001 /*
002 * FileContext.java
003 *
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements. See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership. The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License. You may obtain a copy of the License at
011 *
012 * http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 */
020
021 package org.apache.hadoop.metrics.file;
022
023 import java.io.BufferedOutputStream;
024 import java.io.File;
025 import java.io.FileWriter;
026 import java.io.IOException;
027 import java.io.PrintWriter;
028
029 import org.apache.hadoop.classification.InterfaceAudience;
030 import org.apache.hadoop.classification.InterfaceStability;
031 import org.apache.hadoop.metrics.ContextFactory;
032 import org.apache.hadoop.metrics.spi.AbstractMetricsContext;
033 import org.apache.hadoop.metrics.spi.OutputRecord;
034
035 /**
036 * Metrics context for writing metrics to a file.<p/>
037 *
038 * This class is configured by setting ContextFactory attributes which in turn
039 * are usually configured through a properties file. All the attributes are
040 * prefixed by the contextName. For example, the properties file might contain:
041 * <pre>
042 * myContextName.fileName=/tmp/metrics.log
043 * myContextName.period=5
044 * </pre>
045 * @see org.apache.hadoop.metrics2.sink.FileSink for metrics 2.0.
046 */
047 @InterfaceAudience.Public
048 @InterfaceStability.Evolving
049 @Deprecated
050 public class FileContext extends AbstractMetricsContext {
051
052 /* Configuration attribute names */
053 @InterfaceAudience.Private
054 protected static final String FILE_NAME_PROPERTY = "fileName";
055 @InterfaceAudience.Private
056 protected static final String PERIOD_PROPERTY = "period";
057
058 private File file = null; // file for metrics to be written to
059 private PrintWriter writer = null;
060
061 /** Creates a new instance of FileContext */
062 @InterfaceAudience.Private
063 public FileContext() {}
064
065 @InterfaceAudience.Private
066 public void init(String contextName, ContextFactory factory) {
067 super.init(contextName, factory);
068
069 String fileName = getAttribute(FILE_NAME_PROPERTY);
070 if (fileName != null) {
071 file = new File(fileName);
072 }
073
074 parseAndSetPeriod(PERIOD_PROPERTY);
075 }
076
077 /**
078 * Returns the configured file name, or null.
079 */
080 @InterfaceAudience.Private
081 public String getFileName() {
082 if (file == null) {
083 return null;
084 } else {
085 return file.getName();
086 }
087 }
088
089 /**
090 * Starts or restarts monitoring, by opening in append-mode, the
091 * file specified by the <code>fileName</code> attribute,
092 * if specified. Otherwise the data will be written to standard
093 * output.
094 */
095 @InterfaceAudience.Private
096 public void startMonitoring()
097 throws IOException
098 {
099 if (file == null) {
100 writer = new PrintWriter(new BufferedOutputStream(System.out));
101 } else {
102 writer = new PrintWriter(new FileWriter(file, true));
103 }
104 super.startMonitoring();
105 }
106
107 /**
108 * Stops monitoring, closing the file.
109 * @see #close()
110 */
111 @InterfaceAudience.Private
112 public void stopMonitoring() {
113 super.stopMonitoring();
114
115 if (writer != null) {
116 writer.close();
117 writer = null;
118 }
119 }
120
121 /**
122 * Emits a metrics record to a file.
123 */
124 @InterfaceAudience.Private
125 public void emitRecord(String contextName, String recordName, OutputRecord outRec) {
126 writer.print(contextName);
127 writer.print(".");
128 writer.print(recordName);
129 String separator = ": ";
130 for (String tagName : outRec.getTagNames()) {
131 writer.print(separator);
132 separator = ", ";
133 writer.print(tagName);
134 writer.print("=");
135 writer.print(outRec.getTag(tagName));
136 }
137 for (String metricName : outRec.getMetricNames()) {
138 writer.print(separator);
139 separator = ", ";
140 writer.print(metricName);
141 writer.print("=");
142 writer.print(outRec.getMetric(metricName));
143 }
144 writer.println();
145 }
146
147 /**
148 * Flushes the output writer, forcing updates to disk.
149 */
150 @InterfaceAudience.Private
151 public void flush() {
152 writer.flush();
153 }
154 }