public List<Pair<String, String[]>> getAllMetricKeys() {
    List<Pair<String, String[]>> keys = new ArrayList<>(metrics.size());
    metrics.keySet().forEach(k -> keys.add(k.toStringArray()));
    return keys;
  }
Get all metric keys.

@return [[name, [tags...]], ..., [name, [tags...]]]
iotdb-core/metrics/interface/src/main/java/org/apache/iotdb/metrics/AbstractMetricManager.java