Small refactor to DefaultClient to remove unsafe calls and repeated code

[Adam-McDevitt]

Saw some unsafe calls:

• NonEmptyList.fromListUnsafe
• m.head where m is a List, not a NonEmptyList

that could be easily refactored to a safe call, and an opportunity to move some repeated code into a private function.

[rossabaker]

I like it. Thanks!

[rossabaker]

This is probably a few femtoseconds slower than the original, but since we're about to make an HTTP request, it is probably completely imperceptible. And I like getting rid of the unsafe methods. And if someone wants to reoptimize this, now it's in one place.

[danicheg]

.toList.toNel

In the capacity of a grumpy micro-benchmarker of certain parts of http4s, this will also consume a bit more heap and stress out the GC (in terms of femtoseconds). Unsafe API here is a reasonable choice since we have checks on non-emptiness.

But, I really like this refactoring into the dedicated def 👍🏻

[Adam-McDevitt]

And I like getting rid of the unsafe methods. And if someone wants to reoptimize this, now it's in one place.

Unsafe API here is a reasonable choice since we have checks on non-emptiness.

I'm happy to rework to go with whatever maintainer preference is here. I think the .toNel.fold implementation nicer and more pleasing, but if the performance decrease is deemed important I could push up changes to have the old implementation pulled out into the same helper function.

[Adam-McDevitt]

Which part is it that's expected to add a bit more heap / GC / execution time? Would this be an improvement?

  private def reqWithMediaRangeAndQValue[A](req: Request[F], d: EntityDecoder[F, A]) =
    d.consumes.toList match {
      case head :: next =>
        req.addHeader(Accept(NonEmptyList(head, next).map(MediaRangeAndQValue(_))))
      case Nil => req
    }

[valencik]

Which part is it that's expected to add a bit more heap / GC / execution time? Would this be an improvement?

  private def reqWithMediaRangeAndQValue[A](req: Request[F], d: EntityDecoder[F, A]) =
    d.consumes.toList match {
      case head :: next =>
        req.addHeader(Accept(NonEmptyList(head, next).map(MediaRangeAndQValue(_))))
      case Nil => req
    }

I think this would be an improvement. It avoids allocating the extra Option that using toNel had.
The original implementations avoiding calling toList if the Set was empty, but doing that is just going to return Nil if the set is empty anyways. It's fine.

@Adam-McDevitt, if you're still willing, yes I think your suggestion here would be an improvement.

[danicheg]

Since Ross approved this, it should be enough to move on. I don't really want to be a party pooper. But maybe some third folk will glance at this to have a quorum in opinions.

[valencik]

Thanks for this @Adam-McDevitt, it's a nice clean up.

I do think your latest suggestion avoiding toNel is nice and hope you are able to push a commit with that change. 😺

Approving to not block.

[valencik]

Which part is it that's expected to add a bit more heap / GC / execution time? Would this be an improvement?

  private def reqWithMediaRangeAndQValue[A](req: Request[F], d: EntityDecoder[F, A]) =
    d.consumes.toList match {
      case head :: next =>
        req.addHeader(Accept(NonEmptyList(head, next).map(MediaRangeAndQValue(_))))
      case Nil => req
    }

I think this would be an improvement. It avoids allocating the extra Option that using toNel had.
The original implementations avoiding calling toList if the Set was empty, but doing that is just going to return Nil if the set is empty anyways. It's fine.

@Adam-McDevitt, if you're still willing, yes I think your suggestion here would be an improvement.

[Adam-McDevitt]

Thanks all - I'll push up a change probably today with my latest suggestion.

[Adam-McDevitt]

Updated! :)

[hamnis]

needs a sbt scalafixAll

[danicheg]

Thank you for iterating over this!