104 lines
3.3 KiB
Python
104 lines
3.3 KiB
Python
# Copyright (c) 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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"""
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SchedulerOptions monitors a local .json file for changes and loads
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it if needed. This file is converted to a data structure and passed
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into the filtering and weighing functions which can use it for
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dynamic configuration.
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"""
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import datetime
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import json
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import os
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from oslo_config import cfg
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from oslo_log import log as logging
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from oslo_utils import timeutils
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scheduler_json_config_location_opt = cfg.StrOpt(
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'scheduler_json_config_location',
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default='',
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help='Absolute path to scheduler configuration JSON file.')
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CONF = cfg.CONF
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CONF.register_opt(scheduler_json_config_location_opt)
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LOG = logging.getLogger(__name__)
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class SchedulerOptions(object):
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"""SchedulerOptions monitors a local .json file for changes.
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The file is reloaded if needed and converted to a data structure and
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passed into the filtering and weighing functions which can use it
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for dynamic configuration.
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"""
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def __init__(self):
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super(SchedulerOptions, self).__init__()
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self.data = {}
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self.last_modified = None
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self.last_checked = None
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def _get_file_handle(self, filename):
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"""Get file handle. Broken out for testing."""
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return open(filename)
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def _get_file_timestamp(self, filename):
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"""Get the last modified datetime. Broken out for testing."""
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try:
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return os.path.getmtime(filename)
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except os.error:
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LOG.exception("Could not stat scheduler options file "
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"%(filename)s.",
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{'filename': filename})
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raise
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def _load_file(self, handle):
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"""Decode the JSON file. Broken out for testing."""
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try:
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return json.load(handle)
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except ValueError:
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LOG.exception("Could not decode scheduler options.")
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return {}
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def _get_time_now(self):
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"""Get current UTC. Broken out for testing."""
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return timeutils.utcnow()
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def get_configuration(self, filename=None):
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"""Check the json file for changes and load it if needed."""
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if not filename:
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filename = CONF.scheduler_json_config_location
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if not filename:
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return self.data
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if self.last_checked:
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now = self._get_time_now()
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if now - self.last_checked < datetime.timedelta(minutes=5):
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return self.data
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last_modified = self._get_file_timestamp(filename)
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if (not last_modified or not self.last_modified or
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last_modified > self.last_modified):
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self.data = self._load_file(self._get_file_handle(filename))
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self.last_modified = last_modified
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if not self.data:
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self.data = {}
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return self.data
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