Time calculation of passing slice as a pointer vs as a value

slice_passing.go

package main

import (
	"fmt"
	"time"
	"strconv"
	"strings"
)

func track(msg string) (string, time.Time) {
    return msg, time.Now()
}

func duration(msg string, start time.Time) {
    fmt.Printf("%v: %v\n", msg, time.Since(start))
}

func addValuePointer(foo *[]string) {
	defer duration(track("addValue slice")) // func exec time
	var s strings.Builder	
	for i := 1; i < 50000; i++ {
		t := strconv.Itoa(i)
		s.WriteString(t)
		*foo = append(*foo, s.String())
	}
}

func addValue(foo []string) []string {
	defer duration(track("addValue slice")) // func exec time
	var s strings.Builder	
	for i := 1; i < 50000; i++ {
		t := strconv.Itoa(i)
		s.WriteString(t)		
		foo = append(foo, s.String())
	}
	return foo
}


func main() {
	foo := make([]string, 50, 100)
	boo := make([]string, 50, 100)
	foo = []string{"a", "b"}
	boo = []string{"a", "b"}
	foo = addValue(foo)
	//fmt.Println("foo = ", foo)
	addValuePointer(&boo)
	//fmt.Println("boo = ", boo)
}