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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 serialize a set of communications going through a link using Link::set_concurrency_limit()
*
* This example is very similar to the other asynchronous communication examples, but messages get serialized by the platform.
* Without this call to Link::set_concurrency_limit(2) in main, all messages would be received at the exact same timestamp since
* they are initiated at the same instant and are of the same size. But with this extra configuration to the link, at most 2
* messages can travel through the link at the same time.
*/
#include "simgrid/s4u.hpp"
#include <string>
namespace sg4 = simgrid::s4u;
XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_async_serialize, "Messages specific for this s4u example");
class Sender {
int messages_count; /* - number of messages */
int msg_size; /* - message size in bytes */
public:
explicit Sender(int size, int count) : messages_count(count), msg_size(size) {}
void operator()() const
{
// sphinx-doc: init-begin (this line helps the doc to build; ignore it)
/* ActivitySet in which we store all ongoing communications */
sg4::ActivitySet pending_comms;
/* Mailbox to use */
sg4::Mailbox* mbox = sg4::Mailbox::by_name("receiver");
// sphinx-doc: init-end
/* Start dispatching all messages to receiver */
for (int i = 0; i < messages_count; i++) {
std::string msg_content = "Message " + std::to_string(i);
// Copy the data we send: the 'msg_content' variable is not a stable storage location.
// It will be destroyed when this actor leaves the loop, ie before the receiver gets it
auto* payload = new std::string(msg_content);
XBT_INFO("Send '%s' to '%s'", msg_content.c_str(), mbox->get_cname());
/* Create a communication representing the ongoing communication, and store it in pending_comms */
sg4::CommPtr comm = mbox->put_async(payload, msg_size);
pending_comms.push(comm);
}
XBT_INFO("Done dispatching all messages");
/* Now that all message exchanges were initiated, wait for their completion in one single call */
pending_comms.wait_all();
// sphinx-doc: put-end
XBT_INFO("Goodbye now!");
}
};
/* Receiver actor expects 1 argument: number of messages to be received */
class Receiver {
sg4::Mailbox* mbox;
int messages_count = 10; /* - number of messages */
public:
explicit Receiver(int count) : messages_count(count) { mbox = sg4::Mailbox::by_name("receiver"); }
void operator()()
{
/* Where we store all incoming msgs */
std::map<sg4::CommPtr, std::shared_ptr<std::string*>> pending_msgs;
sg4::ActivitySet pending_comms;
XBT_INFO("Wait for %d messages asynchronously", messages_count);
for (int i = 0; i < messages_count; i++) {
auto msg = std::make_shared<std::string*>();
auto comm = mbox->get_async<std::string>(msg.get());
pending_comms.push(comm);
pending_msgs.insert({comm, msg});
}
while (not pending_comms.empty()) {
auto completed_one = pending_comms.wait_any();
if (completed_one != nullptr){
auto comm = boost::dynamic_pointer_cast<sg4::Comm>(completed_one);
auto msg = *pending_msgs[comm];
XBT_INFO("I got '%s'.", msg->c_str());
/* cleanup memory and remove from map */
delete msg;
pending_msgs.erase(comm);
}
}
}
};
int main(int argc, char* argv[])
{
sg4::Engine e(&argc, argv);
/* Creates the platform
* ________ __________
* | Sender |===============| Receiver |
* |________| Link1 |__________|
*/
auto* zone = e.get_netzone_root();
auto* sender = zone->add_host("sender", 1)->seal();
auto* receiver = zone->add_host("receiver", 1)->seal();
/* create split-duplex link1 (UP/DOWN), limiting the number of concurrent flows in it for 2 */
const auto* link =
zone->add_split_duplex_link("link1", 10e9)->set_latency(10e-6)->set_concurrency_limit(2)->seal();
/* create routes between nodes */
zone->add_route(sender, receiver, {link});
zone->seal();
/* create actors Sender/Receiver */
e.add_actor("receiver", receiver, Receiver(10));
e.add_actor("sender", sender, Sender(1e6, 10));
e.run();
return 0;
}
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