Added age as criteria to not use the cached value added
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3b32ca5e20
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62
__init__.py
62
__init__.py
@ -24,13 +24,12 @@ caching (Caching Module)
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"""
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__DEPENDENCIES__ = []
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import hashlib
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import hmac
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import json
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import logging
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import os
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import pickle
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import sys
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import time
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try:
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from config import APP_NAME as ROOT_LOGGER_NAME
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@ -81,13 +80,20 @@ class property_cache_pickle(object):
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"""
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LOG_PREFIX = 'PickCache:'
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DATA_VERSION_TAG = '_property_cache_data_version_'
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STORAGE_VERSION_TAG = '_storage_version_'
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UID_TAG = '_property_cache_uid_'
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DATA_TAG = '_data_'
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AGE_TAG = '_age_'
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#
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STORAGE_VERSION = 1
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def __init__(self, source_instance, cache_filename, load_all_on_init=False, callback_on_data_storage=None):
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def __init__(self, source_instance, cache_filename, load_all_on_init=False, callback_on_data_storage=None, max_age=None, store_none_value=False):
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self._source_instance = source_instance
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self._cache_filename = cache_filename
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self._load_all_on_init = load_all_on_init
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self._callback_on_data_storage = callback_on_data_storage
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self._max_age = max_age
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self._store_none_value = store_none_value
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self._cached_props = None
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def get(self, key, default=None):
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@ -101,14 +107,27 @@ class property_cache_pickle(object):
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if key in self.keys():
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if self._cached_props is None:
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self._init_cache()
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if self._key_filter(key) not in self._cached_props:
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if self._max_age is None:
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cache_old = False
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else:
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cache_old = time.time() - self._cached_props[self.AGE_TAG].get(self._key_filter(key), 0) > self._max_age
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if cache_old:
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logger.debug("The cached value is old, cached value will be ignored")
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if self._key_filter(key) not in self._cached_props[self.DATA_TAG] or cache_old:
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val = self._source_instance.get(key, None)
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logger.debug("%s Loading property for '%s' from source instance (%s)", self.LOG_PREFIX, key, repr(val))
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self._cached_props[self._key_filter(key)] = val
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if val or self._store_none_value:
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tm = int(time.time())
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logger.debug("Storing value=%s with timestamp=%d to chache", val, tm)
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self._cached_props[self.DATA_TAG][self._key_filter(key)] = val
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self._cached_props[self.AGE_TAG][self._key_filter(key)] = tm
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self._save_cache()
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else:
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logger.debug("%s Providing property for '%s' from cache (%s)", self.LOG_PREFIX, key, repr(self._cached_props.get(self._key_filter(key), default)))
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return self._cached_props.get(self._key_filter(key), default)
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return val
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else:
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logger.debug("%s Providing property for '%s' from cache (%s)", self.LOG_PREFIX,
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key, repr(self._cached_props[self.DATA_TAG].get(self._key_filter(key), default)))
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return self._cached_props[self.DATA_TAG].get(self._key_filter(key), default)
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else:
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logger.info("%s Key '%s' is not in cached_keys. Uncached data will be returned.", self.LOG_PREFIX, key)
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return self._source_instance.get(key, default)
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@ -125,17 +144,31 @@ class property_cache_pickle(object):
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else:
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return self._cached_props.get(self.DATA_VERSION_TAG, None)
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def _storage_version(self):
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if self._cached_props is None:
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return None
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else:
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return self._cached_props.get(self.STORAGE_VERSION_TAG, None)
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def _init_cache(self):
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if not self._load_cache() or self._source_instance.uid() != self._uid() or self._source_instance.data_version() > self._data_version():
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if self._uid() is not None and self._source_instance.uid() != self._uid():
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load_cache = self._load_cache()
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uid = self._source_instance.uid() != self._uid()
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data_version = self._source_instance.data_version() > self._data_version()
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storage_version = self._storage_version() != self.STORAGE_VERSION
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#
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if not load_cache or uid or data_version or storage_version:
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if self._uid() is not None and uid:
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logger.debug("%s Source uid changed, ignoring previous cache data", self.LOG_PREFIX)
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if self._data_version() is not None and self._source_instance.data_version() > self._data_version():
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if self._data_version() is not None and data_version:
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logger.debug("%s Data version increased, ignoring previous cache data", self.LOG_PREFIX)
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self._cached_props = dict()
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if storage_version:
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logger.debug("%s Storage version changed, ignoring previous cache data", self.LOG_PREFIX)
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self._cached_props = {self.AGE_TAG: {}, self.DATA_TAG: {}}
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if self._load_all_on_init:
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self._load_source()
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self._cached_props[self.UID_TAG] = self._source_instance.uid()
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self._cached_props[self.DATA_VERSION_TAG] = self._source_instance.data_version()
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self._cached_props[self.STORAGE_VERSION_TAG] = self.STORAGE_VERSION
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self._save_cache()
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def _load_cache(self):
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@ -149,13 +182,6 @@ class property_cache_pickle(object):
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return False
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def _key_filter(self, key):
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if sys.version_info >= (3, 0):
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tps = [str]
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else:
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tps = [str, unicode]
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if type(key) in tps:
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if key.endswith(self.DATA_VERSION_TAG) or key.endswith(self.UID_TAG):
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return '_' + key
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return key
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def _load_source(self):
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