forked from goodboy/tractor
136 lines
3.0 KiB
Python
136 lines
3.0 KiB
Python
"""
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Our classy exception set.
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"""
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from typing import Dict, Any, Optional, Type
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import importlib
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import builtins
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import traceback
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import trio
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_this_mod = importlib.import_module(__name__)
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class ActorFailure(Exception):
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"General actor failure"
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class RemoteActorError(Exception):
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# TODO: local recontruction of remote exception deats
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"Remote actor exception bundled locally"
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def __init__(
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self,
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message: str,
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suberror_type: Optional[Type[BaseException]] = None,
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**msgdata
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) -> None:
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super().__init__(message)
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self.type = suberror_type
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self.msgdata = msgdata
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# TODO: a trio.MultiError.catch like context manager
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# for catching underlying remote errors of a particular type
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class InternalActorError(RemoteActorError):
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"""Remote internal ``tractor`` error indicating
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failure of some primitive or machinery.
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"""
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class TransportClosed(trio.ClosedResourceError):
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"Underlying channel transport was closed prior to use"
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class ContextCancelled(RemoteActorError):
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"Inter-actor task context cancelled itself on the callee side."
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class NoResult(RuntimeError):
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"No final result is expected for this actor"
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class ModuleNotExposed(ModuleNotFoundError):
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"The requested module is not exposed for RPC"
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class NoRuntime(RuntimeError):
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"The root actor has not been initialized yet"
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def pack_error(
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exc: BaseException,
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tb=None,
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) -> Dict[str, Any]:
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"""Create an "error message" for tranmission over
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a channel (aka the wire).
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"""
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if tb:
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tb_str = ''.join(traceback.format_tb(tb))
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else:
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tb_str = traceback.format_exc()
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return {
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'error': {
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'tb_str': tb_str,
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'type_str': type(exc).__name__,
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}
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}
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def unpack_error(
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msg: Dict[str, Any],
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chan=None,
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err_type=RemoteActorError
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) -> Exception:
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"""Unpack an 'error' message from the wire
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into a local ``RemoteActorError``.
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"""
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error = msg['error']
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tb_str = error.get('tb_str', '')
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message = f"{chan.uid}\n" + tb_str
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type_name = error['type_str']
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suberror_type: Type[BaseException] = Exception
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if type_name == 'ContextCancelled':
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err_type = ContextCancelled
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suberror_type = trio.Cancelled
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else: # try to lookup a suitable local error type
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for ns in [builtins, _this_mod, trio]:
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try:
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suberror_type = getattr(ns, type_name)
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break
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except AttributeError:
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continue
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exc = err_type(
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message,
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suberror_type=suberror_type,
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# unpack other fields into error type init
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**msg['error'],
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)
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return exc
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def is_multi_cancelled(exc: BaseException) -> bool:
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"""Predicate to determine if a ``trio.MultiError`` contains only
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``trio.Cancelled`` sub-exceptions (and is likely the result of
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cancelling a collection of subtasks.
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"""
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return not trio.MultiError.filter(
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lambda exc: exc if not isinstance(exc, trio.Cancelled) else None,
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exc,
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)
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