gistfile1.go

package test

import (
	"math/rand"
	"testing"
	"time"
)

type Customer struct {
	Id  int
	Inv Invoice
}

type Invoice struct {
	IdCustomer int
}

var count = 60
var customers []Customer
var invoices []Invoice

func init() {
	customers = make([]Customer, count)
	invoices = make([]Invoice, count)

	rand.Seed(time.Now().UnixNano())

	for i := 0; i < count; i++ {
		r := rand.Intn(count)
		customers[i] = Customer{Id: r}
		invoices[i] = Invoice{r}
	}
}

func BenchmarkMap(b *testing.B) {
	for n := 0; n < b.N; n++ {
		// Initialize a map
		m := make(map[int]Invoice, len(invoices))
		for _, i := range invoices {
			m[i.IdCustomer] = i
		}

		// this will find the element almost instantly but we had to
		// initialize the map first.
		for _, c := range customers {
			c.Inv = m[c.Id]
		}
	}
}

func BenchmarkSlice(b *testing.B) {
	for n := 0; n < b.N; n++ {
		// search by iterating until we find it
		for _, i := range invoices {
			for _, c := range customers {
				if i.IdCustomer == c.Id {
					c.Inv = i
					break
				}
			}
		}
	}
}