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OpenStack Study: excutils.py**** CubicPower OpenStack Study ****
# 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 nova.openstack.common.gettextutils import _ # noqa
**** CubicPower OpenStack Study **** 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 """
**** CubicPower OpenStack Study **** def __init__(self): self.reraise = True
**** CubicPower OpenStack Study **** def __enter__(self): self.type_, self.value, self.tb, = sys.exc_info() return self
**** CubicPower OpenStack Study **** 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):
**** CubicPower OpenStack Study **** def forever_retry_uncaught_exceptions(infunc):
**** CubicPower OpenStack Study **** 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
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