all: imp docs, restore behavior

internal/bootstrap/resolver.go

@@ -25,7 +25,7 @@ var _ Resolver = &net.Resolver{}
 const ErrNoResolvers errors.Error = "no resolvers specified"
 
 // ParallelResolver is a slice of resolvers that are queried concurrently.  The
-// first successful non-empty response is returned.
+// first successful response is returned.
 type ParallelResolver []Resolver
 
 // type check
@@ -67,30 +67,28 @@ func (r ParallelResolver) LookupNetIP(
 	return nil, errors.Join(errs...)
 }
 
-// lookupAsync tries to lookup for ip of host with r and sends the result into
-// resCh.  It's inteneded to be used as a goroutine.
-func lookupAsync(
-	ctx context.Context,
-	r Resolver,
-	network,
-	host string,
-	resCh chan<- any,
-) {
+// lookupAsync performs a lookup for ip of host with r and sends the result into
+// resCh.  It's inteneded to be used within a separate goroutine.
+func lookupAsync(ctx context.Context, r Resolver, network string, host string, resCh chan<- any) {
 	defer log.OnPanic("parallel lookup")
 
 	addrs, err := lookup(ctx, r, network, host)
-	if err != nil || len(addrs) == 0 {
+	if err != nil {
 		resCh <- err
 	} else {
 		resCh <- addrs
 	}
 }
 
 // lookup tries to lookup ip of host with r.
+//
+// TODO(e.burkov):  Get rid of this function?  It only wraps the actual lookup
+// with dubious logging.
 func lookup(ctx context.Context, r Resolver, network, host string) (addrs []netip.Addr, err error) {
 	start := time.Now()
 	addrs, err = r.LookupNetIP(ctx, network, host)
 	elapsed := time.Since(start)
+
 	if err != nil {
 		log.Debug("parallel lookup: lookup for %s failed in %s: %s", host, elapsed, err)
 	} else {

upstream/resolver.go

@@ -233,7 +233,8 @@ func (r StaticResolver) LookupNetIP(
 }
 
 // ConsequentResolver is a slice of resolvers that are queried in order until
-// the first successful non-empty response.
+// the first successful non-empty response, as opposed to just successful
+// response requirement in [ParallelResolver].
 type ConsequentResolver []Resolver
 
 // type check