#include "src/mc/explo/udpor/EventSet.hpp"
#include "src/mc/explo/udpor/udpor_forward.hpp"
+#include <optional>
+#include <string>
+#include <unordered_map>
+
namespace simgrid::mc::udpor {
class Configuration {
Configuration& operator=(Configuration const&) = default;
Configuration(Configuration&&) = default;
+ explicit Configuration(const UnfoldingEvent* event);
+ explicit Configuration(const EventSet& events);
+ explicit Configuration(const History& history);
+ explicit Configuration(std::initializer_list<const UnfoldingEvent*> events);
+
auto begin() const { return this->events_.begin(); }
auto end() const { return this->events_.end(); }
+ auto cbegin() const { return this->events_.cbegin(); }
+ auto cend() const { return this->events_.cend(); }
- bool contains(UnfoldingEvent* e) const { return this->events_.contains(e); }
+ bool contains(const UnfoldingEvent* e) const { return this->events_.contains(e); }
+ bool contains(const EventSet& events) const { return events.is_subset_of(this->events_); }
const EventSet& get_events() const { return this->events_; }
- const EventSet& get_maximal_events() const { return this->max_events_; }
- UnfoldingEvent* get_latest_event() const { return this->newest_event; }
+ const UnfoldingEvent* get_latest_event() const { return this->newest_event; }
+ std::string to_string() const { return this->events_.to_string(); }
+
+ /**
+ * @brief Insert a new event into the configuration
+ *
+ * When the newly added event is inserted into the configuration,
+ * an assertion is made to ensure that the configuration remains
+ * valid, i.e. that the newly added event's dependencies are contained
+ * within the configuration.
+ *
+ * @param e the event to add to the configuration. If the event is
+ * already a part of the configuration, calling this method has no
+ * effect.
+ *
+ * @throws an invalid argument exception is raised should the event
+ * be missing one of its dependencies
+ *
+ * @note: UDPOR technically enforces the invariant that all newly-added events
+ * will ensure that the configuration is valid. We perform extra checks to ensure
+ * that UDPOR is implemented as expected. There is a performance penalty that
+ * should be noted: checking for maximality requires ensuring that all events in the
+ * configuration have their dependencies containes within the configuration, which
+ * essentially means performing a BFS/DFS over the configuration using a History object.
+ * However, since the slowest part of UDPOR involves enumerating all
+ * subsets of maximal events and computing k-partial alternatives (the
+ * latter definitively an NP-hard problem when optimal), Amdahl's law suggests
+ * we shouldn't focus so much on this (let alone the additional benefit of the
+ * assertions)
+ */
+ void add_event(const UnfoldingEvent* e);
+
+ /**
+ * @brief Whether or not the given event can be added to
+ * this configuration while preserving that the configuration
+ * is causally closed and conflict-free
+ *
+ * A configuration `C` is compatible with an event iff
+ * the event can be added to `C` while preserving that
+ * the configuration is causally closed and conflict-free.
+ *
+ * The method effectively answers the following question:
+ *
+ * "Is `C + {e}` a valid configuration?"
+ */
+ bool is_compatible_with(const UnfoldingEvent* e) const;
+
+ /**
+ * @brief Whether or not the events in the given history can be added to
+ * this configuration while keeping the set of events causally closed
+ * and conflict-free
+ *
+ * A configuration `C` is compatible with a history iff all
+ * events of the history can be added to `C` while preserving
+ * that the configuration is causally closed and conflict-free.
+ *
+ * The method effectively answers the following question:
+ *
+ * "Is `C + (U_i [e_i])` a valid configuration?"
+ */
+ bool is_compatible_with(const History& history) const;
+
+ std::optional<Configuration> compute_alternative_to(const EventSet& D, const Unfolding& U) const;
+ std::optional<Configuration> compute_k_partial_alternative_to(const EventSet& D, const Unfolding& U, size_t k) const;
+
+ /**
+ * @brief Orders the events of the configuration such that
+ * "more recent" events (i.e. those that are farther down in
+ * the event structure's dependency chain) come after those
+ * that appeared "farther in the past"
+ *
+ * @returns a vector `V` with the following property:
+ *
+ * 1. Let i(e) := C -> I map events to their indices in `V`.
+ * For every pair of events e, e' in C, if e < e' then i(e) < i(e')
+ *
+ * Intuitively, events that are closer to the "bottom" of the event
+ * structure appear farther along in the list than those that appear
+ * closer to the "top"
+ */
+ std::vector<const UnfoldingEvent*> get_topologically_sorted_events() const;
+
+ /**
+ * @brief Orders the events of the configuration such that
+ * "more recent" events (i.e. those that are farther down in
+ * the event structure's dependency chain) come before those
+ * that appear "farther in the past"
+ *
+ * @note The events of the event structure are arranged such that
+ * e < e' implies a directed edge from e to e'. However, it is
+ * also useful to be able to traverse the *reverse* graph (for
+ * example when computing the compatibility graph of a configuration),
+ * hence the distinction between "reversed" and the method
+ * "Configuration::get_topologically_sorted_events()"
+ *
+ * @returns a vector `V` with the following property:
+ *
+ * 1. Let i(e) := C -> I map events to their indices in `V`.
+ * For every pair of events e, e' in C, if e < e' then i(e) > i(e')
+ *
+ * Intuitively, events that are closer to the "top" of the event
+ * structure appear farther along in the list than those that appear
+ * closer to the "bottom"
+ */
+ std::vector<const UnfoldingEvent*> get_topologically_sorted_events_of_reverse_graph() const;
+
+ /**
+ * @brief Computes the smallest set of events whose collective histories
+ * capture all events of this configuration
+ *
+ * @invariant The set of all events in the collective histories
+ * of the events returned by this method is equal to the set of events
+ * in this configuration
+ *
+ * @returns the smallest set of events whose events generates
+ * this configuration (denoted `config(E)`)
+ */
+ EventSet get_minimally_reproducible_events() const;
- void add_event(UnfoldingEvent*);
+ /**
+ * @brief Determines the event in the configuration whose associated
+ * transition is the latest of the given actor
+ *
+ * @invariant: At most one event in the configuration will correspond
+ * to `preEvt(C, a)` for any action `a`. This can be argued by contradiction.
+ *
+ * If there were more than one event (`e` and `e'`) in any configuration whose
+ * associated transitions `a` were run by the same actor at the same step, then they
+ * could not be causally related (`<`) since `a` could not be enabled in
+ * both subconfigurations C' and C'' containing the hypothetical events
+ * `e` and `e` + `e'`. Since they would not be contained in each other's histories,
+ * they would be in conflict, which cannot happen between any pair of events
+ * in a configuration. Thus `e` and `e'` cannot exist simultaneously
+ */
+ std::optional<const UnfoldingEvent*> get_latest_event_of(aid_t) const;
+ /**
+ * @brief Determines the most recent transition of the given actor
+ * in this configuration, or `pre(a)` as denoted in the thesis of
+ * The Anh Pham
+ *
+ * Conceptually, the execution of an interleaving of the transitions
+ * (i.e. a topological ordering) of a configuration yields a unique
+ * state `state(C)`. Since actions taken by the same actor are always
+ * dependent with one another, any such interleaving always yields a
+ * unique
+ *
+ * @returns the most recent transition of the given actor
+ * in this configuration, or `std::nullopt` if there are no transitions
+ * in this configuration run by the given actor
+ */
+ std::optional<const Transition*> get_latest_action_of(aid_t aid) const;
+ std::optional<const UnfoldingEvent*> pre_event(aid_t aid) const { return get_latest_event_of(aid); }
private:
/**
* @brief The most recent event added to the configuration
*/
- UnfoldingEvent* newest_event = nullptr;
+ const UnfoldingEvent* newest_event = nullptr;
/**
* @brief The events which make up this configuration
* @invariant For each event `e` in `events_`, the set of
* dependencies of `e` is also contained in `events_`
*
- * TODO: UDPOR enforces this invariant, but perhaps we should
- * too?
+ * @invariant For each pair of events `e` and `e'` in
+ * `events_`, `e` and `e'` are not in conflict
*/
EventSet events_;
/**
- * The <-maxmimal events of the configuration. These are
- * dynamically adjusted as events are added to the configuration
- *
- * @invariant Each event that is part of this set is
+ * @brief Maps actors to the latest events which
+ * are executed by the actor
*
- * 1. a <-maxmimal event of the configuration, in the sense that
- * there is no event in the configuration that is "greater" than it.
- * In UDPOR terminology, each event does not "cause" another event
- *
- * 2. contained in the set of events `events_` which comprise
- * the configuration
+ * @invariant: The events that are contained in the map
+ * are also contained in the set `events_`
*/
- EventSet max_events_;
-
-private:
- void recompute_maxmimal_events(UnfoldingEvent* new_event);
+ std::unordered_map<aid_t, const UnfoldingEvent*> latest_event_mapping;
};
} // namespace simgrid::mc::udpor