Clean Dequeue#takeBetween code
#9768
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| take.flatMap { b => | ||
| takeRemainder(remaining - 1, max - bs.length - 1, acc ++ bs :+ b) | ||
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| } |
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I'm not sure to understand what this take in this remaining > 1 case was bringing
IMO, it'll be faster to just loop as it'll avoid to execute 1 take and then a takeUpTo. Instead it's just execute takeUpTo
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AFAICT it's quite important. takeUpTo will return a Chunk.empty immediately if the queue is empty, but take will asynchronously wait until something is placed in the queue and the calling thread will be notified via the completion of a Promise. With this implementation we're not asynchronously suspending awaiting for an item to be placed in the queue which wastes CPU cycles (potentially indefinitely)
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Should we add a test for this?
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Should we add a test for this?
I'll see if I can come up with one in a followup PR
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| take.flatMap { b => | ||
| takeRemainder(remaining - 1, max - bs.length - 1, acc ++ bs :+ b) | ||
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| } |
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AFAICT it's quite important. takeUpTo will return a Chunk.empty immediately if the queue is empty, but take will asynchronously wait until something is placed in the queue and the calling thread will be notified via the completion of a Promise. With this implementation we're not asynchronously suspending awaiting for an item to be placed in the queue which wastes CPU cycles (potentially indefinitely)
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| if (remaining <= 0) Exit.succeed(acc ++ bs) | ||
| else if (remaining == 1) take.map(b => acc ++ bs :+ b) | ||
| else take.flatMap(b => takeRemainder(remaining - 1, max - bs.length - 1, acc ++ bs :+ b)) |
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@guizmaii I'm thinking that while this is okay for small min / max numbers, it's probably quite unoptimized for large numbers due to the concatenation of Chunks. I wonder if we could use a ChunkBuilder instead when min or max are relatively large.
However perhaps lets look at this at another PR
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That's a good question. I don't really understand well how Chunk/ChunkBuilder are working nor how to get best performances from then, especially about concatenating two Chunk/ChunkBuilder
I know that Chunks concatenation doesn't relocate immediately a new Chunk containing both. It's using final case class Concat[A](override protected val left: Chunk[A], override protected val right: Chunk[A]) to concat lazily
Why do you think using ChunkBuilder would help?
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