fix: reduce Meilisearch load, debounce federation sync (#1012)

* optimize meili trail index

* several fixes

---------

Co-authored-by: Flomp <Flomp@users.noreply.github.com>

db/routes/remote_list.go

@@ -51,8 +51,17 @@ func RemoteListGet(e *core.RequestEvent) error {
 			}
 		} else {
 			updatedAt := record.GetDateTime("updated").Time()
-			if time.Now().UTC().Sub(updatedAt) > 60*time.Minute {
-				go performFullListSync(e.App, ctx, e.Request.URL, record)
+
+			iri := record.GetString("iri")
+			if time.Now().UTC().Sub(updatedAt) > remoteSyncThreshold {
+				if _, alreadySyncing := listSyncing.LoadOrStore(iri, struct{}{}); !alreadySyncing {
+					urlCopy := *e.Request.URL
+					bgCtx := context.WithValue(context.Background(), "actor", ctx.Value("actor"))
+					go func() {
+						defer listSyncing.Delete(iri)
+						performFullListSync(e.App, bgCtx, &urlCopy, record)
+					}()
+				}
 			}
 		}
 	} else {