public static Map<String, UserQuotaState> fetchUserQuotas(final Connection connection,
    final List<Get> gets, Map<TableName, Double> tableMachineQuotaFactors, double factor)
    throws IOException {
    long nowTs = EnvironmentEdgeManager.currentTime();
    Result[] results = doGet(connection, gets);

    Map<String, UserQuotaState> userQuotas = new HashMap<>(results.length);
    for (int i = 0; i < results.length; ++i) {
      byte[] key = gets.get(i).getRow();
      assert isUserRowKey(key);
      String user = getUserFromRowKey(key);

      if (results[i].isEmpty()) {
        userQuotas.put(user, buildDefaultUserQuotaState(connection.getConfiguration(), nowTs));
        continue;
      }

      final UserQuotaState quotaInfo = new UserQuotaState(nowTs);
      userQuotas.put(user, quotaInfo);

      assert Bytes.equals(key, results[i].getRow());

      try {
        parseUserResult(user, results[i], new UserQuotasVisitor() {
          @Override
          public void visitUserQuotas(String userName, String namespace, Quotas quotas) {
            quotas = updateClusterQuotaToMachineQuota(quotas, factor);
            quotaInfo.setQuotas(namespace, quotas);
          }

          @Override
          public void visitUserQuotas(String userName, TableName table, Quotas quotas) {
            quotas = updateClusterQuotaToMachineQuota(quotas,
              tableMachineQuotaFactors.containsKey(table)
                ? tableMachineQuotaFactors.get(table)
                : 1);
            quotaInfo.setQuotas(table, quotas);
          }

          @Override
          public void visitUserQuotas(String userName, Quotas quotas) {
            quotas = updateClusterQuotaToMachineQuota(quotas, factor);
            quotaInfo.setQuotas(quotas);
          }
        });
      } catch (IOException e) {
        LOG.error("Unable to parse user '" + user + "' quotas", e);
        userQuotas.remove(user);
      }
    }
    return userQuotas;
  }
Returns true if the support for quota is enabled
hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/QuotaUtil.java