ring.cc

/*
//@HEADER
// *****************************************************************************
//
//                                   ring.cc
//                       DARMA/vt => Virtual Transport
//
// Copyright 2019-2021 National Technology & Engineering Solutions of Sandia, LLC
// (NTESS). Under the terms of Contract DE-NA0003525 with NTESS, the U.S.
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#include <vt/transport.h>

static int num_total_rings = 2;
static int num_times = 0;

struct RingMsg : vt::Message {
  vt::NodeType from = vt::uninitialized_destination;

  explicit RingMsg(vt::NodeType const& in_from)
    : from(in_from)
  { }
};

static void sendToNext();

static void ring(RingMsg* msg) {
  vt::NodeType this_node = vt::theContext()->getNode();
  vt::NodeType num_nodes = vt::theContext()->getNumNodes();

  fmt::print("{}: Hello from node {}: num_times={}\n", this_node, msg->from, num_times);

  num_times++;

  if (msg->from != num_nodes - 1 or num_times < num_total_rings) {
    sendToNext();
  }
}

static void sendToNext() {
  vt::NodeType this_node = vt::theContext()->getNode();
  vt::NodeType num_nodes = vt::theContext()->getNumNodes();
  vt::NodeType next_node = this_node + 1 >= num_nodes ? 0 : this_node + 1;

  auto msg = vt::makeMessage<RingMsg>(this_node);
  vt::theMsg()->sendMsg<ring>(next_node, msg);
}

int main(int argc, char** argv) {
  vt::initialize(argc, argv);

  vt::NodeType this_node = vt::theContext()->getNode();
  vt::NodeType num_nodes = vt::theContext()->getNumNodes();

  if (num_nodes == 1) {
    return vt::rerror("requires at least 2 nodes");
  }

  if (this_node == 0) {
    sendToNext();
  }

  vt::finalize();

  return 0;
}