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
019package org.apache.hadoop.metrics2.sink;
020
021import java.io.File;
022import java.io.FileWriter;
023import java.io.PrintWriter;
024
025import org.apache.commons.configuration.SubsetConfiguration;
026import org.apache.hadoop.classification.InterfaceAudience;
027import org.apache.hadoop.classification.InterfaceStability;
028import org.apache.hadoop.metrics2.AbstractMetric;
029import org.apache.hadoop.metrics2.MetricsException;
030import org.apache.hadoop.metrics2.MetricsRecord;
031import org.apache.hadoop.metrics2.MetricsSink;
032import org.apache.hadoop.metrics2.MetricsTag;
033
034/**
035 * A metrics sink that writes to a file
036 */
037@InterfaceAudience.Public
038@InterfaceStability.Evolving
039public 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}