98 lines
3.1 KiB
Python
98 lines
3.1 KiB
Python
"""
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Utilities for waffle usage.
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"""
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from abc import ABCMeta
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from contextlib import contextmanager
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import logging
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from waffle.models import Switch
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from waffle.utils import get_setting as waffle_setting
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from waffle import switch_is_active
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from request_cache import get_cache as get_request_cache
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log = logging.getLogger(__name__)
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class WafflePlus(object):
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"""
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Waffle helper class that provides native support for
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namespacing waffle settings and caching within a request.
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"""
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__metaclass__ = ABCMeta
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def __init__(self, namespace, log_prefix=None):
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self.namespace = namespace
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self.log_prefix = log_prefix
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def _namespaced_setting_name(self, setting_name):
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"""
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Returns the namespaced name of the waffle switch/flag.
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"""
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assert self.namespace is not None
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return u'{}.{}'.format(self.namespace, setting_name)
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@staticmethod
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def _get_request_cache():
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"""
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Returns the request cache used by WafflePlus classes.
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"""
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return get_request_cache('WafflePlus')
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class WaffleSwitchPlus(WafflePlus):
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"""
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Waffle Switch helper class that provides native support for
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namespacing waffle switches and caching within a request.
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"""
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def is_enabled(self, switch_name):
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"""
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Returns and caches whether the given waffle switch is enabled.
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"""
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namespaced_switch_name = self._namespaced_setting_name(switch_name)
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value = self._cached_switches.get(namespaced_switch_name)
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if value is None:
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value = switch_is_active(namespaced_switch_name)
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self._cached_switches[namespaced_switch_name] = value
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return value
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@contextmanager
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def override(self, switch_name, active=True):
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"""
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Overrides the active value for the given switch for the duration of this
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contextmanager.
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Note: The value is overridden in the request cache, not in the model.
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"""
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previous_active = self.is_enabled(switch_name)
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try:
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self.override_for_request(switch_name, active)
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yield
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finally:
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self.override_for_request(switch_name, previous_active)
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def override_for_request(self, switch_name, active=True):
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"""
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Overrides the active value for the given switch for the remainder of
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this request (as this is not a context manager).
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Note: The value is overridden in the request cache, not in the model.
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"""
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namespaced_switch_name = self._namespaced_setting_name(switch_name)
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self._cached_switches[namespaced_switch_name] = active
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log.info(u"%sSwitch '%s' set to %s for request.", self.log_prefix, namespaced_switch_name, active)
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@property
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def _cached_switches(self):
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"""
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Returns cached active values of all switches in this namespace.
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"""
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return self._all_cached_switches.setdefault(self.namespace, {})
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@property
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def _all_cached_switches(self):
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"""
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Returns dictionary of all switches in the request cache,
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keyed by namespace.
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"""
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return self._get_request_cache().setdefault('switches', {})
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