ceph/teuthology/contextutil.py
2011-06-16 10:39:26 -07:00

44 lines
1.2 KiB
Python

import contextlib
import sys
import logging
log = logging.getLogger(__name__)
@contextlib.contextmanager
def nested(*managers):
"""
Like contextlib.nested but takes callables returning context
managers, to avoid the major reason why contextlib.nested was
deprecated.
This version also logs any exceptions early, much like run_tasks,
to ease debugging. TODO combine nested and run_tasks.
"""
exits = []
vars = []
exc = (None, None, None)
try:
for mgr_fn in managers:
mgr = mgr_fn()
exit = mgr.__exit__
enter = mgr.__enter__
vars.append(enter())
exits.append(exit)
yield vars
except:
log.exception('Saw exception from nested tasks')
exc = sys.exc_info()
finally:
while exits:
exit = exits.pop()
try:
if exit(*exc):
exc = (None, None, None)
except:
exc = sys.exc_info()
if exc != (None, None, None):
# Don't rely on sys.exc_info() still containing
# the right information. Another exception may
# have been raised and caught by an exit method
raise exc[0], exc[1], exc[2]