dj-loopbreaker

Django library which breaks infinite loops in signals

Installation

pip install dj-loopbreaker

Usage

from loopbreaker import throttle

The problem

Imagine you have a signal like this:

@receiver(post_save, sender=Todo, dispatch_uid="example.say_hi")
@throttle(signal_id="update.todo", expire_after=1)
def update_todo(instance, created, **kwargs):
    # normally this would cause an infinte loop
    instance.done = not instance.done
    instance.save()

Normally that would cause an infinite loop. However, include the @throttle decorator, and it will now make sure that this signal is only executed again after 1 second for this specific instance.

How it works

throttle uses Django's caching mechanism. It will create a key using the following format: {signal_id}.{app_label}{model_name}{instance_id}. The key will expire after expire_after seconds

This means:

• No longer need to worry about making infinite loops in your signals
• No dependencies, or dependencies at your own discretion (we use django's internal caching, so you can set up your caching backend)
• Throttling occurs per instance (not per model)