[120] | 1 | /* |
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| 2 | * FileContext.java |
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| 3 | * |
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| 4 | * Licensed to the Apache Software Foundation (ASF) under one |
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| 5 | * or more contributor license agreements. See the NOTICE file |
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| 6 | * distributed with this work for additional information |
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| 7 | * regarding copyright ownership. The ASF licenses this file |
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| 8 | * to you under the Apache License, Version 2.0 (the |
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| 9 | * "License"); you may not use this file except in compliance |
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| 10 | * with the License. You may obtain a copy of the License at |
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| 11 | * |
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| 12 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 13 | * |
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| 14 | * Unless required by applicable law or agreed to in writing, software |
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| 15 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 16 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 17 | * See the License for the specific language governing permissions and |
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| 18 | * limitations under the License. |
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| 19 | */ |
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| 20 | |
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| 21 | package org.apache.hadoop.metrics.file; |
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| 22 | |
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| 23 | import java.io.BufferedOutputStream; |
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| 24 | import java.io.File; |
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| 25 | import java.io.FileWriter; |
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| 26 | import java.io.IOException; |
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| 27 | import java.io.PrintWriter; |
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| 28 | |
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| 29 | import org.apache.hadoop.metrics.ContextFactory; |
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| 30 | import org.apache.hadoop.metrics.MetricsException; |
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| 31 | import org.apache.hadoop.metrics.spi.AbstractMetricsContext; |
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| 32 | import org.apache.hadoop.metrics.spi.OutputRecord; |
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| 33 | |
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| 34 | /** |
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| 35 | * Metrics context for writing metrics to a file.<p/> |
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| 36 | * |
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| 37 | * This class is configured by setting ContextFactory attributes which in turn |
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| 38 | * are usually configured through a properties file. All the attributes are |
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| 39 | * prefixed by the contextName. For example, the properties file might contain: |
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| 40 | * <pre> |
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| 41 | * myContextName.fileName=/tmp/metrics.log |
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| 42 | * myContextName.period=5 |
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| 43 | * </pre> |
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| 44 | */ |
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| 45 | public class FileContext extends AbstractMetricsContext { |
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| 46 | |
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| 47 | /* Configuration attribute names */ |
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| 48 | protected static final String FILE_NAME_PROPERTY = "fileName"; |
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| 49 | protected static final String PERIOD_PROPERTY = "period"; |
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| 50 | |
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| 51 | private File file = null; // file for metrics to be written to |
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| 52 | private PrintWriter writer = null; |
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| 53 | |
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| 54 | /** Creates a new instance of FileContext */ |
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| 55 | public FileContext() {} |
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| 56 | |
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| 57 | public void init(String contextName, ContextFactory factory) { |
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| 58 | super.init(contextName, factory); |
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| 59 | |
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| 60 | String fileName = getAttribute(FILE_NAME_PROPERTY); |
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| 61 | if (fileName != null) { |
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| 62 | file = new File(fileName); |
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| 63 | } |
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| 64 | |
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| 65 | String periodStr = getAttribute(PERIOD_PROPERTY); |
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| 66 | if (periodStr != null) { |
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| 67 | int period = 0; |
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| 68 | try { |
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| 69 | period = Integer.parseInt(periodStr); |
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| 70 | } catch (NumberFormatException nfe) { |
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| 71 | } |
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| 72 | if (period <= 0) { |
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| 73 | throw new MetricsException("Invalid period: " + periodStr); |
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| 74 | } |
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| 75 | setPeriod(period); |
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| 76 | } |
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| 77 | } |
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| 78 | |
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| 79 | /** |
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| 80 | * Returns the configured file name, or null. |
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| 81 | */ |
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| 82 | public String getFileName() { |
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| 83 | if (file == null) { |
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| 84 | return null; |
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| 85 | } else { |
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| 86 | return file.getName(); |
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| 87 | } |
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| 88 | } |
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| 89 | |
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| 90 | /** |
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| 91 | * Starts or restarts monitoring, by opening in append-mode, the |
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| 92 | * file specified by the <code>fileName</code> attribute, |
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| 93 | * if specified. Otherwise the data will be written to standard |
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| 94 | * output. |
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| 95 | */ |
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| 96 | public void startMonitoring() |
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| 97 | throws IOException |
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| 98 | { |
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| 99 | if (file == null) { |
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| 100 | writer = new PrintWriter(new BufferedOutputStream(System.out)); |
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| 101 | } else { |
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| 102 | writer = new PrintWriter(new FileWriter(file, true)); |
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| 103 | } |
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| 104 | super.startMonitoring(); |
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| 105 | } |
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| 106 | |
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| 107 | /** |
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| 108 | * Stops monitoring, closing the file. |
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| 109 | * @see #close() |
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| 110 | */ |
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| 111 | public void stopMonitoring() { |
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| 112 | super.stopMonitoring(); |
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| 113 | |
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| 114 | if (writer != null) { |
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| 115 | writer.close(); |
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| 116 | writer = null; |
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| 117 | } |
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| 118 | } |
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| 119 | |
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| 120 | /** |
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| 121 | * Emits a metrics record to a file. |
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| 122 | */ |
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| 123 | public void emitRecord(String contextName, String recordName, OutputRecord outRec) { |
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| 124 | writer.print(contextName); |
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| 125 | writer.print("."); |
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| 126 | writer.print(recordName); |
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| 127 | String separator = ": "; |
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| 128 | for (String tagName : outRec.getTagNames()) { |
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| 129 | writer.print(separator); |
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| 130 | separator = ", "; |
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| 131 | writer.print(tagName); |
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| 132 | writer.print("="); |
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| 133 | writer.print(outRec.getTag(tagName)); |
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| 134 | } |
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| 135 | for (String metricName : outRec.getMetricNames()) { |
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| 136 | writer.print(separator); |
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| 137 | separator = ", "; |
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| 138 | writer.print(metricName); |
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| 139 | writer.print("="); |
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| 140 | writer.print(outRec.getMetric(metricName)); |
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| 141 | } |
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| 142 | writer.println(); |
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| 143 | } |
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| 144 | |
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| 145 | /** |
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| 146 | * Flushes the output writer, forcing updates to disk. |
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| 147 | */ |
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| 148 | public void flush() { |
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| 149 | writer.flush(); |
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| 150 | } |
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| 151 | } |
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