ExactCounterMetric.java 文件源码

/**
 * Constructor to create a new counter metric
 * @param nam         the name to publish this metric under
 * @param registry    where the metrics object will be registered
 * @param description metrics description
 * @param topN        how many 'keys' to publish metrics on 
 */
public ExactCounterMetric(final String nam, final MetricsRegistry registry, 
    final String description, int topN) {
  super(nam, description);

  this.counts = new MapMaker().makeComputingMap(
      new Function<String, Counter>() {
        @Override
        public Counter apply(String input) {
          return new Counter();
        }    
      });

  this.lock = new ReentrantReadWriteLock();
  this.topN = topN;

  if (registry != null) {
    registry.add(nam, this);      
  }
}