d08a661812
Hook points allow installing a package that provide a decorator for some function / method. The intent is to use it for organization specific code. The sample config contains an example. See: https://review.openstack.org/171689/ Implements: blueprint hook-point-api Change-Id: If98d9450cfd6b1a2a3cb23d8bc51940c1b6ee37a
122 lines
3.5 KiB
Python
122 lines
3.5 KiB
Python
# Copyright 2015 Rackspace Hosting.
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#
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# Author: Eric Larson <eric.larson@rackspace.com>
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import functools
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from oslo_config import cfg
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from oslo_log import log as logging
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from stevedore import hook
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LOG = logging.getLogger(__name__)
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class BaseHook(object):
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OPTS = [
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cfg.BoolOpt('disabled', default=False)
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]
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def __init__(self, group):
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self.group = group
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@property
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def disabled(self):
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return cfg.CONF[self.group].get('disabled', False)
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def wrapper(self, *args, **kw):
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return self.hook_target(*args, **kw)
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def __call__(self, f):
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# Save our hook target as an attribute for our wrapper method
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self.hook_target = f
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@functools.wraps(self.hook_target)
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def wrapper(*args, **kw):
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if self.disabled:
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return self.hook_target(*args, **kw)
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return self.hook(*args, **kw)
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return wrapper
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class hook_point(object):
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NAMESPACE = 'designate.hook_point'
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def __init__(self, name=None):
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self._name = name
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def update_config_opts(self, group, hooks):
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hooks_found = False
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for hook_impl in hooks:
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hooks_found = True
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# Add any options defined by the hook
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if hasattr(hook_impl.plugin, 'OPTS'):
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cfg.CONF.register_opts(hook_impl.plugin.OPTS, group=group)
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if not hooks_found:
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LOG.debug('No hooks found for %s', group)
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else:
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LOG.debug('Created hook: %s', group)
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def hook_manager(self, name):
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LOG.debug('Looking for hooks with: %s %s', self.NAMESPACE, name)
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return hook.HookManager(self.NAMESPACE, name)
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def find_name(self, func=None):
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"""Derive the hook target path from the function name, unless
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a name has been passed in with the constuctor.
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"""
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if self._name:
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return self._name
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if not func:
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return None
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# derive the name from the function
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self._name = '%s.%s' % (func.__module__, func.__name__)
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return self._name
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def init_hook(self, f):
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"""Set up our hook
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Try to inspect the function for a hook target path if one
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wasn't passed in and set up the necessary config options.
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"""
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self.name = self.find_name(f)
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self.group = 'hook_point:%s' % self.name
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self.hooks = self.hook_manager(self.name)
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self.update_config_opts(self.group, self.hooks)
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def enable_hook(self, ext, f):
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"""Enable the hook.
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This instantiates the hook object and decorates the original
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function.
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"""
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decorator = ext.plugin(self.group)
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f = decorator(f)
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f._hook_point = self # add ourselves for inspection
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return f
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def __call__(self, f):
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# Set up all our hook information based on the function or
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# hook point
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self.init_hook(f)
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for h in self.hooks:
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f = self.enable_hook(h, f)
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return f
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