Switch option from external to hybrid (#14951)

Author: jackal1-66

Generators/include/Generators/GeneratorHybridParam.h

@@ -29,9 +29,10 @@ namespace eventgen
  **/
 
 struct GeneratorHybridParam : public o2::conf::ConfigurableParamHelper<GeneratorHybridParam> {
-  std::string configFile = ""; // JSON configuration file for the generators
-  bool randomize = false;      // randomize the order of the generators, if not generator using fractions
-  int num_workers = 1;         // number of threads available for asyn/parallel event generation
+  std::string configFile = "";    // JSON configuration file for the generators
+  bool randomize = false;         // randomize the order of the generators, if not generator using fractions
+  int num_workers = 1;            // number of threads available for asyn/parallel event generation
+  bool switchExtToHybrid = false; // force external generator to be executed as hybrid mode, useful for Hyperloop MCGEN
   O2ParamDef(GeneratorHybridParam, "GeneratorHybrid");
 };
 

Generators/src/GeneratorFactory.cxx

@@ -93,6 +93,12 @@ void GeneratorFactory::setPrimaryGenerator(o2::conf::SimConfig const& conf, Fair
 
   o2::O2DatabasePDG::addALICEParticles(TDatabasePDG::Instance());
   auto genconfig = conf.getGenerator();
+#if defined(GENERATORS_WITH_PYTHIA8) && defined(GENERATORS_WITH_HEPMC3)
+  if (GeneratorHybridParam::Instance().switchExtToHybrid && (genconfig.compare("external") == 0 || genconfig.compare("extgen") == 0)) {
+    LOG(info) << "Switching external generator to hybrid mode";
+    genconfig = "hybrid";
+  }
+#endif
   LOG(info) << "** Generator to use: '" << genconfig << "'";
   if (genconfig.compare("boxgen") == 0) {
     // a simple "box" generator configurable via BoxGunparam

run/SimExamples/ExternalToHybrid/GeneratorHyperloopHybrid.ini

@@ -0,0 +1,3 @@
+[GeneratorHybrid]
+configFile = ${O2_ROOT}/examples/ExternalToHybrid/sequential.json
+switchExtToHybrid = true

run/SimExamples/ExternalToHybrid/GeneratorHyperloopHybridCocktail.ini

@@ -0,0 +1,3 @@
+[GeneratorHybrid]
+configFile = ${O2_ROOT}/examples/ExternalToHybrid/cocktail.json
+switchExtToHybrid = true

run/SimExamples/ExternalToHybrid/README.md

@@ -0,0 +1,45 @@
+<!-- doxy
+\page refrunSimExamplesExternalToHybrid Example ExternalToHybrid
+/doxy -->
+
+This example demonstrates how to bypass the Hyperloop limitations when using external generators by switching the configuration to hybrid mode, using the new `GeneratorHybrid.switchExtToHybrid` parameter (set to false by default).
+
+This solution works only with updated O2sim versions containing the `switchExtToHybrid` option.
+
+# Configuration Files
+
+Two example configuration files are provided, each pointing to different hybrid JSON files:
+
+- **GeneratorHyperloopHybridCocktail.ini** → Creates a cocktail mixing two Pythia8 based generators and a boxgen instance
+- **GeneratorHyperloopHybrid.ini** → Defines sequential generation of boxgen and EPOS4 events called with an external generator
+
+# Script Description
+
+## rundpl.sh
+
+This script demonstrates event generation using the DPL framework, launching it with the external generator in hybrid mode.
+
+### Available Flags
+
+- **-i, --ini CONFIG** → Specifies the configuration ini file (default: `GeneratorHyperloopHybridCocktail.ini`)
+- **-n, --nevents EVENTS** → Sets the number of events to generate (default: 5)
+- **-h, --help** → Prints usage instructions and o2-sim-dpl-eventgen help
+- **--** → Passes remaining command line arguments to o2-sim-dpl-eventgen
+
+### Usage Examples
+
+Run with default settings (5 events using cocktail configuration):
+```bash
+./rundpl.sh
+```
+
+Generate 10 events using the sequential configuration:
+```bash
+./rundpl.sh -n 10 -i ${O2_ROOT}/examples/ExternalToHybrid/GeneratorHyperloopHybrid.ini
+```
+
+# Requirements
+
+- O2sim version with `switchExtToHybrid` support
+- O2_ROOT and O2DPG_MC_CONFIG_ROOT environment variable must be loaded (possibly via O2sim directly)
+- Appropriate external generator configurations (e.g., EPOS4) must be available

run/SimExamples/ExternalToHybrid/cocktail.json

@@ -0,0 +1,49 @@
+{
+  "generators": [
+    {
+      "cocktail": [
+        {
+          "name": "pythia8",
+          "config": {
+            "config": "${O2_ROOT}/share/Generators/egconfig/pythia8_inel.cfg",
+            "hooksFileName": "",
+            "hooksFuncName": "",
+            "includePartonEvent": false,
+            "particleFilter": "",
+            "verbose": 0
+          }
+        },
+        {
+          "name": "external",
+          "config": {
+            "fileName": "",
+            "funcName": "",
+            "iniFile": "${O2DPG_MC_CONFIG_ROOT}/MC/config/ALICE3/ini/pythia8_pp_13tev.ini"
+          }
+        },
+        {
+          "name": "boxgen",
+          "config": {
+            "pdg": 443,
+            "number": 10,
+            "eta": [
+              -0.8,
+              0.8
+            ],
+            "prange": [
+              0.1,
+              5
+            ],
+            "phirange": [
+              0,
+              360
+            ]
+          }
+        }
+      ]
+    }
+  ],
+  "fractions": [
+    1
+  ]
+}

run/SimExamples/ExternalToHybrid/rundpl.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+#
+# This is a simple example script to bypass the Hyperloop limitations in using
+# external generators only, by switching the generator to the hybrid mode
+
+# This script works only with updated O2sim version containing the switchExtToHybrid option
+
+[ ! "${O2_ROOT}" ] && echo "Error: This needs O2 loaded" && exit 2
+[ ! "${O2DPG_MC_CONFIG_ROOT}" ] && echo "Error: This needs O2DPG loaded" && exit 2
+
+NEV=5
+# Two example ini configurations are provided pointing to different hybrid JSON files
+# One creates a cocktail based on Pythia8, while the other generates sequentially EPOS4 and boxgen events
+ini="${O2_ROOT}/examples/ExternalToHybrid/GeneratorHyperloopHybridCocktail.ini"
+
+usage()
+{
+    cat <<EOF
+Usage: $0 [OPTIONS]
+
+Options:
+
+  -i,--ini     INI         Configuration ini file ($ini)
+  -n,--nevents EVENTS      Number of events ($nev)
+  -h,--help                Print these instructions
+  --                       Rest of command line sent to o2-sim
+
+COMMAND must be quoted if it contains spaces or other special
+characters
+
+Below follows the help output of o2-sim-dpl-eventgen
+
+EOF
+}
+
+if [ "$#" -lt 2 ]; then
+    echo "Running with default values"
+fi
+
+while test $# -gt 0 ; do
+    case $1 in
+        -i|--ini)     ini="$2" ; shift ;;
+        -n|--nevents) NEV=$2 ; shift ;;
+        -h|--help) usage; o2-sim-dpl-eventgen --help full ; exit 0 ;;
+        --)           shift ; break ;;
+        *) echo "Unknown option '$1', did you forget '--'?" >/dev/stderr
+           exit 3
+           ;;
+    esac
+    shift
+done
+
+# Starting the dpl-eventgen simulation
+o2-sim-dpl-eventgen -b --generator external --nEvents $NEV --configFile $ini

run/SimExamples/ExternalToHybrid/sequential.json

@@ -0,0 +1,35 @@
+{
+  "generators": [
+    {
+      "name": "boxgen",
+      "config": {
+        "pdg": 443,
+        "number": 10,
+        "eta": [
+          -0.8,
+          0.8
+        ],
+        "prange": [
+          0.1,
+          5
+        ],
+        "phirange": [
+          0,
+          360
+        ]
+      }
+    },
+    {
+      "name": "external",
+      "config": {
+        "fileName": "",
+        "funcName": "",
+        "iniFile": "${O2DPG_MC_CONFIG_ROOT}/MC/config/examples/ini/GeneratorEPOS4_pp13TeV.ini"
+      }
+    }
+  ],
+  "fractions": [
+    1,
+    1
+  ]
+}