測試 go 介面的動態執行

main.go

// main.go
package main

type Duck interface {
	Quack()
}

type Cat struct {
	Name string
}

//go:noinline
func (c Cat) Quack() {
	// println(c.Name + " meow")
	// _ = c.Name + " meow"
}

func main() {
}

// main_test.go
package main

import (
	"testing"
)

func BenchmarkDirectCall(b *testing.B) {
	c := &Cat{Name: "grooming"}
	for n := 0; n < b.N; n++ {
		// c := &Cat{Name: "grooming"}
		c.Quack()
	}
}

func BenchmarkDynamicDispatchByPointer(b *testing.B) {
	c := Duck(&Cat{Name: "grooming"})
	for n := 0; n < b.N; n++ {
		// c := Duck(&Cat{Name: "grooming"})
		c.Quack()
	}
}

func BenchmarkDynamicDispatchByValue(b *testing.B) {
	c := Duck(Cat{Name: "grooming"})
	for n := 0; n < b.N; n++ {
		// c := Duck(Cat{Name: "grooming"})
		c.Quack()
	}
}

// bash
$ go test -gcflags=-N -benchmem -test.count=1 -test.cpu=1 -test.benchtime=1s -bench .
goos: windows
goarch: amd64
pkg: escape
BenchmarkDirectCall                     593879478                1.97 ns/op            0 B/op          0 allocs/op
BenchmarkDynamicDispatchByPointer       326106717                3.65 ns/op            0 B/op          0 allocs/op
BenchmarkDynamicDispatchByValue         339610946                3.50 ns/op            0 B/op          0 allocs/op
PASS
ok      escape  4.638s

$ go version
go version go1.13.3 windows/amd64