expose counter in register interface

db/dbi.go

@@ -13,7 +13,7 @@ type RegistrationRecord struct {
 
 type DB interface {
 	Close() error
-	Register(p peer.ID, ns string, addrs [][]byte, ttl int) error
+	Register(p peer.ID, ns string, addrs [][]byte, ttl int) (uint64, error)
 	Unregister(p peer.ID, ns string) error
 	CountRegistrations(p peer.ID) (int, error)
 	Discover(ns string, cookie []byte, limit int) ([]RegistrationRecord, []byte, error)

db/sqlite/db.go

@@ -33,6 +33,7 @@ type DB struct {
 	selectPeerRegistrationsC   *sql.Stmt
 	selectPeerRegistrationsNSC *sql.Stmt
 	deleteExpiredRegistrations *sql.Stmt
+	getCounter                 *sql.Stmt
 
 	nonce []byte
 
@@ -189,35 +190,51 @@ func (db *DB) prepareStmts() error {
 	}
 	db.deleteExpiredRegistrations = stmt
 
+	stmt, err = db.db.Prepare("SELECT MAX(counter) FROM Registrations")
+	if err != nil {
+		return err
+	}
+	db.getCounter = stmt
+
 	return nil
 }
 
-func (db *DB) Register(p peer.ID, ns string, addrs [][]byte, ttl int) error {
+func (db *DB) Register(p peer.ID, ns string, addrs [][]byte, ttl int) (uint64, error) {
 	pid := p.Pretty()
 	maddrs := packAddrs(addrs)
 	expire := time.Now().Unix() + int64(ttl)
 
 	tx, err := db.db.Begin()
 	if err != nil {
-		return err
+		return 0, err
 	}
 
 	delOld := tx.Stmt(db.deletePeerRegistrationsNs)
 	insertNew := tx.Stmt(db.insertPeerRegistration)
+	getCounter := tx.Stmt(db.getCounter)
 
 	_, err = delOld.Exec(pid, ns)
 	if err != nil {
 		tx.Rollback()
-		return err
+		return 0, err
 	}
 
 	_, err = insertNew.Exec(pid, ns, expire, maddrs)
 	if err != nil {
 		tx.Rollback()
-		return err
+		return 0, err
 	}
 
-	return tx.Commit()
+	var counter uint64
+	row := getCounter.QueryRow()
+	err = row.Scan(&counter)
+	if err != nil {
+		tx.Rollback()
+		return 0, err
+	}
+
+	err = tx.Commit()
+	return counter, err
 }
 
 func (db *DB) CountRegistrations(p peer.ID) (int, error) {

svc.go

@@ -26,7 +26,7 @@ type RendezvousService struct {
 }
 
 type RendezvousSync interface {
-	Register(p peer.ID, ns string, addrs [][]byte, ttl int)
+	Register(p peer.ID, ns string, addrs [][]byte, ttl int, counter uint64)
 	Unregister(p peer.ID, ns string)
 }
 
@@ -160,7 +160,7 @@ func (rz *RendezvousService) handleRegister(p peer.ID, m *pb.Message_Register) *
 	}
 
 	// ok, seems like we can register
-	err = rz.DB.Register(p, ns, maddrs, ttl)
+	counter, err := rz.DB.Register(p, ns, maddrs, ttl)
 	if err != nil {
 		log.Errorf("Error registering: %s", err.Error())
 		return newRegisterResponseError(pb.Message_E_INTERNAL_ERROR, "database error")
@@ -169,7 +169,7 @@ func (rz *RendezvousService) handleRegister(p peer.ID, m *pb.Message_Register) *
 	log.Infof("registered peer %s %s (%d)", p, ns, ttl)
 
 	for _, rzs := range rz.rzs {
-		rzs.Register(p, ns, maddrs, ttl)
+		rzs.Register(p, ns, maddrs, ttl, counter)
 	}
 
 	return newRegisterResponse(ttl)