rendezvous interface should expose full registration information

- instead of returning PeerInfos, return Registration objects in discovery
- provide utility functions at module level for peer info discovery

client.go

@@ -22,8 +22,14 @@ const DefaultTTL = 2 * 3600 // 2hr
 type Rendezvous interface {
 	Register(ctx context.Context, ns string, ttl int) error
 	Unregister(ctx context.Context, ns string) error
-	Discover(ctx context.Context, ns string, limit int, cookie []byte) ([]pstore.PeerInfo, []byte, error)
-	DiscoverAsync(ctx context.Context, ns string) (<-chan pstore.PeerInfo, error)
+	Discover(ctx context.Context, ns string, limit int, cookie []byte) ([]Registration, []byte, error)
+	DiscoverAsync(ctx context.Context, ns string) (<-chan Registration, error)
+}
+
+type Registration struct {
+	Peer pstore.PeerInfo
+	Ns   string
+	Ttl  int
 }
 
 func NewRendezvousClient(host host.Host, rp peer.ID) Rendezvous {
@@ -111,7 +117,7 @@ func (cli *client) Unregister(ctx context.Context, ns string) error {
 	return w.WriteMsg(req)
 }
 
-func (cli *client) Discover(ctx context.Context, ns string, limit int, cookie []byte) ([]pstore.PeerInfo, []byte, error) {
+func (cli *client) Discover(ctx context.Context, ns string, limit int, cookie []byte) ([]Registration, []byte, error) {
 	s, err := cli.host.NewStream(ctx, cli.rp, RendezvousProto)
 	if err != nil {
 		return nil, nil, err
@@ -124,7 +130,7 @@ func (cli *client) Discover(ctx context.Context, ns string, limit int, cookie []
 	return discoverQuery(ns, limit, cookie, r, w)
 }
 
-func discoverQuery(ns string, limit int, cookie []byte, r ggio.Reader, w ggio.Writer) ([]pstore.PeerInfo, []byte, error) {
+func discoverQuery(ns string, limit int, cookie []byte, r ggio.Reader, w ggio.Writer) ([]Registration, []byte, error) {
 
 	req := newDiscoverMessage(ns, limit, cookie)
 	err := w.WriteMsg(req)
@@ -148,31 +154,31 @@ func discoverQuery(ns string, limit int, cookie []byte, r ggio.Reader, w ggio.Wr
 	}
 
 	regs := res.GetDiscoverResponse().GetRegistrations()
-	pinfos := make([]pstore.PeerInfo, 0, len(regs))
+	result := make([]Registration, 0, len(regs))
 	for _, reg := range regs {
 		pi, err := pbToPeerInfo(reg.GetPeer())
 		if err != nil {
 			log.Errorf("Invalid peer info: %s", err.Error())
 			continue
 		}
-		pinfos = append(pinfos, pi)
+		result = append(result, Registration{Peer: pi, Ns: reg.GetNs(), Ttl: int(reg.GetTtl())})
 	}
 
-	return pinfos, res.GetDiscoverResponse().GetCookie(), nil
+	return result, res.GetDiscoverResponse().GetCookie(), nil
 }
 
-func (cli *client) DiscoverAsync(ctx context.Context, ns string) (<-chan pstore.PeerInfo, error) {
+func (cli *client) DiscoverAsync(ctx context.Context, ns string) (<-chan Registration, error) {
 	s, err := cli.host.NewStream(ctx, cli.rp, RendezvousProto)
 	if err != nil {
 		return nil, err
 	}
 
-	ch := make(chan pstore.PeerInfo)
+	ch := make(chan Registration)
 	go discoverAsync(ctx, ns, s, ch)
 	return ch, nil
 }
 
-func discoverAsync(ctx context.Context, ns string, s inet.Stream, ch chan pstore.PeerInfo) {
+func discoverAsync(ctx context.Context, ns string, s inet.Stream, ch chan Registration) {
 	defer s.Close()
 	defer close(ch)
 
@@ -183,26 +189,26 @@ func discoverAsync(ctx context.Context, ns string, s inet.Stream, ch chan pstore
 
 	var (
 		cookie []byte
-		pi     []pstore.PeerInfo
+		regs   []Registration
 		err    error
 	)
 
 	for {
-		pi, cookie, err = discoverQuery(ns, batch, cookie, r, w)
+		regs, cookie, err = discoverQuery(ns, batch, cookie, r, w)
 		if err != nil {
 			log.Errorf("Error in discovery [%s]: %s", ns, err.Error())
 			return
 		}
 
-		for _, p := range pi {
+		for _, reg := range regs {
 			select {
-			case ch <- p:
+			case ch <- reg:
 			case <-ctx.Done():
 				return
 			}
 		}
 
-		if len(pi) < batch {
+		if len(regs) < batch {
 			select {
 			case <-time.After(2 * time.Minute):
 			case <-ctx.Done():
@@ -211,3 +217,48 @@ func discoverAsync(ctx context.Context, ns string, s inet.Stream, ch chan pstore
 		}
 	}
 }
+
+func DiscoverPeers(ctx context.Context, rz Rendezvous, ns string, limit int, cookie []byte) ([]pstore.PeerInfo, []byte, error) {
+	regs, cookie, err := rz.Discover(ctx, ns, limit, cookie)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	pinfos := make([]pstore.PeerInfo, len(regs))
+	for i, reg := range regs {
+		pinfos[i] = reg.Peer
+	}
+
+	return pinfos, cookie, nil
+}
+
+func DiscoverPeersAsync(ctx context.Context, rz Rendezvous, ns string) (<-chan pstore.PeerInfo, error) {
+	rch, err := rz.DiscoverAsync(ctx, ns)
+	if err != nil {
+		return nil, err
+	}
+
+	ch := make(chan pstore.PeerInfo)
+	go discoverPeersAsync(ctx, rch, ch)
+	return ch, nil
+}
+
+func discoverPeersAsync(ctx context.Context, rch <-chan Registration, ch chan pstore.PeerInfo) {
+	defer close(ch)
+	for {
+		select {
+		case reg, ok := <-rch:
+			if !ok {
+				return
+			}
+
+			select {
+			case ch <- reg.Peer:
+			case <-ctx.Done():
+				return
+			}
+		case <-ctx.Done():
+			return
+		}
+	}
+}