RandomSeedManager.h

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#ifndef MARLINMT_RANDOMSEEDMANAGER_h
#define MARLINMT_RANDOMSEEDMANAGER_h 1

// -- std headers
#include <map>
#include <random>
#include <memory>
#include <functional>
#include <unordered_set>

namespace marlinmt {

  class EventStore ;

  class RandomSeedManager {
  public:
    RandomSeedManager(const RandomSeedManager&) = delete ;
    RandomSeedManager& operator=(const RandomSeedManager&) = delete ;
    ~RandomSeedManager() = default ;

  public:
    // typedefs
    typedef unsigned int                                        SeedType ;
    typedef std::hash<const void*>                              HashFunction ;
    typedef const void *                                        HashArgument ;
    typedef std::size_t                                         HashResult ;
    typedef std::unordered_set<HashResult>                      EntryList ;
    typedef std::map<HashResult, SeedType>                      RandomSeedMap ;
    typedef std::mt19937                                        RandomGenerator ;
    typedef std::uniform_int_distribution<SeedType>             RandomDistribution ;
    // constants
    static const SeedType MinSeed = 0 ;
    static const SeedType MaxSeed = std::numeric_limits<SeedType>::max() ;

  public:
    RandomSeedManager( SeedType globalSeed = static_cast<unsigned int>(time(nullptr)) ) ;

    void addEntry( HashResult entry ) ;

    void addEntry( HashArgument arg ) ;

    std::unique_ptr<RandomSeedMap> generateRandomSeeds( const EventStore * const evt ) ;

  private:
    SeedType getRandom() ;

  private:
    SeedType                _globalSeed {0} ;
    EntryList               _entryList {} ;
    RandomGenerator         _generator {_globalSeed} ;
    RandomDistribution      _rdmDistribution {MinSeed, MaxSeed} ;
  };

} // end namespace marlinmt

#endif