75 lines
2.6 KiB
Python
75 lines
2.6 KiB
Python
# -*- coding: utf-8; -*-
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################################################################################
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#
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# Rattail -- Retail Software Framework
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# Copyright © 2010-2018 Lance Edgar
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#
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# This file is part of Rattail.
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#
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# Rattail is free software: you can redistribute it and/or modify it under the
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# terms of the GNU General Public License as published by the Free Software
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# Foundation, either version 3 of the License, or (at your option) any later
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# version.
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#
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# Rattail is distributed in the hope that it will be useful, but WITHOUT ANY
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# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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# details.
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#
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# You should have received a copy of the GNU General Public License along with
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# Rattail. If not, see <http://www.gnu.org/licenses/>.
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#
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################################################################################
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"""
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Tween Factories
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"""
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from __future__ import unicode_literals, absolute_import
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import six
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from sqlalchemy.exc import OperationalError
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def sqlerror_tween_factory(handler, registry):
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"""
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Produces a tween which will convert ``sqlalchemy.exc.OperationalError``
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instances (caused by database server restart) into a retryable error
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instance, so that a second attempt may be made to connect to the database
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before really giving up.
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.. note::
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This tween alone is not enough to cause the transaction to be retried;
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it only marks the error as being *retryable*. If you wish more than one
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attempt to be made, you must define the ``retry.attempts`` (or
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``tm.attempts`` if running pyramid<1.9) setting within your Pyramid app
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configuration. For more info see `Retrying`_.
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.. _Retrying: http://docs.pylonsproject.org/projects/pyramid_tm/en/latest/#retrying
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"""
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def sqlerror_tween(request):
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try:
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from pyramid_retry import mark_error_retryable
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except ImportError:
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mark_error_retryable = None
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from transaction.interfaces import TransientError
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try:
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response = handler(request)
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except OperationalError as error:
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# if connection is invalid, allow retry
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if error.connection_invalidated:
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if mark_error_retryable:
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mark_error_retryable(error)
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raise error
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else:
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raise TransientError(six.text_type(error))
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# if connection was *not* invalid, raise original error
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raise
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return response
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return sqlerror_tween
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