private void init() {

    if (metricsSource == null) {
      metricsSource = (DatabaseMetricsSource) MetricsServiceImpl.getSource("database");
    }

    if (metricsSource != null) {
      LOG.info("AmbariPerformanceMonitor initialized");

      long interval = Long.parseLong(metricsSource.getConfigurationValue("dumptime", "60000"));
      this.setDumpTime(interval);

      String profileWeight = metricsSource.getConfigurationValue("query.weight", "HEAVY");
      this.setProfileWeight(getWeight(profileWeight));

      isInitialized = true;

    } else {
      LOG.info("AmbariPerformanceMonitor not yet initialized.");
    }
  }
Class to extend the EclipseLink PerformanceMonitor, and dump the collected metrics to the AmbariServer Database Metrics source.
ambari-server/src/main/java/org/apache/ambari/server/metrics/system/impl/AmbariPerformanceMonitor.java