sheenobu/django-eventual-wip

django-eventual-poc

this is a proof-of-concept deferred value calculations by serializing query expressions and throwing them in a job queue.

I wanted to know how you would instrument the django ORM and whether you could build 'smart' query expressions.

Example:

def got_vote(choice: Choice):
    choice.votes = F("votes") + 1
    choice.save()
    choice.refresh_from_db(fields=["votes"])

Can use 'eventual' just by wrapping our Expressions:

from eventual import Eventual

def got_vote(choice: Choice):
    choice.votes = Eventual(F("votes") + 1)
    choice.save()

What happens:

• Eventual(F("votes") + 1) is serialized into a queue.
• F("votes") + 1 is calculated and stored into the votes field, but not written to the db. it can then be returned by your views as-if it was incremented.
• The database write happens in your backend workers.

Usage

Include eventual into INSTALLED_APPS.

Set config details:

EVENTUAL_ENABLED = True
EVENTUAL_JOB_ENGINE = 'myproject.tasks.JobEngine'

Usage - Dramatiq:

Implement handler:

import dramatiq
import eventual

handler = dramatiq.actor(eventual.JobHandler())

class JobEngine:
    def queue(self, data: str):
        handler.send(data)