# Copyright 2012 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import functools
import inspect
import time
import types
from oslo_log import log
from oslo_log import versionutils
from oslo_utils import importutils
import six
import stevedore
from keystone.i18n import _
LOG = log.getLogger(__name__)
[docs]def response_truncated(f):
"""Truncate the list returned by the wrapped function.
This is designed to wrap Manager list_{entity} methods to ensure that
any list limits that are defined are passed to the driver layer. If a
hints list is provided, the wrapper will insert the relevant limit into
the hints so that the underlying driver call can try and honor it. If the
driver does truncate the response, it will update the 'truncated' attribute
in the 'limit' entry in the hints list, which enables the caller of this
function to know if truncation has taken place. If, however, the driver
layer is unable to perform truncation, the 'limit' entry is simply left in
the hints list for the caller to handle.
A _get_list_limit() method is required to be present in the object class
hierarchy, which returns the limit for this backend to which we will
truncate.
If a hints list is not provided in the arguments of the wrapped call then
any limits set in the config file are ignored. This allows internal use
of such wrapped methods where the entire data set is needed as input for
the calculations of some other API (e.g. get role assignments for a given
project).
"""
@functools.wraps(f)
def wrapper(self, *args, **kwargs):
if kwargs.get('hints') is None:
return f(self, *args, **kwargs)
list_limit = self.driver._get_list_limit()
if list_limit:
kwargs['hints'].set_limit(list_limit)
return f(self, *args, **kwargs)
return wrapper
[docs]def load_driver(namespace, driver_name, *args):
try:
driver_manager = stevedore.DriverManager(namespace,
driver_name,
invoke_on_load=True,
invoke_args=args)
return driver_manager.driver
except RuntimeError as e:
LOG.debug('Failed to load %r using stevedore: %s', driver_name, e)
# Ignore failure and continue on.
driver = importutils.import_object(driver_name, *args)
msg = (_(
'Direct import of driver %(name)r is deprecated as of Liberty in '
'favor of its entrypoint from %(namespace)r and may be removed in '
'N.') %
{'name': driver_name, 'namespace': namespace})
versionutils.report_deprecated_feature(LOG, msg)
return driver
class _TraceMeta(type):
"""A metaclass that, in trace mode, will log entry and exit of methods.
This metaclass automatically wraps all methods on the class when
instantiated with a decorator that will log entry/exit from a method
when keystone is run in Trace log level.
"""
@staticmethod
def wrapper(__f, __classname):
__argspec = inspect.getargspec(__f)
__fn_info = '%(module)s.%(classname)s.%(funcname)s' % {
'module': inspect.getmodule(__f).__name__,
'classname': __classname,
'funcname': __f.__name__
}
# NOTE(morganfainberg): Omit "cls" and "self" when printing trace logs
# the index can be calculated at wrap time rather than at runtime.
if __argspec.args and __argspec.args[0] in ('self', 'cls'):
__arg_idx = 1
else:
__arg_idx = 0
@functools.wraps(__f)
def wrapped(*args, **kwargs):
__exc = None
__t = time.time()
__do_trace = LOG.logger.getEffectiveLevel() <= log.TRACE
__ret_val = None
try:
if __do_trace:
LOG.trace('CALL => %s', __fn_info)
__ret_val = __f(*args, **kwargs)
except Exception as e: # nosec
__exc = e
raise
finally:
if __do_trace:
__subst = {
'run_time': (time.time() - __t),
'passed_args': ', '.join([
', '.join([repr(a)
for a in args[__arg_idx:]]),
', '.join(['%(k)s=%(v)r' % {'k': k, 'v': v}
for k, v in kwargs.items()]),
]),
'function': __fn_info,
'exception': __exc,
'ret_val': __ret_val,
}
if __exc is not None:
__msg = ('[%(run_time)ss] %(function)s '
'(%(passed_args)s) => raised '
'%(exception)r')
else:
# TODO(morganfainberg): find a way to indicate if this
# was a cache hit or cache miss.
__msg = ('[%(run_time)ss] %(function)s'
'(%(passed_args)s) => %(ret_val)r')
LOG.trace(__msg, __subst)
return __ret_val
return wrapped
def __new__(meta, classname, bases, class_dict):
final_cls_dict = {}
for attr_name, attr in class_dict.items():
# NOTE(morganfainberg): only wrap public instances and methods.
if (isinstance(attr, types.FunctionType) and
not attr_name.startswith('_')):
attr = _TraceMeta.wrapper(attr, classname)
final_cls_dict[attr_name] = attr
return type.__new__(meta, classname, bases, final_cls_dict)
@six.add_metaclass(_TraceMeta)
[docs]class Manager(object):
"""Base class for intermediary request layer.
The Manager layer exists to support additional logic that applies to all
or some of the methods exposed by a service that are not specific to the
HTTP interface.
It also provides a stable entry point to dynamic backends.
An example of a probable use case is logging all the calls.
"""
driver_namespace = None
def __init__(self, driver_name):
self.driver = load_driver(self.driver_namespace, driver_name)
def __getattr__(self, name):
"""Forward calls to the underlying driver."""
f = getattr(self.driver, name)
if callable(f):
# NOTE(dstanek): only if this is callable (class or function)
# cache this
setattr(self, name, f)
return f