105 lines
3.3 KiB
Python
105 lines
3.3 KiB
Python
#
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# Copyright 2015 Rackspace, 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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import logging
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import os
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import appdirs
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import dogpile.cache
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from iotronicclient.common.i18n import _LW
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LOG = logging.getLogger(__name__)
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AUTHOR = 'openstack'
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PROGNAME = 'python-iotronicclient'
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CACHE = None
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CACHE_DIR = appdirs.user_cache_dir(PROGNAME, AUTHOR)
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CACHE_EXPIRY_ENV_VAR = 'IOTRONICCLIENT_CACHE_EXPIRY' # environment variable
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CACHE_FILENAME = os.path.join(CACHE_DIR, 'iotronic-api-version.dbm')
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DEFAULT_EXPIRY = 300 # seconds
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def _get_cache():
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"""Configure file caching."""
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global CACHE
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if CACHE is None:
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# Ensure cache directory present
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if not os.path.exists(CACHE_DIR):
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os.makedirs(CACHE_DIR)
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# Use the cache expiry if specified in an env var
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expiry_time = os.environ.get(CACHE_EXPIRY_ENV_VAR, DEFAULT_EXPIRY)
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try:
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expiry_time = int(expiry_time)
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except ValueError:
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LOG.warning(_LW("Environment variable %(env_var)s should be an "
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"integer (not '%(curr_val)s'). Using default "
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"expiry of %(default)s seconds instead."),
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{'env_var': CACHE_EXPIRY_ENV_VAR,
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'curr_val': expiry_time,
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'default': DEFAULT_EXPIRY})
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expiry_time = DEFAULT_EXPIRY
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CACHE = dogpile.cache.make_region(key_mangler=str).configure(
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'dogpile.cache.dbm',
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expiration_time=expiry_time,
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arguments={
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"filename": CACHE_FILENAME,
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}
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)
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return CACHE
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def _build_key(host, port):
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"""Build a key based upon the hostname or address supplied."""
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return "%s:%s" % (host, port)
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def save_data(host, port, data):
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"""Save 'data' for a particular 'host' in the appropriate cache dir.
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param host: The host that we need to save data for
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param port.py: The port.py on the host that we need to save data for
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param data: The data we want saved
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"""
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key = _build_key(host, port)
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_get_cache().set(key, data)
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def retrieve_data(host, port, expiry=None):
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"""Retrieve the version stored for an iotronic 'host', if it's not stale.
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Check to see if there is valid cached data for the host/port.py
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combination and return that if it isn't stale.
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param host: The host that we need to retrieve data for
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param port.py: The port.py on the host that we need to retrieve data for
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param expiry: The age in seconds before cached data is deemed invalid
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"""
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# Ensure that a cache file exists first
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if not os.path.isfile(CACHE_FILENAME):
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return None
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key = _build_key(host, port)
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data = _get_cache().get(key, expiration_time=expiry)
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if data == dogpile.cache.api.NO_VALUE:
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return None
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return data
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