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 com.alibaba.jstorm.common.metric;
  
  import backtype.storm.GCState;
  import com.codahale.metrics.Gauge;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * @author JohnFang (xiaojian.fxj@alibaba-inc.com).
   */
  public class FullGcGauge implements Gauge<Double> {
  
      private static final Logger LOG = LoggerFactory.getLogger(FullGcGauge.class);
  
      private double lastFGcNum = 0.0;
  
  
      @Override
      public Double getValue() {
          double newFGcNum = GCState.getOldGenCollectionCount();
          double delta = newFGcNum - lastFGcNum;
          if (delta < 0){
              LOG.warn("new Fgc {} little than old oldFgc {}", newFGcNum, lastFGcNum);
              delta = 0;
          }
          lastFGcNum = newFGcNum;
          return delta;
      }
  }
  