core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/statistic/OSessionStoragePerformanceStatistic.java
public int getCacheHits(String componentName) {
    if (componentName == null)
      return performanceCountersHolder.getCacheHits();

    final PerformanceCountersHolder cHolder = countersByComponent.get(componentName);
    if (cHolder != null)
      return cHolder.getCacheHits();

    return -1;
  }
public int getCacheHits(String componentName) {
    if (componentName == null)
      return performanceCountersHolder.getCacheHits();

    final PerformanceCountersHolder cHolder = countersByComponent.get(componentName);
    if (cHolder != null)
      return cHolder.getCacheHits();

    return -1;
  }
Percent of cache hits for component name of which is passed as method argument. If null value is passed then value for whole
system will be returned. If data for component with passed in name does not exist then <code>-1</code> will be returned.

@param componentName Name of component data of which should be returned. Name is case sensitive.

@return Percent of cache hits or value which is less than 0, which means that value cannot be calculated.