334 lines
11 KiB
Python
334 lines
11 KiB
Python
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# 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
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# modify it under the terms of the GNU Affero General Public License
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# as published by the Free Software Foundation, either version 3 of
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# the License, or (at your option) any later version.
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Affero General Public License for more details.
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# You should have received a copy of the GNU Affero General Public
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# License along with this program. If not, see
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# <https://www.gnu.org/licenses/>.
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'''
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A custom SIGINT handler which mainly shields actor (task)
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cancellation during REPL interaction.
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'''
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from __future__ import annotations
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from typing import (
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TYPE_CHECKING,
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)
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import trio
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from tractor.log import get_logger
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from tractor._state import (
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current_actor,
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is_root_process,
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)
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from ._repl import (
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PdbREPL,
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)
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from ._tty_lock import (
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any_connected_locker_child,
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DebugStatus,
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Lock,
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)
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if TYPE_CHECKING:
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from tractor.ipc import (
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Channel,
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)
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from tractor._runtime import (
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Actor,
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)
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log = get_logger(__name__)
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_ctlc_ignore_header: str = (
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'Ignoring SIGINT while debug REPL in use'
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)
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def sigint_shield(
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signum: int,
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frame: 'frame', # type: ignore # noqa
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*args,
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) -> None:
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'''
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Specialized, debugger-aware SIGINT handler.
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In childred we always ignore/shield for SIGINT to avoid
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deadlocks since cancellation should always be managed by the
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supervising parent actor. The root actor-proces is always
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cancelled on ctrl-c.
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'''
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__tracebackhide__: bool = True
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actor: Actor = current_actor()
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def do_cancel():
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# If we haven't tried to cancel the runtime then do that instead
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# of raising a KBI (which may non-gracefully destroy
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# a ``trio.run()``).
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if not actor._cancel_called:
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actor.cancel_soon()
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# If the runtime is already cancelled it likely means the user
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# hit ctrl-c again because teardown didn't fully take place in
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# which case we do the "hard" raising of a local KBI.
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else:
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raise KeyboardInterrupt
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# only set in the actor actually running the REPL
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repl: PdbREPL|None = DebugStatus.repl
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# TODO: maybe we should flatten out all these cases using
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# a match/case?
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#
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# root actor branch that reports whether or not a child
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# has locked debugger.
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if is_root_process():
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# log.warning(
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log.devx(
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'Handling SIGINT in root actor\n'
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f'{Lock.repr()}'
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f'{DebugStatus.repr()}\n'
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)
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# try to see if the supposed (sub)actor in debug still
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# has an active connection to *this* actor, and if not
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# it's likely they aren't using the TTY lock / debugger
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# and we should propagate SIGINT normally.
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any_connected: bool = any_connected_locker_child()
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problem = (
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f'root {actor.uid} handling SIGINT\n'
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f'any_connected: {any_connected}\n\n'
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f'{Lock.repr()}\n'
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)
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if (
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(ctx := Lock.ctx_in_debug)
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and
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(uid_in_debug := ctx.chan.uid) # "someone" is (ostensibly) using debug `Lock`
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):
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name_in_debug: str = uid_in_debug[0]
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assert not repl
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# if not repl: # but it's NOT us, the root actor.
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# sanity: since no repl ref is set, we def shouldn't
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# be the lock owner!
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assert name_in_debug != 'root'
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# IDEAL CASE: child has REPL as expected
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if any_connected: # there are subactors we can contact
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# XXX: only if there is an existing connection to the
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# (sub-)actor in debug do we ignore SIGINT in this
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# parent! Otherwise we may hang waiting for an actor
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# which has already terminated to unlock.
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#
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# NOTE: don't emit this with `.pdb()` level in
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# root without a higher level.
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log.runtime(
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_ctlc_ignore_header
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+
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f' by child '
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f'{uid_in_debug}\n'
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)
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problem = None
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else:
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problem += (
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'\n'
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f'A `pdb` REPL is SUPPOSEDLY in use by child {uid_in_debug}\n'
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f'BUT, no child actors are IPC contactable!?!?\n'
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)
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# IDEAL CASE: root has REPL as expected
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else:
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# root actor still has this SIGINT handler active without
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# an actor using the `Lock` (a bug state) ??
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# => so immediately cancel any stale lock cs and revert
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# the handler!
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if not DebugStatus.repl:
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# TODO: WHEN should we revert back to ``trio``
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# handler if this one is stale?
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# -[ ] maybe after a counts work of ctl-c mashes?
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# -[ ] use a state var like `stale_handler: bool`?
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problem += (
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'No subactor is using a `pdb` REPL according `Lock.ctx_in_debug`?\n'
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'BUT, the root should be using it, WHY this handler ??\n\n'
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'So either..\n'
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'- some root-thread is using it but has no `.repl` set?, OR\n'
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'- something else weird is going on outside the runtime!?\n'
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)
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else:
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# NOTE: since we emit this msg on ctl-c, we should
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# also always re-print the prompt the tail block!
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log.pdb(
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_ctlc_ignore_header
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+
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f' by root actor..\n'
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f'{DebugStatus.repl_task}\n'
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f' |_{repl}\n'
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)
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problem = None
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# XXX if one is set it means we ARE NOT operating an ideal
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# case where a child subactor or us (the root) has the
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# lock without any other detected problems.
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if problem:
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# detect, report and maybe clear a stale lock request
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# cancel scope.
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lock_cs: trio.CancelScope = Lock.get_locking_task_cs()
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maybe_stale_lock_cs: bool = (
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lock_cs is not None
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and not lock_cs.cancel_called
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)
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if maybe_stale_lock_cs:
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problem += (
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'\n'
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'Stale `Lock.ctx_in_debug._scope: CancelScope` detected?\n'
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f'{Lock.ctx_in_debug}\n\n'
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'-> Calling ctx._scope.cancel()!\n'
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)
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lock_cs.cancel()
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# TODO: wen do we actually want/need this, see above.
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# DebugStatus.unshield_sigint()
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log.warning(problem)
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# child actor that has locked the debugger
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elif not is_root_process():
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log.debug(
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f'Subactor {actor.uid} handling SIGINT\n\n'
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f'{Lock.repr()}\n'
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)
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rent_chan: Channel = actor._parent_chan
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if (
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rent_chan is None
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or
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not rent_chan.connected()
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):
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log.warning(
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'This sub-actor thinks it is debugging '
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'but it has no connection to its parent ??\n'
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f'{actor.uid}\n'
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'Allowing SIGINT propagation..'
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)
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DebugStatus.unshield_sigint()
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repl_task: str|None = DebugStatus.repl_task
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req_task: str|None = DebugStatus.req_task
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if (
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repl_task
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and
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repl
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):
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log.pdb(
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_ctlc_ignore_header
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+
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f' by local task\n\n'
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f'{repl_task}\n'
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f' |_{repl}\n'
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)
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elif req_task:
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log.debug(
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_ctlc_ignore_header
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+
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f' by local request-task and either,\n'
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f'- someone else is already REPL-in and has the `Lock`, or\n'
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f'- some other local task already is replin?\n\n'
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f'{req_task}\n'
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)
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# TODO can we remove this now?
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# -[ ] does this path ever get hit any more?
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else:
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msg: str = (
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'SIGINT shield handler still active BUT, \n\n'
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)
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if repl_task is None:
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msg += (
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'- No local task claims to be in debug?\n'
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)
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if repl is None:
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msg += (
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'- No local REPL is currently active?\n'
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)
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if req_task is None:
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msg += (
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'- No debug request task is active?\n'
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)
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log.warning(
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msg
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+
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'Reverting handler to `trio` default!\n'
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)
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DebugStatus.unshield_sigint()
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# XXX ensure that the reverted-to-handler actually is
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# able to rx what should have been **this** KBI ;)
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do_cancel()
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# TODO: how to handle the case of an intermediary-child actor
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# that **is not** marked in debug mode? See oustanding issue:
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# https://github.com/goodboy/tractor/issues/320
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# elif debug_mode():
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# maybe redraw/print last REPL output to console since
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# we want to alert the user that more input is expect since
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# nothing has been done dur to ignoring sigint.
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if (
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DebugStatus.repl # only when current actor has a REPL engaged
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):
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flush_status: str = (
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'Flushing stdout to ensure new prompt line!\n'
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)
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# XXX: yah, mega hack, but how else do we catch this madness XD
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if (
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repl.shname == 'xonsh'
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):
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flush_status += (
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'-> ALSO re-flushing due to `xonsh`..\n'
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)
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repl.stdout.write(repl.prompt)
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# log.warning(
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log.devx(
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flush_status
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)
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repl.stdout.flush()
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# TODO: better console UX to match the current "mode":
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# -[ ] for example if in sticky mode where if there is output
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# detected as written to the tty we redraw this part underneath
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# and erase the past draw of this same bit above?
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# repl.sticky = True
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# repl._print_if_sticky()
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# also see these links for an approach from `ptk`:
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# https://github.com/goodboy/tractor/issues/130#issuecomment-663752040
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# https://github.com/prompt-toolkit/python-prompt-toolkit/blob/c2c6af8a0308f9e5d7c0e28cb8a02963fe0ce07a/prompt_toolkit/patch_stdout.py
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else:
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log.devx(
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# log.warning(
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'Not flushing stdout since not needed?\n'
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f'|_{repl}\n'
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)
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# XXX only for tracing this handler
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log.devx('exiting SIGINT')
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