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 org.apache.cassandra.utils.ReflectionUtils;
  
  /**
   * An alternative to Dropwizard Counter which implements the same kind of API.
   * it has more efficent inc/dec operations and consumes less memory.
   * The counter logic is implemented using {@link ThreadLocalMetrics} functionality.
   *
   * NOTE: Dropwizard Counter is a concrete class and there is no an interface for Dropwizard Counter logic,
   *   so we have to create an alternative hierarchy.
  */
  public class ThreadLocalCounter extends com.codahale.metrics.Counter implements Counter
  {
      private final int metricId;
  
      ThreadLocalCounter(int metricId)
      {
          this.metricId = metricId;
          ThreadLocalMetrics.destroyWhenUnreachable(this, metricId);
          ReflectionUtils.setFieldToNull(this, com.codahale.metrics.Counter.class, "count"); // reduce metrics memory footprint
      }
  
      public ThreadLocalCounter()
      {
          this(ThreadLocalMetrics.allocateMetricId());
      }
  
      @Override
      public void inc()
      {
          ThreadLocalMetrics.add(metricId, 1);
      }
  
      @Override
      public void inc(long n)
      {
          ThreadLocalMetrics.add(metricId, n);
      }
  
      @Override
      public void dec()
      {
          ThreadLocalMetrics.add(metricId, -1);
      }
  
      @Override
      public void dec(long n)
      {
          ThreadLocalMetrics.add(metricId, -n);
      }
  
      @Override
      public long getCount()
      {
          return ThreadLocalMetrics.getCount(metricId);
      }
  }
  