Make sure barriers do not think they depend on themselves

algorithmsRequiredFor(name) returns pointers to initialized algorithm instances required to be executed for the algorithm named name -- this of course includes a pointer to the algorithm named name. As a result, when these algorithms are used to populate the data dependencies for name, the pointer to the algorithm named name should not be included in that list, as otherwise it will never possible to create an ordering which allows name to be executed...

Hlt/HLTScheduler/src/ControlFlowNode.cpp

@@ -185,6 +185,10 @@ findAllEdges( gsl::not_null<VNode const*> vnode, std::set<std::array<gsl::not_nu
     }
   }
 
+  // check that nodes do not depend on themselves....
+  assert( std::none_of( nodePrerequisites.begin(), nodePrerequisites.end(),
+                        []( const auto& kv ) { return kv.second.find( kv.first ) != kv.second.end(); } ) );
+
   return nodePrerequisites;
 }
 
@@ -206,6 +210,11 @@ bool CFDependenciesMet( gsl::not_null<VNode*>
 std::vector<gsl::not_null<BasicNode*>>
 resolveDependencies( std::set<gsl::not_null<VNode*>>&                                        unordered,
                      std::map<gsl::not_null<VNode*>, std::set<gsl::not_null<VNode*>>> const& nodePrerequisites ) {
+
+  // check that nodes do not depend on themselves....
+  assert( std::none_of( nodePrerequisites.begin(), nodePrerequisites.end(),
+                        []( const auto& kv ) { return kv.second.find( kv.first ) != kv.second.end(); } ) );
+
   std::vector<gsl::not_null<VNode*>> ordered;
   std::set<gsl::not_null<VNode*>>    orderedSet;
   ordered.reserve( unordered.size() );
@@ -229,6 +238,15 @@ resolveDependencies( std::set<gsl::not_null<VNode*>>&
       message += "Unordered ones: \n";
       for ( auto i : unordered ) {
         message += getNameOfVNode( *i );
+        message += " not yet satisfied dependencies:  ";
+        auto const it = nodePrerequisites.find( i );
+        if ( it != nodePrerequisites.end() ) {
+          for ( auto const& pr : it->second ) {
+            if ( orderedSet.find( pr ) != orderedSet.end() ) continue;
+            message += " ";
+            message += getNameOfVNode( *pr );
+          }
+        }
         message += "\n";
       }
       message += "Ordered ones: \n";