--- /dev/null
+/* Copyright (c) 2010-2021. 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 simulate a non-linear resource sharing for
+ * network links.
+ */
+
+#include <simgrid/s4u.hpp>
+
+namespace sg4 = simgrid::s4u;
+
+XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_network_nonlinear, "Messages specific for this s4u example");
+
+/*************************************************************************************************/
+class Sender {
+ int messages_count; /* - number of messages */
+ int msg_size = 1e6; /* - message size in bytes */
+
+public:
+ explicit Sender(int count) : messages_count(count) {}
+ void operator()() const
+ {
+ // sphinx-doc: init-begin (this line helps the doc to build; ignore it)
+ /* Vector in which we store all ongoing communications */
+ std::vector<sg4::CommPtr> pending_comms;
+
+ /* Make a vector of the mailboxes 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 = std::string("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);
+ unsigned long long size = msg_size * (i + 1);
+ XBT_INFO("Send '%s' to '%s, msg size: %llu'", msg_content.c_str(), mbox->get_cname(), size);
+
+ /* Create a communication representing the ongoing communication, and store it in pending_comms */
+ sg4::CommPtr comm = mbox->put_async(payload, size);
+ pending_comms.push_back(comm);
+ }
+
+ XBT_INFO("Done dispatching all messages");
+
+ /* Now that all message exchanges were initiated, wait for their completion in one single call */
+ sg4::Comm::wait_all(pending_comms);
+ // 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()()
+ {
+ /* Vector in which we store all incoming msgs */
+ std::vector<std::unique_ptr<std::string*>> pending_msgs;
+ std::vector<sg4::CommPtr> pending_comms;
+
+ XBT_INFO("Wait for %d messages asynchronously", messages_count);
+ for (int i = 0; i < messages_count; i++) {
+ pending_msgs.push_back(std::make_unique<std::string*>());
+ pending_comms.emplace_back(mbox->get_async<std::string>(pending_msgs[i].get()));
+ }
+ while (not pending_comms.empty()) {
+ ssize_t index = sg4::Comm::wait_any(pending_comms);
+ std::string* msg = *pending_msgs[index];
+ XBT_INFO("I got '%s'.", msg->c_str());
+ /* cleanup memory and remove from vectors */
+ delete msg;
+ pending_comms.erase(pending_comms.begin() + index);
+ pending_msgs.erase(pending_msgs.begin() + index);
+ }
+ }
+};
+
+/*************************************************************************************************/
+/** @brief Non-linear resource sharing for links
+ *
+ * Note that the callback is called twice in this example:
+ * 1) link UP: with the number of active flows (from 9 to 1)
+ * 2) link DOWN: with 0 active flows. A crosstraffic communication is happing
+ * in the down link, but it's not considered as an active flow.
+ */
+static double link_nonlinear(const sg4::Link* link, double capacity, int n)
+{
+ /* emulates a degradation in link according to the number of flows
+ * you probably want something more complex than that and based on real
+ * experiments */
+ capacity = std::min(capacity, capacity * (1.0 - (n - 1) / 10.0));
+ XBT_INFO("Link %s, %d active communications, new capacity %lf", link->get_cname(), n, capacity);
+ return capacity;
+}
+
+/** @brief Create a simple 2-hosts platform */
+static void load_platform()
+{
+ /* Creates the platform
+ * ________ __________
+ * | Sender |===============| Receiver |
+ * |________| Link1 |__________|
+ */
+ auto* zone = sg4::create_full_zone("Zone1");
+ auto* sender = zone->create_host("sender", 1)->seal();
+ auto* receiver = zone->create_host("receiver", 1)->seal();
+
+ auto* link = zone->create_split_duplex_link("link1", 1e6);
+ /* setting same callbacks (could be different) for link UP/DOWN in split-duplex link */
+ link->get_link_up()->set_sharing_policy(
+ sg4::Link::SharingPolicy::NONLINEAR,
+ std::bind(&link_nonlinear, link->get_link_up(), std::placeholders::_1, std::placeholders::_2));
+ link->get_link_down()->set_sharing_policy(
+ sg4::Link::SharingPolicy::NONLINEAR,
+ std::bind(&link_nonlinear, link->get_link_down(), std::placeholders::_1, std::placeholders::_2));
+ link->set_latency(10e-6)->seal();
+
+ /* create routes between nodes */
+ zone->add_route(sender->get_netpoint(), receiver->get_netpoint(), nullptr, nullptr,
+ {{link, sg4::LinkInRoute::Direction::UP}}, true);
+ zone->seal();
+
+ /* create actors Sender/Receiver */
+ sg4::Actor::create("receiver", receiver, Receiver(9));
+ sg4::Actor::create("sender", sender, Sender(9));
+}
+
+/*************************************************************************************************/
+int main(int argc, char* argv[])
+{
+ sg4::Engine e(&argc, argv);
+
+ /* create platform */
+ load_platform();
+
+ /* runs the simulation */
+ e.run();
+
+ return 0;
+}
