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/* Copyright (c) 2010-2025. The SimGrid Team. All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
* under the terms of the license (GNU LGPL) which comes with this package. */
/* This example shows how to use simgrid::s4u::Mailbox::ready() to check for completed communications.
*
* We have a number of peers which send and receive messages in two phases:
* -> sending phase: each one of them sends a number of messages to the others followed
* by a single "finalize" message.
* -> receiving phase: each one of them receives all the available messages that reached
* their corresponding mailbox until it has all the needed "finalize"
* messages to know that no more work needs to be done.
*
* To avoid doing a wait() over the ongoing communications, each peer makes use of the
* simgrid::s4u::Mailbox::ready() method. If it returns true then a following get() will fetch the
* message immediately, if not the peer will sleep for a fixed amount of time before checking again.
*
*/
#include "simgrid/s4u.hpp"
#include <cstdlib>
#include <iostream>
#include <string>
namespace sg4 = simgrid::s4u;
XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_async_ready, "Messages specific for this s4u example");
static void peer(int my_id, int messages_count, size_t payload_size, int peers_count)
{
/* Set myself as the persistent receiver of my mailbox so that messages start flowing to me as soon as they are put
* into it */
sg4::Mailbox* my_mbox = sg4::Mailbox::by_name("peer-" + std::to_string(my_id));
my_mbox->set_receiver(sg4::Actor::self());
sg4::ActivitySet pending_comms;
/* Start dispatching all messages to peers others that myself */
for (int i = 0; i < messages_count; i++) {
for (int peer_id = 0; peer_id < peers_count; peer_id++) {
if (peer_id != my_id) {
sg4::Mailbox* mbox = sg4::Mailbox::by_name("peer-" + std::to_string(peer_id));
std::string message = "Message " + std::to_string(i) + " from peer " + std::to_string(my_id);
auto* payload = new std::string(message); // copy the data we send:
// 'message' is not a stable storage location
XBT_INFO("Send '%s' to '%s'", message.c_str(), mbox->get_cname());
/* Create a communication representing the ongoing communication */
pending_comms.push(mbox->put_async(payload, payload_size));
}
}
}
/* Start sending messages to let peers know that they should stop */
for (int peer_id = 0; peer_id < peers_count; peer_id++) {
if (peer_id != my_id) {
sg4::Mailbox* mbox = sg4::Mailbox::by_name("peer-" + std::to_string(peer_id));
auto* payload = new std::string("finalize"); // Make a copy of the data we will send
pending_comms.push(mbox->put_async(payload, payload_size));
XBT_INFO("Send 'finalize' to 'peer-%d'", peer_id);
}
}
XBT_INFO("Done dispatching all messages");
/* Retrieve all the messages other peers have been sending to me until I receive all the corresponding "Finalize"
* messages */
long pending_finalize_messages = peers_count - 1;
while (pending_finalize_messages > 0) {
if (my_mbox->ready()) {
double start = sg4::Engine::get_clock();
auto received = my_mbox->get_unique<std::string>();
double waiting_time = sg4::Engine::get_clock() - start;
xbt_assert(
waiting_time == 0,
"Expecting the waiting time to be 0 because the communication was supposedly ready, but got %f instead",
waiting_time);
XBT_INFO("I got a '%s'.", received->c_str());
if (*received == "finalize") {
pending_finalize_messages--;
}
} else {
XBT_INFO("Nothing ready to consume yet, I better sleep for a while");
sg4::this_actor::sleep_for(.01);
}
}
XBT_INFO("I'm done, just waiting for my peers to receive the messages before exiting");
pending_comms.wait_all();
XBT_INFO("Goodbye now!");
}
int main(int argc, char* argv[])
{
sg4::Engine e(&argc, argv);
e.load_platform(argv[1]);
e.add_actor("peer", e.host_by_name("Tremblay"), peer, 0, 2, 5e7, 3);
e.add_actor("peer", e.host_by_name("Ruby"), peer, 1, 6, 2.5e5, 3);
e.add_actor("peer", e.host_by_name("Perl"), peer, 2, 0, 5e7, 3);
e.run();
return 0;
}
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