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.File;
022    import java.io.FileWriter;
023    import java.io.PrintWriter;
024    
025    import org.apache.commons.configuration.SubsetConfiguration;
026    import org.apache.hadoop.classification.InterfaceAudience;
027    import org.apache.hadoop.classification.InterfaceStability;
028    import org.apache.hadoop.metrics2.AbstractMetric;
029    import org.apache.hadoop.metrics2.MetricsException;
030    import org.apache.hadoop.metrics2.MetricsRecord;
031    import org.apache.hadoop.metrics2.MetricsSink;
032    import org.apache.hadoop.metrics2.MetricsTag;
033    
034    /**
035     * A metrics sink that writes to a file
036     */
037    @InterfaceAudience.Public
038    @InterfaceStability.Evolving
039    public class FileSink implements MetricsSink {
040      private static final String FILENAME_KEY = "filename";
041      private PrintWriter writer;
042    
043      @Override
044      public void init(SubsetConfiguration conf) {
045        String filename = conf.getString(FILENAME_KEY);
046        try {
047          writer = filename == null
048              ? new PrintWriter(System.out)
049              : new PrintWriter(new FileWriter(new File(filename), true));
050        }
051        catch (Exception e) {
052          throw new MetricsException("Error creating "+ filename, e);
053        }
054      }
055    
056      @Override
057      public void putMetrics(MetricsRecord record) {
058        writer.print(record.timestamp());
059        writer.print(" ");
060        writer.print(record.context());
061        writer.print(".");
062        writer.print(record.name());
063        String separator = ": ";
064        for (MetricsTag tag : record.tags()) {
065          writer.print(separator);
066          separator = ", ";
067          writer.print(tag.name());
068          writer.print("=");
069          writer.print(tag.value());
070        }
071        for (AbstractMetric metric : record.metrics()) {
072          writer.print(separator);
073          separator = ", ";
074          writer.print(metric.name());
075          writer.print("=");
076          writer.print(metric.value());
077        }
078        writer.println();
079      }
080    
081      @Override
082      public void flush() {
083        writer.flush();
084      }
085    }