Today I wrote a simple (silly, I’d say) library that I had in mind since a while to refresh configuration values for JS apps.
The library is called
freshen-up and it comes
from some internal discussions we had at Namshi
on how to refresh some content we load once a
NodeJS app boots.
I was discussing various approaches with Lucio and, even if we don’t need to employ anything like this at the moment, I decided to give it a shot to see how simple it would have been to write down something that would do that.
Turns out there are a few different approaches to do this:
- send a signal to the app and have it reload the configuration: this will work nicely but you need someone else to send the signal to the app, so it might be that when you’re bootstrapping this system you don’t want / need too many actors around; though my overall sense is that this is the most elegant approach
- have the application listen to a message queue and publish a message everytime you need to reload the cache: I feel this is overkill and I am not a big fan of making the application aware of a system like RabbitMQ just for this, I feel it kind of breaks responsibilities / it’s a bit “too much”
- have the application reload the cache at a certain interval: a very simple approach and probably the least “precise” of the options, but feels legit enough when you don’t want to complicate things
I then decided to give a try to the third approach and released freshen-up; it’s usage is pretty straightforward:
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The library will refresh the configuration, by default, every 50ms, though you can override this:
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By the way, you can also use
freshen-up to do other
things like running checks every N seconds:
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That’s basically it: I added a couple tests just in case, though I still think there are better ways to do cache invalidation.