1 /* Copyright (c) 2008-2023. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/mc/explo/udpor/Configuration.hpp"
7 #include "src/mc/explo/udpor/History.hpp"
8 #include "src/mc/explo/udpor/UnfoldingEvent.hpp"
9 #include "src/mc/explo/udpor/maximal_subsets_iterator.hpp"
10 #include "xbt/asserts.h"
16 namespace simgrid::mc::udpor {
18 Configuration::Configuration(std::initializer_list<const UnfoldingEvent*> events)
19 : Configuration(EventSet(std::move(events)))
23 Configuration::Configuration(const EventSet& events) : events_(events)
25 if (!events_.is_valid_configuration()) {
26 throw std::invalid_argument("The events do not form a valid configuration");
30 void Configuration::add_event(const UnfoldingEvent* e)
33 throw std::invalid_argument("Expected a nonnull `UnfoldingEvent*` but received NULL instead");
36 if (this->events_.contains(e)) {
40 this->events_.insert(e);
41 this->newest_event = e;
43 // Preserves the property that the configuration is valid
45 if (!this->events_.contains(history)) {
46 throw std::invalid_argument("The newly added event has dependencies "
47 "which are missing from this configuration");
51 std::vector<const UnfoldingEvent*> Configuration::get_topologically_sorted_events() const
53 if (events_.empty()) {
54 return std::vector<const UnfoldingEvent*>();
57 std::stack<const UnfoldingEvent*> event_stack;
58 std::vector<const UnfoldingEvent*> topological_ordering;
59 EventSet unknown_events = events_;
60 EventSet temporarily_marked_events;
61 EventSet permanently_marked_events;
63 while (not unknown_events.empty()) {
64 EventSet discovered_events;
65 event_stack.push(*unknown_events.begin());
67 while (not event_stack.empty()) {
68 const UnfoldingEvent* evt = event_stack.top();
69 discovered_events.insert(evt);
71 if (not temporarily_marked_events.contains(evt)) {
72 // If this event hasn't yet been marked, do
73 // so now so that if we see it again in a child we can
74 // detect a cycle and if we see it again here
75 // we can detect that the node is re-processed
76 temporarily_marked_events.insert(evt);
78 EventSet immediate_causes = evt->get_immediate_causes();
79 if (!immediate_causes.empty() && immediate_causes.is_subset_of(temporarily_marked_events)) {
80 throw std::invalid_argument("Attempted to perform a topological sort on a configuration "
81 "whose contents contain a cycle. The configuration (and the graph "
82 "connecting all of the events) is an invalid event structure");
84 immediate_causes.subtract(discovered_events);
85 immediate_causes.subtract(permanently_marked_events);
86 const EventSet undiscovered_causes = std::move(immediate_causes);
88 for (const auto cause : undiscovered_causes) {
89 event_stack.push(cause);
92 unknown_events.remove(evt);
93 temporarily_marked_events.remove(evt);
94 permanently_marked_events.insert(evt);
96 // In moving this event to the end of the list,
97 // we are saying this events "happens before" other
98 // events that are added later.
99 topological_ordering.push_back(evt);
101 // Only now do we remove the event, i.e. once
102 // we've processed the same event twice
107 return topological_ordering;
110 std::vector<const UnfoldingEvent*> Configuration::get_topologically_sorted_events_of_reverse_graph() const
112 // The implementation exploits the property that
113 // a topological sorting S^R of the reverse graph G^R
114 // of some graph G is simply the reverse of any
115 // topological sorting S of G.
116 auto topological_events = get_topologically_sorted_events();
117 std::reverse(topological_events.begin(), topological_events.end());
118 return topological_events;
121 EventSet Configuration::get_minimally_reproducible_events() const
123 // The implementation exploits the following observations:
125 // To select the smallest reproducible set of events, we want
126 // to pick events that "knock out" a lot of others. Furthermore,
127 // we need to ensure that the events furthest down in the
128 // causality graph are also selected. If you combine these ideas,
129 // you're basically left with traversing the set of maximal
130 // subsets of C! And we have an iterator for that already!
132 // The next observation is that the moment we don't increase in size
133 // the current maximal set (or decrease the number of events),
134 // we know that the prior set `S` covered the entire history of C and
135 // was maximal. Subsequent sets will miss events earlier in the
136 // topological ordering that appear in `S`
137 EventSet minimally_reproducible_events = EventSet();
139 for (const auto& maximal_set : maximal_subsets_iterator_wrapper(*this)) {
140 if (maximal_set.size() > minimally_reproducible_events.size()) {
141 minimally_reproducible_events = maximal_set;
143 // The moment we see the iterator generate a set of size
144 // that is not monotonically increasing, we can stop:
145 // the set prior was the minimally-reproducible one
146 return minimally_reproducible_events;
149 return minimally_reproducible_events;
152 } // namespace simgrid::mc::udpor