Make sure PrimaryGenerator is destructed

Makes sure that PrimaryGenerators are destructed in o2-sim.

Note that all FairGenerator pointers registered in the PrimaryGenerator
are automatically destructed as well.

Generators/src/PrimaryGenerator.cxx

@@ -40,7 +40,7 @@ namespace eventgen
 PrimaryGenerator::~PrimaryGenerator()
 {
   /** destructor **/
-
+  LOG(info) << "Destructing PrimaryGenerator";
   if (mEmbedFile && mEmbedFile->IsOpen()) {
     mEmbedFile->Close();
     delete mEmbedFile;

run/O2PrimaryServerDevice.h

@@ -105,7 +105,7 @@ class O2PrimaryServerDevice final : public fair::mq::Device
     if (conf.getGenerator().compare("extkin") != 0 || conf.getGenerator().compare("extkinO2") != 0) {
       auto iter = mPrimGeneratorCache.find(conf.getGenerator());
       if (iter != mPrimGeneratorCache.end()) {
-        mPrimGen = iter->second;
+        mPrimGen = iter->second.get();
         LOG(info) << "Found cached generator for " << conf.getGenerator();
       }
     }
@@ -133,7 +133,9 @@ class O2PrimaryServerDevice final : public fair::mq::Device
 
       mPrimGen->Init();
 
-      mPrimGeneratorCache[conf.getGenerator()] = mPrimGen;
+      std::unique_ptr<o2::eventgen::PrimaryGenerator> ptr_wrapper;
+      ptr_wrapper.reset(mPrimGen);
+      mPrimGeneratorCache[conf.getGenerator()] = std::move(ptr_wrapper);
     }
     mPrimGen->SetEvent(&mEventHeader);
 
@@ -668,11 +670,11 @@ class O2PrimaryServerDevice final : public fair::mq::Device
 
   // Keeps various generators instantiated in memory
   // useful when running simulation as a service (when generators
-  // change between batches)
+  // change between batches). Also takes care of resource management of Primary generators via unique ptr
   // TODO: some care needs to be taken (or the user warned) that the caching is based on generator name
   //       and that parameter-based reconfiguration is not yet implemented (for which we would need to hash all
   //       configuration parameters as well)
-  std::map<std::string, o2::eventgen::PrimaryGenerator*> mPrimGeneratorCache;
+  std::map<std::string, std::unique_ptr<o2::eventgen::PrimaryGenerator>> mPrimGeneratorCache;
 
   std::atomic<O2PrimaryServerState> mState{O2PrimaryServerState::Initializing};
   std::atomic<int> mWaitingControlInput{0};