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# -*- coding: utf-8 -*-
# Copyright (C) 2015 Yahoo! Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Eventlet utils helper module.
.. versionadded:: 1.3
"""
import threading
import warnings
from oslo_utils import importutils
from oslo_utils import timeutils
# These may or may not exist; so carefully import them if we can...
_eventlet = importutils.try_import('eventlet')
_patcher = importutils.try_import('eventlet.patcher')
# Attribute that can be used by others to see if eventlet is even currently
# useable (can be used in unittests to skip test cases or test classes that
# require eventlet to work).
EVENTLET_AVAILABLE = all((_eventlet, _patcher))
# Taken from eventlet.py (v0.16.1) patcher code (it's not a accessible set
# for some reason...)
_ALL_PATCH = frozenset(['__builtin__', 'MySQLdb', 'os',
'psycopg', 'select', 'socket', 'thread', 'time'])
def fetch_current_thread_functor():
"""Get the current thread.
If eventlet is used to monkey-patch the threading module, return the
current eventlet greenthread. Otherwise, return the current Python thread.
.. versionadded:: 1.5
"""
# Until https://github.com/eventlet/eventlet/issues/172 is resolved
# or addressed we have to use complicated workaround to get a object
# that will not be recycled; the usage of threading.current_thread()
# doesn't appear to currently be monkey patched and therefore isn't
# reliable to use (and breaks badly when used as all threads share
# the same current_thread() object)...
if not EVENTLET_AVAILABLE:
return threading.current_thread
else:
green_threaded = _patcher.is_monkey_patched('thread')
if green_threaded:
return _eventlet.getcurrent
else:
return threading.current_thread
def warn_eventlet_not_patched(expected_patched_modules=None,
what='this library'):
"""Warns if eventlet is being used without patching provided modules.
:param expected_patched_modules: list of modules to check to ensure that
they are patched (and to warn if they
are not); these names should correspond
to the names passed into the eventlet
monkey_patch() routine. If not provided
then *all* the modules that could be
patched are checked. The currently valid
selection is one or multiple of
['MySQLdb', '__builtin__', 'all', 'os',
'psycopg', 'select', 'socket', 'thread',
'time'] (where 'all' has an inherent
special meaning).
:type expected_patched_modules: list/tuple/iterable
:param what: string to merge into the warnings message to identify
what is being checked (used in forming the emitted warnings
message).
:type what: string
"""
if not expected_patched_modules:
expanded_patched_modules = _ALL_PATCH.copy()
else:
expanded_patched_modules = set()
for m in expected_patched_modules:
if m == 'all':
expanded_patched_modules.update(_ALL_PATCH)
else:
if m not in _ALL_PATCH:
raise ValueError("Unknown module '%s' requested to check"
" if patched" % m)
else:
expanded_patched_modules.add(m)
if EVENTLET_AVAILABLE:
try:
# The patcher code stores a dictionary here of all modules
# names -> whether it was patched...
#
# Example:
#
# >>> _patcher.monkey_patch(os=True)
# >>> print(_patcher.already_patched)
# {'os': True}
maybe_patched = bool(_patcher.already_patched)
except AttributeError:
# Assume it is patched (the attribute used here doesn't appear
# to be a public documented API so we will assume that everything
# is patched when that attribute isn't there to be safe...)
maybe_patched = True
if maybe_patched:
not_patched = []
for m in sorted(expanded_patched_modules):
if not _patcher.is_monkey_patched(m):
not_patched.append(m)
if not_patched:
warnings.warn("It is highly recommended that when eventlet"
" is used that the %s modules are monkey"
" patched when using %s (to avoid"
" spurious or unexpected lock-ups"
" and/or hangs)" % (not_patched, what),
RuntimeWarning, stacklevel=3)
def is_monkey_patched(module):
"""Determines safely is eventlet patching for module enabled or not
:param module: String, module name
:return Bool: True if module is patched, False otherwise
"""
if _patcher is None:
return False
return _patcher.is_monkey_patched(module)
class EventletEvent(object):
"""A class that provides consistent eventlet/threading Event API.
This wraps the eventlet.event.Event class to have the same API as
the standard threading.Event object.
"""
def __init__(self, *args, **kwargs):
super(EventletEvent, self).__init__()
self.clear()
def clear(self):
if getattr(self, '_set', True):
self._set = False
self._event = _eventlet.event.Event()
def is_set(self):
return self._set
isSet = is_set
def set(self):
if not self._set:
self._set = True
self._event.send(True)
def wait(self, timeout=None):
with timeutils.StopWatch(timeout) as sw:
while True:
event = self._event
with _eventlet.timeout.Timeout(sw.leftover(return_none=True),
False):
event.wait()
if event is not self._event:
continue
return self.is_set()
def Event():
if is_monkey_patched("thread"):
return EventletEvent()
else:
return threading.Event()
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