code: public void emitRecord(String contextName, String recordName, OutputRecord outRec) 
      throws IOException
    {
      Calendar currentDate = Calendar.getInstance();
      if (fileName != null) {
        if (currentDate.get(Calendar.DAY_OF_MONTH) != lastRecordDate.get(Calendar.DAY_OF_MONTH)) {
          // rotate to a new context file
          file = new File(getFullFileName(currentDate));
          
          if (writer != null)
            writer.close();
          writer = new PrintWriter(new FileWriter(file, true));
        }
      }
      writer.print(recordDateFormat.format(currentDate.getTime()));
      writer.print(" ");
      writer.print(contextName);
      writer.print(".");
      writer.print(recordName);
      String separator = ": ";
      for (String tagName : outRec.getTagNames()) {
        writer.print(separator);
        separator = ", ";
        writer.print(tagName);
        writer.print("=");
        writer.print(outRec.getTag(tagName));
      }
      for (String metricName : outRec.getMetricNames()) {
        writer.print(separator);
        separator = ", ";
        writer.print(metricName);
        writer.print("=");
        writer.print(outRec.getMetric(metricName));
      }
      writer.println();
      lastRecordDate = currentDate;
    }
docs: Emits a metrics record to a file.