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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.hadoop.hbase.metrics;
20  
21  /**
22   *   BaseSource for dynamic metrics to announce to Metrics2.
23   *   In hbase-hadoop{1|2}-compat there is an implementation of this interface.
24   */
25  public interface BaseSource {
26  
27    String HBASE_METRICS_SYSTEM_NAME = "HBase";
28  
29    /**
30     * Clear out the metrics and re-prepare the source.
31     */
32    void init();
33  
34    /**
35     * Set a gauge to a specific value.
36     *
37     * @param gaugeName the name of the gauge
38     * @param value     the value
39     */
40    void setGauge(String gaugeName, long value);
41  
42    /**
43     * Add some amount to a gauge.
44     *
45     * @param gaugeName the name of the gauge
46     * @param delta     the amount to change the gauge by.
47     */
48    void incGauge(String gaugeName, long delta);
49  
50    /**
51     * Subtract some amount from a gauge.
52     *
53     * @param gaugeName the name of the gauge
54     * @param delta     the amount to change the gauge by.
55     */
56    void decGauge(String gaugeName, long delta);
57  
58    /**
59     * Remove a metric and no longer announce it.
60     *
61     * @param key Name of the gauge to remove.
62     */
63    void removeMetric(String key);
64  
65    /**
66     * Add some amount to a counter.
67     *
68     * @param counterName the name of the counter
69     * @param delta       the amount to change the counter by.
70     */
71    void incCounters(String counterName, long delta);
72  
73    /**
74     * Add some value to a histogram.
75     *
76     * @param name the name of the histogram
77     * @param value the value to add to the histogram
78     */
79    void updateHistogram(String name, long value);
80  
81  
82    /**
83     * Get the metrics context.  For hadoop metrics2 system this is usually an all lowercased string.
84     * eg. regionserver, master, thriftserver
85     *
86     * @return The string context used to register this source to hadoop's metrics2 system.
87     */
88    String getMetricsContext();
89  
90    /**
91     * Get the description of what this source exposes.
92     */
93    String getMetricsDescription();
94  
95    /**
96     * Get the name of the context in JMX that this source will be exposed through.
97     * This is in ObjectName format. With the default context being Hadoop -> HBase
98     */
99    String getMetricsJmxContext();
100 
101   /**
102    * Get the name of the metrics that are being exported by this source.
103    * Eg. IPC, GC, WAL
104    */
105   String getMetricsName();
106 
107 }