#include "src/mc/explo/UdporChecker.hpp"
#include "src/mc/api/State.hpp"
+#include "src/mc/explo/udpor/Comb.hpp"
+#include "src/mc/explo/udpor/History.hpp"
#include "src/mc/explo/udpor/maximal_subsets_iterator.hpp"
+
#include <xbt/asserts.h>
#include <xbt/log.h>
// are no enabled transitions that can be executed from the
// state reached by `C` (denoted `state(C)`), i.e. by some
// execution of the transitions in C obeying the causality
- // relation. Here, then, we would be in a deadlock.
+ // relation. Here, then, we may be in a deadlock (the other
+ // possibility is that we've finished running everything, and
+ // we wouldn't be in deadlock then)
if (enC.empty()) {
get_remote_app().check_deadlock();
}
"the search, yet no events were actually chosen\n"
"*********************************\n\n");
- // Move the application into stateCe and actually make note of that state
+ // Move the application into stateCe and make note of that state
move_to_stateCe(*stateC, *e);
auto stateCe = record_current_state();
// D <-- D + {e}
D.insert(e);
- // TODO: Determine a value of K to use or don't use it at all
constexpr unsigned K = 10;
- if (auto J = compute_partial_alternative(D, C, K); !J.empty()) {
- J.subtract(C.get_events());
-
+ if (auto J_minus_C = compute_k_partial_alternative(D, C, K); J_minus_C.has_value()) {
// Before searching the "right half", we need to make
// sure the program actually reflects the fact
// that we are searching again from `stateC` (the recursive
restore_program_state_to(*stateC);
// Explore(C, D + {e}, J \ C)
- explore(C, D, std::move(J), std::move(stateC), std::move(prev_exC));
+ explore(C, D, std::move(J_minus_C.value()), std::move(stateC), std::move(prev_exC));
}
// D <-- D - {e}
begin != maximal_subsets_iterator(); ++begin) {
const EventSet& maximal_subset = *begin;
- // TODO: Determine if `a` is enabled here
+ // Determining if `a` is enabled here might not be possible while looking at `a` opaquely
+ // We leave the implementation as-is to ensure that any addition would be simple
+ // if it were ever added
const bool enabled_at_config_k = false;
if (enabled_at_config_k) {
}
}
}
-
return incremental_exC;
}
void UdporChecker::restore_program_state_to(const State& stateC)
{
- // TODO: Perform state regeneration in the same manner as is done
- // in the DFSChecker.cpp
+ get_remote_app().restore_initial_state();
+ // TODO: We need to have the stack of past states available at this
+ // point. Since the method is recursive, we'll need to keep track of
+ // this as we progress
}
std::unique_ptr<State> UdporChecker::record_current_state()
return nullptr;
}
-EventSet UdporChecker::compute_partial_alternative(const EventSet& D, const Configuration& C, const unsigned k) const
+std::vector<const UnfoldingEvent*> UdporChecker::pick_k_partial_alternative_events(const EventSet& D,
+ const unsigned k) const
{
- // TODO: Compute k-partial alternatives using [2]
- return EventSet();
+ const unsigned size = std::min(k, static_cast<unsigned>(D.size()));
+ std::vector<const UnfoldingEvent*> D_hat(size);
+
+ // Potentially select intelligently here (e.g. perhaps pick events
+ // with transitions that we know are totally independent)...
+ //
+ // For now, simply pick the first `k` events (any subset suffices)
+ std::copy_n(D.begin(), size, D_hat.begin());
+ return D_hat;
+}
+
+std::optional<EventSet> UdporChecker::compute_k_partial_alternative(const EventSet& D, const Configuration& C,
+ const unsigned k) const
+{
+ // 1. Select k (of |D|, whichever is smaller) arbitrary events e_1, ..., e_k from D
+ const auto D_hat = pick_k_partial_alternative_events(D, k);
+
+ // 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. Since that is a rather complicated addition, we defer to the addition
+ // for a later time...
+ Comb comb(k);
+
+ for (const auto* e : this->unfolding) {
+ for (unsigned i = 0; i < k; i++) {
+ const auto& e_i = D_hat[i];
+ if (const auto e_local_config = History(e);
+ e_i->conflicts_with(e) and (not D.contains(e_local_config)) and C.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 n)
+ 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(std::move(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
+ // NOTE: This function computes J / C, which is what is actually used in UDPOR
+ return History(map_events(*alternative)).get_event_diff_with(C);
}
void UdporChecker::clean_up_explore(const UnfoldingEvent* e, const Configuration& C, const EventSet& D)
{
- // TODO: Perform clean up here
+ 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());
+
+ // Move {e} \ Q_CDU from U to G
+ if (Q_CDU.contains(e)) {
+ this->unfolding.remove(e);
+ }
+
+ // foreach ê in #ⁱ_U(e)
+ for (const auto* e_hat : es_immediate_conflicts) {
+ // Move [ê] \ Q_CDU from U to G
+ const EventSet to_remove = e_hat->get_history().subtracting(Q_CDU);
+ this->unfolding.remove(to_remove);
+ }
}
RecordTrace UdporChecker::get_record_trace()
