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# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
#
# 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 errno
import logging
import os
from typing import TypeAlias, TypedDict
from oslo_config import cfg
LOG = logging.getLogger(__name__)
class CacheEntry(TypedDict):
data: str
mtime: float
CacheT: TypeAlias = dict[str, CacheEntry]
def read_cached_file(
cache: CacheT, filename: str, force_reload: bool = False
) -> tuple[bool, str]:
"""Read from a file if it has been modified.
:param cache: dictionary to hold opaque cache.
:param filename: the file path to read.
:param force_reload: Whether to reload the file.
:returns: A tuple with a boolean specifying if the data is fresh
or not.
"""
if force_reload:
delete_cached_file(cache, filename)
reloaded = False
try:
mtime = os.path.getmtime(filename)
except OSError as err:
msg = err.strerror
LOG.error(
'Config file not found %(filename)s: %(msg)s',
{'filename': filename, 'msg': msg},
)
return True, ''
cache_info = cache.setdefault(filename, {'data': '', 'mtime': 0})
if not cache_info or mtime > cache_info.get('mtime', 0):
LOG.debug('Reloading cached file %s', filename)
try:
with open(filename) as fap:
cache_info['data'] = fap.read()
except OSError as err:
msg = err.strerror
err_code = err.errno
LOG.error(
'IO error loading %(filename)s: %(msg)s',
{'filename': filename, 'msg': msg},
)
if err_code == errno.EACCES:
raise cfg.ConfigFilesPermissionDeniedError((filename,))
except OSError as err:
msg = err.strerror
LOG.error(
'Config file not found %(filename)s: %(msg)s',
{'filename': filename, 'msg': msg},
)
raise cfg.ConfigFilesNotFoundError((filename,))
cache_info['mtime'] = mtime
reloaded = True
return (reloaded, cache_info['data'])
def delete_cached_file(cache: CacheT, filename: str) -> None:
"""Delete cached file if present.
:param cache: dictionary to hold opaque cache.
:param filename: filename to delete
"""
try:
del cache[filename]
except KeyError:
pass
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