1375 lines
52 KiB
Python
1375 lines
52 KiB
Python
# tractor: structured concurrent "actors".
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# Copyright 2018-eternity Tyler Goodlet.
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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'''
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The fundamental cross process SC abstraction: an inter-actor,
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cancel-scope linked task "context".
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A ``Context`` is very similar to the ``trio.Nursery.cancel_scope`` built
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into each ``trio.Nursery`` except it links the lifetimes of memory space
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disjoint, parallel executing tasks in separate actors.
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'''
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from __future__ import annotations
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from collections import deque
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from contextlib import asynccontextmanager as acm
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from dataclasses import (
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dataclass,
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field,
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)
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from functools import partial
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import inspect
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from pprint import pformat
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from typing import (
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Any,
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Callable,
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AsyncGenerator,
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TYPE_CHECKING,
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)
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import warnings
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import trio
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# from .devx import (
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# maybe_wait_for_debugger,
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# pause,
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# )
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from ._exceptions import (
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# _raise_from_no_key_in_msg,
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unpack_error,
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pack_error,
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ContextCancelled,
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# MessagingError,
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RemoteActorError,
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StreamOverrun,
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)
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from .log import get_logger
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from ._ipc import Channel
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from ._streaming import MsgStream
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from ._state import current_actor
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if TYPE_CHECKING:
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from ._portal import Portal
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from ._runtime import Actor
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log = get_logger(__name__)
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async def _drain_to_final_msg(
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ctx: Context,
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) -> list[dict]:
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# ) -> tuple[
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# Any|Exception,
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# list[dict],
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# ]:
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raise_overrun: bool = not ctx._allow_overruns
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# wait for a final context result by collecting (but
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# basically ignoring) any bi-dir-stream msgs still in transit
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# from the far end.
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pre_result_drained: list[dict] = []
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while not ctx._remote_error:
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try:
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# NOTE: this REPL usage actually works here dawg! Bo
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# from .devx._debug import pause
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# await pause()
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# if re := ctx._remote_error:
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# ctx._maybe_raise_remote_err(
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# re,
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# # NOTE: obvi we don't care if we
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# # overran the far end if we're already
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# # waiting on a final result (msg).
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# raise_overrun_from_self=raise_overrun,
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# )
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# TODO: bad idea?
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# with trio.CancelScope() as res_cs:
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# ctx._res_scope = res_cs
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# msg: dict = await ctx._recv_chan.receive()
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# if res_cs.cancelled_caught:
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# from .devx._debug import pause
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# await pause()
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msg: dict = await ctx._recv_chan.receive()
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ctx._result: Any = msg['return']
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log.runtime(
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'Context delivered final result msg:\n'
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f'{pformat(msg)}'
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)
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pre_result_drained.append(msg)
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# NOTE: we don't need to do this right?
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# XXX: only close the rx mem chan AFTER
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# a final result is retreived.
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# if ctx._recv_chan:
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# await ctx._recv_chan.aclose()
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break
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# NOTE: we get here if the far end was
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# `ContextCancelled` in 2 cases:
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# 1. we requested the cancellation and thus
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# SHOULD NOT raise that far end error,
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# 2. WE DID NOT REQUEST that cancel and thus
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# SHOULD RAISE HERE!
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except trio.Cancelled:
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# CASE 2: mask the local cancelled-error(s)
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# only when we are sure the remote error is
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# the source cause of this local task's
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# cancellation.
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if re := ctx._remote_error:
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ctx._maybe_raise_remote_err(re)
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# CASE 1: we DID request the cancel we simply
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# continue to bubble up as normal.
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raise
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except KeyError:
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if 'yield' in msg:
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# far end task is still streaming to us so discard
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log.warning(f'Discarding std "yield"\n{msg}')
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pre_result_drained.append(msg)
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continue
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# TODO: work out edge cases here where
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# a stream is open but the task also calls
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# this?
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# -[ ] should be a runtime error if a stream is open
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# right?
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elif 'stop' in msg:
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log.cancel(
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'Remote stream terminated due to "stop" msg:\n'
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f'{msg}'
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)
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pre_result_drained.append(msg)
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continue
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# internal error should never get here
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assert msg.get('cid'), (
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"Received internal error at portal?"
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)
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# XXX fallthrough to handle expected error XXX
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re: Exception|None = ctx._remote_error
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if re:
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log.critical(
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'Remote ctx terminated due to "error" msg:\n'
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f'{re}'
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)
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assert msg is ctx._cancel_msg
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# NOTE: this solved a super dupe edge case XD
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# this was THE super duper edge case of:
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# - local task opens a remote task,
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# - requests remote cancellation of far end
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# ctx/tasks,
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# - needs to wait for the cancel ack msg
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# (ctxc) or some result in the race case
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# where the other side's task returns
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# before the cancel request msg is ever
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# rxed and processed,
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# - here this surrounding drain loop (which
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# iterates all ipc msgs until the ack or
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# an early result arrives) was NOT exiting
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# since we are the edge case: local task
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# does not re-raise any ctxc it receives
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# IFF **it** was the cancellation
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# requester..
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# will raise if necessary, ow break from
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# loop presuming any error terminates the
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# context!
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ctx._maybe_raise_remote_err(
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re,
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# NOTE: obvi we don't care if we
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# overran the far end if we're already
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# waiting on a final result (msg).
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# raise_overrun_from_self=False,
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raise_overrun_from_self=raise_overrun,
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)
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break # OOOOOF, yeah obvi we need this..
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# XXX we should never really get here
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# right! since `._deliver_msg()` should
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# always have detected an {'error': ..}
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# msg and already called this right!?!
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elif error := unpack_error(
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msg=msg,
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chan=ctx._portal.channel,
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hide_tb=False,
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):
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log.critical('SHOULD NEVER GET HERE!?')
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assert msg is ctx._cancel_msg
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assert error.msgdata == ctx._remote_error.msgdata
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from .devx._debug import pause
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await pause()
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ctx._maybe_cancel_and_set_remote_error(error)
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ctx._maybe_raise_remote_err(error)
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else:
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# bubble the original src key error
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raise
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return pre_result_drained
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# TODO: make this a msgspec.Struct!
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@dataclass
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class Context:
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'''
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An inter-actor, SC transitive, `trio.Task` communication context.
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NB: This class should **never be instatiated directly**, it is allocated
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by the runtime in 2 ways:
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- by entering ``Portal.open_context()`` which is the primary
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public API for any "caller" task or,
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- by the RPC machinery's `._runtime._invoke()` as a `ctx` arg
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to a remotely scheduled "callee" function.
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AND is always constructed using the below ``mk_context()``.
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Allows maintaining task or protocol specific state between
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2 cancel-scope-linked, communicating and parallel executing
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`trio.Task`s. Contexts are allocated on each side of any task
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RPC-linked msg dialog, i.e. for every request to a remote
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actor from a `Portal`. On the "callee" side a context is
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always allocated inside ``._runtime._invoke()``.
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# TODO: more detailed writeup on cancellation, error and
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# streaming semantics..
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A context can be cancelled and (possibly eventually restarted) from
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either side of the underlying IPC channel, it can also open task
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oriented message streams, and acts more or less as an IPC aware
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inter-actor-task ``trio.CancelScope``.
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'''
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chan: Channel
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cid: str # "context id", more or less a unique linked-task-pair id
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# the "feeder" channels for delivering message values to the
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# local task from the runtime's msg processing loop.
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_recv_chan: trio.MemoryReceiveChannel
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_send_chan: trio.MemorySendChannel
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# the "invocation type" of the far end task-entry-point
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# function, normally matching a logic block inside
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# `._runtime.invoke()`.
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_remote_func_type: str | None = None
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# NOTE: (for now) only set (a portal) on the caller side since
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# the callee doesn't generally need a ref to one and should
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# normally need to explicitly ask for handle to its peer if
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# more the the `Context` is needed?
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_portal: Portal | None = None
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# NOTE: each side of the context has its own cancel scope
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# which is exactly the primitive that allows for
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# cross-actor-task-supervision and thus SC.
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_scope: trio.CancelScope | None = None
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# _res_scope: trio.CancelScope|None = None
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# on a clean exit there should be a final value
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# delivered from the far end "callee" task, so
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# this value is only set on one side.
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_result: Any | int = None
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# if the local "caller" task errors this
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# value is always set to the error that was
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# captured in the `Portal.open_context().__aexit__()`
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# teardown.
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_local_error: BaseException | None = None
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# if the either side gets an error from the other
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# this value is set to that error unpacked from an
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# IPC msg.
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_remote_error: BaseException | None = None
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# only set if the local task called `.cancel()`
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_cancel_called: bool = False # did WE cancel the far end?
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# TODO: do we even need this? we can assume that if we're
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# cancelled that the other side is as well, so maybe we should
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# instead just have a `.canceller` pulled from the
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# `ContextCancelled`?
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_canceller: tuple[str, str] | None = None
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# NOTE: we try to ensure assignment of a "cancel msg" since
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# there's always going to be an "underlying reason" that any
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# context was closed due to either a remote side error or
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# a call to `.cancel()` which triggers `ContextCancelled`.
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_cancel_msg: str | dict | None = None
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# NOTE: this state var used by the runtime to determine if the
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# `pdbp` REPL is allowed to engage on contexts terminated via
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# a `ContextCancelled` due to a call to `.cancel()` triggering
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# "graceful closure" on either side:
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# - `._runtime._invoke()` will check this flag before engaging
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# the crash handler REPL in such cases where the "callee"
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# raises the cancellation,
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# - `.devx._debug.lock_tty_for_child()` will set it to `False` if
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# the global tty-lock has been configured to filter out some
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# actors from being able to acquire the debugger lock.
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_enter_debugger_on_cancel: bool = True
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@property
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def cancel_called(self) -> bool:
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'''
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Records whether cancellation has been requested for this context
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by either an explicit call to ``.cancel()`` or an implicit call
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due to an error caught inside the ``Portal.open_context()``
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block.
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'''
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return self._cancel_called
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@property
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def canceller(self) -> tuple[str, str] | None:
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'''
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``Actor.uid: tuple[str, str]`` of the (remote)
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actor-process who's task was cancelled thus causing this
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(side of the) context to also be cancelled.
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'''
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return self._canceller
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@property
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def cancelled_caught(self) -> bool:
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return (
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# the local scope was cancelled either by
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# remote error or self-request
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self._scope.cancelled_caught
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# the local scope was never cancelled
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# and instead likely we received a remote side
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# cancellation that was raised inside `.result()`
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or (
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(se := self._local_error)
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and
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isinstance(se, ContextCancelled)
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and (
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se.canceller == self.canceller
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or
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se is self._remote_error
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)
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)
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)
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# @property
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# def is_waiting_result(self) -> bool:
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# return bool(self._res_scope)
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@property
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def side(self) -> str:
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'''
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Return string indicating which task this instance is wrapping.
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'''
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return 'caller' if self._portal else 'callee'
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# init and streaming state
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_started_called: bool = False
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_stream_opened: bool = False
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# overrun handling machinery
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# NOTE: none of this provides "backpressure" to the remote
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# task, only an ability to not lose messages when the local
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# task is configured to NOT transmit ``StreamOverrun``s back
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# to the other side.
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_overflow_q: deque[dict] = field(
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default_factory=partial(
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deque,
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maxlen=616,
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)
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)
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_scope_nursery: trio.Nursery | None = None
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_in_overrun: bool = False
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_allow_overruns: bool = False
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async def send_yield(
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self,
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data: Any,
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) -> None:
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warnings.warn(
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"`Context.send_yield()` is now deprecated. "
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"Use ``MessageStream.send()``. ",
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DeprecationWarning,
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stacklevel=2,
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)
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await self.chan.send({'yield': data, 'cid': self.cid})
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async def send_stop(self) -> None:
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# await pause()
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await self.chan.send({
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'stop': True,
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'cid': self.cid
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})
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def _maybe_cancel_and_set_remote_error(
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self,
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error: BaseException,
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) -> None:
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'''
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(Maybe) cancel this local scope due to a received remote
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error (normally via an IPC msg) which the actor runtime
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routes to this context.
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Acts as a form of "relay" for a remote error raised in the
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corresponding remote task's `Context` wherein the next time
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the local task exectutes a checkpoint, a `trio.Cancelled`
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will be raised and depending on the type and source of the
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original remote error, and whether or not the local task
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called `.cancel()` itself prior, an equivalent
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`ContextCancelled` or `RemoteActorError` wrapping the
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remote error may be raised here by any of,
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- `Portal.open_context()`
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- `Portal.result()`
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- `Context.open_stream()`
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- `Context.result()`
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when called/closed by actor local task(s).
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NOTEs & TODOs:
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- It is expected that the caller has previously unwrapped
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the remote error using a call to `unpack_error()` and
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provides that output exception value as the input
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`error` argument here.
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- If this is an error message from a context opened by
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`Portal.open_context()` we want to interrupt any
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ongoing local tasks operating within that `Context`'s
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cancel-scope so as to be notified ASAP of the remote
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error and engage any caller handling (eg. for
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cross-process task supervision).
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- In some cases we may want to raise the remote error
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immediately since there is no guarantee the locally
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operating task(s) will attempt to execute a checkpoint
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any time soon; in such cases there are 2 possible
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approaches depending on the current task's work and
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wrapping "thread" type:
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- `trio`-native-and-graceful: only ever wait for tasks
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to exec a next `trio.lowlevel.checkpoint()` assuming
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that any such task must do so to interact with the
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actor runtime and IPC interfaces.
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- (NOT IMPLEMENTED) system-level-aggressive: maybe we
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could eventually interrupt sync code (invoked using
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`trio.to_thread` or some other adapter layer) with
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a signal (a custom unix one for example?
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https://stackoverflow.com/a/5744185) depending on the
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task's wrapping thread-type such that long running
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sync code should never cause the delay of actor
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supervision tasks such as cancellation and respawn
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logic.
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'''
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# XXX: currently this should only be used when
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# `Portal.open_context()` has been opened since it's
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# assumed that other portal APIs like,
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# - `Portal.run()`,
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# - `ActorNursery.run_in_actor()`
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# do their own error checking at their own call points and
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# result processing.
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# XXX: set the remote side's error so that after we cancel
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# whatever task is the opener of this context it can raise
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# that error as the reason.
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# if self._remote_error:
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# return
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# breakpoint()
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log.cancel(
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'Setting remote error for ctx \n'
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f'<= remote ctx uid: {self.chan.uid}\n'
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f'=>\n{error}'
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)
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self._remote_error: BaseException = error
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if (
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isinstance(error, ContextCancelled)
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):
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log.cancel(
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'Remote task-context was cancelled for '
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f'actor: {self.chan.uid}\n'
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f'task: {self.cid}\n'
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f'canceller: {error.canceller}\n'
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)
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# always record the cancelling actor's uid since its cancellation
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# state is linked and we want to know which process was
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# the cause / requester of the cancellation.
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# if error.canceller is None:
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# import pdbp; pdbp.set_trace()
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# breakpoint()
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self._canceller = error.canceller
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|
|
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if self._cancel_called:
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# this is an expected cancel request response message
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# and we **don't need to raise it** in local cancel
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# scope since it will potentially override a real error.
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return
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else:
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log.error(
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f'Remote context error:\n'
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f'{error}\n'
|
|
f'{pformat(self)}\n'
|
|
# f'remote actor: {self.chan.uid}\n'
|
|
# f'cid: {self.cid}\n'
|
|
)
|
|
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!
|
|
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()
|
|
|
|
# TODO: it'd sure be handy to inject our own
|
|
# `trio.Cancelled` subtype here ;)
|
|
# https://github.com/goodboy/tractor/issues/368
|
|
self._scope.cancel()
|
|
|
|
# NOTE: this REPL usage actually works here dawg! Bo
|
|
# await pause()
|
|
|
|
# TODO: maybe we have to use `._res_scope.cancel()` if it
|
|
# exists?
|
|
|
|
async def cancel(
|
|
self,
|
|
timeout: float = 0.616,
|
|
|
|
) -> None:
|
|
'''
|
|
Cancel this inter-actor-task context.
|
|
|
|
Request that the far side cancel it's current linked context,
|
|
Timeout quickly in an attempt to sidestep 2-generals...
|
|
|
|
'''
|
|
side: str = self.side
|
|
log.cancel(
|
|
f'Cancelling {side} side of context to {self.chan.uid}'
|
|
)
|
|
|
|
# await pause()
|
|
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(
|
|
"No portal found, this is likely a callee side context"
|
|
)
|
|
|
|
cid: str = self.cid
|
|
with trio.move_on_after(timeout) as cs:
|
|
cs.shield = True
|
|
log.cancel(
|
|
f'Cancelling stream {cid} to '
|
|
f'{self._portal.channel.uid}'
|
|
)
|
|
|
|
# NOTE: we're telling the far end actor to cancel a task
|
|
# corresponding to *this actor*. The far end local channel
|
|
# instance is passed to `Actor._cancel_task()` implicitly.
|
|
await self._portal.run_from_ns(
|
|
'self',
|
|
'_cancel_task',
|
|
cid=cid,
|
|
)
|
|
|
|
if cs.cancelled_caught:
|
|
# XXX: there's no way to know if the remote task was indeed
|
|
# cancelled in the case where the connection is broken or
|
|
# some other network error occurred.
|
|
# if not self._portal.channel.connected():
|
|
if not self.chan.connected():
|
|
log.cancel(
|
|
'May have failed to cancel remote task '
|
|
f'{cid} for {self._portal.channel.uid}'
|
|
)
|
|
else:
|
|
log.cancel(
|
|
'Timed out on cancel request of remote task '
|
|
f'{cid} for {self._portal.channel.uid}'
|
|
)
|
|
|
|
# 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
|
|
# {'error': trio.Cancelled, cid: "blah"} enough?
|
|
# This probably gets into the discussion in
|
|
# https://github.com/goodboy/tractor/issues/36
|
|
assert self._scope
|
|
self._scope.cancel()
|
|
|
|
@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 = current_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!
|
|
if self._remote_error:
|
|
# NOTE: this is diff then calling
|
|
# `._maybe_raise_from_remote_msg()` specifically
|
|
# because any task entering this `.open_stream()`
|
|
# AFTER cancellation has already been requested,
|
|
# we DO NOT want to absorb any ctxc ACK silently!
|
|
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
|
|
# caller side inside `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(
|
|
self.chan,
|
|
self.cid,
|
|
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._recv_chan._closed:
|
|
raise trio.ClosedResourceError(
|
|
'The underlying channel for this stream was already closed!?'
|
|
)
|
|
|
|
# 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._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: bool = True
|
|
|
|
# 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._push_result()`` 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()
|
|
|
|
# if re := ctx._remote_error:
|
|
# ctx._maybe_raise_remote_err(
|
|
# re,
|
|
# raise_ctxc_from_self_call=True,
|
|
# )
|
|
# await trio.lowlevel.checkpoint()
|
|
|
|
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}'
|
|
)
|
|
|
|
def _maybe_raise_remote_err(
|
|
self,
|
|
err: Exception,
|
|
raise_ctxc_from_self_call: bool = False,
|
|
raise_overrun_from_self: bool = True,
|
|
|
|
) -> ContextCancelled|None:
|
|
'''
|
|
Maybe raise a remote error depending on who (which task from
|
|
which actor) requested a cancellation (if any).
|
|
|
|
'''
|
|
# NOTE: whenever the context's "opener" side (task) **is**
|
|
# the side which requested the cancellation (likekly via
|
|
# ``Context.cancel()``), we don't want to re-raise that
|
|
# cancellation signal locally (would be akin to
|
|
# a ``trio.Nursery`` nursery raising ``trio.Cancelled``
|
|
# whenever ``CancelScope.cancel()`` was called) and
|
|
# instead silently reap the expected cancellation
|
|
# "error"-msg.
|
|
our_uid: tuple[str, str] = current_actor().uid
|
|
if (
|
|
(not raise_ctxc_from_self_call
|
|
and isinstance(err, ContextCancelled)
|
|
and (
|
|
self._cancel_called
|
|
or self.chan._cancel_called
|
|
or self.canceller == our_uid
|
|
or tuple(err.canceller) == our_uid)
|
|
)
|
|
or
|
|
(not raise_overrun_from_self
|
|
and isinstance(err, RemoteActorError)
|
|
and err.msgdata['type_str'] == 'StreamOverrun'
|
|
and tuple(err.msgdata['sender']) == 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
|
|
# which are often superfluous to user handler code. not
|
|
# sure if this is still needed / desired for all operation?
|
|
# TODO: maybe we can only NOT mask if:
|
|
# - [ ] debug mode is enabled or,
|
|
# - [ ] a certain log level is set?
|
|
# - [ ] consider using `.with_traceback()` to filter out
|
|
# 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 err from None
|
|
|
|
async def result(self) -> Any | Exception:
|
|
'''
|
|
From some (caller) side task, wait for and return the final
|
|
result from the remote (callee) side's task.
|
|
|
|
This provides a mechanism for one task running in some actor to wait
|
|
on another task at the other side, in some other actor, to terminate.
|
|
|
|
If the remote task is still in a streaming state (it is delivering
|
|
values from inside a ``Context.open_stream():`` block, then those
|
|
msgs are drained but discarded since it is presumed this side of
|
|
the context has already finished with its own streaming logic.
|
|
|
|
If the remote context (or its containing actor runtime) was
|
|
canceled, either by a local task calling one of
|
|
``Context.cancel()`` or `Portal.cancel_actor()``, we ignore the
|
|
received ``ContextCancelled`` exception if the context or
|
|
underlying IPC channel is marked as having been "cancel called".
|
|
This is similar behavior to using ``trio.Nursery.cancel()``
|
|
wherein tasks which raise ``trio.Cancel`` are silently reaped;
|
|
the main different in this API is in the "cancel called" case,
|
|
instead of just not raising, we also return the exception *as
|
|
the result* since client code may be interested in the details
|
|
of the remote cancellation.
|
|
|
|
'''
|
|
assert self._portal, "Context.result() can not be called from callee!"
|
|
assert self._recv_chan
|
|
|
|
raise_overrun: bool = not self._allow_overruns
|
|
# if re := self._remote_error:
|
|
# return self._maybe_raise_remote_err(
|
|
# re,
|
|
# # NOTE: obvi we don't care if we
|
|
# # overran the far end if we're already
|
|
# # waiting on a final result (msg).
|
|
# raise_overrun_from_self=raise_overrun,
|
|
# )
|
|
|
|
res_placeholder: int = id(self)
|
|
if (
|
|
self._result == res_placeholder
|
|
and not self._remote_error
|
|
and not self._recv_chan._closed # type: ignore
|
|
):
|
|
|
|
# wait for a final context result by collecting (but
|
|
# basically ignoring) any bi-dir-stream msgs still in transit
|
|
# from the far end.
|
|
drained_msgs: list[dict] = await _drain_to_final_msg(ctx=self)
|
|
log.runtime(
|
|
'Ctx drained pre-result msgs:\n'
|
|
f'{drained_msgs}'
|
|
)
|
|
|
|
# TODO: implement via helper func ^^^^
|
|
# pre_result_drained: list[dict] = []
|
|
# while not self._remote_error:
|
|
# try:
|
|
# # NOTE: this REPL usage actually works here dawg! Bo
|
|
# # from .devx._debug import pause
|
|
# # await pause()
|
|
# # if re := self._remote_error:
|
|
# # self._maybe_raise_remote_err(
|
|
# # re,
|
|
# # # NOTE: obvi we don't care if we
|
|
# # # overran the far end if we're already
|
|
# # # waiting on a final result (msg).
|
|
# # raise_overrun_from_self=raise_overrun,
|
|
# # )
|
|
|
|
# # TODO: bad idea?
|
|
# # with trio.CancelScope() as res_cs:
|
|
# # self._res_scope = res_cs
|
|
# # msg: dict = await self._recv_chan.receive()
|
|
# # if res_cs.cancelled_caught:
|
|
|
|
# # from .devx._debug import pause
|
|
# # await pause()
|
|
# msg: dict = await self._recv_chan.receive()
|
|
# self._result: Any = msg['return']
|
|
# log.runtime(
|
|
# 'Context delivered final result msg:\n'
|
|
# f'{pformat(msg)}'
|
|
# )
|
|
# # NOTE: we don't need to do this right?
|
|
# # XXX: only close the rx mem chan AFTER
|
|
# # a final result is retreived.
|
|
# # if self._recv_chan:
|
|
# # await self._recv_chan.aclose()
|
|
# break
|
|
|
|
# # NOTE: we get here if the far end was
|
|
# # `ContextCancelled` in 2 cases:
|
|
# # 1. we requested the cancellation and thus
|
|
# # SHOULD NOT raise that far end error,
|
|
# # 2. WE DID NOT REQUEST that cancel and thus
|
|
# # SHOULD RAISE HERE!
|
|
# except trio.Cancelled:
|
|
|
|
# # CASE 2: mask the local cancelled-error(s)
|
|
# # only when we are sure the remote error is
|
|
# # the source cause of this local task's
|
|
# # cancellation.
|
|
# if re := self._remote_error:
|
|
# self._maybe_raise_remote_err(re)
|
|
|
|
# # CASE 1: we DID request the cancel we simply
|
|
# # continue to bubble up as normal.
|
|
# raise
|
|
|
|
# except KeyError:
|
|
|
|
# if 'yield' in msg:
|
|
# # far end task is still streaming to us so discard
|
|
# log.warning(f'Discarding std "yield"\n{msg}')
|
|
# pre_result_drained.append(msg)
|
|
# continue
|
|
|
|
# # TODO: work out edge cases here where
|
|
# # a stream is open but the task also calls
|
|
# # this?
|
|
# # -[ ] should be a runtime error if a stream is open
|
|
# # right?
|
|
# elif 'stop' in msg:
|
|
# log.cancel(
|
|
# 'Remote stream terminated due to "stop" msg:\n'
|
|
# f'{msg}'
|
|
# )
|
|
# pre_result_drained.append(msg)
|
|
# continue
|
|
|
|
# # internal error should never get here
|
|
# assert msg.get('cid'), (
|
|
# "Received internal error at portal?"
|
|
# )
|
|
|
|
# # XXX fallthrough to handle expected error XXX
|
|
# re: Exception|None = self._remote_error
|
|
# if re:
|
|
# log.critical(
|
|
# 'Remote ctx terminated due to "error" msg:\n'
|
|
# f'{re}'
|
|
# )
|
|
# assert msg is self._cancel_msg
|
|
# # NOTE: this solved a super dupe edge case XD
|
|
# # this was THE super duper edge case of:
|
|
# # - local task opens a remote task,
|
|
# # - requests remote cancellation of far end
|
|
# # ctx/tasks,
|
|
# # - needs to wait for the cancel ack msg
|
|
# # (ctxc) or some result in the race case
|
|
# # where the other side's task returns
|
|
# # before the cancel request msg is ever
|
|
# # rxed and processed,
|
|
# # - here this surrounding drain loop (which
|
|
# # iterates all ipc msgs until the ack or
|
|
# # an early result arrives) was NOT exiting
|
|
# # since we are the edge case: local task
|
|
# # does not re-raise any ctxc it receives
|
|
# # IFF **it** was the cancellation
|
|
# # requester..
|
|
# # will raise if necessary, ow break from
|
|
# # loop presuming any error terminates the
|
|
# # context!
|
|
# self._maybe_raise_remote_err(
|
|
# re,
|
|
# # NOTE: obvi we don't care if we
|
|
# # overran the far end if we're already
|
|
# # waiting on a final result (msg).
|
|
# # raise_overrun_from_self=False,
|
|
# raise_overrun_from_self=raise_overrun,
|
|
# )
|
|
|
|
# break # OOOOOF, yeah obvi we need this..
|
|
|
|
# # XXX we should never really get here
|
|
# # right! since `._deliver_msg()` should
|
|
# # always have detected an {'error': ..}
|
|
# # msg and already called this right!?!
|
|
# elif error := unpack_error(
|
|
# msg=msg,
|
|
# chan=self._portal.channel,
|
|
# hide_tb=False,
|
|
# ):
|
|
# log.critical('SHOULD NEVER GET HERE!?')
|
|
# assert msg is self._cancel_msg
|
|
# assert error.msgdata == self._remote_error.msgdata
|
|
# from .devx._debug import pause
|
|
# await pause()
|
|
# self._maybe_cancel_and_set_remote_error(error)
|
|
# self._maybe_raise_remote_err(error)
|
|
|
|
# else:
|
|
# # bubble the original src key error
|
|
# raise
|
|
|
|
if (
|
|
(re := self._remote_error)
|
|
and self._result == res_placeholder
|
|
):
|
|
maybe_err: Exception|None = self._maybe_raise_remote_err(
|
|
re,
|
|
# NOTE: obvi we don't care if we
|
|
# overran the far end if we're already
|
|
# waiting on a final result (msg).
|
|
# raise_overrun_from_self=False,
|
|
raise_overrun_from_self=(
|
|
raise_overrun
|
|
and
|
|
# only when we ARE NOT the canceller
|
|
# should we raise overruns, bc ow we're
|
|
# raising something we know might happen
|
|
# during cancellation ;)
|
|
(not self._cancel_called)
|
|
),
|
|
)
|
|
if maybe_err:
|
|
self._result = maybe_err
|
|
|
|
return self._result
|
|
|
|
async def started(
|
|
self,
|
|
value: Any | None = None
|
|
|
|
) -> None:
|
|
'''
|
|
Indicate to calling actor's task that this linked context
|
|
has started and send ``value`` to the other side via IPC.
|
|
|
|
On the calling side ``value`` is the second item delivered
|
|
in the tuple returned by ``Portal.open_context()``.
|
|
|
|
'''
|
|
if self._portal:
|
|
raise RuntimeError(
|
|
f'Caller side context {self} can not call started!'
|
|
)
|
|
|
|
elif self._started_called:
|
|
raise RuntimeError(
|
|
f'called `.started()` twice on context with {self.chan.uid}'
|
|
)
|
|
|
|
await self.chan.send({'started': value, 'cid': self.cid})
|
|
self._started_called = True
|
|
|
|
async def _drain_overflows(
|
|
self,
|
|
) -> None:
|
|
'''
|
|
Private task spawned to push newly received msgs to the local
|
|
task which getting overrun by the remote side.
|
|
|
|
In order to not block the rpc msg loop, but also not discard
|
|
msgs received in this context, we need to async push msgs in
|
|
a new task which only runs for as long as the local task is in
|
|
an overrun state.
|
|
|
|
'''
|
|
self._in_overrun = True
|
|
try:
|
|
while self._overflow_q:
|
|
# NOTE: these msgs should never be errors since we always do
|
|
# the check prior to checking if we're in an overrun state
|
|
# inside ``._deliver_msg()``.
|
|
msg = self._overflow_q.popleft()
|
|
try:
|
|
await self._send_chan.send(msg)
|
|
except trio.BrokenResourceError:
|
|
log.warning(
|
|
f"{self._send_chan} consumer is already closed"
|
|
)
|
|
return
|
|
except trio.Cancelled:
|
|
# we are obviously still in overrun
|
|
# but the context is being closed anyway
|
|
# so we just warn that there are un received
|
|
# msgs still..
|
|
self._overflow_q.appendleft(msg)
|
|
fmt_msgs = ''
|
|
for msg in self._overflow_q:
|
|
fmt_msgs += f'{pformat(msg)}\n'
|
|
|
|
log.warning(
|
|
f'Context for {self.cid} is being closed while '
|
|
'in an overrun state!\n'
|
|
'Discarding the following msgs:\n'
|
|
f'{fmt_msgs}\n'
|
|
)
|
|
raise
|
|
|
|
finally:
|
|
# task is now finished with the backlog so mark us as
|
|
# no longer in backlog.
|
|
self._in_overrun = False
|
|
|
|
async def _deliver_msg(
|
|
self,
|
|
msg: dict,
|
|
|
|
# draining: bool = False,
|
|
|
|
) -> bool:
|
|
'''
|
|
Deliver an IPC msg received from a transport-channel to
|
|
this context's underlying mem chan for handling by
|
|
user operating tasks; deliver a bool indicating whether the
|
|
msg was immediately sent.
|
|
|
|
If `._allow_overruns == True` (maybe) append the msg to an
|
|
"overflow queue" and start a "drainer task" (inside the
|
|
`._scope_nursery: trio.Nursery`) which ensures that such
|
|
messages are eventually sent if possible.
|
|
|
|
'''
|
|
cid: str = self.cid
|
|
chan: Channel = self.chan
|
|
from_uid: tuple[str, str] = chan.uid
|
|
send_chan: trio.MemorySendChannel = self._send_chan
|
|
|
|
if re := unpack_error(
|
|
msg,
|
|
self.chan,
|
|
):
|
|
log.error(
|
|
f'Delivering error-msg from {from_uid} to caller {cid}'
|
|
f'{re}'
|
|
)
|
|
self._cancel_msg = msg
|
|
self._maybe_cancel_and_set_remote_error(re)
|
|
|
|
# XXX NEVER do this XXX..!!
|
|
# bc if the error is a ctxc and there is a task
|
|
# waiting on `.result()` we need the msg to be sent
|
|
# over the `send_chan`/`._recv_chan` so that the error
|
|
# is relayed to that waiter task..
|
|
# return True
|
|
#
|
|
# XXX ALSO NO!! XXX
|
|
# if self._remote_error:
|
|
# self._maybe_raise_remote_err(error)
|
|
|
|
if self._in_overrun:
|
|
log.warning(
|
|
f'Capturing overrun-msg from {from_uid} to caller {cid}'
|
|
f'{msg}'
|
|
)
|
|
self._overflow_q.append(msg)
|
|
return False
|
|
|
|
try:
|
|
log.runtime(
|
|
f'Delivering IPC `Context` msg:\n'
|
|
f'<= {from_uid}\n'
|
|
f'=> caller: {cid}\n'
|
|
f'{msg}'
|
|
)
|
|
# from .devx._debug import pause
|
|
# await pause()
|
|
send_chan.send_nowait(msg)
|
|
return True
|
|
# if an error is deteced we should always
|
|
# expect it to be raised by any context (stream)
|
|
# consumer task
|
|
|
|
except trio.BrokenResourceError:
|
|
# TODO: what is the right way to handle the case where the
|
|
# local task has already sent a 'stop' / StopAsyncInteration
|
|
# to the other side but and possibly has closed the local
|
|
# feeder mem chan? Do we wait for some kind of ack or just
|
|
# let this fail silently and bubble up (currently)?
|
|
|
|
# XXX: local consumer has closed their side
|
|
# so cancel the far end streaming task
|
|
log.warning(f"{send_chan} consumer is already closed")
|
|
return False
|
|
|
|
# NOTE XXX: by default we do **not** maintain context-stream
|
|
# backpressure and instead opt to relay stream overrun errors to
|
|
# the sender; the main motivation is that using bp can block the
|
|
# msg handling loop which calls into this method!
|
|
except trio.WouldBlock:
|
|
|
|
# XXX: always push an error even if the local
|
|
# receiver is in overrun state.
|
|
# self._maybe_cancel_and_set_remote_error(msg)
|
|
|
|
local_uid = current_actor().uid
|
|
lines = [
|
|
f'OVERRUN on actor-task context {cid}@{local_uid}!\n'
|
|
# TODO: put remote task name here if possible?
|
|
f'sender: {from_uid}',
|
|
f'msg: {msg}',
|
|
# TODO: put task func name here and maybe an arrow
|
|
# from sender to overrunner?
|
|
# f'local task {self.func_name}'
|
|
]
|
|
if not self._stream_opened:
|
|
lines.insert(
|
|
1,
|
|
f'\n*** No stream open on `{local_uid[0]}` side! ***\n'
|
|
)
|
|
|
|
text = '\n'.join(lines)
|
|
|
|
# XXX: lul, this really can't be backpressure since any
|
|
# blocking here will block the entire msg loop rpc sched for
|
|
# a whole channel.. maybe we should rename it?
|
|
if self._allow_overruns:
|
|
text += f'\nStarting overflow queuing task on msg: {msg}'
|
|
log.warning(text)
|
|
if (
|
|
not self._in_overrun
|
|
):
|
|
self._overflow_q.append(msg)
|
|
n = self._scope_nursery
|
|
assert not n.child_tasks
|
|
try:
|
|
n.start_soon(
|
|
self._drain_overflows,
|
|
)
|
|
except RuntimeError:
|
|
# if the nursery is already cancelled due to
|
|
# this context exiting or in error, we ignore
|
|
# the nursery error since we never expected
|
|
# anything different.
|
|
return False
|
|
else:
|
|
# raise local overrun and immediately pack as IPC
|
|
# msg for far end.
|
|
try:
|
|
raise StreamOverrun(
|
|
text,
|
|
sender=from_uid,
|
|
)
|
|
except StreamOverrun as err:
|
|
err_msg: dict[str, dict] = pack_error(
|
|
err,
|
|
cid=cid,
|
|
)
|
|
# err_msg['cid']: str = cid
|
|
try:
|
|
await chan.send(err_msg)
|
|
except trio.BrokenResourceError:
|
|
# XXX: local consumer has closed their side
|
|
# so cancel the far end streaming task
|
|
log.warning(f"{chan} is already closed")
|
|
|
|
return False
|
|
|
|
|
|
def mk_context(
|
|
chan: Channel,
|
|
cid: str,
|
|
msg_buffer_size: int = 2**6,
|
|
|
|
**kwargs,
|
|
|
|
) -> Context:
|
|
'''
|
|
Internal factory to create an inter-actor task ``Context``.
|
|
|
|
This is called by internals and should generally never be called
|
|
by user code.
|
|
|
|
'''
|
|
send_chan: trio.MemorySendChannel
|
|
recv_chan: trio.MemoryReceiveChannel
|
|
send_chan, recv_chan = trio.open_memory_channel(msg_buffer_size)
|
|
|
|
ctx = Context(
|
|
chan,
|
|
cid,
|
|
_send_chan=send_chan,
|
|
_recv_chan=recv_chan,
|
|
**kwargs,
|
|
)
|
|
ctx._result: int | Any = id(ctx)
|
|
return ctx
|
|
|
|
|
|
def context(func: Callable) -> Callable:
|
|
'''
|
|
Mark an async function as a streaming routine with ``@context``.
|
|
|
|
'''
|
|
# TODO: apply whatever solution ``mypy`` ends up picking for this:
|
|
# https://github.com/python/mypy/issues/2087#issuecomment-769266912
|
|
func._tractor_context_function = True # type: ignore
|
|
|
|
sig = inspect.signature(func)
|
|
params = sig.parameters
|
|
if 'ctx' not in params:
|
|
raise TypeError(
|
|
"The first argument to the context function "
|
|
f"{func.__name__} must be `ctx: tractor.Context`"
|
|
)
|
|
return func
|