fix(backend): fixed panic in db service

backend/cmd/db/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"log"
 	"openreplay/backend/internal/config/db"
 	"openreplay/backend/internal/db/datasaver"
@@ -65,7 +66,7 @@ func main() {
 
 		session, err := pg.GetSession(sessionID)
 		if session == nil {
-			if err != nil {
+			if err != nil && !errors.Is(err, cache.NilSessionInCacheError) {
 				log.Printf("Error on session retrieving from cache: %v, SessionID: %v, Message: %v", err, sessionID, msg)
 			}
 			return

backend/pkg/db/cache/session.go

@@ -1,14 +1,19 @@
 package cache
 
 import (
+	"errors"
 	"github.com/jackc/pgx/v4"
 
 	. "openreplay/backend/pkg/db/types"
 )
 
+var NilSessionInCacheError = errors.New("nil session in error")
+
 func (c *PGCache) GetSession(sessionID uint64) (*Session, error) {
 	if s, inCache := c.sessions[sessionID]; inCache {
-		// TODO: review. Might cause bugs in case of multiple PG instances
+		if s == nil {
+			return s, NilSessionInCacheError
+		}
 		return s, nil
 	}
 	s, err := c.Conn.GetSession(sessionID)

backend/pkg/sessions/builder.go

@@ -53,11 +53,11 @@ func (b *builder) handleMessage(message Message, messageID uint64) {
 		return
 	}
 	if timestamp < b.timestamp {
-		log.Printf("skip message with wrong timestamp, sessID: %d, msgID: %d, type: %d", b.sessionID, messageID, message.TypeID())
-		return
+		log.Printf("skip message with wrong timestamp, sessID: %d, msgID: %d, type: %d, msgTS: %d, lastTS: %d", b.sessionID, messageID, message.TypeID(), timestamp, b.timestamp)
+	} else {
+		b.timestamp = timestamp
 	}
 
-	b.timestamp = timestamp
 	b.lastSystemTime = time.Now()
 	for _, p := range b.processors {
 		if rm := p.Handle(message, messageID, b.timestamp); rm != nil {