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ValueGauge xref
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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.giraph.metrics;
20  
21  import com.yammer.metrics.core.Gauge;
22  
23  /**
24   * A Gauge that holds a value.
25   *
26   * @param <T> type of value being held.
27   */
28  public class ValueGauge<T extends Number> extends Gauge<T> {
29    /** value held by this class */
30    private T val;
31  
32    /**
33     * Constructor that registers Gauge in MetricsRegistry.
34     *
35     * @param registry GiraphMetricsRegistry to use.
36     * @param name String name of Gauge.
37     */
38    public ValueGauge(GiraphMetricsRegistry registry, String name) {
39      registry.getGauge(name, this);
40    }
41  
42    @Override
43    public T value() {
44      return val;
45    }
46  
47    /**
48     * Get double representation of value held.
49     *
50     * @return double value
51     */
52    public double getDouble() {
53      return val != null ? val.doubleValue() : 0.0d;
54    }
55  
56    /**
57     * Get long representation of value held.
58     *
59     * @return long value
60     */
61    public long getLong() {
62      return val != null ? val.longValue() : 0L;
63    }
64  
65    /**
66     * Set value held by this object.
67     *
68     * @param value value to set.
69     * @return this
70     */
71    public ValueGauge<T> set(T value) {
72      this.val = value;
73      return this;
74    }
75  }