content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.cassandra.metrics;
  
  import com.google.common.annotations.VisibleForTesting;
  
  import com.codahale.metrics.Meter;
  
  import static org.apache.cassandra.metrics.CassandraMetricsRegistry.Metrics;
  
  public class CacheAccessMetrics
  {
      /**
       * Total number of cache hits
       */
      public final Meter hits;
  
      /**
       * Total number of cache misses
       */
      public final Meter misses;
  
      /**
       * Total number of cache requests
       */
      public final Meter requests;
  
      public final RatioGaugeSet hitRate;
  
      public final RatioGaugeSet missRate;
  
      protected final MetricNameFactory factory;
  
      public CacheAccessMetrics(MetricNameFactory factory)
      {
          this.factory = factory;
  
          this.hits = Metrics.meter(factory.createMetricName("Hits"));
          this.misses = Metrics.meter(factory.createMetricName("Misses"));
          this.requests = Metrics.meter(factory.createMetricName("Requests"));
  
          this.hitRate = new RatioGaugeSet(hits, requests, factory, "%sHitRate");
          this.missRate = new RatioGaugeSet(misses, requests, factory, "%sMissRate");
      }
  
      @VisibleForTesting
      public void reset()
      {
          // No actual reset happens. The Meter counter is put to zero but will not reset the moving averages
          // It rather injects a weird value into them.
          // This method is being only used by CacheMetricsTest and CachingBench so fixing this issue was acknowledged
          // but not considered mandatory to be fixed now (CASSANDRA-16228)
          hits.mark(-hits.getCount());
          misses.mark(-misses.getCount());
          requests.mark(-requests.getCount());
      }
  }
  