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+/* Copyright (c) 2017-2023. 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 demonstrates how to dynamically modify a graph of tasks.
+ *
+ * Assuming we have two instances of a service placed on different hosts,
+ * we want to send data alternatively to thoses instances.
+ *
+ * We consider the following graph:
+ *
+ * comm0 -> exec1 -> comm1
+ * ↳-> exec2 ->comm2
+ *
+ * With exec1 and exec2 on different hosts.
+ */
+
+#include "simgrid/plugins/task.hpp"
+#include "simgrid/s4u.hpp"
+
+XBT_LOG_NEW_DEFAULT_CATEGORY(task_switch_host, "Messages specific for this task example");
+
+int main(int argc, char* argv[])
+{
+ simgrid::s4u::Engine e(&argc, argv);
+ e.load_platform(argv[1]);
+ simgrid::plugins::Task::init();
+
+ // Retrieve hosts
+ auto* tremblay = e.host_by_name("Tremblay");
+ auto* jupiter = e.host_by_name("Jupiter");
+ auto* fafard = e.host_by_name("Fafard");
+
+ // Create tasks
+ auto comm0 = simgrid::plugins::CommTask::init("comm0");
+ comm0->set_bytes(1e7);
+ comm0->set_source(tremblay);
+ auto exec1 = simgrid::plugins::ExecTask::init("exec1", 1e9, jupiter);
+ auto exec2 = simgrid::plugins::ExecTask::init("exec2", 1e9, fafard);
+ auto comm1 = simgrid::plugins::CommTask::init("comm1", 1e7, jupiter, tremblay);
+ auto comm2 = simgrid::plugins::CommTask::init("comm2", 1e7, fafard, tremblay);
+
+ // Create the initial graph by defining dependencies between tasks
+ comm0->add_successor(exec2);
+ exec1->add_successor(comm1);
+ exec2->add_successor(comm2);
+
+ // Add a function to be called when tasks end for log purpose
+ simgrid::plugins::Task::on_end_cb([](const simgrid::plugins::Task* t) {
+ XBT_INFO("Task %s finished (%d)", t->get_name().c_str(), t->get_count());
+ });
+
+ // Add a function to be called before each executions of comm0
+ // This function modifies the graph of tasks by adding or removing
+ // successors to comm0
+ comm0->on_this_start([exec1, exec2, jupiter, fafard](simgrid::plugins::Task* t) {
+ auto* comm0 = dynamic_cast<simgrid::plugins::CommTask*>(t);
+ static int count = 0;
+ if (count % 2 == 0) {
+ comm0->set_destination(jupiter);
+ comm0->add_successor(exec1);
+ comm0->remove_successor(exec2);
+ } else {
+ comm0->set_destination(fafard);
+ comm0->add_successor(exec2);
+ comm0->remove_successor(exec1);
+ }
+ count++;
+ });
+
+ // Enqueue four executions for task comm0
+ comm0->enqueue_execs(4);
+
+ // Start the simulation
+ e.run();
+ return 0;
+}