X-Git-Url: http://bilbo.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/301109703c933c28285e0223836a570eaeb8875a..d60b44af675a79ff27e2b1ddbcbe0d9885905d2b:/src/mc/explo/udpor/Configuration.cpp

diff --git a/src/mc/explo/udpor/Configuration.cpp b/src/mc/explo/udpor/Configuration.cpp
index a05d3a7a0a..7f242d780b 100644
--- a/src/mc/explo/udpor/Configuration.cpp
+++ b/src/mc/explo/udpor/Configuration.cpp
@@ -6,6 +6,7 @@
 #include "src/mc/explo/udpor/Configuration.hpp"
 #include "src/mc/explo/udpor/History.hpp"
 #include "src/mc/explo/udpor/UnfoldingEvent.hpp"
+#include "src/mc/explo/udpor/maximal_subsets_iterator.hpp"
 #include "xbt/asserts.h"
 
 #include <algorithm>
@@ -14,7 +15,8 @@
 
 namespace simgrid::mc::udpor {
 
-Configuration::Configuration(std::initializer_list<UnfoldingEvent*> events) : Configuration(EventSet(std::move(events)))
+Configuration::Configuration(std::initializer_list<const UnfoldingEvent*> events)
+    : Configuration(EventSet(std::move(events)))
 {
 }
 
@@ -25,7 +27,7 @@ Configuration::Configuration(const EventSet& events) : events_(events)
   }
 }
 
-void Configuration::add_event(UnfoldingEvent* e)
+void Configuration::add_event(const UnfoldingEvent* e)
 {
   if (e == nullptr) {
     throw std::invalid_argument("Expected a nonnull `UnfoldingEvent*` but received NULL instead");
@@ -46,14 +48,14 @@ void Configuration::add_event(UnfoldingEvent* e)
   }
 }
 
-std::vector<UnfoldingEvent*> Configuration::get_topologically_sorted_events() const
+std::vector<const UnfoldingEvent*> Configuration::get_topologically_sorted_events() const
 {
   if (events_.empty()) {
-    return std::vector<UnfoldingEvent*>();
+    return std::vector<const UnfoldingEvent*>();
   }
 
-  std::stack<UnfoldingEvent*> event_stack;
-  std::vector<UnfoldingEvent*> topological_ordering;
+  std::stack<const UnfoldingEvent*> event_stack;
+  std::vector<const UnfoldingEvent*> topological_ordering;
   EventSet unknown_events = events_;
   EventSet temporarily_marked_events;
   EventSet permanently_marked_events;
@@ -63,7 +65,7 @@ std::vector<UnfoldingEvent*> Configuration::get_topologically_sorted_events() co
     event_stack.push(*unknown_events.begin());
 
     while (not event_stack.empty()) {
-      UnfoldingEvent* evt = event_stack.top();
+      const UnfoldingEvent* evt = event_stack.top();
       discovered_events.insert(evt);
 
       if (not temporarily_marked_events.contains(evt)) {
@@ -87,10 +89,6 @@ std::vector<UnfoldingEvent*> Configuration::get_topologically_sorted_events() co
           event_stack.push(cause);
         }
       } else {
-        // Mark this event as:
-        // 1. discovered across all DFSs performed
-        // 2. permanently marked
-        // 3. part of the topological search
         unknown_events.remove(evt);
         temporarily_marked_events.remove(evt);
         permanently_marked_events.insert(evt);
@@ -101,7 +99,7 @@ std::vector<UnfoldingEvent*> Configuration::get_topologically_sorted_events() co
         topological_ordering.push_back(evt);
 
         // Only now do we remove the event, i.e. once
-        // we've processed the same event again
+        // we've processed the same event twice
         event_stack.pop();
       }
     }
@@ -109,9 +107,9 @@ std::vector<UnfoldingEvent*> Configuration::get_topologically_sorted_events() co
   return topological_ordering;
 }
 
-std::vector<UnfoldingEvent*> Configuration::get_topologically_sorted_events_of_reverse_graph() const
+std::vector<const UnfoldingEvent*> Configuration::get_topologically_sorted_events_of_reverse_graph() const
 {
-  // The method exploits the property that
+  // 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.
@@ -120,4 +118,35 @@ std::vector<UnfoldingEvent*> Configuration::get_topologically_sorted_events_of_r
   return topological_events;
 }
 
+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 = EventSet();
+
+  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;
+}
+
 } // namespace simgrid::mc::udpor