* under the terms of the license (GNU LGPL) which comes with this package. */
#include "src/mc/explo/udpor/Configuration.hpp"
+#include "src/mc/explo/udpor/Comb.hpp"
+#include "src/mc/explo/udpor/History.hpp"
+#include "src/mc/explo/udpor/Unfolding.hpp"
+#include "src/mc/explo/udpor/UnfoldingEvent.hpp"
+#include "src/mc/explo/udpor/maximal_subsets_iterator.hpp"
+#include "src/xbt/utils/iter/variable_for_loop.hpp"
+#include "xbt/asserts.h"
+
+#include <algorithm>
+#include <stdexcept>
namespace simgrid::mc::udpor {
-void Configuration::add_event(UnfoldingEvent* e)
+Configuration::Configuration(std::initializer_list<const UnfoldingEvent*> events)
+ : Configuration(EventSet(std::move(events)))
+{
+}
+
+Configuration::Configuration(const UnfoldingEvent* e) : Configuration(e->get_local_config())
{
+ // The local configuration should always be a valid configuration. We
+ // check the invariant regardless as a sanity check
+}
+
+Configuration::Configuration(const History& history) : Configuration(history.get_all_events()) {}
+
+Configuration::Configuration(const EventSet& events) : events_(events)
+{
+ if (not events_.is_valid_configuration()) {
+ throw std::invalid_argument("The events do not form a valid configuration");
+ }
+
+ // Since we add in topological order under `<`, we know that the "most-recent"
+ // transition executed by each actor will appear last
+ for (const UnfoldingEvent* e : get_topologically_sorted_events()) {
+ this->latest_event_mapping[e->get_actor()] = e;
+ }
+}
+
+void Configuration::add_event(const UnfoldingEvent* e)
+{
+ if (e == nullptr) {
+ throw std::invalid_argument("Expected a nonnull `UnfoldingEvent*` but received NULL instead");
+ }
+
+ // The event is already a member of the configuration: there's
+ // nothing to do in this case
+ if (this->events_.contains(e)) {
+ return;
+ }
+
+ // Preserves the property that the configuration is conflict-free
+ if (e->conflicts_with_any(this->events_)) {
+ throw std::invalid_argument("The newly added event conflicts with the events already "
+ "contained in the configuration. Adding this event violates "
+ "the property that a configuration is conflict-free");
+ }
+
this->events_.insert(e);
- this->newest_event = e;
+ this->newest_event = e;
+ this->latest_event_mapping[e->get_actor()] = e;
+
+ // Preserves the property that the configuration is causally closed
+ if (auto history = History(e); not this->events_.contains(history)) {
+ throw std::invalid_argument("The newly added event has dependencies "
+ "which are missing from this configuration");
+ }
+}
+
+bool Configuration::is_compatible_with(const UnfoldingEvent* e) const
+{
+ // 1. `e`'s history must be contained in the configuration;
+ // otherwise adding the event would violate the invariant
+ // that a configuration is causally-closed
+ //
+ // 2. `e` itself must not conflict with any events of
+ // the configuration; otherwise adding the event would
+ // violate the invariant that a configuration is conflict-free
+ return contains(e->get_history()) && (not e->conflicts_with_any(this->events_));
+}
+
+bool Configuration::is_compatible_with(const History& history) const
+{
+ // Note: We don't need to check if the `C` will be causally-closed
+ // after adding `history` to it since a) `C` itself is already
+ // causally-closed and b) the history is already causally closed
+ const auto event_diff = history.get_event_diff_with(*this);
+
+ // The events that are contained outside of the configuration
+ // must themselves be free of conflicts.
+ if (not event_diff.is_conflict_free()) {
+ return false;
+ }
+
+ // Now we need only ensure that there are no conflicts
+ // between events of the configuration and the events
+ // that lie outside of the configuration. There is no
+ // need to check if there are conflicts in `C`: we already
+ // know that it's conflict free
+ const auto begin = simgrid::xbt::variable_for_loop<const EventSet>{{event_diff}, {this->events_}};
+ const auto end = simgrid::xbt::variable_for_loop<const EventSet>();
+ return std::none_of(begin, end, [=](const auto event_pair) {
+ const UnfoldingEvent* e1 = *event_pair[0];
+ const UnfoldingEvent* e2 = *event_pair[1];
+ return e1->conflicts_with(e2);
+ });
+}
- // TODO: Re-compute the maxmimal events
+std::vector<const UnfoldingEvent*> Configuration::get_topologically_sorted_events() const
+{
+ return this->events_.get_topological_ordering();
+}
+
+std::vector<const UnfoldingEvent*> Configuration::get_topologically_sorted_events_of_reverse_graph() const
+{
+ return this->events_.get_topological_ordering_of_reverse_graph();
+}
+
+EventSet Configuration::get_minimally_reproducible_events() const
+{
+ // The implementation exploits the following observations:
+ //
+ // To select the smallest reproducible set of events, we want
+ // to pick events that "knock out" a lot of others. Furthermore,
+ // we need to ensure that the events furthest down in the
+ // causality graph are also selected. If you combine these ideas,
+ // you're basically left with traversing the set of maximal
+ // subsets of C! And we have an iterator for that already!
+ //
+ // The next observation is that the moment we don't increase in size
+ // the current maximal set (or decrease the number of events),
+ // we know that the prior set `S` covered the entire history of C and
+ // was maximal. Subsequent sets will miss events earlier in the
+ // topological ordering that appear in `S`
+ EventSet minimally_reproducible_events;
+
+ for (const auto& maximal_set : maximal_subsets_iterator_wrapper<Configuration>(*this)) {
+ if (maximal_set.size() > minimally_reproducible_events.size()) {
+ minimally_reproducible_events = maximal_set;
+ } else {
+ // The moment we see the iterator generate a set of size
+ // that is not monotonically increasing, we can stop:
+ // the set prior was the minimally-reproducible one
+ return minimally_reproducible_events;
+ }
+ }
+ return minimally_reproducible_events;
+}
+
+std::optional<Configuration> Configuration::compute_alternative_to(const EventSet& D, const Unfolding& U) const
+{
+ // A full alternative can be computed by checking against everything in D
+ return compute_k_partial_alternative_to(D, U, D.size());
+}
+
+std::optional<Configuration> Configuration::compute_k_partial_alternative_to(const EventSet& D, const Unfolding& U,
+ size_t k) const
+{
+ // 1. Select k (of |D|, whichever is smaller) arbitrary events e_1, ..., e_k from D
+ const size_t k_alt_size = std::min(k, D.size());
+ const auto D_hat = [&k_alt_size, &D]() {
+ std::vector<const UnfoldingEvent*> D_hat(k_alt_size);
+ // TODO: Since any subset suffices for computing `k`-partial alternatives,
+ // potentially select intelligently here (e.g. perhaps pick events
+ // with transitions that we know are totally independent). This may be
+ // especially important if the enumeration is the slowest part of
+ // UDPOR
+ //
+ // For now, simply pick the first `k` events
+ std::copy_n(D.begin(), k_alt_size, D_hat.begin());
+ return D_hat;
+ }();
+
+ // 2. Build a U-comb <s_1, ..., s_k> of size k, where spike `s_i` contains
+ // all events in conflict with `e_i`
+ //
+ // 3. EXCEPT those events e' for which [e'] + C is not a configuration or
+ // [e'] intersects D
+ //
+ // NOTE: This is an expensive operation as we must traverse the entire unfolding
+ // and compute `C.is_compatible_with(History)` for every event in the structure :/.
+ // A later performance improvement would be to incorporate the work of Nguyen et al.
+ // into SimGrid which associated additonal data structures with each unfolding event.
+ // Since that is a rather complicated addition, we defer it to a later time...
+ Comb comb(k);
+
+ for (const auto* e : U) {
+ for (size_t i = 0; i < k_alt_size; i++) {
+ const UnfoldingEvent* e_i = D_hat[i];
+ if (const auto e_local_config = History(e);
+ e_i->conflicts_with(e) and (not D.intersects(e_local_config)) and is_compatible_with(e_local_config)) {
+ comb[i].push_back(e);
+ }
+ }
+ }
+
+ // 4. Find any such combination <e_1', ..., e_k'> in comb satisfying
+ // ~(e_i' # e_j') for i != j
+ //
+ // NOTE: This is a VERY expensive operation: it enumerates all possible
+ // ways to select an element from each spike. Unfortunately there's no
+ // way around the enumeration, as computing a full alternative in general is
+ // NP-complete (although computing the k-partial alternative is polynomial in
+ // the number of events)
+ const auto map_events = [](const std::vector<Spike::const_iterator>& spikes) {
+ std::vector<const UnfoldingEvent*> events;
+ for (const auto& event_in_spike : spikes) {
+ events.push_back(*event_in_spike);
+ }
+ return EventSet(events);
+ };
+ const auto alternative =
+ std::find_if(comb.combinations_begin(), comb.combinations_end(),
+ [&map_events](const auto& vector) { return map_events(vector).is_conflict_free(); });
+
+ // No such alternative exists
+ if (alternative == comb.combinations_end()) {
+ return std::nullopt;
+ }
+
+ // 5. J := [e_1] + [e_2] + ... + [e_k] is a k-partial alternative
+ return Configuration(History(map_events(*alternative)));
+}
+
+std::optional<const UnfoldingEvent*> Configuration::get_latest_event_of(aid_t aid) const
+{
+ if (const auto latest_event = latest_event_mapping.find(aid); latest_event != latest_event_mapping.end()) {
+ return std::optional<const UnfoldingEvent*>{latest_event->second};
+ }
+ return std::nullopt;
+}
+
+std::optional<const Transition*> Configuration::get_latest_action_of(aid_t aid) const
+{
+ if (const auto latest_event = get_latest_event_of(aid); latest_event.has_value()) {
+ return std::optional<const Transition*>{latest_event.value()->get_transition()};
+ }
+ return std::nullopt;
}
} // namespace simgrid::mc::udpor