a small performance test

perf.go

package main

import (
	"fmt"
	"time"
	ma "github.com/multiformats/go-multiaddr"
)

var addrs = []string{
	"/ip4/127.0.0.1/tcp/4001/ipfs/QmPdJvfK74MknGSYS2E54EEzKcEY6c19D8BzcCPbW7Sjna",
	"/ip4/159.203.36.22/tcp/4001/ipfs/QmPdJvfK74MknGSYS2E54EEzKcEY6c19D8BzcCPbW7Sjna",
	"/ip4/10.20.0.5/tcp/4001/ipfs/QmPdJvfK74MknGSYS2E54EEzKcEY6c19D8BzcCPbW7Sjna",
	"/ip6/::1/tcp/4001/ipfs/QmPdJvfK74MknGSYS2E54EEzKcEY6c19D8BzcCPbW7Sjna",
	"/ip6/2604:a880:cad:d0::bf0:e001/tcp/4001/ipfs/QmPdJvfK74MknGSYS2E54EEzKcEY6c19D8BzcCPbW7Sjna",
	"/ip4/159.203.36.22/tcp/4001/ipfs/QmPdJvfK74MknGSYS2E54EEzKcEY6c19D8BzcCPbW7Sjna",
	"/ip6/2604:a880:cad:d0::bf0:e001/tcp/4001/ipfs/QmPdJvfK74MknGSYS2E54EEzKcEY6c19D8BzcCPbW7Sjna",
}

func main() {
	maddrs := make([]ma.Multiaddr, 0, len(addrs))
	for _, addr := range addrs {
		maddr, err := ma.NewMultiaddr(addr)
		if err != nil {
			fmt.Println(err)
			return
		}
		maddrs = append(maddrs, maddr)
	}

	a := []ma.Multiaddr{
		maddrs[0], maddrs[1], maddrs[2],
	}
	b := []ma.Multiaddr{
		maddrs[3], maddrs[4], maddrs[5],
	}
	c := []ma.Multiaddr{
		maddrs[2], maddrs[4], maddrs[6],
	}

	N := 1000000

	var merged []ma.Multiaddr 

	timeA := time.Now()
	for i:=0;i<N;i++{
		merged = mergeAddrs1(a,b,c)
	}
	timeB := time.Now()

	for i:=0;i<N;i++{
		merged = mergeAddrs2(a,b,c)
	}
	timeC := time.Now()

	fmt.Println("mergeAddrs1", timeB.Sub(timeA))
	fmt.Println("mergeAddrs2", timeC.Sub(timeB))
	fmt.Println(merged)
}

// mergeAddrs merges input address lists, leave only unique addresses
func mergeAddrs1(addrLists ...[]ma.Multiaddr) (uniqueAddrs []ma.Multiaddr) {
	// calculate an approximate output `uniqueAddrs` length
	var addrCountUpperBound int
	for _, addrList := range addrLists {
		addrCountUpperBound += len(addrList)
	}
	exists := make(map[string]bool, addrCountUpperBound)
	uniqueAddrs = make([]ma.Multiaddr, 0, addrCountUpperBound)
	for _, addrList := range addrLists {
		for _, addr := range addrList {
			k := string(addr.Bytes())
			if exists[k] {
				continue
			}
			exists[k] = true
			uniqueAddrs = append(uniqueAddrs, addr)
		}
	}
	return uniqueAddrs
}

// mergeAddrs merges input address lists, leave only unique addresses
func mergeAddrs2(addrLists ...[]ma.Multiaddr) (uniqueAddrs []ma.Multiaddr) {
	exists := make(map[string]bool)
	for _, addrList := range addrLists {
		for _, addr := range addrList {
			k := string(addr.Bytes())
			if exists[k] {
				continue
			}
			exists[k] = true
			uniqueAddrs = append(uniqueAddrs, addr)
		}
	}
	return uniqueAddrs
}