sRNG.cc

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/*
  Implementation of class sRNG

  - separators: X
  - doxygen: X
  - default initialization: X
  - CASTOR_DEBUG: none
  - CASTOR_VERBOSE: X
*/

#include "sRNG.hh"

sRNG *sRNG::mp_Instance = NULL;


// =====================================================================
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sRNG::sRNG()
{
  mp_Instance = NULL;
  m_verbose = 5;
  mp_Engines.clear();
  mp_NonThreadedEngine = NULL;
}



// =====================================================================
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/*
  \brief Destructor of sRNG. Do nothing by default
*/
sRNG::~sRNG()
{
  if(mp_NonThreadedEngine) delete mp_NonThreadedEngine;
}



// =====================================================================
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/*
  \fn Initialize
  \param a_nbThreads
  \brief Instanciate a number of RNG according to the number of threads used in openMP
  \details It uses a std::random_device as initial seed for each thread
  \return 0 if success, positive value otherwise
*/
int sRNG::Initialize(int a_nbThreads)
{
  if(m_verbose >=3) if(m_verbose>=3) Cout("sRNG::Initialize ..."<< endl); 
  
  for(int th=0; th<a_nbThreads; th++)
  {
    std::random_device rd;
    mp_Engines.push_back(Engine(rd()));
  }

  std::random_device rd_single;
  mp_NonThreadedEngine = new Engine(rd_single());
    
  return 0;
}



// =====================================================================
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int sRNG::Initialize(int64_t a_seed, int a_nbThreads)
{
  if(m_verbose >=3) Cout("sRNG::Initialize with provided seed..."<< endl); 
    
  if (a_seed<0)
  {
    Cout("***** sRNG::Initialize()-> Error : seed for RNG should be >=0 !" << endl);
    return 1;
  }
  
  for(int th=0; th<a_nbThreads; th++)
  {
    mp_Engines.push_back(Engine(a_seed));
    if(m_verbose>=3) Cout("sRNG::Initialize()->Seed for thread "<< th << " : " << a_seed << endl);
    a_seed++;
  }

  mp_NonThreadedEngine = new Engine(a_seed);

  return 0;
}



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/*
  \fn GenerateRdmNber
  \brief Generate a random number for the thread whose index is recovered from the ompenMP function
  \todo Perhaps getting the thread index from argument rather than directly from the function.
  \todo But this implementation allows the RNG to be used anywhere in the code
  \todo Perhaps create a random distribution on the fly, and offer the possibility to select lower/upper bounds via argument parameters
  \return a random generated number in [0. ; 1.)
*/
double sRNG::GenerateRdmNber()
{
  #ifdef CASTOR_VERBOSE
  if(m_verbose >=4) Cout("sRNG::GenerateRdmNber..."<< endl); 
  #endif
  
  int id=0;
  #ifdef CASTOR_OMP
  id = omp_get_thread_num();
  #endif
  return mp_Distribution(mp_Engines[id]);
} 



// =====================================================================
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/*
  \fn GenerateNonThreadedRdmNber
  \brief Generate a random number using the not thread safe random generator, for use in sequential
  parts of an otherwise multithreaded code
  \return double random number
*/
double sRNG::GenerateNonThreadedRdmNber()
{
  #ifdef CASTOR_VERBOSE
  if(m_verbose >=4) Cout("sRNG::GenerateNonThreadedRdmNber..."<< endl); 
  #endif
  
  return mp_Distribution((*mp_NonThreadedEngine));
} 



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/*
  \fn GetNonThreadedGenerator
  \brief Get the not thread safe random generator, for use in sequential
  parts of an otherwise multithreaded code
  \return double random number
*/
sRNG::Engine* sRNG::GetNonThreadedGenerator()
{
   #ifdef CASTOR_VERBOSE
  if(m_verbose >=4) Cout("sRNG::GetNonThreadedGenerator..."<< endl); 
  #endif
  
  return mp_NonThreadedEngine;
}