1 /* Copyright (c) 2010-2021. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 /* This example shows how to use simgrid::s4u::Mailbox::ready() to check for completed communications.
8 * We have a number of peers which send and receive messages in two phases:
9 * -> sending phase: each one of them sends a number of messages to the others followed
10 * by a single "finalize" message.
11 * -> receiving phase: each one of them receives all the available messages that reached
12 * their corresponding mailbox until it has all the needed "finalize"
13 * messages to know that no more work needs to be done.
15 * To avoid doing a wait() over the ongoing communications, each peer makes use of the
16 * simgrid::s4u::Mailbox::ready() method. If it returns true then a following get() will fetch the
17 * message immediately, if not the peer will sleep for a fixed amount of time before checking again.
21 #include "simgrid/s4u.hpp"
25 namespace sg4 = simgrid::s4u;
27 XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_async_ready, "Messages specific for this s4u example");
29 static void peer(int my_id, int messages_count, size_t payload_size, int peers_count)
31 /* Set myself as the persistent receiver of my mailbox so that messages start flowing to me as soon as they are put
33 sg4::Mailbox* my_mbox = sg4::Mailbox::by_name(std::string("peer-") + std::to_string(my_id));
34 my_mbox->set_receiver(sg4::Actor::self());
36 std::vector<sg4::CommPtr> pending_comms;
38 /* Start dispatching all messages to peers others that myself */
39 for (int i = 0; i < messages_count; i++) {
40 for (int peer_id = 0; peer_id < peers_count; peer_id++) {
41 if (peer_id != my_id) {
42 sg4::Mailbox* mbox = sg4::Mailbox::by_name(std::string("peer-") + std::to_string(peer_id));
43 std::string message = std::string("Message ") + std::to_string(i) + " from peer " + std::to_string(my_id);
44 auto* payload = new std::string(message); // copy the data we send:
45 // 'msgName' is not a stable storage location
46 XBT_INFO("Send '%s' to '%s'", message.c_str(), mbox->get_cname());
47 /* Create a communication representing the ongoing communication */
48 pending_comms.push_back(mbox->put_async(payload, payload_size));
53 /* Start sending messages to let peers know that they should stop */
54 for (int peer_id = 0; peer_id < peers_count; peer_id++) {
55 if (peer_id != my_id) {
56 sg4::Mailbox* mbox = sg4::Mailbox::by_name(std::string("peer-") + std::to_string(peer_id));
57 auto* payload = new std::string("finalize"); // Make a copy of the data we will send
58 pending_comms.push_back(mbox->put_async(payload, payload_size));
59 XBT_INFO("Send 'finalize' to 'peer-%d'", peer_id);
62 XBT_INFO("Done dispatching all messages");
64 /* Retrieve all the messages other peers have been sending to me until I receive all the corresponding "Finalize"
66 long pending_finalize_messages = peers_count - 1;
67 while (pending_finalize_messages > 0) {
68 if (my_mbox->ready()) {
69 double start = sg4::Engine::get_clock();
70 auto received = my_mbox->get_unique<std::string>();
71 double waiting_time = sg4::Engine::get_clock() - start;
74 "Expecting the waiting time to be 0 because the communication was supposedly ready, but got %f instead",
76 XBT_INFO("I got a '%s'.", received->c_str());
77 if (*received == "finalize") {
78 pending_finalize_messages--;
81 XBT_INFO("Nothing ready to consume yet, I better sleep for a while");
82 sg4::this_actor::sleep_for(.01);
86 XBT_INFO("I'm done, just waiting for my peers to receive the messages before exiting");
87 sg4::Comm::wait_all(pending_comms);
89 XBT_INFO("Goodbye now!");
92 int main(int argc, char* argv[])
94 sg4::Engine e(&argc, argv);
95 e.load_platform(argv[1]);
97 sg4::Actor::create("peer", e.host_by_name("Tremblay"), peer, 0, 2, 5e7, 3);
98 sg4::Actor::create("peer", e.host_by_name("Ruby"), peer, 1, 6, 2.5e5, 3);
99 sg4::Actor::create("peer", e.host_by_name("Perl"), peer, 2, 0, 5e7, 3);