Micro optimization for #features on ActiveRecord adapter

[bkeepers]

I noticed #features was calling Gate.all.map(&:key).to_set to get the list of features, which will pull a lot of data over the wire to get the list of features. This replaces it with Gate.distinct.pluck(:key).to_set. Thankfully, #features is not used in our hot code path internally (get_all with memoization is used when checking #enabled?), but this could have some impact for those with large actor sets.

$ ruby benchmarks/active_record_ips.rb

# Before:
            features      6.453k (± 8.3%) i/s -     32.604k in   5.088062s
# After:
            features     10.130k (± 8.6%) i/s -     50.661k in   5.038290s

This benchmark uses an sqlite in-memory database, so the results should be even more dramatic over a network connection.

[jnunemaker]

this could have some impact for those with large actor sets.

You said Gate and actor sets a few times which confused me but I think you meant Feature and large feature sets.

This is great! Good find.

[bkeepers]

You said Gate and actor sets a few times which confused me but I think you meant Feature and large feature sets.

I did actually mean gates and actor sets. Since this is querying the gates table, it loads all gate data to just get the distinct feature names. So if you enable a single feature for a lot of actors, then calling Flipper.features will pull all the actor data over the wire just to get the feature list.

[jnunemaker]

Ok. I saw @feature_class everywhere not @gate_class so I guess I don't understand where gates were even being queried but that's ok. Regardless this is a good improvement!

[bkeepers]

🤦‍♂️ wow, I must be low on sleep or something. You’re absolutely right. I was thinking it was gates. Now I’m confused where the improvement is coming from.

Must just be large feature sets like you said.

[jnunemaker]

🤣. I was definitely feeling crazy when you said you meant gate. Haha.

This would definitely improve getting features as plucking a column is way faster than pulling all feature data across wire and instantiating AR objects. It's a good change especially for lots of features.