0790add5aa
Added Traverse Helper and unit-tests Simplified generate UUID function Change-Id: I307fc689e592b94e4e084d0e6a164e11c5ec4429
154 lines
4.7 KiB
Python
154 lines
4.7 KiB
Python
# Copyright (c) 2013 Mirantis, Inc.
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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 eventlet
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import types
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from collections import deque
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from functools import wraps
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from muranoapi.openstack.common import log as logging
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log = logging.getLogger(__name__)
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class TraverseHelper(object):
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@staticmethod
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def get(path, source):
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"""
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Provides the ability to traverse a data source made up of any
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combination of lists and dicts. Has simple rules for selecting item of
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the list:
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* each item should have id property
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* to select item from the list, specify id value
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Examples:
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source = {'obj': {'attr': True}}
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value = TraverseHelper.get('/obj/attr', source)
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source = {'obj': [
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{'id': '1', 'value': 1},
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{'id': '2s', 'value': 2},
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]}
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value = TraverseHelper.get('/obj/2s/value', source)
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:param path: string with path to desired value
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:param source: python object (list or dict)
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:return: object
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:raise: ValueError if object is malformed
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"""
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if path.startswith('/'):
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path = path[1:]
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queue = deque(path.split('/'))
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obj = source
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while len(queue):
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path = queue.popleft()
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if isinstance(obj, types.ListType):
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filtered = filter(lambda i: 'id' in i and i['id'] == path, obj)
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obj = filtered[0] if filtered else None
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elif isinstance(obj, types.DictionaryType):
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obj = obj[path] if path else obj
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else:
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raise ValueError('Object or path is malformed')
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return obj
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@staticmethod
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def update(path, value, source):
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"""
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Updates value selected with specified path.
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Warning: Root object could not be updated
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:param path: string with path to desired value
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:param value: value
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:param source: python object (list or dict)
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"""
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parent_path = '/'.join(path.split('/')[:-1])
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node = TraverseHelper.get(parent_path, source)
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key = path[1:].split('/')[-1]
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node[key] = value
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@staticmethod
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def insert(path, value, source):
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"""
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Inserts new item to selected list.
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:param path: string with path to desired value
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:param value: value
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:param source: python object (list or dict)
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"""
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node = TraverseHelper.get(path, source)
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node.append(value)
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def retry(ExceptionToCheck, tries=4, delay=3, backoff=2):
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"""Retry calling the decorated function using an exponential backoff.
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http://www.saltycrane.com/blog/2009/11/trying-out-retry-decorator-python/
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original from: http://wiki.python.org/moin/PythonDecoratorLibrary#Retry
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:param ExceptionToCheck: the exception to check. may be a tuple of
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exceptions to check
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:type ExceptionToCheck: Exception or tuple
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:param tries: number of times to try (not retry) before giving up
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:type tries: int
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:param delay: initial delay between retries in seconds
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:type delay: int
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:param backoff: backoff multiplier e.g. value of 2 will double the delay
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each retry
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:type backoff: int
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"""
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def deco_retry(f):
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@wraps(f)
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def f_retry(*args, **kwargs):
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mtries, mdelay = tries, delay
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forever = mtries == -1
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while forever or mtries > 1:
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try:
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return f(*args, **kwargs)
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except ExceptionToCheck as e:
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log.exception(e)
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log.info("Retrying in {0} seconds...".format(mdelay))
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eventlet.sleep(mdelay)
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if not forever:
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mtries -= 1
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if mdelay < 60:
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mdelay *= backoff
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return f(*args, **kwargs)
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return f_retry
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return deco_retry
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def handle(f):
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"""Handles exception in wrapped function and writes to log."""
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@wraps(f)
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def f_handle(*args, **kwargs):
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try:
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return f(*args, **kwargs)
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except Exception as e:
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log.exception(e)
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return f_handle
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