This document describes the current stable version of Celery (4.1). For development docs, go here.
Source code for celery.utils.serialization
# -*- coding: utf-8 -*-
"""Utilities for safely pickling exceptions."""
from __future__ import absolute_import, unicode_literals
import datetime
import numbers
import sys
from base64 import b64encode as base64encode, b64decode as base64decode
from functools import partial
from inspect import getmro
from itertools import takewhile
from kombu.utils.encoding import bytes_to_str, str_to_bytes
from celery.five import (
bytes_if_py2, python_2_unicode_compatible, items, reraise, string_t,
)
from .encoding import safe_repr
try:
import cPickle as pickle
except ImportError:
import pickle # noqa
PY33 = sys.version_info >= (3, 3)
__all__ = [
'UnpickleableExceptionWrapper', 'subclass_exception',
'find_pickleable_exception', 'create_exception_cls',
'get_pickleable_exception', 'get_pickleable_etype',
'get_pickled_exception', 'strtobool',
]
#: List of base classes we probably don't want to reduce to.
try:
unwanted_base_classes = (StandardError, Exception, BaseException, object)
except NameError: # pragma: no cover
unwanted_base_classes = (Exception, BaseException, object) # py3k
[docs]def subclass_exception(name, parent, module): # noqa
"""Create new exception class."""
return type(bytes_if_py2(name), (parent,), {'__module__': module})
[docs]def find_pickleable_exception(exc, loads=pickle.loads,
dumps=pickle.dumps):
"""Find first pickleable exception base class.
With an exception instance, iterate over its super classes (by MRO)
and find the first super exception that's pickleable. It does
not go below :exc:`Exception` (i.e., it skips :exc:`Exception`,
:class:`BaseException` and :class:`object`). If that happens
you should use :exc:`UnpickleableException` instead.
Arguments:
exc (BaseException): An exception instance.
Returns:
Exception: Nearest pickleable parent exception class
(except :exc:`Exception` and parents), or if the exception is
pickleable it will return :const:`None`.
"""
exc_args = getattr(exc, 'args', [])
for supercls in itermro(exc.__class__, unwanted_base_classes):
try:
superexc = supercls(*exc_args)
loads(dumps(superexc))
except Exception: # pylint: disable=broad-except
pass
else:
return superexc
def itermro(cls, stop):
return takewhile(lambda sup: sup not in stop, getmro(cls))
[docs]def create_exception_cls(name, module, parent=None):
"""Dynamically create an exception class."""
if not parent:
parent = Exception
return subclass_exception(name, parent, module)
@python_2_unicode_compatible
[docs]class UnpickleableExceptionWrapper(Exception):
"""Wraps unpickleable exceptions.
Arguments:
exc_module (str): See :attr:`exc_module`.
exc_cls_name (str): See :attr:`exc_cls_name`.
exc_args (Tuple[Any, ...]): See :attr:`exc_args`.
Example:
>>> def pickle_it(raising_function):
... try:
... raising_function()
... except Exception as e:
... exc = UnpickleableExceptionWrapper(
... e.__class__.__module__,
... e.__class__.__name__,
... e.args,
... )
... pickle.dumps(exc) # Works fine.
"""
#: The module of the original exception.
exc_module = None
#: The name of the original exception class.
exc_cls_name = None
#: The arguments for the original exception.
exc_args = None
def __init__(self, exc_module, exc_cls_name, exc_args, text=None):
safe_exc_args = []
for arg in exc_args:
try:
pickle.dumps(arg)
safe_exc_args.append(arg)
except Exception: # pylint: disable=broad-except
safe_exc_args.append(safe_repr(arg))
self.exc_module = exc_module
self.exc_cls_name = exc_cls_name
self.exc_args = safe_exc_args
self.text = text
Exception.__init__(self, exc_module, exc_cls_name, safe_exc_args, text)
[docs] def restore(self):
return create_exception_cls(self.exc_cls_name,
self.exc_module)(*self.exc_args)
def __str__(self):
return self.text
@classmethod
[docs] def from_exception(cls, exc):
return cls(exc.__class__.__module__,
exc.__class__.__name__,
getattr(exc, 'args', []),
safe_repr(exc))
[docs]def get_pickleable_exception(exc):
"""Make sure exception is pickleable."""
try:
pickle.loads(pickle.dumps(exc))
except Exception: # pylint: disable=broad-except
pass
else:
return exc
nearest = find_pickleable_exception(exc)
if nearest:
return nearest
return UnpickleableExceptionWrapper.from_exception(exc)
[docs]def get_pickleable_etype(cls, loads=pickle.loads, dumps=pickle.dumps):
"""Get pickleable exception type."""
try:
loads(dumps(cls))
except Exception: # pylint: disable=broad-except
return Exception
else:
return cls
[docs]def get_pickled_exception(exc):
"""Reverse of :meth:`get_pickleable_exception`."""
if isinstance(exc, UnpickleableExceptionWrapper):
return exc.restore()
return exc
def b64encode(s):
return bytes_to_str(base64encode(str_to_bytes(s)))
def b64decode(s):
return base64decode(str_to_bytes(s))
[docs]def strtobool(term, table={'false': False, 'no': False, '0': False,
'true': True, 'yes': True, '1': True,
'on': True, 'off': False}):
"""Convert common terms for true/false to bool.
Examples (true/false/yes/no/on/off/1/0).
"""
if isinstance(term, string_t):
try:
return table[term.lower()]
except KeyError:
raise TypeError('Cannot coerce {0!r} to type bool'.format(term))
return term
def _datetime_to_json(dt):
# See "Date Time String Format" in the ECMA-262 specification.
if isinstance(dt, datetime.datetime):
r = dt.isoformat()
if dt.microsecond:
r = r[:23] + r[26:]
if r.endswith('+00:00'):
r = r[:-6] + 'Z'
return r
elif isinstance(dt, datetime.time):
r = dt.isoformat()
if dt.microsecond:
r = r[:12]
return r
else:
return dt.isoformat()
def jsonify(obj,
builtin_types=(numbers.Real, string_t), key=None,
keyfilter=None,
unknown_type_filter=None):
"""Transform object making it suitable for json serialization."""
from kombu.abstract import Object as KombuDictType
_jsonify = partial(jsonify, builtin_types=builtin_types, key=key,
keyfilter=keyfilter,
unknown_type_filter=unknown_type_filter)
if isinstance(obj, KombuDictType):
obj = obj.as_dict(recurse=True)
if obj is None or isinstance(obj, builtin_types):
return obj
elif isinstance(obj, (tuple, list)):
return [_jsonify(v) for v in obj]
elif isinstance(obj, dict):
return {
k: _jsonify(v, key=k) for k, v in items(obj)
if (keyfilter(k) if keyfilter else 1)
}
elif isinstance(obj, (datetime.date, datetime.time)):
return _datetime_to_json(obj)
elif isinstance(obj, datetime.timedelta):
return str(obj)
else:
if unknown_type_filter is None:
raise ValueError(
'Unsupported type: {0!r} {1!r} (parent: {2})'.format(
type(obj), obj, key))
return unknown_type_filter(obj)
# Since PyPy 3 targets Python 3.2, 'raise exc from None' will
# raise a TypeError so we need to look for Python 3.3 or newer
if PY33: # pragma: no cover
from vine.five import exec_
_raise_with_context = None # for flake8
exec_("""def _raise_with_context(exc, ctx): raise exc from ctx""")
def raise_with_context(exc):
exc_info = sys.exc_info()
if not exc_info:
raise exc
elif exc_info[1] is exc:
raise
_raise_with_context(exc, exc_info[1])
else:
def raise_with_context(exc):
exc_info = sys.exc_info()
if not exc_info:
raise exc
if exc_info[1] is exc:
raise
elif exc_info[2]:
reraise(type(exc), exc, exc_info[2])
raise exc
