Go benchmark: concrete method call vs call through an interface

method_bench.go

package bench

import "testing"

func Benchmark_InterfaceMethods(b *testing.B) {
	s := &Struct{}

	for n := 0; n < b.N; n++ {
		s.Method()
	}
}

func Benchmark_ConcreteMethods(b *testing.B) {
	s := &Struct{}
	var i Interface = s

	for n := 0; n < b.N; n++ {
		i.Method()
	}
}

type Struct struct {
	val uint
}

func (s *Struct) Method() {
	s.val++
}

type Interface interface {
	Method()
}

/*
Amazingly the call via an interface is faster (trivially).

goos: darwin
goarch: amd64
pkg: github.com/jakecoffman/tanklets/cmd/bench
Benchmark_InterfaceMethods-4    1000000000               2.01 ns/op
Benchmark_ConcreteMethods-4     1000000000               2.20 ns/op
PASS
*/