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1   /**
2    * Copyright (c) 2002-2011 "Neo Technology,"
3    * Network Engine for Objects in Lund AB [http://neotechnology.com]
4    *
5    * This file is part of Neo4j.
6    *
7    * Neo4j is free software: you can redistribute it and/or modify
8    * it under the terms of the GNU General Public License as published by
9    * the Free Software Foundation, either version 3 of the License, or
10   * (at your option) any later version.
11   *
12   * This program is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   * GNU General Public License for more details.
16   *
17   * You should have received a copy of the GNU General Public License
18   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
19   */
20  package org.neo4j.server.rrd;
21  
22  import org.rrd4j.core.Sample;
23  
24  import javax.management.MalformedObjectNameException;
25  import java.io.IOException;
26  import java.util.Date;
27  
28  /**
29   * Manages sampling the state of the database and storing the samples in a round
30   * robin database instance.
31   */
32  public class RrdSampler {
33      /**
34       * The current sampling object. This is created when calling #start().
35       */
36      private Sample sample;
37      private Sampleable[] samplables;
38  
39      /**
40       * Keep track of whether to run the update task or not.
41       */
42      protected RrdSampler(Sample sample, Sampleable... samplables) throws MalformedObjectNameException {
43          this.sample = sample;
44          this.samplables = samplables;
45      }
46  
47      /*
48       * This method is called each time we want a snapshot of the current system
49       * state. Data sources to work with are defined in {@link
50       * RrdManager#getRrdDB()}
51       */
52      public Sample updateSample() {
53          try {
54              sample.setTime(new Date().getTime());
55              for (Sampleable samplable : samplables) {
56                  sample.setValue(samplable.getName(), samplable.getValue());
57              }
58  
59              sample.update();
60              return sample;
61          } catch (IOException e) {
62              throw new RuntimeException("IO Error trying to access round robin database path. See nested exception.", e);
63          }
64      }
65  }