From 79ff0c4e83a871d768ec1368cefe4d3c64430c56 Mon Sep 17 00:00:00 2001 From: Russell Bryant Date: Tue, 1 May 2012 15:24:18 -0400 Subject: Add save_and_reraise_exception(). This patch adds save_and_reraise_exception() to a new module, openstack.common.excutils. This is based on the function of the same name from nova.utils. It is used by nova.rpc, so something equivalent is needed in openstack-common before nova.rpc can be moved here. Change-Id: Icec574a081837e0f2d0548a5759d21b0352dbee6 --- openstack/common/excutils.py | 49 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 openstack/common/excutils.py (limited to 'openstack') diff --git a/openstack/common/excutils.py b/openstack/common/excutils.py new file mode 100644 index 0000000..3cb678e --- /dev/null +++ b/openstack/common/excutils.py @@ -0,0 +1,49 @@ +# vim: tabstop=4 shiftwidth=4 softtabstop=4 + +# Copyright 2011 OpenStack LLC. +# 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 contextlib +import logging +import sys +import traceback + + +@contextlib.contextmanager +def save_and_reraise_exception(): + """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 reraised 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 reraised. + """ + type_, value, tb = sys.exc_info() + try: + yield + except Exception: + logging.error('Original exception being dropped: %s' % + (traceback.format_exception(type_, value, tb))) + raise + raise type_, value, tb -- cgit