polish gurobi environment code

ortools/gurobi/BUILD

@@ -9,11 +9,12 @@ cc_library(
         "environment.h",
     ],
     deps = [
+        "//ortools/base",
+        "//ortools/base:dynamic_library",
         "@com_google_absl//absl/status",
+        "@com_google_absl//absl/statusor",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/synchronization",
         "@com_google_absl//absl/types:optional",
-        "//ortools/base:dynamic_library",
-        "//ortools/base",
-    ]
-)
+    ],
+)

ortools/gurobi/environment.cc

@@ -25,14 +25,15 @@ namespace operations_research {
 
 bool GurobiIsCorrectlyInstalled(
     const std::string& gurobi_shared_library_full_path) {
-  GRBenv* env;
-  if (!LoadGurobiEnvironment(&env, gurobi_shared_library_full_path).ok()) {
+  absl::StatusOr<GRBenv*> status =
+      LoadGurobiEnvironment(gurobi_shared_library_full_path);
+  if (!status.ok()) {
     return false;
   }
 
-  if (env == nullptr) return false;
+  if (status.value() == nullptr) return false;
 
-  GRBfreeenv(env);
+  GRBfreeenv(status.value());
 
   return true;
 }
@@ -280,9 +281,10 @@ bool LoadGurobiSharedLibrary(
 
 }  // namespace
 
-absl::Status LoadGurobiEnvironment(
-    GRBenv** env, const std::string& gurobi_shared_library_full_path) {
+absl::StatusOr<GRBenv*> LoadGurobiEnvironment(
+    const std::string& gurobi_shared_library_full_path) {
   constexpr int GRB_OK = 0;
+  GRBenv* env = nullptr;
   const char kGurobiEnvErrorMsg[] =
       "Could not load Gurobi environment. Is gurobi correctly installed and"
       " licensed on this machine ? ";
@@ -294,10 +296,10 @@ absl::Status LoadGurobiEnvironment(
     return absl::FailedPreconditionError(kGurobiEnvNoSharedLibraryMsg);
   }
 
-  if (GRBloadenv(env, nullptr) != 0 || *env == nullptr) {
+  if (GRBloadenv(&env, nullptr) != 0 || env == nullptr) {
     return absl::FailedPreconditionError(
-        absl::StrFormat("%s %s", kGurobiEnvErrorMsg, GRBgeterrormsg(*env)));
+        absl::StrFormat("%s %s", kGurobiEnvErrorMsg, GRBgeterrormsg(env)));
   }
-  return absl::OkStatus();
+  return env;
 }
 }  // namespace operations_research

ortools/gurobi/environment.h

@@ -15,6 +15,7 @@
 #define OR_TOOLS_GUROBI_ENVIRONMENT_H_
 
 #include "absl/status/status.h"
+#include "absl/status/statusor.h"
 #include "ortools/base/commandlineflags.h"
 #include "ortools/base/dynamic_library.h"
 #include "ortools/base/logging.h"
@@ -36,11 +37,11 @@ namespace operations_research {
 // successfully created and assigned to 'env'.
 // You can add the full path for the shared library by passing the
 // 'gurobi_shared_library_full_path' argument.
-absl::Status LoadGurobiEnvironment(
-    GRBenv** env, const std::string& gurobi_shared_library_full_path);
+absl::StatusOr<GRBenv*> LoadGurobiEnvironment(
+    const std::string& gurobi_shared_library_full_path);
 
 // Checks the that Gurobi is correctly installed, and that licenses can be
-// obtained. This method will attempt grab a license, and then release it.
+// obtained. This method will try to grab a license, and then release it.
 bool GurobiIsCorrectlyInstalled(
     const std::string& gurobi_shared_library_full_path);
 

ortools/linear_solver/gurobi_interface.cc

@@ -612,7 +612,10 @@ GurobiInterface::GurobiInterface(MPSolver* const solver, bool mip)
       env_(nullptr),
       mip_(mip),
       current_solution_index_(0) {
-  CHECK_OK(LoadGurobiEnvironment(&env_, GurobiSharedLibraryFullPath()));
+  const absl::StatusOr<GRBenv*> status =
+      LoadGurobiEnvironment(GurobiSharedLibraryFullPath());
+  CHECK_OK(status.status());
+  env_ = status.value();
   CheckedGurobiCall(GRBnewmodel(env_, &model_, solver_->name_.c_str(),
                                 0,          // numvars
                                 nullptr,    // obj

ortools/linear_solver/gurobi_proto_solver.cc

@@ -283,8 +283,8 @@ absl::StatusOr<MPSolutionResponse> GurobiSolveProto(
     // `LoadGurobiEnvironment()` since this function still returns a non null
     // value even when it fails.
     gurobi_env_was_created = true;
-    RETURN_IF_ERROR(
-        LoadGurobiEnvironment(&gurobi_env, GurobiSharedLibraryFullPath()));
+    ASSIGN_OR_RETURN(gurobi_env,
+                     LoadGurobiEnvironment(GurobiSharedLibraryFullPath()));
   }
 
   GRBmodel* gurobi_model = nullptr;