private static void sketch()

in hbase-table-reporter/src/main/java/org/apache/hbase/reporter/TableReporter.java [257:326]
63 lines of code
7 McCabe index (conditional complexity)

  private static void sketch(Configuration configuration, String tableNameAsStr, int limit,
    double fraction, int threads, String isoNow, String encodedRegionName)
    throws IOException, InterruptedException, ExecutionException {
    TableName tableName = TableName.valueOf(tableNameAsStr);
    AccumlatingSketch totalSketches = new AccumlatingSketch();
    long startTime = System.currentTimeMillis();
    int count = 0;
    try (Connection connection = ConnectionFactory.createConnection(configuration)) {
      // Get list of Regions. If 'fraction', get this fraction of all Regions. If
      // encodedRegionName, then set fraction to 1.0 in case the returned set does not
      // include the encodedRegionName we're looking for.
      List<RegionInfo> regions = getRegions(connection, tableName, fraction, encodedRegionName);
      count = regions.size();
      if (count <= 0) {
        throw new HBaseIOException("Empty regions list; fraction " + fraction +
            " too severe or communication problems?");
      } else {
        System.out.println(Instant.now().toString() + " Scanning " + tableNameAsStr +
            " regions=" + count + ", " + regions);
      }
      ExecutorService es =
          Executors.newFixedThreadPool(threads, new ThreadFactory() {
            @Override
            public Thread newThread(Runnable r) {
              Thread t = new Thread(r);
              t.setDaemon(true);
              return t;
            }
          });
      try {
        List<SketchRegion> srs = regions.stream().
                map(ri -> new SketchRegion(connection, tableName, ri, limit)).
                collect(Collectors.toList());
        List<Future<SketchRegion>> futures = new ArrayList<>(srs.size());
        for (SketchRegion sr: srs) {
          // Do submit rather than inokeall; invokeall blocks until all done.
          // This way I get control back after all submitted.
          futures.add(es.submit(sr));
        }
        // Avoid java.util.ConcurrentModificationException
        List<Future<SketchRegion>> removals = new ArrayList<>();
        while (!futures.isEmpty()) {
          for (Future<SketchRegion> future: futures) {
            if (future.isDone()) {
              SketchRegion sr = future.get();
              sr.getSketches().print(Instant.now().toString() +
                  " region=" + sr.getRegionInfo().getRegionNameAsString() + ", duration=" +
                  (Duration.ofMillis(sr.getDuration()).toString()));
              totalSketches.add(sr.getSketches());
              removals.add(future);
            }
          }
          if (!removals.isEmpty()) {
            futures.removeAll(removals);
            removals.clear();
          }
          Thread.sleep(1000);
        }
      } finally {
        es.shutdown();
      }
    }
    Sketches sketches = totalSketches.get();
    String isoDuration = Duration.ofMillis(System.currentTimeMillis() - startTime).toString();
    sketches.print(Instant.now().toString() + " Totals for " + tableNameAsStr +
            " regions=" + count + ", limit=" + limit + ", fraction=" + fraction +
            ", took=" + isoDuration);
    // Dump out the gnuplot files. Saves time generating graphs.
    dumpGnuplotDataFiles(isoNow, sketches, tableNameAsStr, count, isoDuration);
  }