code: public static List<InvocationStat> getInvocationStatSnapshots(List<InvocationStat> stats) {
          List<InvocationStat> snapshots = new ArrayList<InvocationStat>(stats.size());
          for (InvocationStat stat : stats) {
              InvocationStat snapshot = stat.snapshot();
              if (snapshot.getInvokeCount() <= 0) {
                  if (stat.getUselessCycle().incrementAndGet() > 6) {
                      // 6 个时间窗口无调用，删除统计
                      InvocationStatFactory.removeInvocationStat(stat);
                      InvocationStatDimension dimension = stat.getDimension();
                      String appName = dimension.getAppName();
                      if (LOGGER.isDebugEnabled(appName)) {
                          LOGGER.debugWithApp(appName, "Remove invocation stat : {}, {} because of useless cycle > 6",
                              dimension.getDimensionKey(), dimension.getProviderInfo());
                      }
                  }
              } else {
                  stat.getUselessCycle().set(0);
                  snapshots.add(snapshot);
              }
          }
          return snapshots;
      }
docs: 对批量Invocation对应的InvocationStat进行一个快照
  
  @param stats Dimensions of invocation statistics
  @return List<InvocationStat>