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# Copyright (c) 2011 Canonical Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public
# License along with this program. If not, see
# <http://www.gnu.org/licenses/>.
"""Things to ease working with cassandra."""
from pycassa.pool import InvalidRequestError
def workaround_1779(callable, *args, **kwargs):
"""Workaround cassandra not being able to do concurrent schema edits.
The callable is tried until it does not raised InvalidRequestException
with why = "Previous version mismatch. cannot apply."
:param callable: The callable to call.
:param args: The args for it.
:param kwargs: The kwargs for it.
:return: The result of calling the callable.
"""
while True:
# Workaround https://issues.apache.org/jira/browse/CASSANDRA-1779:
# Cassandra cannot do concurrent schema changes.
try:
return callable(*args, **kwargs)
break
except InvalidRequestError as e:
if e.why != 'Previous version mismatch. cannot apply.':
raise
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