corner case: all messages deleted but pill counter not cleared

server/topic.go

@@ -1716,21 +1716,27 @@ func (t *Topic) replyGetData(sess *Session, id string, req *MsgGetOpts) error {
 			count = len(messages)
 			for i := count - 1; i >= 0; i-- {
 				mm := messages[i]
-
-				from := types.ParseUid(mm.From)
-				msg := &ServerComMessage{Data: &MsgServerData{
+				sess.queueOut(&ServerComMessage{Data: &MsgServerData{
 					Topic:     t.original(sess.uid),
 					Head:      mm.Head,
 					SeqId:     mm.SeqId,
-					From:      from.UserId(),
+					From:      types.ParseUid(mm.From).UserId(),
 					Timestamp: mm.CreatedAt,
-					Content:   mm.Content}}
-
-				sess.queueOut(msg)
+					Content:   mm.Content}})
 			}
 		}
 	}
 
+	// Request for all available data returned no results while the client expects results
+	// because t.lastID > 0. Generate an empty data message to indicate that all messages
+	// have been deleted.
+	if count == 0 && t.lastID > 0 && (req == nil || (req.BeforeId == 0 && req.SinceId == 0)) {
+		sess.queueOut(&ServerComMessage{Data: &MsgServerData{
+			Topic:     t.original(sess.uid),
+			SeqId:     t.lastID,
+			Timestamp: now}})
+	}
+
 	// Inform the requester that all the data has been served.
 	reply := NoErr(id, t.original(sess.uid), now)
 	reply.Ctrl.Params = map[string]interface{}{"what": "data", "count": count}

tinode-db/gendb.go

@@ -247,6 +247,11 @@ func genDb(reset bool, dbSource string, data *Data) {
 
 	seqIds := map[string]int{}
 
+	// Shuffle messages
+	rand.Shuffle(len(data.Messages), func(i, j int) {
+		data.Messages[i], data.Messages[j] = data.Messages[j], data.Messages[i]
+	})
+
 	now := time.Now().UTC().Add(-time.Minute).Round(time.Millisecond)
 	// Starting 4 days ago.
 	timestamp := now.Add(time.Hour * time.Duration(-24*4))
@@ -275,7 +280,7 @@ func genDb(reset bool, dbSource string, data *Data) {
 
 		seqIds[topic]++
 		seqId := seqIds[topic]
-		str := data.Messages[rand.Intn(len(data.Messages))]
+		str := data.Messages[i%len(data.Messages)]
 		// Max time between messages is 2 hours, averate - 1 hour, time is increasing as seqId increases
 		timestamp = timestamp.Add(time.Microsecond * time.Duration(rand.Intn(increment)))
 		if err = store.Messages.Save(&types.Message{