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.sidecar.metrics;
  
  import java.util.concurrent.atomic.AtomicLong;
  
  import com.codahale.metrics.Gauge;
  import com.codahale.metrics.Metric;
  
  /**
   * {@link DeltaGauge} is a Gauge that tracks a cumulative value, which can be updated by passing delta values. The
   * cumulative value tracked is reset once the gauge is read.
   */
  public class DeltaGauge implements Gauge<Long>, Metric
  {
      private final AtomicLong count;
  
      public DeltaGauge()
      {
          this.count = new AtomicLong(0L);
      }
  
      /**
       * Increments the cumulative value tracked by this {@link DeltaGauge}
       */
      public void increment()
      {
          count.incrementAndGet();
      }
  
      /**
       * Updates cumulative value tracked with delta.
       *
       * @param delta value for updating cumulative count.
       */
      public void update(long delta)
      {
          count.addAndGet(delta);
      }
  
      /**
       * Returns the cumulative value tracked by this gauge and resets it to 0.
       * Note: {@code count} is not expected to overflow
       *
       * @return count value
       */
      @Override
      public Long getValue()
      {
          return count.getAndSet(0L);
      }
  }
  