thread_local_storage.h

// ---------------------------------------------------------------------
//
// Copyright (C) 2011 - 2017 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_thread_local_storage_h
#  define dealii_thread_local_storage_h


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

#  ifdef DEAL_II_WITH_THREADS
#    include <tbb/enumerable_thread_specific.h>
#  endif



DEAL_II_NAMESPACE_OPEN



namespace Threads
{
  template <typename T>
  class ThreadLocalStorage
  {
  public:
    ThreadLocalStorage() = default;

    explicit ThreadLocalStorage(const T &t);

    ThreadLocalStorage(const ThreadLocalStorage<T> &t);

    T &
    get();

    T &
    get(bool &exists);

    operator T &();

    ThreadLocalStorage<T> &
    operator=(const T &t);

    void
    clear();

#  ifdef DEAL_II_WITH_THREADS
    tbb::enumerable_thread_specific<T> &
#  else
    T &
#  endif
    get_implementation();

  private:
#  ifdef DEAL_II_WITH_THREADS

    tbb::enumerable_thread_specific<T> data;
#  else
    T data;
#  endif
  };

  // ----------------- inline and template functions --------------------------

  template <typename T>
  inline ThreadLocalStorage<T>::ThreadLocalStorage(const T &t)
    : data(t)
  {}


  template <typename T>
  inline ThreadLocalStorage<T>::ThreadLocalStorage(
    const ThreadLocalStorage<T> &t)
    : data(t)
  {}


  template <typename T>
  inline T &
  ThreadLocalStorage<T>::get()
  {
#  ifdef DEAL_II_WITH_THREADS
    return data.local();
#  else
    return data;
#  endif
  }


  template <typename T>
  inline T &
  ThreadLocalStorage<T>::get(bool &exists)
  {
#  ifdef DEAL_II_WITH_THREADS
    return data.local(exists);
#  else
    exists = true;
    return data;
#  endif
  }


  template <typename T>
  inline ThreadLocalStorage<T>::operator T &()
  {
    return get();
  }


  template <typename T>
  inline ThreadLocalStorage<T> &
  ThreadLocalStorage<T>::operator=(const T &t)
  {
    get() = t;
    return *this;
  }


  template <typename T>
  inline
#  ifdef DEAL_II_WITH_THREADS
    tbb::enumerable_thread_specific<T> &
#  else
    T &
#  endif
    ThreadLocalStorage<T>::get_implementation()
  {
    return data;
  }



  template <typename T>
  inline void
  ThreadLocalStorage<T>::clear()
  {
#  ifdef DEAL_II_WITH_THREADS
    data.clear();
#  else
    data = T{};
#  endif
  }
} // namespace Threads

//---------------------------------------------------------------------------
DEAL_II_NAMESPACE_CLOSE
// end of #ifndef dealii_thread_local_storage_h
#endif
//---------------------------------------------------------------------------