#include "src/mc/explo/udpor/History.hpp"
#include "src/mc/explo/udpor/maximal_subsets_iterator.hpp"
+#include <numeric>
#include <xbt/asserts.h>
#include <xbt/log.h>
#include <xbt/string.hpp>
// exploration would lead to a so-called
// "sleep-set blocked" trace.
if (enC.is_subset_of(D)) {
- XBT_DEBUG("en(C) is a subset of the sleep set D (size %zu); if we"
+ XBT_DEBUG("en(C) is a subset of the sleep set D (size %zu); if we "
"kept exploring, we'd hit a sleep-set blocked trace",
D.size());
XBT_DEBUG("The current configuration has %zu elements", C.get_events().size());
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());
EventSet extension = ExtensionSetCalculator::partially_extend(C, &unfolding, transition);
exC.form_union(extension);
}
{
EventSet enC;
for (const auto e : exC) {
- if (not e->conflicts_with(C)) {
+ if (C.is_compatible_with(e)) {
enC.insert(e);
}
}
void UdporChecker::clean_up_explore(const UnfoldingEvent* e, const Configuration& C, const EventSet& D)
{
- const EventSet C_union_D = C.get_events().make_union(D);
- const EventSet es_immediate_conflicts = this->unfolding.get_immediate_conflicts_of(e);
- const EventSet Q_CDU = C_union_D.make_union(es_immediate_conflicts.get_local_config());
+ // The "clean-up set" conceptually represents
+ // those events which will no longer be considered
+ // by UDPOR during its exploration. The concept is
+ // introduced to avoid modification during iteration
+ // over the current unfolding to determine who needs to
+ // be removed. Since sets are unordered, it's quite possible
+ // that e.g. two events `e` and `e'` such that `e < e'`
+ // which are determined eligible for removal are removed
+ // in the order `e` and then `e'`. Determining that `e'`
+ // needs to be removed requires that its history be in
+ // tact to e.g. compute the conflicts with the event.
+ //
+ // Thus, we compute the set and remove all of the events
+ // at once in lieu of removing events while iterating over them.
+ // We can hypothesize that processing the events in reverse
+ // topological order would prevent any issues concerning
+ // the order in which are processed
+ EventSet clean_up_set;
+
+ // Q_(C, D, U) = C u D u U (complicated expression)
+ // See page 9 of "Unfolding-based Partial Order Reduction"
+
+ // "C u D" portion
+ const EventSet C_union_D = C.get_events().make_union(D);
+
+ // "U (complicated expression)" portion
+ const EventSet conflict_union = std::accumulate(
+ C_union_D.begin(), C_union_D.end(), EventSet(), [&](const EventSet acc, const UnfoldingEvent* e_prime) {
+ return acc.make_union(unfolding.get_immediate_conflicts_of(e_prime));
+ });
+
+ const EventSet Q_CDU = C_union_D.make_union(conflict_union.get_local_config());
+
+ XBT_DEBUG("Computed Q_CDU as '%s'", Q_CDU.to_string().c_str());
// Move {e} \ Q_CDU from U to G
if (not Q_CDU.contains(e)) {
- XBT_DEBUG("Removing %s from U to G...", e->to_string().c_str());
- this->unfolding.remove(e);
+ XBT_DEBUG("Moving %s from U to G...", e->to_string().c_str());
+ clean_up_set.insert(e);
}
// foreach ê in #ⁱ_U(e)
- for (const auto* e_hat : es_immediate_conflicts) {
+ for (const auto* e_hat : this->unfolding.get_immediate_conflicts_of(e)) {
// Move [ê] \ Q_CDU from U to G
- const EventSet to_remove = e_hat->get_history().subtracting(Q_CDU);
- XBT_DEBUG("Removing {%s} from U to G...", to_remove.to_string().c_str());
- this->unfolding.remove(to_remove);
+ const EventSet to_remove = e_hat->get_local_config().subtracting(Q_CDU);
+ XBT_DEBUG("Moving {%s} from U to G...", to_remove.to_string().c_str());
+ clean_up_set.form_union(to_remove);
}
+
+ // TODO: We still perhaps need to
+ // figure out how to deal with the fact that the previous
+ // extension sets computed for past configurations
+ // contain events that may be removed from `U`. Perhaps
+ // it would be best to keep them around forever (they
+ // are moved to `G` after all and can be discarded at will,
+ // which means they may never have to be removed at all).
+ //
+ // Of course, the benefit of moving them into the set `G`
+ // is that the computation for immediate conflicts becomes
+ // more efficient (we have to search all of `U` for such conflicts,
+ // and there would be no reason to search those events
+ // that UDPOR has marked as no longer being important)
+ // For now, there appear to be no "obvious" issues (although
+ // UDPOR's behavior is often far from obvious...)
+ this->unfolding.remove(clean_up_set);
}
RecordTrace UdporChecker::get_record_trace()
