code: private void syncMetaFromCache(String topology, TopologyMetricContext tmContext) {
          if (!tmContext.syncMeta()) {
              Map<String, Long> meta = context.getMetricCache().getMeta(topology);
              if (meta != null) {
                  tmContext.getMemMeta().putAll(meta);
              }
              tmContext.setSyncMeta(true);
          }
      }
docs: sync metric meta from rocks db into mem cache on startup