bench_test.go

package main

import "testing"

// Original version that returns by value
type Thing struct {
	c *Config
}

func (t *Thing) Config() Config {
	return *t.c
}

type Config struct {
	name string
	foo  [10]int
	bar  [20]int
}

func (c Config) Foo(i int) int {
	return c.foo[i]
}

func (c Config) Bar(i int) int {
	return c.bar[i]
}

func newThing() Thing {
	return Thing{
		c: &Config{
			name: "woohoo",
			foo:  [10]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10},
			bar:  [20]int{33, 34, 35},
		},
	}
}

func BenchmarkConfigByValue(b *testing.B) {
	t := newThing()

	var a, x int
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		a = t.Config().Foo(1)
		x = t.Config().Bar(2)
	}
	// Use the variables to prevent optimizer from eliminating the code
	_ = a
	_ = x
}

func BenchmarkConfigByPointer(b *testing.B) {
	t := newThing()

	var a, x int
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		a = t.c.Foo(1)
		x = t.c.Bar(2)
	}
	// Use the variables to prevent optimizer from eliminating the code
	_ = a
	_ = x
}

func BenchmarkConfigByValueWithLocal(b *testing.B) {
	t := newThing()

	var a, x int
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		// Store config in local variable to avoid double copy
		c := t.Config()
		a = c.Foo(1)
		x = c.Bar(2)
	}
	// Use the variables to prevent optimizer from eliminating the code
	_ = a
	_ = x
}