Method respondAsciiQuery

src/tsd/GraphHandler.java:920–975

Respond to a query that wants the output in ASCII. When a query specifies the "ascii" query string parameter, we send the data points back to the client in plain text instead of sending a PNG. @param query The query we're currently serving. @param max_age The maximum time (in seconds) we wanna a

(final HttpQuery query,
                                        final int max_age,
                                        final String basepath,
                                        final Plot plot)

   * @param plot The plot object to generate Gnuplot's input files.
   */
  private static void respondAsciiQuery(final HttpQuery query,
                                        final int max_age,
                                        final String basepath,
                                        final Plot plot) {
    final String path = basepath + ".txt";
    PrintWriter asciifile;
    try {
      asciifile = new PrintWriter(path);
    } catch (IOException e) {
      query.internalError(e);
      return;
    }
    try {
      final StringBuilder tagbuf = new StringBuilder();
      for (final DataPoints dp : plot.getDataPoints()) {
        final String metric = dp.metricName();
        tagbuf.setLength(0);
        for (final Map.Entry<String, String> tag : dp.getTags().entrySet()) {
          tagbuf.append(' ').append(tag.getKey())
            .append('=').append(tag.getValue());
        }
        for (final DataPoint d : dp) {
          if (d.isInteger()) {
            printMetricHeader(asciifile, metric, d.timestamp());
            asciifile.print(d.longValue());
          } else {
            // Doubles require extra processing.
            final double value = d.doubleValue();

            // Value might be NaN or infinity.
            if (Double.isInfinite(value)) {
              // Infinity is invalid.
              throw new IllegalStateException("Infinity:" + value
                + " d=" + d + ", query=" + query);
            } else if (Double.isNaN(value)) {
              // NaNs should be skipped.
              continue;
            }

            printMetricHeader(asciifile, metric, d.timestamp());
            asciifile.print(value);
          }

          asciifile.print(tagbuf);
          asciifile.print('\n');
        }
      }
    } finally {
      asciifile.close();
    }
    try {
      query.sendFile(path, max_age);
    } catch (IOException e) {
      query.internalError(e);
    }
  }

  /**