refactor database interface and implementation into db subpackage

We now have:
- db/dbi.go -- interface, no dependency on any particular database
- db/sqlite/... -- sqlite implementation, depends on dbi
- the rendezvous.NewRendezvousService API has been redefined to NewRendezvouServiceWithDB
  service importer constructs the database of choice
- the rendezvous package has no dependences on db implementation, so clients can import
  without linking SQLite in the binary

client_test.go

@@ -15,7 +15,7 @@ func TestClientRegistrationAndDiscovery(t *testing.T) {
 
 	hosts := getRendezvousHosts(t, ctx, 5)
 
-	svc, err := NewRendezvousService(ctx, hosts[0], ":memory:")
+	svc, err := makeRendezvousService(ctx, hosts[0], ":memory:")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -74,7 +74,7 @@ func TestClientRegistrationAndDiscoveryAsync(t *testing.T) {
 
 	hosts := getRendezvousHosts(t, ctx, 5)
 
-	svc, err := NewRendezvousService(ctx, hosts[0], ":memory:")
+	svc, err := makeRendezvousService(ctx, hosts[0], ":memory:")
 	if err != nil {
 		t.Fatal(err)
 	}

db/dbi.go

@@ -0,0 +1,21 @@
+package dbi
+
+import (
+	peer "github.com/libp2p/go-libp2p-peer"
+)
+
+type RegistrationRecord struct {
+	Id    peer.ID
+	Addrs [][]byte
+	Ns    string
+	Ttl   int
+}
+
+type DB interface {
+	Close() error
+	Register(p peer.ID, ns string, addrs [][]byte, ttl int) error
+	Unregister(p peer.ID, ns string) error
+	CountRegistrations(p peer.ID) (int, error)
+	Discover(ns string, cookie []byte, limit int) ([]RegistrationRecord, []byte, error)
+	ValidCookie(ns string, cookie []byte) bool
+}

db/sqlite/db.go

@@ -1,4 +1,4 @@
-package rendezvous
+package db
 
 import (
 	"bytes"
@@ -11,11 +11,16 @@ import (
 	"os"
 	"time"
 
+	dbi "github.com/libp2p/go-libp2p-rendezvous/db"
+
 	_ "github.com/mattn/go-sqlite3"
 
+	logging "github.com/ipfs/go-log"
 	peer "github.com/libp2p/go-libp2p-peer"
 )
 
+var log = logging.Logger("rendezvous/db")
+
 type DB struct {
 	db *sql.DB
 
@@ -240,7 +245,7 @@ func (db *DB) Unregister(p peer.ID, ns string) error {
 	return err
 }
 
-func (db *DB) Discover(ns string, cookie []byte, limit int) ([]RegistrationRecord, []byte, error) {
+func (db *DB) Discover(ns string, cookie []byte, limit int) ([]dbi.RegistrationRecord, []byte, error) {
 	now := time.Now().Unix()
 
 	var (
@@ -278,10 +283,10 @@ func (db *DB) Discover(ns string, cookie []byte, limit int) ([]RegistrationRecor
 
 	defer rows.Close()
 
-	regs := make([]RegistrationRecord, 0, limit)
+	regs := make([]dbi.RegistrationRecord, 0, limit)
 	for rows.Next() {
 		var (
-			reg    RegistrationRecord
+			reg    dbi.RegistrationRecord
 			rid    string
 			rns    string
 			expire int64

db/sqlite/db_test.go

@@ -1,4 +1,4 @@
-package rendezvous
+package db
 
 import (
 	"bytes"

proto.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 
+	db "github.com/libp2p/go-libp2p-rendezvous/db"
 	pb "github.com/libp2p/go-libp2p-rendezvous/pb"
 
 	logging "github.com/ipfs/go-log"
@@ -21,13 +22,6 @@ const (
 	DefaultTTL = 2 * 3600 // 2hr
 )
 
-type RegistrationRecord struct {
-	Id    peer.ID
-	Addrs [][]byte
-	Ns    string
-	Ttl   int
-}
-
 type RendezvousError struct {
 	Status pb.Message_ResponseStatus
 	Text   string
@@ -120,7 +114,7 @@ func newRegisterResponseError(status pb.Message_ResponseStatus, text string) *pb
 	return r
 }
 
-func newDiscoverResponse(regs []RegistrationRecord, cookie []byte) *pb.Message_DiscoverResponse {
+func newDiscoverResponse(regs []db.RegistrationRecord, cookie []byte) *pb.Message_DiscoverResponse {
 	r := new(pb.Message_DiscoverResponse)
 	r.Status = pb.Message_OK.Enum()
 

svc.go

@@ -1,9 +1,9 @@
 package rendezvous
 
 import (
-	"context"
 	"fmt"
 
+	db "github.com/libp2p/go-libp2p-rendezvous/db"
 	pb "github.com/libp2p/go-libp2p-rendezvous/pb"
 
 	ggio "github.com/gogo/protobuf/io"
@@ -21,7 +21,7 @@ const (
 )
 
 type RendezvousService struct {
-	DB  *DB
+	DB  db.DB
 	rzs []RendezvousSync
 }
 
@@ -30,17 +30,7 @@ type RendezvousSync interface {
 	Unregister(p peer.ID, ns string)
 }
 
-func NewRendezvousService(ctx context.Context, host host.Host, dbpath string, rzs ...RendezvousSync) (*RendezvousService, error) {
+func NewRendezvousService(host host.Host, db db.DB, rzs ...RendezvousSync) *RendezvousService {
-	db, err := OpenDB(ctx, dbpath)
-	if err != nil {
-		return nil, err
-	}
-
-	rz := NewRendezvousServiceWithDB(host, db, rzs...)
-	return rz, nil
-}
-
-func NewRendezvousServiceWithDB(host host.Host, db *DB, rzs ...RendezvousSync) *RendezvousService {
 	rz := &RendezvousService{DB: db, rzs: rzs}
 	host.SetStreamHandler(RendezvousProto, rz.handleStream)
 	return rz

svc_test.go

@@ -6,6 +6,7 @@ import (
 	"math/rand"
 	"testing"
 
+	db "github.com/libp2p/go-libp2p-rendezvous/db/sqlite"
 	pb "github.com/libp2p/go-libp2p-rendezvous/pb"
 
 	ggio "github.com/gogo/protobuf/io"
@@ -53,13 +54,22 @@ func getRendezvousClients(t *testing.T, hosts []host.Host) []Rendezvous {
 	return clients
 }
 
+func makeRendezvousService(ctx context.Context, host host.Host, path string) (*RendezvousService, error) {
+	dbi, err := db.OpenDB(ctx, path)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewRendezvousService(host, dbi), nil
+}
+
 func TestSVCRegistrationAndDiscovery(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
 	hosts := getRendezvousHosts(t, ctx, 5)
 
-	svc, err := NewRendezvousService(ctx, hosts[0], ":memory:")
+	svc, err := makeRendezvousService(ctx, hosts[0], ":memory:")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -169,7 +179,7 @@ func TestSVCErrors(t *testing.T) {
 
 	hosts := getRendezvousHosts(t, ctx, 2)
 
-	svc, err := NewRendezvousService(ctx, hosts[0], ":memory:")
+	svc, err := makeRendezvousService(ctx, hosts[0], ":memory:")
 	if err != nil {
 		t.Fatal(err)
 	}