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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 contextlib
import errno
import logging
import os
import tempfile
from oslo.utils import excutils
LOG = logging.getLogger(__name__)
_FILE_CACHE = {}
def ensure_tree(path):
"""Create a directory (and any ancestor directories required)
:param path: Directory to create
"""
try:
os.makedirs(path)
except OSError as exc:
if exc.errno == errno.EEXIST:
if not os.path.isdir(path):
raise
else:
raise
def read_cached_file(filename, force_reload=False):
"""Read from a file if it has been modified.
:param force_reload: Whether to reload the file.
:returns: A tuple with a boolean specifying if the data is fresh
or not.
"""
global _FILE_CACHE
if force_reload:
delete_cached_file(filename)
reloaded = False
mtime = os.path.getmtime(filename)
cache_info = _FILE_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(filename):
"""Delete cached file if present.
:param filename: filename to delete
"""
global _FILE_CACHE
if filename in _FILE_CACHE:
del _FILE_CACHE[filename]
def delete_if_exists(path, remove=os.unlink):
"""Delete a file, but ignore file not found error.
:param path: File to delete
:param remove: Optional function to remove passed path
"""
try:
remove(path)
except OSError as e:
if e.errno != errno.ENOENT:
raise
@contextlib.contextmanager
def remove_path_on_error(path, remove=delete_if_exists):
"""Protect code that wants to operate on PATH atomically.
Any exception will cause PATH to be removed.
:param path: File to work with
:param remove: Optional function to remove passed path
"""
try:
yield
except Exception:
with excutils.save_and_reraise_exception():
remove(path)
def file_open(*args, **kwargs):
"""Open file
see built-in open() documentation for more details
Note: The reason this is kept in a separate module is to easily
be able to provide a stub module that doesn't alter system
state at all (for unit tests)
"""
return open(*args, **kwargs)
def write_to_tempfile(content, path=None, suffix='', prefix='tmp'):
"""Create temporary file or use existing file.
This util is needed for creating temporary file with
specified content, suffix and prefix. If path is not None,
it will be used for writing content. If the path doesn't
exist it'll be created.
:param content: content for temporary file.
:param path: same as parameter 'dir' for mkstemp
:param suffix: same as parameter 'suffix' for mkstemp
:param prefix: same as parameter 'prefix' for mkstemp
For example: it can be used in database tests for creating
configuration files.
"""
if path:
ensure_tree(path)
(fd, path) = tempfile.mkstemp(suffix=suffix, dir=path, prefix=prefix)
try:
os.write(fd, content)
finally:
os.close(fd)
return path
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