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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  package org.apache.hadoop.hbase.metrics;
19  
20  import org.apache.commons.logging.Log;
21  import org.apache.commons.logging.LogFactory;
22  import org.apache.hadoop.metrics.MetricsRecord;
23  import org.apache.hadoop.metrics.util.MetricsRegistry;
24  import org.apache.hadoop.metrics.util.MetricsTimeVaryingRate;
25  import org.apache.hadoop.util.StringUtils;
26  
27  /**
28   * This class extends MetricsTimeVaryingRate to let the metrics
29   * persist past a pushMetric() call
30   */
31  public class PersistentMetricsTimeVaryingRate extends MetricsTimeVaryingRate {
32    protected static final Log LOG =
33      LogFactory.getLog("org.apache.hadoop.hbase.metrics");
34  
35    protected boolean reset = false;
36    protected long lastOper = 0;
37    protected long totalOps = 0;
38  
39    /**
40     * Constructor - create a new metric
41     * @param nam the name of the metrics to be used to publish the metric
42     * @param registry - where the metrics object will be registered
43     * @param description metrics description
44     */
45    public PersistentMetricsTimeVaryingRate(final String nam, 
46        final MetricsRegistry registry, 
47        final String description) {
48      super(nam, registry, description);
49    }
50  
51    /**
52     * Constructor - create a new metric
53     * @param nam the name of the metrics to be used to publish the metric
54     * @param registry - where the metrics object will be registered
55     */
56    public PersistentMetricsTimeVaryingRate(final String nam, 
57        MetricsRegistry registry) {
58      this(nam, registry, NO_DESCRIPTION);
59    }
60  
61    /**
62     * Push updated metrics to the mr.
63     * 
64     * Note this does NOT push to JMX
65     * (JMX gets the info via {@link #getPreviousIntervalAverageTime()} and
66     * {@link #getPreviousIntervalNumOps()}
67     *
68     * @param mr owner of this metric
69     */
70    @Override
71    public synchronized void pushMetric(final MetricsRecord mr) {
72      // this will reset the currentInterval & num_ops += prevInterval()
73      super.pushMetric(mr);
74      // since we're retaining prevInterval(), we don't want to do the incr
75      // instead, we want to set that value because we have absolute ops
76      try {
77        mr.setMetric(getName() + "_num_ops", totalOps);
78      } catch (Exception e) {
79        LOG.info("pushMetric failed for " + getName() + "\n" +
80            StringUtils.stringifyException(e));
81      }
82      if (reset) {
83        // use the previous avg as our starting min/max/avg
84        super.inc(getPreviousIntervalAverageTime());
85        reset = false;
86      } else {
87        // maintain the stats that pushMetric() cleared
88        maintainStats();
89      }
90    }
91    
92    /**
93     * Increment the metrics for numOps operations
94     * @param numOps - number of operations
95     * @param time - time for numOps operations
96     */
97    @Override
98    public synchronized void inc(final int numOps, final long time) {
99      super.inc(numOps, time);
100     totalOps += numOps;
101   }
102   
103   /**
104    * Increment the metrics for numOps operations
105    * @param time - time for numOps operations
106    */
107   @Override
108   public synchronized void inc(final long time) {
109     super.inc(time);
110     ++totalOps;
111   }
112   
113   /**
114    * Rollover to a new interval
115    * NOTE: does not reset numOps.  this is an absolute value
116    */
117   public synchronized void resetMinMaxAvg() {
118     reset = true;
119   }
120 
121   /* MetricsTimeVaryingRate will reset every time pushMetric() is called
122    * This is annoying for long-running stats that might not get a single 
123    * operation in the polling period.  This function ensures that values
124    * for those stat entries don't get reset.
125    */
126   protected void maintainStats() {
127     int curOps = this.getPreviousIntervalNumOps();
128     if (curOps > 0) {
129       long curTime = this.getPreviousIntervalAverageTime();
130       long totalTime = curTime * curOps;
131       if (curTime == 0 || totalTime / curTime == curOps) {
132         super.inc(curOps, totalTime);
133       } else {
134         LOG.info("Stats for " + this.getName() + " overflowed! resetting");
135       }
136     }
137   }
138 }