1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
/* Copyright (c) 2017-2025. 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 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/s4u.hpp"
XBT_LOG_NEW_DEFAULT_CATEGORY(task_switch_host, "Messages specific for this task example");
namespace sg4 = simgrid::s4u;
int main(int argc, char* argv[])
{
sg4::Engine e(&argc, argv);
e.load_platform(argv[1]);
// 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 = sg4::CommTask::init("comm0");
comm0->set_bytes(1e7);
comm0->set_source(tremblay);
auto exec1 = sg4::ExecTask::init("exec1", 1e9, jupiter);
auto exec2 = sg4::ExecTask::init("exec2", 1e9, fafard);
auto comm1 = sg4::CommTask::init("comm1", 1e7, jupiter, tremblay);
auto comm2 = sg4::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
sg4::Task::on_completion_cb(
[](const sg4::Task* t) { XBT_INFO("Task %s finished (%d)", t->get_name().c_str(), t->get_count()); });
// Add a function to be called before each firing of comm0
// This function modifies the graph of tasks by adding or removing
// successors to comm0
comm0->on_this_start_cb([&comm0, exec1, exec2, jupiter, fafard](const sg4::Task*) {
static int count = 0;
if (count % 2 == 0)
comm0->set_destination(jupiter);
else
comm0->set_destination(fafard);
count++;
});
comm0->on_this_completion_cb([&comm0, exec1, exec2](const sg4::Task*) {
static int count = 0;
if (count % 2 == 0) {
comm0->add_successor(exec1);
comm0->remove_successor(exec2);
} else {
comm0->add_successor(exec2);
comm0->remove_successor(exec1);
}
count++;
});
// Enqueue four firings for task comm0
comm0->enqueue_firings(4);
// Start the simulation
e.run();
return 0;
}
|
