From 571ed94e23c9aefbd5f81f1a800eb5f1dddd8ae9 Mon Sep 17 00:00:00 2001
From: Martin Quinson <martin.quinson@loria.fr>
Date: Tue, 1 Mar 2016 16:52:57 +0100
Subject: [PATCH 1/1] create a singleton for s4u::Engine

---
 include/simgrid/s4u/engine.hpp |  4 ++++
 src/s4u/s4u_engine.cpp         | 18 +++++++++++++++---
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/include/simgrid/s4u/engine.hpp b/include/simgrid/s4u/engine.hpp
index b81a57f591..2c9fa3cd13 100644
--- a/include/simgrid/s4u/engine.hpp
+++ b/include/simgrid/s4u/engine.hpp
@@ -47,6 +47,10 @@ public:
   /** @brief Retrieve the simulation time */
   static double getClock();
   
+  /** @brief Retrieve the engine singleton */
+  static s4u::Engine *instance();
+private:
+  static s4u::Engine *instance_;
 };
 }} // namespace simgrid::sgo
 
diff --git a/src/s4u/s4u_engine.cpp b/src/s4u/s4u_engine.cpp
index ca3415a2fc..ce3cc47f76 100644
--- a/src/s4u/s4u_engine.cpp
+++ b/src/s4u/s4u_engine.cpp
@@ -12,14 +12,26 @@
 XBT_LOG_NEW_CATEGORY(s4u,"Log channels of the S4U (Simgrid for you) interface");
 using namespace simgrid;
 
-double s4u::Engine::getClock() {
-  return SIMIX_get_clock();
-}
+s4u::Engine *s4u::Engine::instance_ = nullptr; /* That singleton is awful, but I don't see no other solution right now. */
+
 
 s4u::Engine::Engine(int *argc, char **argv) {
+  xbt_assert(s4u::Engine::instance_ == nullptr, "It is currently forbidden to create more than one instance of s4u::Engine");
+  s4u::Engine::instance_ = this;
+
   SIMIX_global_init(argc, argv);
 }
 
+s4u::Engine *s4u::Engine::instance() {
+  if (s4u::Engine::instance_ == nullptr)
+    new Engine(0,nullptr);
+  return s4u::Engine::instance_;
+}
+
+double s4u::Engine::getClock() {
+  return SIMIX_get_clock();
+}
+
 void s4u::Engine::loadPlatform(const char *platf) {
   SIMIX_create_environment(platf);
 }
-- 
2.20.1