OpenStack library for messaging
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# Copyright 2011 OpenStack Foundation.
# Copyright 2012, Red Hat, Inc.
#
# 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.
"""
Exception related utilities.
"""
import logging
import sys
import time
import traceback
import six
from oslo.messaging.openstack.common.gettextutils import _ # noqa
class save_and_reraise_exception(object):
"""Save current exception, run some code and then re-raise.
In some cases the exception context can be cleared, resulting in None
being attempted to be re-raised after an exception handler is run. This
can happen when eventlet switches greenthreads or when running an
exception handler, code raises and catches an exception. In both
cases the exception context will be cleared.
To work around this, we save the exception state, run handler code, and
then re-raise the original exception. If another exception occurs, the
saved exception is logged and the new exception is re-raised.
In some cases the caller may not want to re-raise the exception, and
for those circumstances this context provides a reraise flag that
can be used to suppress the exception. For example::
except Exception:
with save_and_reraise_exception() as ctxt:
decide_if_need_reraise()
if not should_be_reraised:
ctxt.reraise = False
"""
def __init__(self):
self.reraise = True
def __enter__(self):
self.type_, self.value, self.tb, = sys.exc_info()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
if exc_type is not None:
logging.error(_('Original exception being dropped: %s'),
traceback.format_exception(self.type_,
self.value,
self.tb))
return False
if self.reraise:
six.reraise(self.type_, self.value, self.tb)
def forever_retry_uncaught_exceptions(infunc):
def inner_func(*args, **kwargs):
last_log_time = 0
last_exc_message = None
exc_count = 0
while True:
try:
return infunc(*args, **kwargs)
except Exception as exc:
this_exc_message = six.u(str(exc))
if this_exc_message == last_exc_message:
exc_count += 1
else:
exc_count = 1
# Do not log any more frequently than once a minute unless
# the exception message changes
cur_time = int(time.time())
if (cur_time - last_log_time > 60 or
this_exc_message != last_exc_message):
logging.exception(
_('Unexpected exception occurred %d time(s)... '
'retrying.') % exc_count)
last_log_time = cur_time
last_exc_message = this_exc_message
exc_count = 0
# This should be a very rare event. In case it isn't, do
# a sleep.
time.sleep(1)
return inner_func