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.Closeable;
022    import java.io.File;
023    import java.io.FileWriter;
024    import java.io.IOException;
025    import java.io.PrintWriter;
026    
027    import org.apache.commons.configuration.SubsetConfiguration;
028    import org.apache.hadoop.classification.InterfaceAudience;
029    import org.apache.hadoop.classification.InterfaceStability;
030    import org.apache.hadoop.metrics2.AbstractMetric;
031    import org.apache.hadoop.metrics2.MetricsException;
032    import org.apache.hadoop.metrics2.MetricsRecord;
033    import org.apache.hadoop.metrics2.MetricsSink;
034    import org.apache.hadoop.metrics2.MetricsTag;
035    
036    /**
037     * A metrics sink that writes to a file
038     */
039    @InterfaceAudience.Public
040    @InterfaceStability.Evolving
041    public class FileSink implements MetricsSink, Closeable {
042      private static final String FILENAME_KEY = "filename";
043      private PrintWriter writer;
044    
045      @Override
046      public void init(SubsetConfiguration conf) {
047        String filename = conf.getString(FILENAME_KEY);
048        try {
049          writer = filename == null
050              ? new PrintWriter(System.out)
051              : new PrintWriter(new FileWriter(new File(filename), true));
052        }
053        catch (Exception e) {
054          throw new MetricsException("Error creating "+ filename, e);
055        }
056      }
057    
058      @Override
059      public void putMetrics(MetricsRecord record) {
060        writer.print(record.timestamp());
061        writer.print(" ");
062        writer.print(record.context());
063        writer.print(".");
064        writer.print(record.name());
065        String separator = ": ";
066        for (MetricsTag tag : record.tags()) {
067          writer.print(separator);
068          separator = ", ";
069          writer.print(tag.name());
070          writer.print("=");
071          writer.print(tag.value());
072        }
073        for (AbstractMetric metric : record.metrics()) {
074          writer.print(separator);
075          separator = ", ";
076          writer.print(metric.name());
077          writer.print("=");
078          writer.print(metric.value());
079        }
080        writer.println();
081      }
082    
083      @Override
084      public void flush() {
085        writer.flush();
086      }
087    
088      @Override
089      public void close() throws IOException {
090        writer.close();
091      }
092    }