BaseHadronizer.cc

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#include "GeneratorInterface/Core/interface/BaseHadronizer.h"
#include "FWCore/ParameterSet/interface/Registry.h"
 
#include <random>
#include <sys/wait.h>
 
namespace gen {
 
  const std::vector<std::string> BaseHadronizer::theSharedResources;
 
  BaseHadronizer::BaseHadronizer(edm::ParameterSet const& ps) : randomIndex_(-1), gridpackPaths_(1) {
    if (ps.exists("RandomizedParameters")) {
      std::vector<edm::ParameterSet> randomizedParameters =
          ps.getParameter<std::vector<edm::ParameterSet> >("RandomizedParameters");
      randomInitWeights_.resize(randomizedParameters.size());
      randomInitConfigDescriptions_.resize(randomizedParameters.size());
      gridpackPaths_.resize(randomizedParameters.size());
      for (unsigned int irand = 0; irand < randomizedParameters.size(); ++irand) {
        randomInitWeights_[irand] = randomizedParameters[irand].getParameter<double>("ConfigWeight");
        if (randomizedParameters[irand].exists("ConfigDescription")) {
          randomInitConfigDescriptions_[irand] =
              randomizedParameters[irand].getParameter<std::string>("ConfigDescription");
        }
        if (randomizedParameters[irand].exists("GridpackPath")) {
          gridpackPaths_[irand] = randomizedParameters[irand].getParameter<std::string>("GridpackPath");
        }
      }
    } else {
      if (ps.exists("GridpackPath")) {
        gridpackPaths_[0] = ps.getParameter<std::string>("GridpackPath");
      }
    }
 
    runInfo().setFilterEfficiency(ps.getUntrackedParameter<double>("filterEfficiency", -1.));
    runInfo().setExternalXSecLO(GenRunInfoProduct::XSec(ps.getUntrackedParameter<double>("crossSection", -1.)));
    runInfo().setExternalXSecNLO(GenRunInfoProduct::XSec(ps.getUntrackedParameter<double>("crossSectionNLO", -1.)));
  }
 
  std::unique_ptr<GenLumiInfoHeader> BaseHadronizer::getGenLumiInfoHeader() const {
    auto genLumiInfoHeader = std::make_unique<GenLumiInfoHeader>();
 
    //fill information on randomized configs for parameter scans
    genLumiInfoHeader->setRandomConfigIndex(randomIndex_);
    if (randomIndex_ >= 0) {
      genLumiInfoHeader->setConfigDescription(randomInitConfigDescription());
    }
 
    return genLumiInfoHeader;
  }
 
  void BaseHadronizer::randomizeIndex(edm::LuminosityBlock const& lumi, CLHEP::HepRandomEngine* rengine) {
    if (!randomInitWeights_.empty()) {
      //randomly select from a list of provided configuration sets (for parameter scans)
 
      //seeds std 32-bit mersene twister with HepRandomEngine state plus run and lumi section numbers
      //(random engine state will be the same for every lumi section in a job)
      std::vector<long unsigned int> seeds = rengine->put();
      seeds.push_back(lumi.id().run());
      seeds.push_back(lumi.id().luminosityBlock());
      std::seed_seq seedseq(seeds.begin(), seeds.end());
      std::mt19937 randgen(seedseq);
      std::discrete_distribution<int> randdist(randomInitWeights_.begin(), randomInitWeights_.end());
 
      randomIndex_ = randdist(randgen);
    }
  }
 
  void BaseHadronizer::generateLHE(edm::LuminosityBlock const& lumi,
                                   CLHEP::HepRandomEngine* rengine,
                                   unsigned int ncpu) {
    if (gridpackPath().empty()) {
      return;
    }
 
    //get random seed from HepRandomEngine state plus run and lumi section numbers
    //(random engine state will be the same for every lumi section in a job)
    std::vector<long unsigned int> seeds = rengine->put();
    seeds.push_back(lumi.id().run());
    seeds.push_back(lumi.id().luminosityBlock());
    std::seed_seq seedseq(seeds.begin(), seeds.end());
    std::array<unsigned int, 1> lheseed;
    seedseq.generate(lheseed.begin(), lheseed.end());
 
    constexpr unsigned int maxseed = 30081 * 30081;  //madgraph cannot handle seeds larger than this
    unsigned int seedval = lheseed[0] % (maxseed + 1);
 
    unsigned int nevents = edm::pset::Registry::instance()
                               ->getMapped(lumi.processHistory().rbegin()->parameterSetID())
                               ->getParameter<edm::ParameterSet>("@main_input")
                               .getUntrackedParameter<unsigned int>("numberEventsInLuminosityBlock");
 
    std::ostringstream nevStream;
    nevStream << nevents;
 
    std::ostringstream randomStream;
    randomStream << seedval;
 
    edm::FileInPath script("GeneratorInterface/LHEInterface/data/run_generic_tarball_cvmfs.sh");
    const char* outfilename = "cmsgrid_final.lhe";
 
    std::array<std::string, 5> argStrs;
    argStrs[0] = script.fullPath();
    argStrs[1] = gridpackPath();
    argStrs[2] = nevStream.str();
    argStrs[3] = randomStream.str();
    argStrs[4] = std::to_string(ncpu);
    std::array<char*, 6> args{
        {&argStrs[0][0], &argStrs[1][0], &argStrs[2][0], &argStrs[3][0], &argStrs[4][0], nullptr}};
 
    pid_t pid = fork();
 
    if (pid == -1) {
      // error, failed to fork()
      throw cms::Exception("BaseHadronizer::generateLHE") << "Unable to fork a child";
    } else if (pid == 0) {
      //child
      execvp(args[0], std::begin(args));
      _exit(1);  // exec never returns
    } else {
      //parent
      int status;
      waitpid(pid, &status, 0);
      if (status) {
        throw cms::Exception("BaseHadronizer::generateLHE") << "Failed to execute script";
      }
    }
    FILE* lhef = std::fopen(outfilename, "r");
    if (!lhef) {
      throw cms::Exception("BaseHadronizer::generateLHE") << "Output file " << outfilename << " not found.";
    }
    std::fclose(lhef);
 
    lheFile_ = outfilename;
  }
 
  void BaseHadronizer::cleanLHE() {
    if (lheFile_.empty()) {
      return;
    }
 
    std::remove(lheFile_.c_str());
  }
 
}  // namespace gen