411 lines
13 KiB
Python
411 lines
13 KiB
Python
# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (C) 2012 Yahoo! Inc. All Rights Reserved.
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# Copyright (C) 2013 Rackspace Hosting All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import collections
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import copy
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import errno
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import functools
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import logging
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import os
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import six
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import sys
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import traceback
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from taskflow import exceptions
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from taskflow.utils import reflection
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LOG = logging.getLogger(__name__)
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def wraps(fn):
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"""This will not be needed in python 3.2 or greater which already has this
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built-in to its functools.wraps method.
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"""
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def wrapper(f):
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f = functools.wraps(fn)(f)
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f.__wrapped__ = getattr(fn, '__wrapped__', fn)
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return f
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return wrapper
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def get_version_string(obj):
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"""Gets a object's version as a string.
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Returns string representation of object's version taken from
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its 'version' attribute, or None if object does not have such
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attribute or its version is None.
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"""
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obj_version = getattr(obj, 'version', None)
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if isinstance(obj_version, (list, tuple)):
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obj_version = '.'.join(str(item) for item in obj_version)
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if obj_version is not None and not isinstance(obj_version,
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six.string_types):
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obj_version = str(obj_version)
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return obj_version
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def get_duplicate_keys(iterable, key=None):
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if key is not None:
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iterable = six.moves.map(key, iterable)
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keys = set()
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duplicates = set()
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for item in iterable:
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if item in keys:
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duplicates.add(item)
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keys.add(item)
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return duplicates
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class AttrDict(dict):
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"""Helper utility class to create a class that can be accessed by
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attribute name from a dictionary that contains a set of keys and values.
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"""
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@staticmethod
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def _is_valid_attribute_name(name):
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if not isinstance(name, six.string_types) or len(name) == 0:
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return False
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if name.lower().startswith('self') or name.startswith("_"):
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return False
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if not name[0].isalpha():
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return False
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for i in range(1, len(name)):
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if not (name[i].isalpha() or name[i].isdigit()):
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return False
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return True
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def __init__(self, **kwargs):
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for (k, v) in kwargs.items():
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if not self._is_valid_attribute_name(k):
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raise AttributeError("Invalid attribute name: '%s'" % (k))
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self[k] = v
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def __getattr__(self, name):
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if not self._is_valid_attribute_name(name):
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raise AttributeError("Invalid attribute name: '%s'" % (name))
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try:
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return self[name]
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except KeyError:
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raise AttributeError("No attributed named: '%s'" % (name))
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def __setattr__(self, name, value):
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if not self._is_valid_attribute_name(name):
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raise AttributeError("Invalid attribute name: '%s'" % (name))
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self[name] = value
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class ExponentialBackoff(object):
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"""An iterable object that will yield back an exponential delay sequence
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provided an exponent and a number of items to yield. This object may be
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iterated over multiple times (yielding the same sequence each time).
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"""
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def __init__(self, attempts, exponent=2):
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self.attempts = int(attempts)
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self.exponent = exponent
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def __iter__(self):
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if self.attempts <= 0:
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raise StopIteration()
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for i in xrange(0, self.attempts):
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yield self.exponent ** i
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def __str__(self):
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return "ExponentialBackoff: %s" % ([str(v) for v in self])
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def as_bool(val):
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"""Converts an arbitary value into a boolean."""
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if isinstance(val, bool):
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return val
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if isinstance(val, six.string_types):
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if val.lower() in ('f', 'false', '0', 'n', 'no'):
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return False
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if val.lower() in ('t', 'true', '1', 'y', 'yes'):
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return True
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return bool(val)
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def as_int(obj, quiet=False):
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"""Converts an arbitary value into a integer."""
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# Try "2" -> 2
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try:
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return int(obj)
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except (ValueError, TypeError):
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pass
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# Try "2.5" -> 2
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try:
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return int(float(obj))
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except (ValueError, TypeError):
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pass
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# Eck, not sure what this is then.
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if not quiet:
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raise TypeError("Can not translate %s to an integer." % (obj))
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return obj
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# Taken from oslo-incubator file-utils but since that module pulls in a large
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# amount of other files it does not seem so useful to include that full
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# module just for this function.
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def ensure_tree(path):
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"""Create a directory (and any ancestor directories required)
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:param path: Directory to create
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"""
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try:
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os.makedirs(path)
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except OSError as exc:
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if exc.errno == errno.EEXIST:
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if not os.path.isdir(path):
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raise
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else:
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raise
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class TransitionNotifier(object):
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"""A utility helper class that can be used to subscribe to
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notifications of events occuring as well as allow a entity to post said
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notifications to subscribers.
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"""
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RESERVED_KEYS = ('details',)
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ANY = '*'
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def __init__(self):
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self._listeners = collections.defaultdict(list)
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def reset(self):
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self._listeners = collections.defaultdict(list)
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def notify(self, state, details):
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listeners = list(self._listeners.get(self.ANY, []))
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for i in self._listeners[state]:
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if i not in listeners:
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listeners.append(i)
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if not listeners:
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return
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for (callback, args, kwargs) in listeners:
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if args is None:
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args = []
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if kwargs is None:
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kwargs = {}
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kwargs['details'] = details
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try:
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callback(state, *args, **kwargs)
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except Exception:
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LOG.exception(("Failure calling callback %s to notify about"
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" state transition %s"), callback, state)
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def register(self, state, callback, args=None, kwargs=None):
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assert isinstance(callback, collections.Callable)
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for i, (cb, args, kwargs) in enumerate(self._listeners.get(state, [])):
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if cb is callback:
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raise ValueError("Callback %s already registered" % (callback))
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if kwargs:
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for k in self.RESERVED_KEYS:
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if k in kwargs:
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raise KeyError(("Reserved key '%s' not allowed in "
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"kwargs") % k)
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kwargs = copy.copy(kwargs)
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if args:
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args = copy.copy(args)
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self._listeners[state].append((callback, args, kwargs))
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def deregister(self, state, callback):
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if state not in self._listeners:
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return
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for i, (cb, args, kwargs) in enumerate(self._listeners[state]):
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if cb is callback:
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self._listeners[state].pop(i)
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break
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def copy_exc_info(exc_info):
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"""Make copy of exception info tuple, as deep as possible"""
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if exc_info is None:
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return None
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exc_type, exc_value, tb = exc_info
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# NOTE(imelnikov): there is no need to copy type, and
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# we can't copy traceback
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return (exc_type, copy.deepcopy(exc_value), tb)
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def are_equal_exc_info_tuples(ei1, ei2):
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if ei1 == ei2:
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return True
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if ei1 is None or ei2 is None:
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return False # if both are None, we returned True above
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# NOTE(imelnikov): we can't compare exceptions with '=='
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# because we want exc_info be equal to it's copy made with
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# copy_exc_info above
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if ei1[0] is not ei2[0]:
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return False
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if not all((type(ei1[1]) == type(ei2[1]),
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str(ei1[1]) == str(ei2[1]),
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repr(ei1[1]) == repr(ei2[1]))):
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return False
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if ei1[2] == ei2[2]:
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return True
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tb1 = traceback.format_tb(ei1[2])
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tb2 = traceback.format_tb(ei2[2])
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return tb1 == tb2
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class Failure(object):
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"""Object that represents failure.
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Failure objects encapsulate exception information so that
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it can be re-used later to re-raise or inspect.
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"""
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def __init__(self, exc_info=None, **kwargs):
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if not kwargs:
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if exc_info is None:
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exc_info = sys.exc_info()
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self._exc_info = exc_info
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self._exc_type_names = list(
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reflection.get_all_class_names(exc_info[0], up_to=Exception))
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if not self._exc_type_names:
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raise TypeError('Invalid exception type: %r' % exc_info[0])
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self._exception_str = str(self._exc_info[1])
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self._traceback_str = ''.join(
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traceback.format_tb(self._exc_info[2]))
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else:
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self._exc_info = exc_info # may be None
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self._exception_str = kwargs.pop('exception_str')
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self._exc_type_names = kwargs.pop('exc_type_names', [])
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self._traceback_str = kwargs.pop('traceback_str', None)
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if kwargs:
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raise TypeError(
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'Failure.__init__ got unexpected keyword argument(s): %s'
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% ', '.join(six.iterkeys(kwargs)))
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def _matches(self, other):
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if self is other:
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return True
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return (self._exc_type_names == other._exc_type_names
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and self.exception_str == other.exception_str
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and self.traceback_str == other.traceback_str)
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def matches(self, other):
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if not isinstance(other, Failure):
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return False
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if self.exc_info is None or other.exc_info is None:
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return self._matches(other)
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else:
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return self == other
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def __eq__(self, other):
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if not isinstance(other, Failure):
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return NotImplemented
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return (self._matches(other) and
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are_equal_exc_info_tuples(self.exc_info, other.exc_info))
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def __ne__(self, other):
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return not (self == other)
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# NOTE(imelnikov): obj.__hash__() should return same values for equal
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# objects, so we should redefine __hash__. Failure equality semantics
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# is a bit complicated, so for now we just mark Failure objects as
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# unhashable. See python docs on object.__hash__ for more info:
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# http://docs.python.org/2/reference/datamodel.html#object.__hash__
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__hash__ = None
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@property
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def exception(self):
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"""Exception value, or None if exception value is not present.
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Exception value may be lost during serialization.
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"""
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if self._exc_info:
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return self._exc_info[1]
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else:
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return None
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@property
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def exception_str(self):
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"""String representation of exception."""
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return self._exception_str
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@property
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def exc_info(self):
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"""Exception info tuple or None."""
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return self._exc_info
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@property
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def traceback_str(self):
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"""Exception traceback as string."""
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return self._traceback_str
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@staticmethod
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def reraise_if_any(failures):
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"""Re-raise exceptions if argument is not empty.
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If argument is empty list, this method returns None. If
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argument is list with single Failure object in it,
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this failure is reraised. Else, WrappedFailure exception
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is raised with failures list as causes.
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"""
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failures = list(failures)
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if len(failures) == 1:
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failures[0].reraise()
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elif len(failures) > 1:
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raise exceptions.WrappedFailure(failures)
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def reraise(self):
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"""Re-raise captured exception"""
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if self._exc_info:
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six.reraise(*self._exc_info)
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else:
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raise exceptions.WrappedFailure([self])
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def check(self, *exc_classes):
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"""Check if any of exc_classes caused the failure
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Arguments of this method can be exception types or type
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names (stings). If captured excption is instance of
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exception of given type, the corresponding argument is
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returned. Else, None is returned.
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"""
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for cls in exc_classes:
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if isinstance(cls, type):
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err = reflection.get_class_name(cls)
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else:
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err = cls
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if err in self._exc_type_names:
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return cls
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return None
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def __str__(self):
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return 'Failure: %s: %s' % (self._exc_type_names[0],
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self._exception_str)
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def __iter__(self):
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"""Iterate over exception type names"""
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for et in self._exc_type_names:
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yield et
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def copy(self):
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return Failure(exc_info=copy_exc_info(self.exc_info),
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exception_str=self.exception_str,
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traceback_str=self.traceback_str,
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exc_type_names=self._exc_type_names[:])
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