24078a6edb
Decorator caches methods' results, the key is composed from function name and its parameters. Implementation of cache itself should be in object implementing decorated method. Cache backend should be taken from oslo-incubator. Related-Bug: #1276440 Change-Id: Ibe3f1b2eb10b9601ad76ec24b7f0e3551b4013e2
294 lines
10 KiB
Python
294 lines
10 KiB
Python
# Copyright 2011, VMware, Inc.
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# All Rights Reserved.
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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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#
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# Borrowed from nova code base, more utilities will be added/borrowed as and
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# when needed.
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"""Utilities and helper functions."""
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import datetime
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import functools
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import hashlib
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import logging as std_logging
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import os
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import random
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import signal
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import socket
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import uuid
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from eventlet.green import subprocess
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from oslo.config import cfg
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from neutron.common import constants as q_const
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from neutron.openstack.common import lockutils
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from neutron.openstack.common import log as logging
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TIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
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LOG = logging.getLogger(__name__)
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SYNCHRONIZED_PREFIX = 'neutron-'
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synchronized = lockutils.synchronized_with_prefix(SYNCHRONIZED_PREFIX)
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class cache_method_results(object):
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"""This decorator is intended for object methods only."""
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def __init__(self, func):
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self.func = func
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functools.update_wrapper(self, func)
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self._first_call = True
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self._not_cached = object()
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def _get_from_cache(self, target_self, *args, **kwargs):
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func_name = "%(module)s.%(class)s.%(func_name)s" % {
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'module': target_self.__module__,
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'class': target_self.__class__.__name__,
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'func_name': self.func.__name__,
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}
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key = (func_name,) + args
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if kwargs:
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key += dict2tuple(kwargs)
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try:
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item = target_self._cache.get(key, self._not_cached)
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except TypeError:
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LOG.debug(_("Method %(func_name)s cannot be cached due to "
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"unhashable parameters: args: %(args)s, kwargs: "
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"%(kwargs)s"),
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{'func_name': func_name,
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'args': args,
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'kwargs': kwargs})
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return self.func(target_self, *args, **kwargs)
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if item is self._not_cached:
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item = self.func(target_self, *args, **kwargs)
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target_self._cache.set(key, item, None)
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return item
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def __call__(self, target_self, *args, **kwargs):
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if not hasattr(target_self, '_cache'):
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raise NotImplementedError(
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"Instance of class %(module)s.%(class)s must contain _cache "
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"attribute" % {
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'module': target_self.__module__,
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'class': target_self.__class__.__name__})
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if not target_self._cache:
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if self._first_call:
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LOG.debug(_("Instance of class %(module)s.%(class)s doesn't "
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"contain attribute _cache therefore results "
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"cannot be cached for %(func_name)s."),
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{'module': target_self.__module__,
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'class': target_self.__class__.__name__,
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'func_name': self.func.__name__})
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self._first_call = False
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return self.func(target_self, *args, **kwargs)
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return self._get_from_cache(target_self, *args, **kwargs)
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def __get__(self, obj, objtype):
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return functools.partial(self.__call__, obj)
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def read_cached_file(filename, cache_info, reload_func=None):
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"""Read from a file if it has been modified.
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:param cache_info: dictionary to hold opaque cache.
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:param reload_func: optional function to be called with data when
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file is reloaded due to a modification.
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:returns: data from file
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"""
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mtime = os.path.getmtime(filename)
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if not cache_info or mtime != cache_info.get('mtime'):
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LOG.debug(_("Reloading cached file %s"), filename)
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with open(filename) as fap:
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cache_info['data'] = fap.read()
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cache_info['mtime'] = mtime
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if reload_func:
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reload_func(cache_info['data'])
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return cache_info['data']
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def find_config_file(options, config_file):
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"""Return the first config file found.
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We search for the paste config file in the following order:
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* If --config-file option is used, use that
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* Search for the configuration files via common cfg directories
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:retval Full path to config file, or None if no config file found
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"""
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fix_path = lambda p: os.path.abspath(os.path.expanduser(p))
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if options.get('config_file'):
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if os.path.exists(options['config_file']):
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return fix_path(options['config_file'])
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dir_to_common = os.path.dirname(os.path.abspath(__file__))
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root = os.path.join(dir_to_common, '..', '..', '..', '..')
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# Handle standard directory search for the config file
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config_file_dirs = [fix_path(os.path.join(os.getcwd(), 'etc')),
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fix_path(os.path.join('~', '.neutron-venv', 'etc',
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'neutron')),
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fix_path('~'),
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os.path.join(cfg.CONF.state_path, 'etc'),
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os.path.join(cfg.CONF.state_path, 'etc', 'neutron'),
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fix_path(os.path.join('~', '.local',
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'etc', 'neutron')),
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'/usr/etc/neutron',
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'/usr/local/etc/neutron',
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'/etc/neutron/',
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'/etc']
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if 'plugin' in options:
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config_file_dirs = [
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os.path.join(x, 'neutron', 'plugins', options['plugin'])
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for x in config_file_dirs
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]
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if os.path.exists(os.path.join(root, 'plugins')):
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plugins = [fix_path(os.path.join(root, 'plugins', p, 'etc'))
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for p in os.listdir(os.path.join(root, 'plugins'))]
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plugins = [p for p in plugins if os.path.isdir(p)]
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config_file_dirs.extend(plugins)
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for cfg_dir in config_file_dirs:
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cfg_file = os.path.join(cfg_dir, config_file)
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if os.path.exists(cfg_file):
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return cfg_file
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def _subprocess_setup():
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# Python installs a SIGPIPE handler by default. This is usually not what
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# non-Python subprocesses expect.
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signal.signal(signal.SIGPIPE, signal.SIG_DFL)
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def subprocess_popen(args, stdin=None, stdout=None, stderr=None, shell=False,
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env=None):
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return subprocess.Popen(args, shell=shell, stdin=stdin, stdout=stdout,
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stderr=stderr, preexec_fn=_subprocess_setup,
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close_fds=True, env=env)
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def parse_mappings(mapping_list, unique_values=True):
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"""Parse a list of of mapping strings into a dictionary.
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:param mapping_list: a list of strings of the form '<key>:<value>'
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:param unique_values: values must be unique if True
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:returns: a dict mapping keys to values
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"""
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mappings = {}
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for mapping in mapping_list:
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mapping = mapping.strip()
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if not mapping:
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continue
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split_result = mapping.split(':')
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if len(split_result) != 2:
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raise ValueError(_("Invalid mapping: '%s'") % mapping)
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key = split_result[0].strip()
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if not key:
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raise ValueError(_("Missing key in mapping: '%s'") % mapping)
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value = split_result[1].strip()
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if not value:
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raise ValueError(_("Missing value in mapping: '%s'") % mapping)
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if key in mappings:
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raise ValueError(_("Key %(key)s in mapping: '%(mapping)s' not "
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"unique") % {'key': key, 'mapping': mapping})
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if unique_values and value in mappings.itervalues():
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raise ValueError(_("Value %(value)s in mapping: '%(mapping)s' "
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"not unique") % {'value': value,
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'mapping': mapping})
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mappings[key] = value
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return mappings
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def get_hostname():
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return socket.gethostname()
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def compare_elements(a, b):
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"""Compare elements if a and b have same elements.
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This method doesn't consider ordering
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"""
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if a is None:
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a = []
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if b is None:
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b = []
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return set(a) == set(b)
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def dict2str(dic):
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return ','.join("%s=%s" % (key, val)
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for key, val in sorted(dic.iteritems()))
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def str2dict(string):
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res_dict = {}
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for keyvalue in string.split(','):
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(key, value) = keyvalue.split('=', 1)
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res_dict[key] = value
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return res_dict
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def dict2tuple(d):
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items = d.items()
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items.sort()
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return tuple(items)
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def diff_list_of_dict(old_list, new_list):
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new_set = set([dict2str(l) for l in new_list])
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old_set = set([dict2str(l) for l in old_list])
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added = new_set - old_set
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removed = old_set - new_set
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return [str2dict(a) for a in added], [str2dict(r) for r in removed]
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def is_extension_supported(plugin, ext_alias):
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return ext_alias in getattr(
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plugin, "supported_extension_aliases", [])
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def log_opt_values(log):
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cfg.CONF.log_opt_values(log, std_logging.DEBUG)
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def is_valid_vlan_tag(vlan):
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return q_const.MIN_VLAN_TAG <= vlan <= q_const.MAX_VLAN_TAG
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def get_random_string(length):
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"""Get a random hex string of the specified length.
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based on Cinder library
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cinder/transfer/api.py
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"""
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rndstr = ""
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random.seed(datetime.datetime.now().microsecond)
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while len(rndstr) < length:
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rndstr += hashlib.sha224(str(random.random())).hexdigest()
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return rndstr[0:length]
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def get_dhcp_agent_device_id(network_id, host):
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# Split host so as to always use only the hostname and
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# not the domain name. This will guarantee consistentcy
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# whether a local hostname or an fqdn is passed in.
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local_hostname = host.split('.')[0]
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host_uuid = uuid.uuid5(uuid.NAMESPACE_DNS, str(local_hostname))
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return 'dhcp%s-%s' % (host_uuid, network_id)
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