group_rooted.cc

/*
//@HEADER
// *****************************************************************************
//
//                               group_rooted.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>

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

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

static void hello_world(HelloMsg* msg) {
  fmt::print("{}: Hello from node {}\n", vt::theContext()->getNode(), msg->from);
}

static void hello_group_handler(HelloMsg* msg) {
  fmt::print("{}: Hello from group {}\n", vt::theContext()->getNode(), msg->from);
}

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) {
    auto msg = vt::makeMessage<HelloMsg>(this_node);
    vt::theMsg()->broadcastMsg<hello_world>(msg);

    using RangeType = vt::group::region::Range;
    auto list = std::make_unique<RangeType>(num_nodes / 2, num_nodes);

    vt::theGroup()->newGroup(std::move(list), [=](vt::GroupType group){
      auto gmsg = vt::makeMessage<HelloMsg>(this_node);
      vt::envelopeSetGroup(gmsg->env, group);
      vt::theMsg()->broadcastMsg<hello_group_handler>(gmsg);
    });
  }

  vt::finalize();

  return 0;
}