From 601571014b5c15043e8f55522c80ebd563ffe111 Mon Sep 17 00:00:00 2001
From: Ingmar Schoegl <ischoegl@lsu.edu>
Date: Tue, 30 Mar 2021 13:55:56 -0500
Subject: [PATCH] [Kinetics] tweak performance of MultiRate

---
 include/cantera/kinetics/MultiRate.h | 26 +++++++++++++-------------
 include/cantera/kinetics/Reaction.h  |  4 ----
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/include/cantera/kinetics/MultiRate.h b/include/cantera/kinetics/MultiRate.h
index 9d5799c2bab..f8256fa8eee 100644
--- a/include/cantera/kinetics/MultiRate.h
+++ b/include/cantera/kinetics/MultiRate.h
@@ -70,7 +70,7 @@ class MultiBulkRates final : public MultiRateBase
 
     virtual ReactionRateBase& rate(size_t rxn_index) override {
         size_t j = m_indices[rxn_index];
-        return static_cast<ReactionRateBase&>(m_rates[j]);
+        return static_cast<ReactionRateBase&>(m_rxn_rates.at(j).second);
     }
 
     virtual void add(const size_t rxn_index,
@@ -85,17 +85,16 @@ class MultiBulkRates final : public MultiRateBase
                  "Reaction rate is already linked to a reaction rate "
                  "evaluator. Re-linked reaction rates are not allowed");
         }
-        size_t j = m_rates.size();
+        size_t j = m_rxn_rates.size();
         m_indices[rxn_index] = j;
-        m_rates.push_back(static_cast<RateType&>(*rate));
-        m_rxn.push_back(rxn_index);
+        m_rxn_rates.emplace_back(rxn_index, static_cast<RateType&>(*rate));
         // keep link to original object
         m_bases.push_back(rate);
     }
 
     virtual bool replace(const size_t rxn_index,
                          shared_ptr<ReactionRateBase> rate) override {
-        if (!m_rates.size()) {
+        if (!m_rxn_rates.size()) {
             throw CanteraError("MultiBulkRate::replace",
                  "Invalid operation: cannot replace rate object "
                  "in empty rate handler.");
@@ -103,7 +102,7 @@ class MultiBulkRates final : public MultiRateBase
             throw CanteraError("MultiBulkRate::replace",
                  "Invalid operation: cannot replace rate object of type '{}' "
                  "with a new rate of type '{}'.",
-                 m_rates[0].type(), rate->type());
+                 m_rxn_rates.at(0).second.type(), rate->type());
         } else if (rate->linked()) {
             // ensure there are no dangling objects (unlikely)
             throw CanteraError("MultiBulkRate::replace",
@@ -112,7 +111,7 @@ class MultiBulkRates final : public MultiRateBase
         }
         if (m_indices.find(rxn_index) != m_indices.end()) {
             size_t j = m_indices[rxn_index];
-            m_rates[j] = static_cast<RateType&>(*rate);
+            m_rxn_rates.at(j).second = static_cast<RateType&>(*rate);
             // release evaluator from previously used rate object and update
             m_bases[j]->releaseEvaluator();
             m_bases[j] = rate;
@@ -123,8 +122,8 @@ class MultiBulkRates final : public MultiRateBase
 
     virtual void getRateConstants(const ThermoPhase& bulk,
                                   double* kf, double* concm) const override {
-        for (size_t i = 0; i < m_rates.size(); i++) {
-            kf[m_rxn[i]] = m_rates[i].eval(m_shared, concm[m_rxn[i]]);
+        for (const auto& rxn : m_rxn_rates) {
+            kf[rxn.first] = rxn.second.eval(m_shared, concm[rxn.first]);
         }
     }
 
@@ -135,8 +134,8 @@ class MultiBulkRates final : public MultiRateBase
             // update reaction-specific data for each reaction. This loop
             // is efficient as all function calls are de-virtualized, and
             // all of the rate objects are contiguous in memory
-            for (size_t i = 0; i < m_rates.size(); i++) {
-                m_rates[i].update(m_shared, concm[m_rxn[i]]);
+            for (auto& rxn : m_rxn_rates) {
+                rxn.second.update(m_shared, concm[rxn.first]);
             }
         }
     }
@@ -145,8 +144,9 @@ class MultiBulkRates final : public MultiRateBase
     //! Raw pointers to reaction rate objects managed by Reaction object
     std::vector<shared_ptr<ReactionRateBase>> m_bases;
 
-    std::vector<RateType> m_rates; //!< Reaction rate objects
-    std::vector<size_t> m_rxn; //!< Index within overall rate vector
+    //! Vector of pairs of reaction rates indices and reaction rates
+    std::vector<std::pair<size_t, RateType>> m_rxn_rates;
+
     std::map<size_t, size_t> m_indices; //!< Mapping of indices
     DataType m_shared;
 };
diff --git a/include/cantera/kinetics/Reaction.h b/include/cantera/kinetics/Reaction.h
index 1b7d1a97dfb..d4830fd8a3d 100644
--- a/include/cantera/kinetics/Reaction.h
+++ b/include/cantera/kinetics/Reaction.h
@@ -341,10 +341,6 @@ class Reaction3 : public Reaction
     virtual void setParameters(const AnyMap& node, const Kinetics& kin);
 
     //! Get pointer to third-body
-    shared_ptr<ThirdBody> thirdBody() {
-        return m_third_body;
-    }
-
     shared_ptr<ThirdBody> thirdBody() const {
         return m_third_body;
     }