Source code for zenpy.lib.cache

import logging
from threading import RLock

import cachetools

from zenpy.lib.api_objects import BaseObject
from zenpy.lib.exception import ZenpyCacheException
from zenpy.lib.util import get_object_type

__author__ = 'facetoe'

log = logging.getLogger(__name__)


[docs]class ZenpyCache(object): """ Wrapper class for the various cachetools caches. Adds ability to change cache implementations on the fly and change the maxsize setting. """ AVAILABLE_CACHES = [c for c in dir(cachetools) if c.endswith('Cache') and c != 'Cache'] def __init__(self, cache_impl, maxsize, **kwargs): self.cache = self._get_cache_impl(cache_impl, maxsize, **kwargs) self.purge_lock = RLock()
[docs] def set_cache_impl(self, cache_impl, maxsize, **kwargs): """ Change cache implementation. The contents of the old cache will be transferred to the new one. :param cache_impl: Name of cache implementation, must exist in AVAILABLE_CACHES """ new_cache = self._get_cache_impl(cache_impl, maxsize, **kwargs) self._populate_new_cache(new_cache) self.cache = new_cache
[docs] def pop(self, key, default=None): return self.cache.pop(key, default)
[docs] def items(self): return self.cache.items()
@property def impl_name(self): """ Name of current cache implementation """ return self.cache.__class__.__name__ @property def maxsize(self): """ Current max size """ return self.cache.maxsize
[docs] def set_maxsize(self, maxsize, **kwargs): """ Set maxsize. This involves creating a new cache and transferring the items. """ new_cache = self._get_cache_impl(self.impl_name, maxsize, **kwargs) self._populate_new_cache(new_cache) self.cache = new_cache
[docs] def purge(self): """ Purge the cache of all items. """ with self.purge_lock: self.cache.clear()
@property def currsize(self): return len(self.cache) def _populate_new_cache(self, new_cache): for key, value in self.cache.items(): new_cache[key] = value def _get_cache_impl(self, cache_impl, maxsize, **kwargs): if cache_impl not in self.AVAILABLE_CACHES: raise ZenpyCacheException( "No such cache: %s, available caches: %s" % (cache_impl, str(self.AVAILABLE_CACHES))) return getattr(cachetools, cache_impl)(maxsize, **kwargs) def __iter__(self): return self.cache.__iter__() def __getitem__(self, item): return self.cache[item] def __setitem__(self, key, value): if not issubclass(type(value), BaseObject): raise ZenpyCacheException("{} is not a subclass of BaseObject!".format(type(value))) self.cache[key] = value def __delitem__(self, key): del self.cache[key] def __contains__(self, item): return item in self.cache def __len__(self): return len(self.cache)
[docs]class ZenpyCacheManager: """ Interface to the various caches. """ def __init__(self, disabled=False): self.disabled = disabled self.mapping = { 'user': ZenpyCache('LRUCache', maxsize=10000), 'organization': ZenpyCache('LRUCache', maxsize=10000), 'group': ZenpyCache('LRUCache', maxsize=10000), 'brand': ZenpyCache('LRUCache', maxsize=10000), 'ticket': ZenpyCache('TTLCache', maxsize=10000, ttl=30), 'request': ZenpyCache('LRUCache', maxsize=10000), 'ticket_field': ZenpyCache('LRUCache', maxsize=10000), 'sharing_agreement': ZenpyCache('TTLCache', maxsize=10000, ttl=6000), 'identity': ZenpyCache('LRUCache', maxsize=10000) }
[docs] def add(self, zenpy_object): """ Add a Zenpy object to the relevant cache. If no cache exists for this object nothing is done. """ object_type = get_object_type(zenpy_object) if object_type not in self.mapping or self.disabled: return attr_name = self._cache_key_attribute(object_type) cache_key = getattr(zenpy_object, attr_name) log.debug("Caching: [{}({}={})]".format(zenpy_object.__class__.__name__, attr_name, cache_key)) self.mapping[object_type][cache_key] = zenpy_object
[docs] def delete(self, to_delete): """ Purge one or more items from the relevant caches """ if not isinstance(to_delete, list): to_delete = [to_delete] for zenpy_object in to_delete: object_type = get_object_type(zenpy_object) object_cache = self.mapping.get(object_type, None) if object_cache: removed_object = object_cache.pop(zenpy_object.id, None) if removed_object: log.debug("Cache RM: [%s %s]" % (object_type.capitalize(), zenpy_object.id))
[docs] def get(self, object_type, cache_key): """ Query the cache for a Zenpy object """ if object_type not in self.mapping or self.disabled: return None cache = self.mapping[object_type] if cache_key in cache: log.debug("Cache HIT: [%s %s]" % (object_type.capitalize(), cache_key)) return cache[cache_key] else: log.debug('Cache MISS: [%s %s]' % (object_type.capitalize(), cache_key))
[docs] def query_cache_by_object(self, zenpy_object): """ Convenience method for testing. Given an object, return the cached version """ object_type = get_object_type(zenpy_object) cache_key = self._cache_key_attribute(object_type) return self.get(object_type, getattr(zenpy_object, cache_key))
[docs] def purge_cache(self, object_type): """ Purge the named cache of all values. If no cache exists for object_type, nothing is done """ if object_type in self.mapping: cache = self.mapping[object_type] log.debug("Purging [{}] cache of {} values.".format(object_type, len(cache))) cache.purge()
[docs] def in_cache(self, zenpy_object): """ Determine whether or not this object is in the cache """ object_type = get_object_type(zenpy_object) cache_key_attr = self._cache_key_attribute(object_type) return self.get(object_type, getattr(zenpy_object, cache_key_attr)) is not None
[docs] def should_cache(self, zenpy_object): """ Determine whether or not this object should be cached (ie, a cache exists for it's object_type) """ return get_object_type(zenpy_object) in self.mapping
[docs] def disable(self): """Disables cache""" self.disabled = True
[docs] def enable(self): """Enables cache""" self.disabled = False
[docs] def status(self): """Returns current cache status""" return 'Cache disabled' if self.disabled else 'Cache enabled'
[docs] def get_cache_engines(self): """Returns list of caches available in cachetools""" return ZenpyCache.AVAILABLE_CACHES
def _cache_key_attribute(self, object_type): """ Return the attribute used as the cache_key for a particular object type. """ # This function used to return the key for objects that are not referenced by id. # These objects are no longer cached (UserField, OrganizationalField) and so the # function has no purpose anymore. I'm leaving it here in case it comes in handy again return 'id'