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EDIT :: pickling_support.py

import copyreg from functools import partial from types import TracebackType from . import Frame from . import Traceback def unpickle_traceback(tb_frame, tb_lineno, tb_next): ret = object.__new__(Traceback) ret.tb_frame = tb_frame ret.tb_lineno = tb_lineno ret.tb_next = tb_next return ret.as_traceback() def pickle_traceback(tb, *, get_locals=None): return unpickle_traceback, ( Frame(tb.tb_frame, get_locals=get_locals), tb.tb_lineno, tb.tb_next and Traceback(tb.tb_next, get_locals=get_locals), ) # Note: Older versions of tblib will generate pickle archives that call unpickle_exception() with # fewer arguments. We assign default values to some of the arguments to support this. def unpickle_exception(func, args, cause, tb, context=None, suppress_context=False, notes=None): inst = func(*args) inst.__cause__ = cause inst.__traceback__ = tb inst.__context__ = context inst.__suppress_context__ = suppress_context if notes is not None: inst.__notes__ = notes return inst def pickle_exception(obj): # All exceptions, unlike generic Python objects, define __reduce_ex__ # __reduce_ex__(4) should be no different from __reduce_ex__(3). # __reduce_ex__(5) could bring benefits in the unlikely case the exception # directly contains buffers, but PickleBuffer objects will cause a crash when # running on protocol=4, and there's no clean way to figure out the current # protocol from here. Note that any object returned by __reduce_ex__(3) will # still be pickled with protocol 5 if pickle.dump() is running with it. rv = obj.__reduce_ex__(3) if isinstance(rv, str): raise TypeError('str __reduce__ output is not supported') assert isinstance(rv, tuple) assert len(rv) >= 2 return ( unpickle_exception, rv[:2] + ( obj.__cause__, obj.__traceback__, obj.__context__, obj.__suppress_context__, # __notes__ doesn't exist prior to Python 3.11; and even on Python 3.11 it may be absent getattr(obj, '__notes__', None), ), ) + rv[2:] def _get_subclasses(cls): # Depth-first traversal of all direct and indirect subclasses of cls to_visit = [cls] while to_visit: this = to_visit.pop() yield this to_visit += list(this.__subclasses__()) def install(*exc_classes_or_instances, get_locals=None): """ Args: get_locals (callable): A function that take a frame argument and returns a dict. See :class:`tblib.Traceback` class for example. """ copyreg.pickle(TracebackType, partial(pickle_traceback, get_locals=get_locals)) if not exc_classes_or_instances: for exception_cls in _get_subclasses(BaseException): copyreg.pickle(exception_cls, pickle_exception) return for exc in exc_classes_or_instances: if isinstance(exc, BaseException): _install_for_instance(exc, set()) elif isinstance(exc, type) and issubclass(exc, BaseException): copyreg.pickle(exc, pickle_exception) # Allow using @install as a decorator for Exception classes if len(exc_classes_or_instances) == 1: return exc else: raise TypeError(f'Expected subclasses or instances of BaseException, got {type(exc)}') def _install_for_instance(exc, seen): assert isinstance(exc, BaseException) # Prevent infinite recursion if we somehow get a self-referential exception. (Self-referential # exceptions should never normally happen, but if it did somehow happen, we want to pickle the # exception faithfully so the developer can troubleshoot why it happened.) if id(exc) in seen: return seen.add(id(exc)) copyreg.pickle(type(exc), pickle_exception) if exc.__cause__ is not None: _install_for_instance(exc.__cause__, seen) if exc.__context__ is not None: _install_for_instance(exc.__context__, seen) # This case is meant to cover BaseExceptionGroup on Python 3.11 as well as backports like the # exceptiongroup module if hasattr(exc, 'exceptions') and isinstance(exc.exceptions, (tuple, list)): for subexc in exc.exceptions: if isinstance(subexc, BaseException): _install_for_instance(subexc, seen)

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