Function sample

src/linux/perf.cpp:258–321

Future<hashmap<string, mesos::PerfStatistics>> sample(
    const set<string>& events,
    const set<string>& cgroups,
    const Duration& duration)
{
  // Is this a no-op?
  if (cgroups.empty()) {
    return hashmap<string, mesos::PerfStatistics>();
  }

  vector<string> argv = {
    "stat",

    // System-wide collection from all CPUs.
    "--all-cpus",

    // Print counts using a CSV-style output to make it easy to import
    // directly into spreadsheets. Columns are separated by the string
    // specified in PERF_DELIMITER.
    "--field-separator", PERF_DELIMITER,

    // Ensure all output goes to stdout.
    "--log-fd", "1"
  };

  // Add all pairwise combinations of event and cgroup.
  foreach (const string& event, events) {
    foreach (const string& cgroup, cgroups) {
      argv.push_back("--event");
      argv.push_back(event);
      argv.push_back("--cgroup");
      argv.push_back(cgroup);
    }
  }

  argv.push_back("--");
  argv.push_back("sleep");
  argv.push_back(stringify(duration.secs()));

  Time start = Clock::now();

  internal::Perf* perf = new internal::Perf(argv);
  Future<string> output = perf->output();
  spawn(perf, true);

  // TODO(pbrett): Don't wait for these forever!
  return output
    .then([start, duration](const string output)
        -> Future<hashmap<string, mesos::PerfStatistics>> {
      Try<hashmap<string, mesos::PerfStatistics>> result =
        perf::parse(output);

      if (result.isError()) {
        return Failure("Failed to parse perf sample: " + result.error());
      }

      foreachvalue (mesos::PerfStatistics& statistics, result.get()) {
        statistics.set_timestamp(start.secs());