public TimelineMetricCache getTimelineMetricsCache() {
    if (configuration.isMetricsCacheDisabled()) {
      return null;
    }

    if (!isCacheInitialized) {
      initializeCache();
    }
    return timelineMetricsCache;
  }
Return an instance of a Ehcache
@return @TimelineMetricCache or null if caching is disabled through config.
ambari-server/src/main/java/org/apache/ambari/server/controller/metrics/timeline/cache/TimelineMetricCacheProvider.java