Improved seed and option files handling (#2032)

Each instance of GeneratorEPOS4 will now have a different seed, based on the call order to the gRandom function, and the options files will be separated for each instance. This should fix some issues when calling the generator in parallel or simply in sequence.

Author: jackal1-66

MC/config/examples/epos4/generator_EPOS4.C

@@ -43,19 +43,26 @@ FairGenerator* generateEPOS4(const std::string &name, const int& nEvents)
         buffer << line << "\n";
     }
     file.close();
+    auto gen = new GeneratorEPOS4();
+    auto &param0 = o2::eventgen::GeneratorFileOrCmdParam::Instance();
+    auto &param = o2::eventgen::GeneratorHepMCParam::Instance();
+    auto &conf = o2::conf::SimConfig::Instance();
+    // Randomise seed (useful for multiple instances of the generator)
+    int randomSeed = gRandom->Integer(conf.getStartSeed());
     // Write the updated content back to a file in the current directory
-    std::ofstream outFile("cfg.optns");
+    std::string optnsFileName(Form("cfg%d.optns", randomSeed));
+    std::ofstream outFile(optnsFileName);
     outFile << buffer.str();
     if (!found)
     {
         outFile << "set nfull " + std::to_string(nEvents);
     }
     outFile.close();
-    auto gen = new GeneratorEPOS4();
-    auto& param0 = o2::eventgen::GeneratorFileOrCmdParam::Instance();
-    auto& param = o2::eventgen::GeneratorHepMCParam::Instance();
-    auto& conf = o2::conf::SimConfig::Instance();
+    optnsFileName = optnsFileName.substr(0, optnsFileName.find_last_of('.')); // remove the .optns extension
     // setup the HepMC generator to run with automatic FIFOs
     gen->setup(param0, param, conf);
+    // Replace seed and optns file
+    gen->setCmd(param0.cmd + " -i " + optnsFileName);
+    gen->setSeed(randomSeed);
     return gen;
 }

MC/config/examples/ini/GeneratorEPOS4.ini

@@ -3,7 +3,7 @@ fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/epos4/generator_EPOS4.C
 funcName=generateEPOS4("${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/epos4/generator/example.optns", 2147483647)
 
 [GeneratorFileOrCmd]
-cmd=${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/epos4/epos.sh -i cfg
+cmd=${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/epos4/epos.sh
 bMaxSwitch=none
 
 # Set to version 2 if EPOS4.0.0 is used

MC/config/examples/ini/GeneratorEPOS4HQ.ini

@@ -4,7 +4,7 @@ fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/epos4/generator_EPOS4.C
 funcName=generateEPOS4("${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/epos4/generator/examplehq.optns", 2147483647)
 
 [GeneratorFileOrCmd]
-cmd=${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/epos4/epos.sh -i cfg
+cmd=${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/epos4/epos.sh
 bMaxSwitch=none
 
 [HepMC]