138 lines
3.8 KiB
Python
138 lines
3.8 KiB
Python
# Copyright 2011 OpenStack Foundation.
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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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import contextlib
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import errno
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import os
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import tempfile
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from neutron.openstack.common import excutils
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from neutron.openstack.common.gettextutils import _
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from neutron.openstack.common import log as logging
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LOG = logging.getLogger(__name__)
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_FILE_CACHE = {}
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def ensure_tree(path):
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"""Create a directory (and any ancestor directories required)
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:param path: Directory to create
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"""
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try:
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os.makedirs(path)
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except OSError as exc:
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if exc.errno == errno.EEXIST:
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if not os.path.isdir(path):
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raise
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else:
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raise
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def read_cached_file(filename, force_reload=False):
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"""Read from a file if it has been modified.
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:param force_reload: Whether to reload the file.
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:returns: A tuple with a boolean specifying if the data is fresh
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or not.
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"""
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global _FILE_CACHE
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if force_reload and filename in _FILE_CACHE:
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del _FILE_CACHE[filename]
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reloaded = False
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mtime = os.path.getmtime(filename)
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cache_info = _FILE_CACHE.setdefault(filename, {})
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if not cache_info or mtime > cache_info.get('mtime', 0):
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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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reloaded = True
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return (reloaded, cache_info['data'])
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def delete_if_exists(path, remove=os.unlink):
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"""Delete a file, but ignore file not found error.
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:param path: File to delete
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:param remove: Optional function to remove passed path
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"""
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try:
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remove(path)
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except OSError as e:
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if e.errno != errno.ENOENT:
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raise
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@contextlib.contextmanager
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def remove_path_on_error(path, remove=delete_if_exists):
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"""Protect code that wants to operate on PATH atomically.
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Any exception will cause PATH to be removed.
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:param path: File to work with
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:param remove: Optional function to remove passed path
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"""
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try:
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yield
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except Exception:
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with excutils.save_and_reraise_exception():
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remove(path)
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def file_open(*args, **kwargs):
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"""Open file
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see built-in file() documentation for more details
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Note: The reason this is kept in a separate module is to easily
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be able to provide a stub module that doesn't alter system
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state at all (for unit tests)
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"""
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return file(*args, **kwargs)
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def write_to_tempfile(content, path=None, suffix='', prefix='tmp'):
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"""Create temporary file or use existing file.
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This util is needed for creating temporary file with
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specified content, suffix and prefix. If path is not None,
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it will be used for writing content. If the path doesn't
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exist it'll be created.
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:param content: content for temporary file.
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:param path: same as parameter 'dir' for mkstemp
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:param suffix: same as parameter 'suffix' for mkstemp
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:param prefix: same as parameter 'prefix' for mkstemp
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For example: it can be used in database tests for creating
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configuration files.
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"""
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if path:
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ensure_tree(path)
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(fd, path) = tempfile.mkstemp(suffix=suffix, dir=path, prefix=prefix)
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try:
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os.write(fd, content)
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finally:
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os.close(fd)
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return path
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