1 | /** |
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2 | * Licensed to the Apache Software Foundation (ASF) under one |
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3 | * or more contributor license agreements. See the NOTICE file |
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4 | * distributed with this work for additional information |
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5 | * regarding copyright ownership. The ASF licenses this file |
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6 | * to you under the Apache License, Version 2.0 (the |
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7 | * "License"); you may not use this file except in compliance |
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8 | * with the License. You may obtain a copy of the License at |
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9 | * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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11 | * |
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12 | * Unless required by applicable law or agreed to in writing, software |
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13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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15 | * See the License for the specific language governing permissions and |
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16 | * limitations under the License. |
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17 | */ |
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18 | package org.apache.hadoop.metrics; |
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19 | |
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20 | import java.net.InetAddress; |
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21 | import java.net.UnknownHostException; |
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22 | |
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23 | import org.apache.commons.logging.Log; |
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24 | import org.apache.commons.logging.LogFactory; |
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25 | |
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26 | /** |
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27 | * Utility class to simplify creation and reporting of hadoop metrics. |
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28 | * |
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29 | * For examples of usage, see NameNodeMetrics. |
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30 | * @see org.apache.hadoop.metrics.MetricsRecord |
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31 | * @see org.apache.hadoop.metrics.MetricsContext |
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32 | * @see org.apache.hadoop.metrics.ContextFactory |
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33 | */ |
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34 | public class MetricsUtil { |
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35 | |
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36 | public static final Log LOG = |
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37 | LogFactory.getLog(MetricsUtil.class); |
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38 | |
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39 | /** |
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40 | * Don't allow creation of a new instance of Metrics |
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41 | */ |
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42 | private MetricsUtil() {} |
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43 | |
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44 | public static MetricsContext getContext(String contextName) { |
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45 | return getContext(contextName, contextName); |
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46 | } |
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47 | |
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48 | /** |
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49 | * Utility method to return the named context. |
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50 | * If the desired context cannot be created for any reason, the exception |
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51 | * is logged, and a null context is returned. |
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52 | */ |
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53 | public static MetricsContext getContext(String refName, String contextName) { |
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54 | MetricsContext metricsContext; |
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55 | try { |
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56 | metricsContext = |
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57 | ContextFactory.getFactory().getContext(refName, contextName); |
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58 | if (!metricsContext.isMonitoring()) { |
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59 | metricsContext.startMonitoring(); |
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60 | } |
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61 | } catch (Exception ex) { |
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62 | LOG.error("Unable to create metrics context " + contextName, ex); |
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63 | metricsContext = ContextFactory.getNullContext(contextName); |
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64 | } |
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65 | return metricsContext; |
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66 | } |
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67 | |
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68 | /** |
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69 | * Utility method to create and return new metrics record instance within the |
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70 | * given context. This record is tagged with the host name. |
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71 | * |
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72 | * @param context the context |
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73 | * @param recordName name of the record |
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74 | * @return newly created metrics record |
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75 | */ |
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76 | public static MetricsRecord createRecord(MetricsContext context, |
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77 | String recordName) |
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78 | { |
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79 | MetricsRecord metricsRecord = context.createRecord(recordName); |
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80 | metricsRecord.setTag("hostName", getHostName()); |
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81 | return metricsRecord; |
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82 | } |
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83 | |
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84 | /** |
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85 | * Returns the host name. If the host name is unobtainable, logs the |
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86 | * exception and returns "unknown". |
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87 | */ |
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88 | private static String getHostName() { |
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89 | String hostName = null; |
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90 | try { |
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91 | hostName = InetAddress.getLocalHost().getHostName(); |
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92 | } |
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93 | catch (UnknownHostException ex) { |
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94 | LOG.info("Unable to obtain hostName", ex); |
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95 | hostName = "unknown"; |
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96 | } |
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97 | return hostName; |
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98 | } |
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99 | |
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100 | } |
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