* 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 <stack>
#include <stdexcept>
namespace simgrid::mc::udpor {
{
}
+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 (!events_.is_valid_configuration()) {
+ 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)
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 valid
- History history(e);
- if (!this->events_.contains(history)) {
+ // 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");
}
}
-std::vector<const UnfoldingEvent*> Configuration::get_topologically_sorted_events() const
+bool Configuration::is_compatible_with(const UnfoldingEvent* e) const
{
- if (events_.empty()) {
- return std::vector<const UnfoldingEvent*>();
- }
+ // 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_));
+}
- std::stack<const UnfoldingEvent*> event_stack;
- std::vector<const UnfoldingEvent*> topological_ordering;
- EventSet unknown_events = events_;
- EventSet temporarily_marked_events;
- EventSet permanently_marked_events;
-
- while (not unknown_events.empty()) {
- EventSet discovered_events;
- event_stack.push(*unknown_events.begin());
-
- while (not event_stack.empty()) {
- const UnfoldingEvent* evt = event_stack.top();
- discovered_events.insert(evt);
-
- if (not temporarily_marked_events.contains(evt)) {
- // If this event hasn't yet been marked, do
- // so now so that if we see it again in a child we can
- // detect a cycle and if we see it again here
- // we can detect that the node is re-processed
- temporarily_marked_events.insert(evt);
-
- EventSet immediate_causes = evt->get_immediate_causes();
- if (!immediate_causes.empty() && immediate_causes.is_subset_of(temporarily_marked_events)) {
- throw std::invalid_argument("Attempted to perform a topological sort on a configuration "
- "whose contents contain a cycle. The configuration (and the graph "
- "connecting all of the events) is an invalid event structure");
- }
- immediate_causes.subtract(discovered_events);
- immediate_causes.subtract(permanently_marked_events);
- const EventSet undiscovered_causes = std::move(immediate_causes);
-
- for (const auto cause : undiscovered_causes) {
- event_stack.push(cause);
- }
- } else {
- unknown_events.remove(evt);
- temporarily_marked_events.remove(evt);
- permanently_marked_events.insert(evt);
-
- // In moving this event to the end of the list,
- // we are saying this events "happens before" other
- // events that are added later.
- topological_ordering.push_back(evt);
-
- // Only now do we remove the event, i.e. once
- // we've processed the same event twice
- event_stack.pop();
- }
- }
+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;
}
- return topological_ordering;
+
+ // 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);
+ });
+}
+
+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
{
- // The implementation exploits the property that
- // a topological sorting S^R of the reverse graph G^R
- // of some graph G is simply the reverse of any
- // topological sorting S of G.
- auto topological_events = get_topologically_sorted_events();
- std::reverse(topological_events.begin(), topological_events.end());
- return topological_events;
+ return this->events_.get_topological_ordering_of_reverse_graph();
}
EventSet Configuration::get_minimally_reproducible_events() const
// 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 = EventSet();
+ EventSet minimally_reproducible_events;
- for (const auto& maximal_set : maximal_subsets_iterator_wrapper(*this)) {
+ 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 {
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(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
+ 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
