From dd28db3ab46471a295546160f25f8a921b940cb1 Mon Sep 17 00:00:00 2001
From: Abdoulbari Zakir <azakir@neverhack.com>
Date: Wed, 15 Nov 2023 08:32:47 -0800
Subject: [PATCH] check available Solvers once per program

---
 .../multisolver_interface/SolverFactory.cpp   | 20 +++++++++++------
 .../multisolver_interface/SolverFactory.h     | 22 +++++++++++++------
 2 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/src/cpp/multisolver_interface/SolverFactory.cpp b/src/cpp/multisolver_interface/SolverFactory.cpp
index ef50caa3d..f0b6932ee 100644
--- a/src/cpp/multisolver_interface/SolverFactory.cpp
+++ b/src/cpp/multisolver_interface/SolverFactory.cpp
@@ -8,18 +8,24 @@
 #endif
 #include "LogUtils.h"
 #include "multisolver_interface/SolverFactory.h"
+std::vector<std::string> tmp;
 
-SolverFactory::SolverFactory() {
-  _available_solvers.clear();
-  if ((isXpress_available_ = LoadXpress::XpressIsCorrectlyInstalled())) {
-    _available_solvers.push_back(XPRESS_STR);
-  }
+std::vector<std::string> SolverLoader::GetAvailableSolvers() {
+  if (tmp.empty()) {
+    if (LoadXpress::XpressIsCorrectlyInstalled()) {
+      tmp.push_back(XPRESS_STR);
+    }
 #ifdef COIN_OR
-  _available_solvers.push_back(CLP_STR);
-  _available_solvers.push_back(CBC_STR);
+    tmp.push_back(CLP_STR);
+    tmp.push_back(CBC_STR);
 #endif
+  }
+  return tmp;
 }
 
+SolverFactory::SolverFactory()
+    : _available_solvers(SolverLoader::GetAvailableSolvers()) {}
+
 SolverAbstract::Ptr SolverFactory::create_solver(
     const std::string &solver_name, const SOLVER_TYPE solver_type) const {
   if (solver_name == "") {
diff --git a/src/cpp/multisolver_interface/include/multisolver_interface/SolverFactory.h b/src/cpp/multisolver_interface/include/multisolver_interface/SolverFactory.h
index 36949841d..332eedb71 100644
--- a/src/cpp/multisolver_interface/include/multisolver_interface/SolverFactory.h
+++ b/src/cpp/multisolver_interface/include/multisolver_interface/SolverFactory.h
@@ -8,6 +8,15 @@ enum class SOLVER_TYPE { INTEGER, CONTINUOUS };
 const std::string UNKNOWN_STR("UNKNOWN"), COIN_STR("COIN"), CBC_STR("CBC"),
     CLP_STR("CLP"), XPRESS_STR("XPRESS");
 
+/*!
+ * \class class SolverLoader
+ * \brief Class to check if supported solvers are available
+ */
+class SolverLoader {
+ public:
+  static std::vector<std::string> GetAvailableSolvers();
+};
+
 /*!
  * \class class SolverFactory
  * \brief Class to manage the creation of solvers from the different
@@ -31,9 +40,8 @@ class SolverFactory {
    * @param solver_name : Name of the solver to use
    */
   SolverAbstract::Ptr create_solver(const std::string &solver_name) const;
-  SolverAbstract::Ptr create_solver(
-      const std::string &solver_name,
-      SolverLogManager&log_manager) const;
+  SolverAbstract::Ptr create_solver(const std::string &solver_name,
+                                    SolverLogManager &log_manager) const;
 
   /**
    * @brief Creates and returns to an object solver from the wanted
@@ -44,9 +52,9 @@ class SolverFactory {
    */
   SolverAbstract::Ptr create_solver(const std::string &solver_name,
                                     const SOLVER_TYPE solver_type) const;
-  SolverAbstract::Ptr create_solver(
-      const std::string &solver_name, const SOLVER_TYPE solver_type,
-      SolverLogManager&log_manager) const;
+  SolverAbstract::Ptr create_solver(const std::string &solver_name,
+                                    const SOLVER_TYPE solver_type,
+                                    SolverLogManager &log_manager) const;
 
   /**
    * @brief Copy constructor : Creates and returns to an object solver from the
@@ -63,5 +71,5 @@ class SolverFactory {
    */
   const std::vector<std::string> &get_solvers_list() const;
 
-    bool isXpress_available_ = false;
+  bool isXpress_available_ = false;
 };