1 /* Copyright (c) 2007-2023. The SimGrid Team.
2 * All rights reserved. */
4 /* This program is free software; you can redistribute it and/or modify it
5 * under the terms of the license (GNU LGPL) which comes with this package. */
7 #ifndef SIMGRID_MC_UDPOR_CHECKER_HPP
8 #define SIMGRID_MC_UDPOR_CHECKER_HPP
10 #include "src/mc/explo/Exploration.hpp"
11 #include "src/mc/explo/udpor/Configuration.hpp"
12 #include "src/mc/explo/udpor/EventSet.hpp"
13 #include "src/mc/explo/udpor/Unfolding.hpp"
14 #include "src/mc/explo/udpor/UnfoldingEvent.hpp"
15 #include "src/mc/mc_record.hpp"
20 namespace simgrid::mc::udpor {
23 * @brief Performs exploration of a concurrent system via the
26 * The `UdporChecker` implementation is based primarily off three papers,
27 * herein referred to as [1], [2], and [3] respectively, as well as the
28 * current implementation of `tiny_simgrid`:
30 * 1. "Unfolding-based Partial Order Reduction" by Rodriguez et al.
31 * 2. "Quasi-Optimal Partial Order Reduction" by Nguyen et al.
32 * 3. The Anh Pham's Thesis "Exploration efficace de l'espace ..."
34 class XBT_PRIVATE UdporChecker : public Exploration {
36 explicit UdporChecker(const std::vector<char*>& args);
39 RecordTrace get_record_trace() override;
40 std::vector<std::string> get_textual_trace() override;
42 inline std::unique_ptr<State> get_current_state() { return std::make_unique<State>(get_remote_app()); }
45 Unfolding unfolding = Unfolding();
48 * @brief A collection of specialized functions which can incrementally
49 * compute the extension of a configuration based on the action taken
51 using ExtensionFunction = std::function<EventSet(const Configuration&, const std::shared_ptr<Transition>)>;
52 std::unordered_map<Transition::Type, ExtensionFunction> incremental_extension_functions =
53 std::unordered_map<Transition::Type, ExtensionFunction>();
56 * @brief Explores the unfolding of the concurrent system
57 * represented by the ModelChecker instance "mcmodel_checker"
59 * This function performs the actual search following the
60 * UDPOR algorithm according to [1].
62 * @param C the current configuration from which UDPOR will be used
63 * to explore expansions of the concurrent system being modeled
64 * @param D the set of events that should not be considered by UDPOR
65 * while performing its searches, in order to avoid sleep-set blocked
66 * executions. See [1] for more details
67 * @param A the set of events to "guide" UDPOR in the correct direction
68 * when it returns back to a node in the unfolding and must decide among
69 * events to select from `ex(C)`. See [1] for more details
70 * @param stateC the state of the program after having executed `C`,
71 * viz. `state(C)` using the notation of [1]
73 * TODO: Add the optimization where we can check if e == e_prior
74 * to prevent repeated work when computing ex(C)
76 void explore(const Configuration& C, EventSet D, EventSet A, std::unique_ptr<State> stateC, EventSet prev_exC);
79 * @brief Identifies the next event from the unfolding of the concurrent system
80 * that should next be explored as an extension of a configuration with
81 * enabled events `enC`
83 * @param A The set of events `A` maintained by the UDPOR algorithm to help
84 * determine how events should be selected. See the original paper [1] for more details
86 * @param enC The set `enC` of enabled events from the extension set `exC` used
87 * by the UDPOR algorithm to select new events to search. See the original
88 * paper [1] for more details
90 const UnfoldingEvent* select_next_unfolding_event(const EventSet& A, const EventSet& enC);
93 * @brief Computes the sets `ex(C)` and `en(C)` of the given configuration
94 * `C` as an incremental computation from the the previous computation of `ex(C)`
96 * A central component to UDPOR is the computation of the set `ex(C)`. The
97 * extension set `ex(C)` of a configuration `C` is defined as the set of events
98 * outside of `C` whose full dependency chain is contained in `C` (see [1]
101 * In general, computing `ex(C)` is very expensive. In paper [3], The Anh Pham
102 * shows a method of incremental computation of the set `ex(C)` under the
103 * conclusions afforded under the computation model in consideration, of which
104 * SimGrid is apart, which allow for `ex(C)` to be computed much more efficiently.
105 * Intuitively, the idea is to take advantage of the fact that you can avoid a lot
106 * of repeated computation by exploiting the aforementioned properties (in [3]) in
107 * what is akin to a dynamic programming optimization. See [3] for more details
109 * @param C the configuration based on which the two sets `ex(C)` and `en(C)` are
111 * @param stateC the state of the program after having executed C (viz. `state(C)`)
112 * @param prev_exC the previous value of `ex(C)`, viz. that which was computed for
113 * the configuration `C' := C - {e}`
114 * @returns the extension set `ex(C)` of `C`
116 EventSet compute_exC(const Configuration& C, const State& stateC, const EventSet& prev_exC);
119 * @brief Computes a portion of the extension set of a configuration given
120 * some action `action` by directly enumerating all maximal subsets of C
121 * (i.e. without specializations based on the action)
123 EventSet compute_exC_by_enumeration(const Configuration& C, const std::shared_ptr<Transition> action);
125 EventSet compute_enC(const Configuration& C, const EventSet& exC) const;
130 void move_to_stateCe(State& stateC, const UnfoldingEvent& e);
133 * @brief Creates a new snapshot of the state of the progam undergoing
136 * @returns the handle used to uniquely identify this state later in the
137 * exploration of the unfolding. You provide this handle to an event in the
138 * unfolding to regenerate past states
140 std::unique_ptr<State> record_current_state();
145 void restore_program_state_to(const State& stateC);
150 void clean_up_explore(const UnfoldingEvent* e, const Configuration& C, const EventSet& D);
152 } // namespace simgrid::mc::udpor