/*

  * 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.giraph.metrics;

 import com.yammer.metrics.core.Gauge;

 /**

  * A Gauge that holds a value.

  *

  * @param <T> type of value being held.

  */

 public class ValueGauge<T extends Number> extends Gauge<T> {

   /** value held by this class */

   private T val;

   /**

    * Constructor that registers Gauge in MetricsRegistry.

    *

    * @param registry GiraphMetricsRegistry to use.

    * @param name String name of Gauge.

    */

   public ValueGauge(GiraphMetricsRegistry registry, String name) {

     registry.getGauge(name, this);

   }

   @Override

   public T value() {

     return val;

   }

   /**

    * Get double representation of value held.

    *

    * @return double value

    */

   public double getDouble() {

     return val != null ? val.doubleValue() : 0.0d;

   }

   /**

    * Get long representation of value held.

    *

    * @return long value

    */

   public long getLong() {

     return val != null ? val.longValue() : 0L;

   }

   /**

    * Set value held by this object.

    *

    * @param value value to set.

    * @return this

    */

   public ValueGauge<T> set(T value) {

     this.val = value;

     return this;

   }

 }