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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 logging
import os
LOG = logging.getLogger(__name__)
def read_cached_file(cache, filename, force_reload=False):
"""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
mtime = os.path.getmtime(filename)
cache_info = cache.setdefault(filename, {})
if not cache_info or mtime > cache_info.get('mtime', 0):
LOG.debug("Reloading cached file %s", filename)
with open(filename) as fap:
cache_info['data'] = fap.read()
cache_info['mtime'] = mtime
reloaded = True
return (reloaded, cache_info['data'])
def delete_cached_file(cache, filename):
"""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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