What is a barrier and how to use it

[gutjuri]

Hello,
I'm struggeling to fully grasp the concept of barriers, since I could not find documentation on it.

Suppose I have a Jiff application and I want to measure the time taken for share distribution, computation and opening.
Would a programme structured like this be able to do this accurately?

// Setup of jiffClient omitted.
// suppose that compute_parties = [1,2,3], input_parties = [4,5,6,7,8] and all_parties = [1,2,3,4,5,6,7,8]
// This is the code ran by a compute party. The input parties perform no computation but only send input shares.

var mean = function (X) {
  // [conversion of X to array of shares omitted] 
  var sum = X[0];
  for (var i = 1; i < X.length; i++) {
    sum = sum.sadd(X[i]);
  }
  return sum.cdiv(X.length);
};

// the computation code
var compute = function () {
  log("starting computation");
  jiffClient.wait_for(all_parties, function () {
    jiffClient.start_barrier();
    var t_start_recv = process.hrtime.bigint();
    log("all input parties ready");
    var X = jiffClient.share(null, null, compute_parties, input_parties);

    jiffClient.end_barrier().then(() => {
      var t_end_recv = process.hrtime.bigint();

      log(
        `received all secret shares in ${
          Number(t_end_recv - t_start_recv) / 1000000
        } ms`
      );
    });


    jiffClient.start_barrier();
    var start_t = process.hrtime.bigint();
    var m1 = mean(X);

    jiffClient.end_barrier().then(() => {
      var end_t = process.hrtime.bigint();
      console.log(`Computed result in ${Number(end_t - start_t) / 1000000} ms`);

        var start_t_open = process.hrtime.bigint();
        jiffClient.open(m1, compute_parties).then((res) => {
          var end_t_open = process.hrtime.bigint();
          console.log("res: ", res.toString());
          console.log(
            `Opened result in ${Number(end_t_open - start_t_open) / 1000000} ms`
          );
          jiffClient.disconnect(true, true);
        });
    });
  });
};

// wait only for the compute parties to preprocess
jiffClient.wait_for(compute_parties, function () {
  log("all compute parties ready");
  // no preprocessing: use server as crypto provider
  log("skipping preprocessing, server is crypto provider");
  compute();
});

log("submitted wait_for callback...");

I'd like to be able to accurately measure the duration of secret sharing, computation and share opening, because I want to compare these numbers among different platforms. Are barriers the right tool for this?