#1941: add EpochStack in termination.h

src/vt/termination/termination.h

@@ -71,6 +71,18 @@ namespace vt { namespace term {
 
 using DijkstraScholtenTerm = term::ds::StateDS;
 
+struct EpochStack {
+  using DataType = epoch::detail::EpochImplType;
+
+  void push(DataType in) { stack_[cur_++] = in; }
+  DataType top() const { return stack_[cur_-1]; }
+  void pop() { cur_--; }
+  int size() const { return cur_; }
+
+  int cur_ = 0;
+  std::array<DataType, 64> stack_;
+};
+
 /**
  * \struct TerminationDetector
  *
@@ -102,6 +114,7 @@ struct TerminationDetector :
   using SuccessorBagType   = EpochDependency::SuccessorBagType;
   using EpochGraph         = termination::graph::EpochGraph;
   using EpochGraphMsg      = termination::graph::EpochGraphMsg<EpochGraph>;
+  using EpochStackType     = EpochStack;
 
   /**
    * \internal \brief Construct a termination detector
@@ -407,11 +420,9 @@ struct TerminationDetector :
    * \param[in] state the epoch state
    * \param[in] num_units number of units
    * \param[in] produce whether its a produce or consume
-   * \param[in] node the node producing to or consuming from
    */
-  void produceConsumeState(
-    TermStateType& state, TermCounterType const num_units, bool produce,
-    NodeType node
+  inline void produceConsumeState(
+    TermStateType& state, TermCounterType const num_units, bool produce
   );
 
   /**
@@ -422,7 +433,7 @@ struct TerminationDetector :
    * \param[in] produce whether its a produce or consume
    * \param[in] node the node producing to or consuming from
    */
-  void produceConsume(
+  inline void produceConsume(
     EpochType epoch = any_epoch_sentinel, TermCounterType num_units = 1,
     bool produce = true, NodeType node = uninitialized_destination
   );
@@ -772,11 +783,26 @@ struct TerminationDetector :
    */
   static void epochContinueHandler(TermMsg* msg);
 
-private:
+public:
+  inline EpochType getEpoch() const;
+  inline EpochType getGlobalEpoch() const;
+  inline void pushEpoch(EpochType const& epoch);
+  inline EpochType popEpoch(EpochType const& epoch = no_epoch);
+
+  inline void pushEpochFast(EpochType epoch) {
+    epoch_stack_.push(epoch.get());
+  }
+  inline void popEpochFast(EpochType epoch) {
+    epoch_stack_.pop();
+  }
+
+  inline EpochStackType& getEpochStack() { return epoch_stack_; }
+
   // global termination state
   TermStateType any_epoch_state_;
   // hang detector termination state
   TermStateType hang_;
+private:
   // epoch termination state
   EpochContainerType<TermStateType> epoch_state_        = {};
   // ready epoch list (misnomer: finishedEpoch was invoked)
@@ -785,6 +811,8 @@ struct TerminationDetector :
   std::unordered_set<EpochType> epoch_wait_status_      = {};
   // has printed epoch graph during abort
   bool has_printed_epoch_graph                          = false;
+  NodeType this_node_ = uninitialized_destination;
+  EpochStackType epoch_stack_;
 };
 
 }} // end namespace vt::term