redis: use pubsub instead of keyspace events (#1450)

internal/databroker/server.go

@@ -465,7 +465,6 @@ func (srv *Server) newDB(recordType string) (db storage.Backend, err error) {
 		db, err = redis.New(
 			srv.cfg.storageConnectionString,
 			recordType,
-			int64(srv.cfg.deletePermanentlyAfter.Seconds()),
 			redis.WithTLSConfig(tlsConfig),
 		)
 		if err != nil {

pkg/storage/redis/redis.go

@@ -26,34 +26,33 @@ import (
 
 // Name is the storage type name for redis backend.
 const Name = config.StorageRedisName
-const watchAction = "zadd"
 
 var _ storage.Backend = (*DB)(nil)
 
 // DB wraps redis conn to interact with redis server.
 type DB struct {
-	pool                   *redis.Pool
-	deletePermanentlyAfter int64
-	recordType             string
-	lastVersionKey         string
-	versionSet             string
-	deletedSet             string
-	tlsConfig              *tls.Config
-	notifyChMu             sync.Mutex
+	pool                  *redis.Pool
+	recordType            string
+	lastVersionKey        string
+	lastVersionChannelKey string
+	versionSet            string
+	deletedSet            string
+	tlsConfig             *tls.Config
+	notifyChMu            sync.Mutex
 
 	closeOnce sync.Once
 	closed    chan struct{}
 }
 
 // New returns new DB instance.
-func New(rawURL, recordType string, deletePermanentAfter int64, opts ...Option) (*DB, error) {
+func New(rawURL, recordType string, opts ...Option) (*DB, error) {
 	db := &DB{
-		deletePermanentlyAfter: deletePermanentAfter,
-		recordType:             recordType,
-		versionSet:             recordType + "_version_set",
-		deletedSet:             recordType + "_deleted_set",
-		lastVersionKey:         recordType + "_last_version",
-		closed:                 make(chan struct{}),
+		recordType:            recordType,
+		versionSet:            recordType + "_version_set",
+		deletedSet:            recordType + "_deleted_set",
+		lastVersionKey:        recordType + "_last_version",
+		lastVersionChannelKey: recordType + "_last_version_ch",
+		closed:                make(chan struct{}),
 	}
 
 	for _, o := range opts {
@@ -122,6 +121,7 @@ func (db *DB) Put(ctx context.Context, id string, data *anypb.Any) (err error) {
 		{"MULTI": nil},
 		{"HSET": {db.recordType, id, string(b)}},
 		{"ZADD": {db.versionSet, lastVersion, id}},
+		{"PUBLISH": {db.lastVersionChannelKey, lastVersion}},
 	}
 	if err := db.tx(c, cmds); err != nil {
 		return err
@@ -217,6 +217,7 @@ func (db *DB) Delete(ctx context.Context, id string) (err error) {
 		{"HSET": {db.recordType, id, string(b)}},
 		{"SADD": {db.deletedSet, id}},
 		{"ZADD": {db.versionSet, lastVersion, id}},
+		{"PUBLISH": {db.lastVersionChannelKey, lastVersion}},
 	}
 	if err := db.tx(c, cmds); err != nil {
 		return err
@@ -265,7 +266,7 @@ func (db *DB) doNotifyLoop(ctx context.Context, ch chan struct{}) {
 		psc.Conn.Close()
 	}(&psc)
 
-	if err := db.subscribeRedisChannel(&psc); err != nil {
+	if err := psc.Subscribe(db.lastVersionChannelKey); err != nil {
 		log.Error().Err(err).Msg("failed to subscribe to version set channel")
 		return
 	}
@@ -281,9 +282,6 @@ func (db *DB) doNotifyLoop(ctx context.Context, ch chan struct{}) {
 		case redis.Message:
 			log.Debug().Str("action", string(v.Data)).Msg("got redis message")
 			recordOperation(ctx, time.Now(), "sub_received", nil)
-			if string(v.Data) != watchAction {
-				continue
-			}
 
 			select {
 			case <-db.closed:
@@ -315,7 +313,7 @@ func (db *DB) doNotifyLoop(ctx context.Context, ch chan struct{}) {
 			log.Warn().Msg("retry with new connection")
 			_ = psc.Conn.Close()
 			psc.Conn = db.pool.Get()
-			_ = db.subscribeRedisChannel(&psc)
+			_ = psc.Subscribe(db.lastVersionChannelKey)
 		}
 	}
 }
@@ -339,26 +337,11 @@ func (db *DB) watch(ctx context.Context, ch chan struct{}) {
 	}
 }
 
-func (db *DB) subscribeRedisChannel(psc *redis.PubSubConn) error {
-	return psc.PSubscribe("__keyspace*__:" + db.versionSet)
-}
-
 // Watch returns a channel to the caller, when there is a change to the version set,
 // sending message to the channel to notify the caller.
 func (db *DB) Watch(ctx context.Context) <-chan struct{} {
 	ch := make(chan struct{})
-	go func() {
-		c := db.pool.Get()
-		// Setup notifications, we only care about changes to db.version_set.
-		if _, err := c.Do("CONFIG", "SET", "notify-keyspace-events", "Kz"); err != nil {
-			log.Error().Err(err).Msg("failed to setup redis notification")
-			c.Close()
-			return
-		}
-		c.Close()
-		db.watch(ctx, ch)
-	}()
-
+	go db.watch(ctx, ch)
 	return ch
 }
 

pkg/storage/redis/redis_test.go

@@ -73,7 +73,7 @@ func runWithRedisDockerImage(t *testing.T, runOpts *dockertest.RunOptions, withT
 	address := fmt.Sprintf(scheme+"://localhost:%s/0", resource.GetPort("6379/tcp"))
 	if err := pool.Retry(func() error {
 		var err error
-		db, err = New(address, "record_type", int64(time.Hour.Seconds()), WithTLSConfig(tlsConfig(address, t)))
+		db, err = New(address, "record_type", WithTLSConfig(tlsConfig(address, t)))
 		if err != nil {
 			return err
 		}