sync access to map of pointers

syncmap.go

package syncmap

import (
	"fmt"
	"sync"
)

type S struct {
	name string
}

var m = make(map[string]*S)
var mu sync.Mutex

func set(key string, s *S) {
	mu.Lock()
	fmt.Printf("set (%p) %s\n", s, s)
	m[key] = s
	mu.Unlock()
}

func get(key string) *S {
	mu.Lock()
	defer mu.Unlock()
	return m[key]
}

syncmap_test.go

package syncmap

import (
	"fmt"
	"testing"
)

func TestSync(t *testing.T) {
	go func() {
		set("key", &S{name: "a"})
		s := get("key")
		s.name = "c"
		fmt.Println(get("key"))
	}()

	set("key", &S{name: "b"})
	s := get("key")
	s.name = "d"
	set("key", s)
}