precice-hash.cpp

#define BOOST_ALL_DYN_LINK

#include <string>
#include <functional>
#include <iostream>
#include <boost/uuid/name_generator.hpp>
#include <boost/uuid/string_generator.hpp>
#include <boost/uuid/uuid_io.hpp>
#include <boost/filesystem.hpp>

// g++ -std=c++11  precice-hash.cpp  -lboost_system -lboost_filesystem

using namespace std;


size_t std_hash(std::string const & acceptorName,
                std::string const & requesterName,
                std::string const & mesh,
                int rank)
{
  std::string s = acceptorName + requesterName + std::to_string(rank);
  std::hash<std::string> h;
  return h(s);
}

std::string boost_hash(std::string const & acceptorName,
                       std::string const & requesterName,
                       std::string const & mesh,
                       int rank)
{
  boost::uuids::string_generator ns_gen;
  auto ns = ns_gen("af7ce8f2-a9ee-46cb-38ee-71c318aa3580"); // md5 hash of precice.org
                                              
  boost::uuids::name_generator_latest gen{ns};
  std::string s = acceptorName + requesterName + mesh + std::to_string(rank);
  std::string h = boost::uuids::to_string(gen(s));
  std::remove(h.begin(), h.end(), '-');
  return h;
}

void write_connection_info(std::string const & acceptorName,
                           std::string const & requesterName,
                           std::string const & mesh,
                           int rank,
                           std::string addressDirectory,
                           std::string info)
{
  using namespace boost::filesystem;
  const int firstLevelLen = 2;

  auto hash = boost_hash(acceptorName, requesterName, mesh, rank);

  cout << "Hash = " << hash << endl;
  path p = path(addressDirectory) / path(hash.substr(0, firstLevelLen));
  create_directories(p);

  p /= hash.substr(firstLevelLen);
  cout << p << endl;  

  std::ofstream ofs(p.string());
  ofs << info;
}

int main()
{
  cout << std_hash("a", "b", "m", 0) << endl;
  cout << std_hash("a", "b", "m", 1) << endl;
  cout << std_hash("a", "b", "m", 2) << endl;
  cout << std_hash("a", "b", "m", 3) << endl;
  cout << endl;
  cout << boost_hash("a", "b", "m", 0) << endl;
  cout << boost_hash("a", "b", "m", 1) << endl;
  cout << boost_hash("a", "b", "m", 2) << endl;
  cout << boost_hash("a", "b", "m", 3) << endl;
  cout << endl;
  write_connection_info("a", "b", "m", 0, "precice-conns", "info");
  return 0;
}