The idea of this benchmark is to determine the performance cost of when we pass around interfaces instead of the concrete struct and getting a field on the struct vs calling a `get` method on the interface

golang_benchmark_interface_methods.go

//The idea of this benchmark is to determine the
//  performance cost of when we pass around interfaces
//  instead of the concrete struct and getting a field
//  on the struct vs calling a `get` method on the
//  interface

package test

import (
	"testing"
)

var (
	globalInt64 int64
	usr         *user = &user{25}
	iUser       User  = usr
)

type User interface {
	GetId() int64
}

type user struct {
	Id int64
}

func (u *user) GetId() int64 {
	return u.Id
}

func BenchmarkStructField(b *testing.B) {
	var g int64
	for n := 0; n < b.N; n++ {
		g = usr.Id
		if g > 24 {
			g = 0
		}
	}
	globalInt64 = g
}

func BenchmarkInterfaceMethod(b *testing.B) {
	var g int64
	for n := 0; n < b.N; n++ {
		g = iUser.GetId()
		if g > 24 {
			g = 0
		}
	}
	globalInt64 = g
}