vector_stack_builder.scala

package test

import org.openjdk.jmh.annotations._

import scala.collection.immutable.Stack
import scala.collection.mutable

/*
  Benchmark                           Mode  Cnt       Score       Error   Units
  TestBenchmark.stack_1000           thrpt   20       7.446 ±     0.338  ops/ms
  TestBenchmark.vector_1000          thrpt   20   19401.495 ±   754.851  ops/ms
  TestBenchmark.vector_builder_1000  thrpt   20  142296.432 ± 40669.008  ops/ms
*/
@State(Scope.Benchmark)
@BenchmarkMode(Array(Mode.Throughput))
class TestBenchmark {

  import scala.collection.immutable

  var b: mutable.Builder[Any, Vector[Any]] = _
  var v: immutable.Vector[Any] = _
  var s: immutable.Stack[Any] = _

  @Setup(Level.Iteration)
  def init = {
    b = Vector.newBuilder[Any]
    b.sizeHint(1000)

    v = Vector.empty[Any]
    s = Stack.empty[Any]
  }

  @Benchmark
  @OperationsPerInvocation(1000)
  def vector_1000 = {
    1 to 1000 foreach { _ => v :+= "" }
    v
  }

  @Benchmark
  @OperationsPerInvocation(1000)
  def stack_1000 = {
    1 to 1000 foreach { _ => s :+= "" }
    s
  }

  @Benchmark
  @OperationsPerInvocation(1000)
  def vector_builder_1000 = {
    1 to 1000 foreach { _ => b += "" }
    b.result()
  }

}