TypedArray benchmarks

TypedArrayBenchmark.kt

import kotlinx.benchmark.*

@State(Scope.Benchmark)
@BenchmarkMode(Mode.Throughput)
@Warmup(iterations = 4, time = 5, timeUnit = BenchmarkTimeUnit.SECONDS)
@Measurement(iterations = 4, time = 5, timeUnit = BenchmarkTimeUnit.SECONDS)
public class ByteArrayBenchmark {
  private val fromArray: ByteArray

  @Param("15", "100", "1000", "5000", "15000", "100000", "1000000")
  public var newSize: Int = 0

  public constructor() {
    val size = 10000
    val range = 0..255
    val array = ByteArray(size)

    for (i in 0..<size) {
      array[i] = range.random().toByte()
    }

    fromArray = array
  }

  @Benchmark
  public fun typedArraySet(blackhole: Blackhole) {
    val size = fromArray.size
    val toArray = when {
      newSize < 16 || size < 16 -> ktFillFrom(fromArray, ByteArray(newSize))
      newSize > size -> ByteArray(newSize).also { copy ->
        copy.asDynamic().set(fromArray, 0)
      }
      else -> fromArray.asDynamic().slice(0, newSize)
    }

    blackhole.consume(toArray.unsafeCast<Any>())
  }

  @Benchmark
  public fun fillFrom(blackhole: Blackhole) {
    val toArray = ktFillFrom(fromArray, ByteArray(newSize))
    blackhole.consume(toArray)
  }

  private fun ktFillFrom(src: dynamic, dst: dynamic): ByteArray {
    val srcLen: Int = src.length
    val dstLen: Int = dst.length
    var index: Int = 0
    val arr = dst.unsafeCast<Array<Any?>>()
    while (index < srcLen && index < dstLen) {
      arr[index] = src[index]
      index++
    }
    return dst
  }
}