namespace simgrid::mc::udpor {
+maximal_subsets_iterator::maximal_subsets_iterator(const EventSet& events, std::optional<node_filter_function> filter,
+ std::optional<size_t> maximum_subset_size)
+ : maximum_subset_size(maximum_subset_size), current_maximal_set({EventSet()})
+{
+ const auto candidate_ordering = events.get_topological_ordering_of_reverse_graph();
+ if (filter.has_value()) {
+ // Only store the events in the ordering that "matter" to us
+ std::copy_if(std::move_iterator(candidate_ordering.begin()), std::move_iterator(candidate_ordering.end()),
+ std::back_inserter(topological_ordering), filter.value());
+ } else {
+ topological_ordering = std::move(candidate_ordering);
+ }
+}
+
void maximal_subsets_iterator::increment()
{
+ // Termination condition
if (current_maximal_set == std::nullopt) {
return;
}
+ // Stop immediately if there's nothing to search
if (topological_ordering.empty()) {
- // Stop immediately if there's nothing to search
current_maximal_set = std::nullopt;
return;
}
- // The initial step simply allows us to move past the initial empty set correctly
- if (!has_started_searching) {
- has_started_searching = true;
-
- // Otherwise, the very first step is to push the very first
- // element of the topological ordering
- add_element_to_current_maximal_set(*topological_ordering.begin());
- backtrack_points.push(topological_ordering.begin());
- } else {
-
- const auto next_event_ref = continue_traversal_of_maximal_events_tree();
- if (next_event_ref == topological_ordering.end()) {
- current_maximal_set = std::nullopt;
- return;
+ const auto next_event_ref = [&]() {
+ if (!has_started_searching) {
+ has_started_searching = true;
+ return bookkeeper.find_next_candidate_event(topological_ordering.begin(), topological_ordering.end());
+ } else {
+ return continue_traversal_of_maximal_events_tree();
}
+ }();
- // We found some other event `e'` which is not in causally related with anything
- // that currently exists in `current_maximal_set`. Add it in
- add_element_to_current_maximal_set(*next_event_ref);
- backtrack_points.push(next_event_ref);
+ // Out of events: we've finished
+ if (next_event_ref == topological_ordering.end()) {
+ current_maximal_set = std::nullopt;
+ return;
}
+
+ // We found some other event `e'` which is not in causally related with anything
+ // that currently exists in `current_maximal_set`, so add it in
+ add_element_to_current_maximal_set(*next_event_ref);
+ backtrack_points.push(next_event_ref);
}
maximal_subsets_iterator::topological_order_position
return topological_ordering.end();
}
+ xbt_assert(current_maximal_set.has_value(), "Traversal continued even after the termination condition "
+ "was met. Please verify that the termination condition "
+ "of the iterator has not been modified");
+
// 1. First, check if we can keep expanding from the
// maximal set that we currently have
- {
+ if (can_grow_maximal_set()) {
// This is an iterator which points to the latest event `e` that
// was added to what is currently the maximal set
const auto latest_event_ref = backtrack_points.top();
const auto next_event_ref = bookkeeper.find_next_candidate_event(latest_event_ref, topological_ordering.end());
// If we can expand from what we currently have, we can stop
- if (next_event_ref != topological_ordering.end() and should_consider_event(*next_event_ref)) {
+ if (next_event_ref != topological_ordering.end()) {
return next_event_ref;
}
}
// Otherwise, we backtrack: we repeatedly pop off events that we know we
// are finished with
while (not backtrack_points.empty()) {
- // Otherwise, if we can't find another event to add after `e` that
- // we need to consider, we retry after first removing the latest event.
- // This effectively tests "check now with all combinations that3
- // exclude the latest event".
- //
// Note: it is important to remove the element FIRST before performing
- // the second search, as removal may enable dependencies of `e` to be selected
+ // the search, as removal may enable dependencies of `e` to be selected
const auto latest_event_ref = backtrack_points.top();
remove_element_from_current_maximal_set(*latest_event_ref);
backtrack_points.pop();
// to consider those events that could be added AFTER `e` and
// not `e` itself again
const auto next_event_ref = bookkeeper.find_next_candidate_event(latest_event_ref + 1, topological_ordering.end());
-
- // If we finally found some event AFTER removal, we can stop
- if (next_event_ref != topological_ordering.end() and should_consider_event(*next_event_ref)) {
+ if (next_event_ref != topological_ordering.end()) {
return next_event_ref;
}
}
return topological_ordering.end();
}
-bool maximal_subsets_iterator::should_consider_event(const UnfoldingEvent* e) const
-{
- if (filter_function.has_value()) {
- return filter_function.value()(e);
- }
- return true; // If nobody specified a filter, we default to considering the event
-}
-
bool maximal_subsets_iterator::bookkeeper::is_candidate_event(const UnfoldingEvent* e) const
{
if (const auto e_count = event_counts.find(e); e_count != event_counts.end()) {
void maximal_subsets_iterator::add_element_to_current_maximal_set(const UnfoldingEvent* e)
{
+ xbt_assert(can_grow_maximal_set(), "Attempting to add an event to the maximal set "
+ "when doing so would increase the size past the "
+ "prescribed limit. This indicates that detecting when "
+ "to stop growing the maximal set when continuing the "
+ "search is broken");
xbt_assert(current_maximal_set.has_value(), "Attempting to add an event to the maximal set "
"when iteration has completed. This indicates that "
"the termination condition for the iterator is broken");
bookkeeper.mark_removed_from_maximal_set(e);
}
+bool maximal_subsets_iterator::can_grow_maximal_set() const
+{
+ if (not current_maximal_set.has_value()) {
+ return true;
+ }
+ if (maximum_subset_size.has_value()) {
+ return current_maximal_set.value().size() < maximum_subset_size.value();
+ }
+ return true;
+}
+
maximal_subsets_iterator::topological_order_position
maximal_subsets_iterator::bookkeeper::find_next_candidate_event(topological_order_position first,
topological_order_position last) const
void maximal_subsets_iterator::bookkeeper::mark_included_in_maximal_set(const UnfoldingEvent* e)
{
- const auto e_history = e->get_history();
- for (const auto e_hist : e_history) {
+ const auto e_local_config = e->get_local_config();
+ for (const auto e_hist : e_local_config) {
event_counts[e_hist]++;
}
}
void maximal_subsets_iterator::bookkeeper::mark_removed_from_maximal_set(const UnfoldingEvent* e)
{
- const auto e_history = e->get_history();
- for (const auto e_hist : e_history) {
+ const auto e_local_config = e->get_local_config();
+ for (const auto e_hist : e_local_config) {
xbt_assert(event_counts.find(e_hist) != event_counts.end(),
"Invariant Violation: Attempted to remove an event which was not previously added");
xbt_assert(event_counts[e_hist] > 0, "Invariant Violation: An event `e` had a count of `0` at this point "
