EventSet exC = prev_exC;
exC.remove(e_cur);
+ // IMPORTANT NOTE: In order to have deterministic results, we need to process
+ // the actors in a deterministic manner so that events are discovered by
+ // UDPOR in a deterministic order. The processing done here always processes
+ // actors in a consistent order since `std::map` is by-default ordered using
+ // `std::less<Key>` (see the return type of `State::get_actors_list()`)
for (const auto& [aid, actor_state] : stateC.get_actors_list()) {
for (const auto& transition : actor_state.get_enabled_transitions()) {
XBT_DEBUG("\t Considering partial extension for %s", transition->to_string().c_str());
"empty before attempting to select an event from it?");
}
+ // UDPOR's exploration is non-deterministic (as is DPOR's)
+ // in the sense that at any given point there may
+ // be multiple paths that can be followed. The correctness and optimality
+ // of the algorithm remains unaffected by the route taken by UDPOR when
+ // given multiple choices; but to ensure that SimGrid itself has deterministic
+ // behavior on all platforms, we always pick events with lower id's
+ // to ensure we explore the unfolding deterministically.
if (A.empty()) {
- return const_cast<UnfoldingEvent*>(*(enC.begin()));
- }
-
- for (const auto& event : A) {
- if (enC.contains(event)) {
- return const_cast<UnfoldingEvent*>(event);
- }
+ const auto min_event = std::min_element(enC.begin(), enC.end(),
+ [](const auto e1, const auto e2) { return e1->get_id() < e2->get_id(); });
+ return const_cast<UnfoldingEvent*>(*min_event);
+ } else {
+ const auto intersection = A.make_intersection(enC);
+ const auto min_event = std::min_element(intersection.begin(), intersection.end(),
+ [](const auto e1, const auto e2) { return e1->get_id() < e2->get_id(); });
+ return const_cast<UnfoldingEvent*>(*min_event);
}
- return nullptr;
}
void UdporChecker::clean_up_explore(const UnfoldingEvent* e, const Configuration& C, const EventSet& D)
