perf(nuxt): don't dedupe fewer than two middleware/plugins

[GalacticHypernova]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This PR returns early in the uniqueBy function that is used to gather all the unique plugins/middleware/etc whenever the input array is empty (which isn't unrealistic, if someone doesn't use any plugins for example) or contains a single file (guaranteed to be unique), avoiding all the computation afterwards and increasing performance in both cases by ~66.67%.
With the following benchmark I have gotten the following results:

 function uniqueByNonReg<T, K extends keyof T>(arr: T[], key: K) {
  if (arr.length < 2) {
    return arr;
  }

  const res: T[] = [];
  const seen = new Set<T[K]>();

  for (const item of arr) {
    if (seen.has(item[key])) {
      continue;
    }

    seen.add(item[key]);
    res.push(item);
  }

  return res;
}

 function uniqueBy<T, K extends keyof T> (arr: T[], key: K) {
  const res: T[] = []
  const seen = new Set<T[K]>()
  for (const item of arr) {
    if (seen.has(item[key])) { continue }
    seen.add(item[key])
    res.push(item)
  }
  return res
}

console.time('regularEmpty')
for(let i=0;i<100000;i++){
  uniqueBy([],'name')
}
console.timeEnd('regularEmpty')
console.time('nonRegularEmpty')
for(let i=0;i<100000;i++){
  uniqueByNonReg([],'name')
}
console.timeEnd('nonRegularEmpty')

console.time('regularSingle')
for(let i=0;i<100000;i++){
  uniqueBy([{name:'f'}],'name')
}
console.timeEnd('regularSingle')
console.time('nonRegularSingle')
for(let i=0;i<100000;i++){
  uniqueByNonReg([{name:'f'}],'name')
}
console.timeEnd('nonRegularSingle')

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

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[GalacticHypernova]

I will look into optimizing the entire Set handling as well (perhaps rework it to a Map?), but from my current benchmarks the results are inconclusive and quite mixed (potentially because of it running online, which I will do some offline testing soon) so I have not added that part yet.

[GalacticHypernova]

Update: the new update (the single file early return) yields even faster results, I will soon post new benchmark results

[danielroe]

Nuxt itself will always add more than 2 plugins, which means the additional check is likely to increase the time required when resolving plugins.

(Though I don't see the harm in adding this check as it might be relevant for middleware - Nuxt only adds one by default.)

[GalacticHypernova]

which means the additional check is likely to increase the time required when resolving plugins.

Well, the check is O(1), so it doesn't add time at all compared to the time it saves (as you mentioned with the middleware). I'm not sure about the usability of that function in modules and the likes, but could people use it in their own modules or to register their own middleware/plugins?

[danielroe]

It adds time (technically) because it will always be false when resolving plugins.

This function is only used to deduplicate plugins and middleware in this file.

[GalacticHypernova]

I see. Allow me to benchmark this really quickly.

EDIT: The results are as follows:

Of course there is deviation a bit because it's online, but in the offline results I got the following:

So yes, while it does go up by 0.4 ms it saves in both empty and single filed directories ~66.67% and up to ~80%, which in comparison is a lot faster. The most is has ever gotten to was around ~+2ms to execution time in the multiple section but gets rid of ~4ms in the empty and ~7ms in the single.
Here is an example of such statistics:

Now, it's possible to make an overload of this function, but do you think it's worth it?