X-Git-Url: http://bilbo.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/a123c47d727be0441ca0702d10a3ef63437deca7..fe4080b8dd04acb2074ca72d36e3019acddea455:/src/mc/explo/udpor/Configuration.cpp diff --git a/src/mc/explo/udpor/Configuration.cpp b/src/mc/explo/udpor/Configuration.cpp index 084854de7f..2dd00cb265 100644 --- a/src/mc/explo/udpor/Configuration.cpp +++ b/src/mc/explo/udpor/Configuration.cpp @@ -4,15 +4,244 @@ * 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 +#include namespace simgrid::mc::udpor { -void Configuration::add_event(UnfoldingEvent* e) +Configuration::Configuration(std::initializer_list 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{{event_diff}, {this->events_}}; + const auto end = simgrid::xbt::variable_for_loop(); + 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 Configuration::get_topologically_sorted_events() const +{ + return this->events_.get_topological_ordering(); +} + +std::vector 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(*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::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::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 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 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 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& spikes) { + std::vector 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 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{latest_event->second}; + } + return std::nullopt; +} + +std::optional 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{latest_event.value()->get_transition()}; + } + return std::nullopt; } } // namespace simgrid::mc::udpor