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/* Copyright (c) 2007-2025. 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 simple example demonstrates the Comm::sento_init() Comm::sento_async() functions,
that can be used to create a direct communication from one host to another without
relying on the mailbox mechanism.
There is not much to say, actually: The _init variant creates the communication and
leaves it unstarted (in case you want to modify this communication before it starts),
while the _async variant creates and start it. In both cases, you need to wait() it.
It is mostly useful when you want to have a centralized simulation of your settings,
with a central actor declaring all communications occurring on your distributed system.
*/
#include <simgrid/s4u.hpp>
namespace sg4 = simgrid::s4u;
XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_comm_host2host, "Messages specific for this s4u example");
static void sender(sg4::Host* h1, sg4::Host* h2, sg4::Host* h3, sg4::Host* h4)
{
XBT_INFO("Send c12 with sendto_async(%s -> %s), and c34 with sendto_init(%s -> %s)", h1->get_cname(), h2->get_cname(),
h3->get_cname(), h4->get_cname());
auto c12 = sg4::Comm::sendto_async(h1, h2, 1.5e7); // Creates and start a direct communication
auto c34 = sg4::Comm::sendto_init(h3, h4); // Creates but do not start another direct communication
c34->set_payload_size(1e7); // Specify the amount of bytes to exchange in this comm
// You can also detach() communications that you never plan to test() or wait().
// Here we create a communication that only slows down the other ones
auto noise = sg4::Comm::sendto_init(h1, h2);
noise->set_payload_size(10000);
noise->detach();
XBT_INFO("After creation, c12 is %s (remaining: %.2e bytes); c34 is %s (remaining: %.2e bytes)",
c12->get_state_str(), c12->get_remaining(), c34->get_state_str(), c34->get_remaining());
sg4::this_actor::sleep_for(1);
XBT_INFO("One sec later, c12 is %s (remaining: %.2e bytes); c34 is %s (remaining: %.2e bytes)",
c12->get_state_str(), c12->get_remaining(), c34->get_state_str(), c34->get_remaining());
c34->start();
XBT_INFO("After c34->start,c12 is %s (remaining: %.2e bytes); c34 is %s (remaining: %.2e bytes)",
c12->get_state_str(), c12->get_remaining(), c34->get_state_str(), c34->get_remaining());
c12->wait();
XBT_INFO("After c12->wait, c12 is %s (remaining: %.2e bytes); c34 is %s (remaining: %.2e bytes)",
c12->get_state_str(), c12->get_remaining(), c34->get_state_str(), c34->get_remaining());
c34->wait();
XBT_INFO("After c34->wait, c12 is %s (remaining: %.2e bytes); c34 is %s (remaining: %.2e bytes)",
c12->get_state_str(), c12->get_remaining(), c34->get_state_str(), c34->get_remaining());
/* As usual, you don't have to explicitly start communications that were just init()ed.
The wait() will start it automatically. */
auto c14 = sg4::Comm::sendto_init(h1, h4);
c14->set_payload_size(100)->wait(); // Chaining 2 operations on this new communication
}
int main(int argc, char* argv[])
{
sg4::Engine e(&argc, argv);
e.load_platform(argv[1]);
e.add_actor("sender", e.host_by_name("Boivin"), sender, e.host_by_name("Tremblay"), e.host_by_name("Jupiter"),
e.host_by_name("Fafard"), e.host_by_name("Ginette"));
e.run();
XBT_INFO("Total simulation time: %.3f", sg4::Engine::get_clock());
return 0;
}
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