Suor/django-cacheops

A slick ORM cache with automatic granular event-driven invalidation.

Alexander Schepanovski

@Suor

What do you mean by second level granularity?

So it's

@cached(timeout=30 * 60)
def _get_a(start, end):
    a = some_function_call(start, end)
    # Do cache empty results
    if not a:
        raise UncachedResult(a)

    return a

def get_a(start, end):
    try:
        return _get_a(start, end)
    except UncachedResult as e:
        return e.result

Chetan Dhembre

@chetandhembre

end = datetime.now()
start = end - timedelta(days-12)

what will get key of cache result for _get_a()?

Alexander Schepanovski

@Suor

To get a key:

_get_a.key(start, end)

To invalidate:

_get_a.invalidate(start, end)

Chetan Dhembre

@chetandhembre

i want to cache result for 30 minutes ..
so result for datetime.datetime(2016, 10, 14, 12, 17, 0, 0) will be same for datetime.datetime(2016, 10, 14, 12, 3, 0, 0)

Alexander Schepanovski

@Suor

Then do not pass timestamp to _get_a() and some_func(), pass dates.

Chetan Dhembre

@chetandhembre

i can not

Alexander Schepanovski

@Suor

why?

Your function doesn't depend on time, right?

Chetan Dhembre

@chetandhembre

it depend on time .. but i want to cache result on interval of time .. so result i will get 12:00 PM same result i will return for next 30 minutes

Alexander Schepanovski

@Suor

When you need to round your times to 30 min intervals then use that as arguments.

Chetan Dhembre

@chetandhembre

problem with that is if i invalidate data on 12:15 due to some bug or issue.. and then again cache result it will calcaulate result for 12:00 as i am sending things in 30 min interval

i hope i am able to explain my usecase

Alexander Schepanovski

@Suor

Should there be single result at each given time?

Chetan Dhembre

@chetandhembre

yeah

Alexander Schepanovski

@Suor

Then you should have single cache key not depending on anything

So cache a function without arguments and calc dates within it

Chetan Dhembre

@chetandhembre

it is not also possible my function gets start and end from another function .. i guess cacheops wont help me with my unique usecase

atleast function level cache

will use from cacheops import cache in this case

Alexander Schepanovski

@Suor

You can use custom key func here

Chetan Dhembre

@chetandhembre

like?

does cacheops provide this feature? it is in TODOS

Alexander Schepanovski

@Suor

def _key_func(func, args, kwargs, extra=None):
    start, end = args
    # ...
    return key

@cached_as(timeout=30 * 60, key_func=_key_func)
def _get_a(start, end):
    a = some_function_call(start, end)
    # Do not cache empty results
    if not a:
        raise UncachedResult(a)

    return a

Chetan Dhembre

@chetandhembre

this is great ..

Alexander Schepanovski

@Suor

I feel that you are overcomplicating though.

Chetan Dhembre

@chetandhembre

why i havent read it before

Alexander Schepanovski

@Suor

Because it's not documented

Chetan Dhembre

@chetandhembre

Chetan Dhembre

@chetandhembre

btw thanks for cacheops

Alexander Schepanovski

@Suor

you are welcome

Chetan Dhembre

@chetandhembre

it just work.. like nginx and redis respect

Alexander Schepanovski

@Suor

Thanks

Harish Sundararaj

@harishzen

Hi. I'm wondering if there is any documentation out there comparing this with johnny cache?

Alexander Schepanovski

@Suor

Johnny-cache is not supported anymore, it's working analog is django-cachalot. The main difference between cacheops and both of them is that they invalidate entire table every time any changes to it is made whereas cacheops is granular.

Chetan Dhembre

@chetandhembre

can i use cacheops without django?

as our django app using cacheops do not want to use different lib for caching

Alexander Schepanovski

@Suor

The smart part of cacheops caches django ORM querysets and other things basing on that, so I can't see how it could be used without django.

Simple and file cache might be used separately, you'll still need django as dependency and to configure them

Not sure what's the issue with the app

Chetan Dhembre

@chetandhembre

I want to use simple cache.. but at start of cacheops it expect to read config from settings file

Chetan Dhembre

@chetandhembre

got it

Chetan Dhembre

@chetandhembre

i guess still i have some issue

from cacheops.simple import RedisCache

I am importing this

Alexander Schepanovski

@Suor

You can configure django with django.conf.settings.configure()

codegeschrei

@codegeschrei

Hey there! I just wanted to ask why caching in admin is turned off?

Alexander Schepanovski

@Suor

To be extra safe. And more for historical reasons, there were lots of limitations in invalidating m2m for example.

Another reason - caching for admin doesn't make sense anyway: low traffic, high updates, different queries than in the app. Useless bloat.

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