Invalidating package pages not updating mavericks
There’s a case that certain group of methods operate the same data and it’s impractical to invalidate individual entries.
Here’s article by Eric Florenzano which explains the idea. When we want to tag a cache entry, first we need to create the tag entries. Value of tag entry is set to random value each time tag is created.
from cache_utils.decorators import cached @cached(60) def foo(x, y=0): print 'foo is called' return x y foo(1,2) # foo is called foo(1,2) foo(5,6) # foo is called foo(5,6) foo.invalidate(1,2) foo(1,2) # foo is called foo(5,6) foo(x=2) # foo is called foo(x=2) class Foo(object): @cached(60) def foo(self, x,y): print "foo is called" return x y obj = Foo() obj.foo(1,2) # foo is called obj.foo(1,2) from import models from cache_utils.decorators import cached class City Manager(models. 'self' parameter is ignored @cached(60*60*24, 'cities') def default(self): return self.active() # cache a method result.
'self' parameter is ignored, args and # kwargs are used to construct cache key @cached(60*60*24, 'cities') def get(self, *args, **kwargs): return super(City Manager, self).get(*args, **kwargs) class City(models. field declarations objects = City Manager() # an example how to cache django model methods by instance id def has_offers(self): @cached(30) def offer_count(pk): return self.offer_set.count() return history_count(self.pk) 0 # cache the function result based on passed parameter @cached(60*60*24, 'cities') def get_cities(slug) return City.objects.get(slug=slug) # cache for 'cities' group can be invalidated at once def invalidate_city(sender, **kwargs): cache.invalidate_group('cities') pre_delete.connect(invalidate_city, City) post_save.connect(invalidate_city, City) @cached(60) def foo(param) return ..
This means that the speed of operation is constant and irrelevant of number of items already stored. In particular, it often happens when method returns complex values, spanning multiple entities.
When a callable (function or method) is cached, the key is calculated per invocation from callable itself and passed arguments. Cache tagging makes it possible to mark this group of method results with a tag and invalidate them all at once.
During an experiment, a participant will be asked to perform a certain task, while a massive magnetic field pulsates through their body, picking up tiny changes in the blood flow of the brain.
These tiny changes can signal to scientists that certain regions of the brain have suddenly kicked into gear, such as the insular cortex region during gaming, which has been linked to 'higher' cognitive functions such as language processing, empathy, and compassion.
As usually a feature built on-top of another feature adds complexity. All operations become O(n) where is number of entry tags.
However since we can rarely need more than a few dozens of tags, practically it is still O(1).
It wasn’t an intension to provide some statistically significant performance estimation. Before I wrote the library I looked through the Cheese Shop for one that fits my needs.Tags: Adult Dating, affair dating, sex dating