diff --git a/tractor/_context.py b/tractor/_context.py index 81db66c..ec64b15 100644 --- a/tractor/_context.py +++ b/tractor/_context.py @@ -86,7 +86,10 @@ from .msg import ( from ._ipc import ( Channel, ) -from ._streaming import MsgStream +from ._streaming import ( + MsgStream, + open_stream_from_ctx, +) from ._state import ( current_actor, debug_mode, @@ -978,198 +981,6 @@ class Context: assert self._scope self._scope.cancel() - # TODO? should we move this to `._streaming` much like we - # moved `Portal.open_context()`'s def to this mod? - @acm - async def open_stream( - self, - allow_overruns: bool|None = False, - msg_buffer_size: int|None = None, - - ) -> AsyncGenerator[MsgStream, None]: - ''' - Open a ``MsgStream``, a bi-directional stream connected to the - cross-actor (far end) task for this ``Context``. - - This context manager must be entered on both the caller and - callee for the stream to logically be considered "connected". - - A ``MsgStream`` is currently "one-shot" use, meaning if you - close it you can not "re-open" it for streaming and instead you - must re-establish a new surrounding ``Context`` using - ``Portal.open_context()``. In the future this may change but - currently there seems to be no obvious reason to support - "re-opening": - - pausing a stream can be done with a message. - - task errors will normally require a restart of the entire - scope of the inter-actor task context due to the nature of - ``trio``'s cancellation system. - - ''' - actor: Actor = self._actor - - # If the surrounding context has been cancelled by some - # task with a handle to THIS, we error here immediately - # since it likely means the surrounding lexical-scope has - # errored, been `trio.Cancelled` or at the least - # `Context.cancel()` was called by some task. - if self._cancel_called: - - # XXX NOTE: ALWAYS RAISE any remote error here even if - # it's an expected `ContextCancelled` due to a 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! - self.maybe_raise( - raise_ctxc_from_self_call=True, - ) - # NOTE: this is diff then calling - # `._maybe_raise_remote_err()` specifically - # because we want to raise a ctxc on any task entering this `.open_stream()` - # AFTER cancellation was already been requested, - # we DO NOT want to absorb any ctxc ACK silently! - # if 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 - ): - raise RuntimeError( - 'Context.started()` must be called before opening a stream' - ) - - # NOTE: in one way streaming this only happens on the - # parent-ctx-task side (on the side that calls - # `Actor.start_remote_task()`) so if you try to send - # a stop from the caller to the callee in the - # single-direction-stream case you'll get a lookup error - # currently. - ctx: Context = actor.get_context( - chan=self.chan, - cid=self.cid, - nsf=self._nsf, - # side=self.side, - - msg_buffer_size=msg_buffer_size, - allow_overruns=allow_overruns, - ) - ctx._allow_overruns: bool = allow_overruns - assert ctx is self - - # XXX: If the underlying channel feeder receive mem chan has - # been closed then likely client code has already exited - # a ``.open_stream()`` block prior or there was some other - # unanticipated error or cancellation from ``trio``. - - if ctx._rx_chan._closed: - raise trio.ClosedResourceError( - 'The underlying channel for this stream was already closed!\n' - ) - - # NOTE: implicitly this will call `MsgStream.aclose()` on - # `.__aexit__()` due to stream's parent `Channel` type! - # - # XXX NOTE XXX: ensures the stream is "one-shot use", - # which specifically means that on exit, - # - signal ``trio.EndOfChannel``/``StopAsyncIteration`` to - # the far end indicating that the caller exited - # the streaming context purposefully by letting - # the exit block exec. - # - this is diff from the cancel/error case where - # a cancel request from this side or an error - # should be sent to the far end indicating the - # stream WAS NOT just closed normally/gracefully. - async with MsgStream( - ctx=self, - rx_chan=ctx._rx_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: bool = True - self._stream = stream - - # XXX: do we need this? - # ensure we aren't cancelled before yielding the stream - # await trio.lowlevel.checkpoint() - yield stream - - # XXX: (MEGA IMPORTANT) if this is a root opened process we - # wait for any immediate child in debug before popping the - # context from the runtime msg loop otherwise inside - # ``Actor._deliver_ctx_payload()`` the msg will be discarded and in - # the case where that msg is global debugger unlock (via - # a "stop" msg for a stream), this can result in a deadlock - # where the root is waiting on the lock to clear but the - # child has already cleared it and clobbered IPC. - # - # await maybe_wait_for_debugger() - - # XXX TODO: pretty sure this isn't needed (see - # note above this block) AND will result in - # a double `.send_stop()` call. The only reason to - # put it here would be to due with "order" in - # terms of raising any remote error (as per - # directly below) or bc the stream's - # `.__aexit__()` block might not get run - # (doubtful)? Either way if we did put this back - # in we also need a state var to avoid the double - # stop-msg send.. - # - # await stream.aclose() - - # NOTE: absorb and do not raise any - # EoC received from the other side such that - # it is not raised inside the surrounding - # context block's scope! - except trio.EndOfChannel as eoc: - if ( - eoc - and - stream.closed - ): - # sanity, can remove? - assert eoc is stream._eoc - - log.warning( - 'Stream was terminated by EoC\n\n' - # NOTE: won't show the error but - # does show txt followed by IPC msg. - f'{str(eoc)}\n' - ) - - finally: - if self._portal: - try: - self._portal._streams.remove(stream) - except KeyError: - log.warning( - f'Stream was already destroyed?\n' - f'actor: {self.chan.uid}\n' - f'ctx id: {self.cid}' - ) - # TODO: replace all the `._maybe_raise_remote_err()` usage # with instances of this!! def maybe_raise( @@ -1178,6 +989,14 @@ class Context: **kwargs, ) -> Exception|None: + ''' + Check for for a remote error delivered by the runtime from + our peer (task); if set immediately raise. + + This is a convenience wrapper for + `._maybe_raise_remote_err(self._remote_error)`. + + ''' __tracebackhide__: bool = hide_tb if re := self._remote_error: return self._maybe_raise_remote_err( @@ -1290,8 +1109,7 @@ class Context: raise remote_error - # TODO: change to `.wait_for_result()`? - async def result( + async def wait_for_result( self, hide_tb: bool = True, @@ -1380,18 +1198,27 @@ class Context: (not self._cancel_called) ) ) + # TODO: eventually make `.outcome: Outcome` and thus return + # `self.outcome.unwrap()` here! return self.outcome # TODO: switch this with above! # -[ ] should be named `.wait_for_outcome()` and instead do # a `.outcome.Outcome.unwrap()` ? # - # @property - # def result(self) -> Any|None: - # if self._final_result_is_set(): - # return self._result - - # raise RuntimeError('No result is available!') + async def result( + self, + *args, + **kwargs, + ) -> Any|Exception: + log.warning( + '`Context.result()` is DEPRECATED!\n' + 'Use `Context.[no]wait_for_result()` instead!\n' + ) + return await self.wait_for_result( + *args, + **kwargs, + ) @property def maybe_error(self) -> BaseException|None: @@ -1447,6 +1274,9 @@ class Context: return self._result is not Unresolved # def get_result_nowait(self) -> Any|None: + # def get_outcome_nowait(self) -> Any|None: + # def recv_result_nowait(self) -> Any|None: + # def receive_outcome_nowait(self) -> Any|None: # TODO: use `outcome.Outcome` here instead? @property def outcome(self) -> ( @@ -1476,7 +1306,6 @@ class Context: def has_outcome(self) -> bool: return bool(self.maybe_error) or self._final_result_is_set() - # @property def repr_outcome( self, show_error_fields: bool = False, @@ -1498,7 +1327,8 @@ class Context: # just deliver the type name. if ( (reprol := getattr(merr, 'reprol', False)) - and show_error_fields + and + show_error_fields ): return reprol() @@ -1515,10 +1345,6 @@ class Context: repr(merr) ) - # just the type name - # else: # but wen? - # return type(merr).__name__ - # for all other errors show their regular output return ( str(merr) @@ -1572,7 +1398,7 @@ class Context: _, # any non-unresolved value None, ) if self._final_result_is_set(): - status = 'returned' + status = 'result-returned' # normal operation but still in a pre-`Return`-result # dialog phase @@ -1940,6 +1766,11 @@ class Context: # ow, indicate unable to deliver by default return False + # NOTE: similar to `Portal.open_context()`, this impl is found in + # the `._streaming`` mod to make reading/groking the details + # simpler code-org-wise. + open_stream = open_stream_from_ctx + # TODO: exception tb masking by using a manual # `.__aexit__()`/.__aenter__()` pair on a type? diff --git a/tractor/_streaming.py b/tractor/_streaming.py index 016577d..314a93b 100644 --- a/tractor/_streaming.py +++ b/tractor/_streaming.py @@ -26,6 +26,7 @@ import inspect from pprint import pformat from typing import ( Any, + AsyncGenerator, Callable, AsyncIterator, TYPE_CHECKING, @@ -51,6 +52,7 @@ from tractor.msg import ( ) if TYPE_CHECKING: + from ._runtime import Actor from ._context import Context from ._ipc import Channel @@ -550,6 +552,213 @@ class MsgStream(trio.abc.Channel): # ... +@acm +async def open_stream_from_ctx( + ctx: Context, + allow_overruns: bool|None = False, + msg_buffer_size: int|None = None, + +) -> AsyncGenerator[MsgStream, None]: + ''' + Open a `MsgStream`, a bi-directional msg transport dialog + connected to the cross-actor peer task for an IPC `Context`. + + This context manager must be entered in both the "parent" (task + which entered `Portal.open_context()`) and "child" (RPC task + which is decorated by `@context`) tasks for the stream to + logically be considered "open"; if one side begins sending to an + un-opened peer, depending on policy config, msgs will either be + queued until the other side opens and/or a `StreamOverrun` will + (eventually) be raised. + + ------ - ------ + + Runtime semantics design: + + A `MsgStream` session adheres to "one-shot use" semantics, + meaning if you close the scope it **can not** be "re-opened". + + Instead you must re-establish a new surrounding RPC `Context` + (RTC: remote task context?) using `Portal.open_context()`. + + In the future this *design choice* may need to be changed but + currently there seems to be no obvious reason to support such + semantics.. + + - "pausing a stream" can be supported with a message implemented + by the `tractor` application dev. + + - any remote error will normally require a restart of the entire + `trio.Task`'s scope due to the nature of `trio`'s cancellation + (`CancelScope`) system and semantics (level triggered). + + ''' + actor: Actor = ctx._actor + + # If the surrounding context has been cancelled by some + # task with a handle to THIS, we error here immediately + # since it likely means the surrounding lexical-scope has + # errored, been `trio.Cancelled` or at the least + # `Context.cancel()` was called by some task. + if ctx._cancel_called: + + # XXX NOTE: ALWAYS RAISE any remote error here even if + # it's an expected `ContextCancelled` due to a 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! + ctx.maybe_raise( + raise_ctxc_from_self_call=True, + ) + # NOTE: this is diff then calling + # `._maybe_raise_remote_err()` specifically + # because we want to raise a ctxc on any task entering this `.open_stream()` + # AFTER cancellation was already been requested, + # we DO NOT want to absorb any ctxc ACK silently! + # if ctx._remote_error: + # raise ctx._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'{ctx}' + ) + + if ( + not ctx._portal + and not ctx._started_called + ): + raise RuntimeError( + 'Context.started()` must be called before opening a stream' + ) + + # NOTE: in one way streaming this only happens on the + # parent-ctx-task side (on the side that calls + # `Actor.start_remote_task()`) so if you try to send + # a stop from the caller to the callee in the + # single-direction-stream case you'll get a lookup error + # currently. + ctx: Context = actor.get_context( + chan=ctx.chan, + cid=ctx.cid, + nsf=ctx._nsf, + # side=ctx.side, + + msg_buffer_size=msg_buffer_size, + allow_overruns=allow_overruns, + ) + ctx._allow_overruns: bool = allow_overruns + assert ctx is ctx + + # XXX: If the underlying channel feeder receive mem chan has + # been closed then likely client code has already exited + # a ``.open_stream()`` block prior or there was some other + # unanticipated error or cancellation from ``trio``. + + if ctx._rx_chan._closed: + raise trio.ClosedResourceError( + 'The underlying channel for this stream was already closed!\n' + ) + + # NOTE: implicitly this will call `MsgStream.aclose()` on + # `.__aexit__()` due to stream's parent `Channel` type! + # + # XXX NOTE XXX: ensures the stream is "one-shot use", + # which specifically means that on exit, + # - signal ``trio.EndOfChannel``/``StopAsyncIteration`` to + # the far end indicating that the caller exited + # the streaming context purposefully by letting + # the exit block exec. + # - this is diff from the cancel/error case where + # a cancel request from this side or an error + # should be sent to the far end indicating the + # stream WAS NOT just closed normally/gracefully. + async with MsgStream( + ctx=ctx, + rx_chan=ctx._rx_chan, + ) as stream: + + # NOTE: we track all existing streams per portal for + # the purposes of attempting graceful closes on runtime + # cancel requests. + if ctx._portal: + ctx._portal._streams.add(stream) + + try: + ctx._stream_opened: bool = True + ctx._stream = stream + + # XXX: do we need this? + # ensure we aren't cancelled before yielding the stream + # await trio.lowlevel.checkpoint() + yield stream + + # XXX: (MEGA IMPORTANT) if this is a root opened process we + # wait for any immediate child in debug before popping the + # context from the runtime msg loop otherwise inside + # ``Actor._deliver_ctx_payload()`` the msg will be discarded and in + # the case where that msg is global debugger unlock (via + # a "stop" msg for a stream), this can result in a deadlock + # where the root is waiting on the lock to clear but the + # child has already cleared it and clobbered IPC. + # + # await maybe_wait_for_debugger() + + # XXX TODO: pretty sure this isn't needed (see + # note above this block) AND will result in + # a double `.send_stop()` call. The only reason to + # put it here would be to due with "order" in + # terms of raising any remote error (as per + # directly below) or bc the stream's + # `.__aexit__()` block might not get run + # (doubtful)? Either way if we did put this back + # in we also need a state var to avoid the double + # stop-msg send.. + # + # await stream.aclose() + + # NOTE: absorb and do not raise any + # EoC received from the other side such that + # it is not raised inside the surrounding + # context block's scope! + except trio.EndOfChannel as eoc: + if ( + eoc + and + stream.closed + ): + # sanity, can remove? + assert eoc is stream._eoc + + log.warning( + 'Stream was terminated by EoC\n\n' + # NOTE: won't show the error but + # does show txt followed by IPC msg. + f'{str(eoc)}\n' + ) + + finally: + if ctx._portal: + try: + ctx._portal._streams.remove(stream) + except KeyError: + log.warning( + f'Stream was already destroyed?\n' + f'actor: {ctx.chan.uid}\n' + f'ctx id: {ctx.cid}' + ) + + + def stream(func: Callable) -> Callable: ''' Mark an async function as a streaming routine with ``@stream``.