001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.metrics2.sink;
020    
021    import java.io.BufferedOutputStream;
022    import java.io.File;
023    import java.io.FileWriter;
024    import java.io.PrintWriter;
025    
026    import org.apache.commons.configuration.SubsetConfiguration;
027    import org.apache.hadoop.classification.InterfaceAudience;
028    import org.apache.hadoop.classification.InterfaceStability;
029    import org.apache.hadoop.metrics2.AbstractMetric;
030    import org.apache.hadoop.metrics2.MetricsException;
031    import org.apache.hadoop.metrics2.MetricsRecord;
032    import org.apache.hadoop.metrics2.MetricsSink;
033    import org.apache.hadoop.metrics2.MetricsTag;
034    
035    /**
036     * A metrics sink that writes to a file
037     */
038    @InterfaceAudience.Public
039    @InterfaceStability.Evolving
040    public class FileSink implements MetricsSink {
041      private static final String FILENAME_KEY = "filename";
042      private PrintWriter writer;
043    
044      @Override
045      public void init(SubsetConfiguration conf) {
046        String filename = conf.getString(FILENAME_KEY);
047        try {
048          writer = filename == null
049              ? new PrintWriter(System.out)
050              : new PrintWriter(new FileWriter(new File(filename), true));
051        }
052        catch (Exception e) {
053          throw new MetricsException("Error creating "+ filename, e);
054        }
055      }
056    
057      @Override
058      public void putMetrics(MetricsRecord record) {
059        writer.print(record.timestamp());
060        writer.print(" ");
061        writer.print(record.context());
062        writer.print(".");
063        writer.print(record.name());
064        String separator = ": ";
065        for (MetricsTag tag : record.tags()) {
066          writer.print(separator);
067          separator = ", ";
068          writer.print(tag.name());
069          writer.print("=");
070          writer.print(tag.value());
071        }
072        for (AbstractMetric metric : record.metrics()) {
073          writer.print(separator);
074          separator = ", ";
075          writer.print(metric.name());
076          writer.print("=");
077          writer.print(metric.value());
078        }
079        writer.println();
080      }
081    
082      @Override
083      public void flush() {
084        writer.flush();
085      }
086    }