subscriptor.h

// ---------------------------------------------------------------------
//
// Copyright (C) 1998 - 2019 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, redistribute
// it, and/or modify it under the terms of the GNU Lesser General
// Public License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// The full text of the license can be found in the file LICENSE.md at
// the top level directory of deal.II.
//
// ---------------------------------------------------------------------

#ifndef dealii_subscriptor_h
#define dealii_subscriptor_h


#include <deal.II/base/config.h>

#include <deal.II/base/exceptions.h>

#include <atomic>
#include <cstring>
#include <map>
#include <mutex>
#include <string>
#include <typeinfo>
#include <vector>

DEAL_II_NAMESPACE_OPEN

class Subscriptor
{
public:
  Subscriptor();

  Subscriptor(const Subscriptor &);

  Subscriptor(Subscriptor &&) noexcept;

  virtual ~Subscriptor();

  Subscriptor &
  operator=(const Subscriptor &);

  Subscriptor &
  operator=(Subscriptor &&) noexcept;

  void
  subscribe(std::atomic<bool> *const validity,
            const std::string &      identifier = "") const;

  void
  unsubscribe(std::atomic<bool> *const validity,
              const std::string &      identifier = "") const;

  unsigned int
  n_subscriptions() const;

  template <typename StreamType>
  void
  list_subscribers(StreamType &stream) const;

  void
  list_subscribers() const;

  DeclException3(ExcInUse,
                 int,
                 std::string,
                 std::string,
                 << "Object of class " << arg2 << " is still used by " << arg1
                 << " other objects."
                 << "\n\n"
                 << "(Additional information: " << arg3 << ")\n\n"
                 << "See the entry in the Frequently Asked Questions of "
                 << "deal.II (linked to from http://www.dealii.org/) for "
                 << "a lot more information on what this error means and "
                 << "how to fix programs in which it happens.");

  DeclException2(ExcNoSubscriber,
                 std::string,
                 std::string,
                 << "No subscriber with identifier <" << arg2
                 << "> subscribes to this object of class " << arg1
                 << ". Consequently, it cannot be unsubscribed.");

  template <class Archive>
  void
  serialize(Archive &ar, const unsigned int version);

private:
  mutable std::atomic<unsigned int> counter;

  mutable std::map<std::string, unsigned int> counter_map;

  using map_value_type = decltype(counter_map)::value_type;

  using map_iterator = decltype(counter_map)::iterator;

  mutable std::vector<std::atomic<bool> *> validity_pointers;

  mutable const std::type_info *object_info;

  void
  check_no_subscribers() const noexcept;

  static std::mutex mutex;
};

//---------------------------------------------------------------------------

inline Subscriptor::Subscriptor()
  : counter(0)
  , object_info(nullptr)
{}



inline Subscriptor::Subscriptor(const Subscriptor &)
  : counter(0)
  , object_info(nullptr)
{}



inline Subscriptor &
Subscriptor::operator=(const Subscriptor &s)
{
  object_info = s.object_info;
  return *this;
}



inline unsigned int
Subscriptor::n_subscriptions() const
{
  return counter;
}



template <class Archive>
inline void
Subscriptor::serialize(Archive &, const unsigned int)
{
  // do nothing, as explained in the
  // documentation of this function
}

template <typename StreamType>
inline void
Subscriptor::list_subscribers(StreamType &stream) const
{
  std::lock_guard<std::mutex> lock(mutex);

  for (const auto &it : counter_map)
    stream << it.second << '/' << counter << " subscriptions from \""
           << it.first << '\"' << std::endl;
}

DEAL_II_NAMESPACE_CLOSE

#endif