benchmark_slice_ extraction.go

package main

import (
	"reflect"
	"testing"
)

type Hoge struct {
	ID   int64
	Name string
}

type Hoge2 struct {
	ID2   int64
	Name2 string
}

var (
	list  = []Hoge{{1, "Mark"}, {2, "John"}, {3, "Bob"}, {4, "Alex"}}
	list2 = []Hoge2{{1, "Mark"}, {2, "John"}, {3, "Bob"}, {4, "Alex"}}
)

// ①for文で直接抜き出すパターン
func Benchmark_NormalLoop(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ids := make([]int64, len(list))
		for i, v := range list {
			ids[i] = v.ID
		}
		ids2 := make([]int64, len(list2))
		for i, v := range list2 {
			ids2[i] = v.ID2
		}
	}
}

// ②reflectパッケージで処理するパターン
func Benchmark_ReflectLoop(b *testing.B) {
	for i := 0; i < b.N; i++ {
		GetInt64SlicesBySpecifiedField(&list, `ID`)
		GetInt64SlicesBySpecifiedField(&list2, `ID2`)
	}
}

func GetInt64SlicesBySpecifiedField(p interface{}, fieldName string) []int64 {
	v := reflect.ValueOf(p).Elem()
	len := v.Len()
	slices := make([]int64, len)

	switch v.Kind() {
	case reflect.Slice:
		for i := 0; i < len; i++ {
			slices[i] = v.Index(i).FieldByName(fieldName).Int()
		}
	}

	return slices
}

// ③IFでの実装パターン
func Benchmark_IFLoop(b *testing.B) {
	for i := 0; i < b.N; i++ {
		getIDs(list3)
		getIDs(list4)
	}
}

type HogesI interface {
	GetIDs() []int64
}

func getIDs(list HogesI) []int64 {
	return list.GetIDs()
}

type Hoges []Hoge

func (h *Hoges) GetIDs() []int64 {
	ids := make([]int64, len(*h))
	for i, v := range *h {
		ids[i] = v.ID
	}
	return ids
}

type Hoges2 []Hoge2

func (h *Hoges2) GetIDs() []int64 {
	ids := make([]int64, len(*h))
	for i, v := range *h {
		ids[i] = v.ID2
	}
	return ids
}

var (
	list3 = &Hoges{
		Hoge{1, "Mark"},
		Hoge{2, "John"},
		Hoge{3, "Bob"},
		Hoge{4, "Alex"},
	}
	list4 = &Hoges2{
		Hoge2{1, "Mark"},
		Hoge2{2, "John"},
		Hoge2{3, "Bob"},
		Hoge2{4, "Alex"},
	}
)