// syncMapCache implements statCache, backed by a sync.Map
type syncMapCache struct {
	src    StatSource
	lookup sync.Map
}

func (smc *syncMapCache) get(name string) *statSet {
	val, _ := smc.lookup.Load(name)
	if set, ok := val.(*statSet); ok {
		return set
	}

	// create a new statSet, but don't store it if one was added since the last
	// load. This is not ideal since we can't atomically create the set and
	// write it.
	set, _ := smc.lookup.LoadOrStore(name, newStatSet(smc.src, name))
	return set.(*statSet)
}