosedResourceError(
-                'The underlying channel for this stream was already closed!?')
+                'The underlying channel for this stream was already closed!?'
+            )
 
         async with MsgStream(
             ctx=self,
             rx_chan=ctx._recv_chan,
         ) as stream:
 
+            # NOTE: we track all existing streams per portal for
+            # the purposes of attempting graceful closes on runtime
+            # cancel requests.
             if self._portal:
                 self._portal._streams.add(stream)
 
             try:
-                self._stream_opened = True
+                self._stream_opened: bool = True
 
                 # XXX: do we need this?
                 # ensure we aren't cancelled before yielding the stream
                 # await trio.lowlevel.checkpoint()
                 yield stream
 
-                # NOTE: Make the stream "one-shot use".  On exit, signal
+                # NOTE: Make the stream "one-shot use".  On exit,
-                # ``trio.EndOfChannel``/``StopAsyncIteration`` to the
+                # signal
-                # far end.
+                # ``trio.EndOfChannel``/``StopAsyncIteration`` to
+                # the far end.
                 await stream.aclose()
 
             finally:
@@ -495,14 +598,22 @@ class Context:
         # whenever  ``CancelScope.cancel()`` was called) and
         # instead silently reap the expected cancellation
         # "error"-msg.
+        our_uid: tuple[str, str] = current_actor().uid
         if (
             isinstance(err, ContextCancelled)
             and (
                 self._cancel_called
                 or self.chan._cancel_called
-                or tuple(err.canceller) == current_actor().uid
+                or self.canceller == our_uid
+                or tuple(err.canceller) == our_uid
             )
         ):
+            # NOTE: we set the local scope error to any "self
+            # cancellation" error-response thus "absorbing"
+            # the error silently B)
+            if self._local_error is None:
+                self._local_error = err
+
             return err
 
         # NOTE: currently we are masking underlying runtime errors
@@ -515,7 +626,7 @@ 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
+        # __tracebackhide__: bool = True
         raise err from None
 
     async def result(self) -> Any | Exception:
@@ -544,7 +655,6 @@ class Context:
         of the remote cancellation.
 
         '''
-        __tracebackhide__: bool = True
         assert self._portal, "Context.result() can not be called from callee!"
         assert self._recv_chan
 
@@ -607,13 +717,15 @@ class Context:
                         "Received internal error at portal?"
                     )
 
-                    err = unpack_error(
+                    if err:= unpack_error(
                         msg,
                         self._portal.channel
-                    )  # from msgerr
+                    ):  # from msgerr
+                        self._maybe_cancel_and_set_remote_error(err)
+                        self._maybe_raise_remote_err(err)
 
-                    err = self._maybe_raise_remote_err(err)
+                    else:
-                    self._remote_error = err
+                        raise
 
         if re := self._remote_error:
             return self._maybe_raise_remote_err(re)
@@ -724,13 +836,17 @@ class Context:
             f"Delivering {msg} from {uid} to caller {cid}"
         )
 
-        error = msg.get('error')
+        if (
-        if error := unpack_error(
+            msg.get('error')  # check for field
-                msg,
+            and (
-                self.chan,
+                error := unpack_error(
+                    msg,
+                    self.chan,
+                )
+            )
         ):
             self._cancel_msg = msg
-            await self._maybe_cancel_and_set_remote_error(error)
+            self._maybe_cancel_and_set_remote_error(error)
 
         if (
             self._in_overrun
@@ -765,7 +881,7 @@ class Context:
 
             # XXX: always push an error even if the local
             # receiver is in overrun state.
-            # await self._maybe_cancel_and_set_remote_error(msg)
+            # self._maybe_cancel_and_set_remote_error(msg)
 
             local_uid = current_actor().uid
             lines = [

tractor/_runtime.py

@@ -86,12 +86,14 @@ async def _invoke(
     ] = trio.TASK_STATUS_IGNORED,
 ):
     '''
-    Invoke local func and deliver result(s) over provided channel.
+    Schedule a `trio` task-as-func and deliver result(s) over
+    connected IPC channel.
 
-    This is the core "RPC task" starting machinery.
+    This is the core "RPC" `trio.Task` scheduling machinery used to start every
+    remotely invoked function, normally in `Actor._service_n: trio.Nursery`.
 
     '''
-    __tracebackhide__ = True
+    __tracebackhide__: bool = True
     treat_as_gen: bool = False
     failed_resp: bool = False
 
@@ -209,6 +211,8 @@ async def _invoke(
                 # far end async gen to tear down
                 await chan.send({'stop': True, 'cid': cid})
 
+        # TODO: every other "func type" should be implemented from
+        # a special case of a context eventually!
         elif context:
             # context func with support for bi-dir streaming
             await chan.send({'functype': 'context', 'cid': cid})
@@ -219,21 +223,30 @@ async def _invoke(
                     ctx._scope = nurse.cancel_scope
                     task_status.started(ctx)
                     res = await coro
-                    await chan.send({'return': res, 'cid': cid})
+                    await chan.send({
+                        'return': res,
+                        'cid': cid
+                    })
 
             # XXX: do we ever trigger this block any more?
             except (
                 BaseExceptionGroup,
                 trio.Cancelled,
-            ):
+            ) as scope_error:
-                # if a context error was set then likely
-                # thei multierror was raised due to that
-                if ctx._remote_error is not None:
-                    raise ctx._remote_error
 
-                # maybe TODO: pack in ``trio.Cancelled.__traceback__`` here
+                # always set this (callee) side's exception as the
-                # so they can be unwrapped and displayed on the caller
+                # local error on the context
-                # side?
+                ctx._local_error: BaseException = scope_error
+
+                # if a remote error was set then likely the
+                # exception group was raised due to that, so
+                # and we instead raise that error immediately!
+                if re := ctx._remote_error:
+                    ctx._maybe_raise_remote_err(re)
+
+                # maybe TODO: pack in
+                # ``trio.Cancelled.__traceback__`` here so they can
+                # be unwrapped and displayed on the caller side?
                 raise
 
             finally:
@@ -244,11 +257,11 @@ async def _invoke(
                 # don't pop the local context until we know the
                 # associated child isn't in debug any more
                 await _debug.maybe_wait_for_debugger()
-                ctx = actor._contexts.pop((chan.uid, cid))
+                ctx: Context = actor._contexts.pop((chan.uid, cid))
-                if ctx:
+                log.runtime(
-                    log.runtime(
+                    f'Context entrypoint {func} was terminated:\n'
-                        f'Context entrypoint {func} was terminated:\n{ctx}'
+                    f'{ctx}'
-                    )
+                )
 
             if ctx.cancelled_caught:
 
@@ -256,43 +269,43 @@ async def _invoke(
                 # before raising any context cancelled case
                 # so that real remote errors don't get masked as
                 # ``ContextCancelled``s.
-                re = ctx._remote_error
+                if re := ctx._remote_error:
-                if re:
                     ctx._maybe_raise_remote_err(re)
 
-                fname = func.__name__
+                fname: str = func.__name__
                 cs: trio.CancelScope = ctx._scope
                 if cs.cancel_called:
-                    canceller = ctx._cancelled_remote
+                    canceller: tuple = ctx.canceller
+                    msg: str = (
+                        f'`{fname}()`@{actor.uid} cancelled by '
+                    )
 
                     # NOTE / TODO: if we end up having
                     # ``Actor._cancel_task()`` call
                     # ``Context.cancel()`` directly, we're going to
-                    # need to change this logic branch since it will
+                    # need to change this logic branch since it
-                    # always enter..
+                    # will always enter..
                     if ctx._cancel_called:
-                        msg = f'`{fname}()`@{actor.uid} cancelled itself'
+                        msg += 'itself '
-
-                    else:
-                        msg = (
-                            f'`{fname}()`@{actor.uid} '
-                            'was remotely cancelled by '
-                        )
 
                     # if the channel which spawned the ctx is the
                     # one that cancelled it then we report that, vs.
                     # it being some other random actor that for ex.
                     # some actor who calls `Portal.cancel_actor()`
                     # and by side-effect cancels this ctx.
-                    if canceller == ctx.chan.uid:
+                    elif canceller == ctx.chan.uid:
-                        msg += f'its caller {canceller}'
+                        msg += f'its caller {canceller} '
+
                     else:
                         msg += f'remote actor {canceller}'
 
                     # TODO: does this ever get set any more or can
                     # we remove it?
                     if ctx._cancel_msg:
-                        msg += f' with msg:\n{ctx._cancel_msg}'
+                        msg += (
+                            ' with msg:\n'
+                            f'{ctx._cancel_msg}'
+                        )
 
                     # task-contex was either cancelled by request using
                     # ``Portal.cancel_actor()`` or ``Context.cancel()``
@@ -305,10 +318,13 @@ async def _invoke(
                         canceller=canceller,
                     )
 
+        # regular async function
         else:
-            # regular async function
             try:
-                await chan.send({'functype': 'asyncfunc', 'cid': cid})
+                await chan.send({
+                    'functype': 'asyncfunc',
+                    'cid': cid
+                })
             except trio.BrokenResourceError:
                 failed_resp = True
                 if is_rpc:
@@ -322,7 +338,7 @@ async def _invoke(
                 ctx._scope = cs
                 task_status.started(ctx)
                 result = await coro
-                fname = func.__name__
+                fname: str = func.__name__
                 log.runtime(f'{fname}() result: {result}')
                 if not failed_resp:
                     # only send result if we know IPC isn't down
@@ -1162,7 +1178,12 @@ class Actor:
             - return control the parent channel message loop
 
         '''
-        log.cancel(f"{self.uid} is trying to cancel")
+        log.cancel(
+            f'{self.uid} requested to cancel by:\n'
+            f'{requesting_uid}'
+        )
+
+        # TODO: what happens here when we self-cancel tho?
         self._cancel_called_by_remote: tuple = requesting_uid
         self._cancel_called = True
 
@@ -1177,7 +1198,9 @@ class Actor:
                 dbcs.cancel()
 
             # kill all ongoing tasks
-            await self.cancel_rpc_tasks(requesting_uid=requesting_uid)
+            await self.cancel_rpc_tasks(
+                requesting_uid=requesting_uid,
+            )
 
             # stop channel server
             self.cancel_server()
@@ -1207,8 +1230,8 @@ class Actor:
         self,
         cid: str,
         chan: Channel,
-
         requesting_uid: tuple[str, str] | None = None,
+
     ) -> bool:
         '''
         Cancel a local task by call-id / channel.
@@ -1225,7 +1248,7 @@ class Actor:
             # this ctx based lookup ensures the requested task to
             # be cancelled was indeed spawned by a request from this channel
             ctx, func, is_complete = self._rpc_tasks[(chan, cid)]
-            scope = ctx._scope
+            scope: trio.CancelScope = ctx._scope
         except KeyError:
             log.cancel(f"{cid} has already completed/terminated?")
             return True
@@ -1235,10 +1258,10 @@ class Actor:
             f"peer: {chan.uid}\n")
 
         if (
-            ctx._cancelled_remote is None
+            ctx._canceller is None
             and requesting_uid
         ):
-            ctx._cancelled_remote: tuple = requesting_uid
+            ctx._canceller: tuple = requesting_uid
 
         # don't allow cancelling this function mid-execution
         # (is this necessary?)
@@ -1248,6 +1271,7 @@ class Actor:
         # TODO: shouldn't we eventually be calling ``Context.cancel()``
         # directly here instead (since that method can handle both
         # side's calls into it?
+        # await ctx.cancel()
         scope.cancel()
 
         # wait for _invoke to mark the task complete
@@ -1275,9 +1299,12 @@ class Actor:
         registered for each.
 
         '''
-        tasks = self._rpc_tasks
+        tasks: dict = self._rpc_tasks
         if tasks:
-            log.cancel(f"Cancelling all {len(tasks)} rpc tasks:\n{tasks} ")
+            log.cancel(
+                f'Cancelling all {len(tasks)} rpc tasks:\n'
+                f'{tasks}'
+            )
             for (
                 (chan, cid),
                 (ctx, func, is_complete),
@@ -1295,7 +1322,9 @@ class Actor:
                     )
 
             log.cancel(
-                f"Waiting for remaining rpc tasks to complete {tasks}")
+                'Waiting for remaining rpc tasks to complete:\n'
+                f'{tasks}'
+            )
             await self._ongoing_rpc_tasks.wait()
 
     def cancel_server(self) -> None: