aligned_vector.h

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// ---------------------------------------------------------------------
//
// Copyright (C) 2011 - 2020 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_aligned_vector_h
#define dealii_aligned_vector_h

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

#include <deal.II/base/exceptions.h>
#include <deal.II/base/memory_consumption.h>
#include <deal.II/base/parallel.h>
#include <deal.II/base/utilities.h>

// boost::serialization::make_array used to be in array.hpp, but was
// moved to a different file in BOOST 1.64
#include <boost/version.hpp>
#if BOOST_VERSION >= 106400
#  include <boost/serialization/array_wrapper.hpp>
#else
#  include <boost/serialization/array.hpp>
#endif
#include <boost/serialization/split_member.hpp>

#include <cstring>
#include <type_traits>



DEAL_II_NAMESPACE_OPEN


template <class T>
class AlignedVector
{
public:
  using value_type      = T;
  using pointer         = value_type *;
  using const_pointer   = const value_type *;
  using iterator        = value_type *;
  using const_iterator  = const value_type *;
  using reference       = value_type &;
  using const_reference = const value_type &;
  using size_type       = std::size_t;

  AlignedVector();

  AlignedVector(const size_type size, const T &init = T());

  ~AlignedVector();

  AlignedVector(const AlignedVector<T> &vec);

  AlignedVector(AlignedVector<T> &&vec) noexcept;

  AlignedVector &
  operator=(const AlignedVector<T> &vec);

  AlignedVector &
  operator=(AlignedVector<T> &&vec) noexcept;

  void
  resize_fast(const size_type size);

  void
  resize(const size_type size_in);

  void
  resize(const size_type size_in, const T &init);

  void
  reserve(const size_type size_alloc);

  void
  clear();

  void
  push_back(const T in_data);

  reference
  back();

  const_reference
  back() const;

  template <typename ForwardIterator>
  void
  insert_back(ForwardIterator begin, ForwardIterator end);

  void
  fill();

  void
  fill(const T &element);

  void
  swap(AlignedVector<T> &vec);

  bool
  empty() const;

  size_type
  size() const;

  size_type
  capacity() const;

  reference operator[](const size_type index);

  const_reference operator[](const size_type index) const;

  pointer
  data();

  const_pointer
  data() const;

  iterator
  begin();

  iterator
  end();

  const_iterator
  begin() const;

  const_iterator
  end() const;

  size_type
  memory_consumption() const;

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

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

#ifdef DOXYGEN

  template <class Archive>
  void
  serialize(Archive &archive, const unsigned int version);
#else
  // This macro defines the serialize() method that is compatible with
  // the templated save() and load() method that have been implemented.
  BOOST_SERIALIZATION_SPLIT_MEMBER()
#endif

private:
  T *data_begin;

  T *data_end;

  T *allocated_end;
};


// ------------------------------- inline functions --------------------------

namespace internal
{
  template <typename T>
  class AlignedVectorCopy : private parallel::ParallelForInteger
  {
    static const std::size_t minimum_parallel_grain_size =
      160000 / sizeof(T) + 1;

  public:
    AlignedVectorCopy(const T *const source_begin,
                      const T *const source_end,
                      T *const       destination)
      : source_(source_begin)
      , destination_(destination)
    {
      Assert(source_end >= source_begin, ExcInternalError());
      Assert(source_end == source_begin || destination != nullptr,
             ExcInternalError());
      const std::size_t size = source_end - source_begin;
      if (size < minimum_parallel_grain_size)
        AlignedVectorCopy::apply_to_subrange(0, size);
      else
        apply_parallel(0, size, minimum_parallel_grain_size);
    }

    virtual void
    apply_to_subrange(const std::size_t begin,
                      const std::size_t end) const override
    {
      if (end == begin)
        return;

      // for classes trivial assignment can use memcpy. cast element to
      // (void*) to silence compiler warning for virtual classes (they will
      // never arrive here because they are non-trivial).

      if (std::is_trivial<T>::value == true)
        std::memcpy(static_cast<void *>(destination_ + begin),
                    static_cast<const void *>(source_ + begin),
                    (end - begin) * sizeof(T));
      else
        for (std::size_t i = begin; i < end; ++i)
          new (&destination_[i]) T(source_[i]);
    }

  private:
    const T *const source_;
    T *const       destination_;
  };


  template <typename T>
  class AlignedVectorMove : private parallel::ParallelForInteger
  {
    static const std::size_t minimum_parallel_grain_size =
      160000 / sizeof(T) + 1;

  public:
    AlignedVectorMove(T *const source_begin,
                      T *const source_end,
                      T *const destination)
      : source_(source_begin)
      , destination_(destination)
    {
      Assert(source_end >= source_begin, ExcInternalError());
      Assert(source_end == source_begin || destination != nullptr,
             ExcInternalError());
      const std::size_t size = source_end - source_begin;
      if (size < minimum_parallel_grain_size)
        AlignedVectorMove::apply_to_subrange(0, size);
      else
        apply_parallel(0, size, minimum_parallel_grain_size);
    }

    virtual void
    apply_to_subrange(const std::size_t begin,
                      const std::size_t end) const override
    {
      if (end == begin)
        return;

      // for classes trivial assignment can use memcpy. cast element to
      // (void*) to silence compiler warning for virtual classes (they will
      // never arrive here because they are non-trivial).

      if (std::is_trivial<T>::value == true)
        std::memcpy(static_cast<void *>(destination_ + begin),
                    static_cast<void *>(source_ + begin),
                    (end - begin) * sizeof(T));
      else
        for (std::size_t i = begin; i < end; ++i)
          {
            // initialize memory (copy construct by placement new), and
            // destruct the source
            new (&destination_[i]) T(std::move(source_[i]));
            source_[i].~T();
          }
    }

  private:
    T *const source_;
    T *const destination_;
  };


  template <typename T, bool initialize_memory>
  class AlignedVectorSet : private parallel::ParallelForInteger
  {
    static const std::size_t minimum_parallel_grain_size =
      160000 / sizeof(T) + 1;

  public:
    AlignedVectorSet(const std::size_t size,
                     const T &         element,
                     T *const          destination)
      : element_(element)
      , destination_(destination)
      , trivial_element(false)
    {
      if (size == 0)
        return;
      Assert(destination != nullptr, ExcInternalError());

      // do not use memcmp for long double because on some systems it does not
      // completely fill its memory and may lead to false positives in
      // e.g. valgrind
      if (std::is_trivial<T>::value == true &&
          std::is_same<T, long double>::value == false)
        {
          const unsigned char zero[sizeof(T)] = {};
          // cast element to (void*) to silence compiler warning for virtual
          // classes (they will never arrive here because they are
          // non-trivial).
          if (std::memcmp(zero,
                          static_cast<const void *>(&element),
                          sizeof(T)) == 0)
            trivial_element = true;
        }
      if (size < minimum_parallel_grain_size)
        AlignedVectorSet::apply_to_subrange(0, size);
      else
        apply_parallel(0, size, minimum_parallel_grain_size);
    }

    virtual void
    apply_to_subrange(const std::size_t begin,
                      const std::size_t end) const override
    {
      // for classes with trivial assignment of zero can use memset. cast
      // element to (void*) to silence compiler warning for virtual
      // classes (they will never arrive here because they are
      // non-trivial).
      if (std::is_trivial<T>::value == true && trivial_element)
        std::memset(static_cast<void *>(destination_ + begin),
                    0,
                    (end - begin) * sizeof(T));
      else
        copy_construct_or_assign(
          begin, end, std::integral_constant<bool, initialize_memory>());
    }

  private:
    const T &  element_;
    mutable T *destination_;
    bool       trivial_element;

    // copy assignment operation
    void
    copy_construct_or_assign(const std::size_t begin,
                             const std::size_t end,
                             std::integral_constant<bool, false>) const
    {
      for (std::size_t i = begin; i < end; ++i)
        destination_[i] = element_;
    }

    // copy constructor (memory initialization)
    void
    copy_construct_or_assign(const std::size_t begin,
                             const std::size_t end,
                             std::integral_constant<bool, true>) const
    {
      for (std::size_t i = begin; i < end; ++i)
        new (&destination_[i]) T(element_);
    }
  };



  template <typename T, bool initialize_memory>
  class AlignedVectorDefaultInitialize : private parallel::ParallelForInteger
  {
    static const std::size_t minimum_parallel_grain_size =
      160000 / sizeof(T) + 1;

  public:
    AlignedVectorDefaultInitialize(const std::size_t size, T *const destination)
      : destination_(destination)
    {
      if (size == 0)
        return;
      Assert(destination != nullptr, ExcInternalError());

      if (size < minimum_parallel_grain_size)
        AlignedVectorDefaultInitialize::apply_to_subrange(0, size);
      else
        apply_parallel(0, size, minimum_parallel_grain_size);
    }

    virtual void
    apply_to_subrange(const std::size_t begin,
                      const std::size_t end) const override
    {
      // for classes with trivial assignment of zero can use memset. cast
      // element to (void*) to silence compiler warning for virtual
      // classes (they will never arrive here because they are
      // non-trivial).
      if (std::is_trivial<T>::value == true)
        std::memset(static_cast<void *>(destination_ + begin),
                    0,
                    (end - begin) * sizeof(T));
      else
        default_construct_or_assign(
          begin, end, std::integral_constant<bool, initialize_memory>());
    }

  private:
    mutable T *destination_;

    // copy assignment operation
    void
    default_construct_or_assign(const std::size_t begin,
                                const std::size_t end,
                                std::integral_constant<bool, false>) const
    {
      for (std::size_t i = begin; i < end; ++i)
        destination_[i] = std::move(T());
    }

    // copy constructor (memory initialization)
    void
    default_construct_or_assign(const std::size_t begin,
                                const std::size_t end,
                                std::integral_constant<bool, true>) const
    {
      for (std::size_t i = begin; i < end; ++i)
        new (&destination_[i]) T;
    }
  };

} // end of namespace internal


#ifndef DOXYGEN


template <class T>
inline AlignedVector<T>::AlignedVector()
  : data_begin(nullptr)
  , data_end(nullptr)
  , allocated_end(nullptr)
{}



template <class T>
inline AlignedVector<T>::AlignedVector(const size_type size, const T &init)
  : data_begin(nullptr)
  , data_end(nullptr)
  , allocated_end(nullptr)
{
  if (size > 0)
    resize(size, init);
}



template <class T>
inline AlignedVector<T>::~AlignedVector()
{
  clear();
}



template <class T>
inline AlignedVector<T>::AlignedVector(const AlignedVector<T> &vec)
  : data_begin(nullptr)
  , data_end(nullptr)
  , allocated_end(nullptr)
{
  // copy the data from vec
  reserve(vec.data_end - vec.data_begin);
  data_end = allocated_end;
  internal::AlignedVectorCopy<T>(vec.data_begin, vec.data_end, data_begin);
}



template <class T>
inline AlignedVector<T>::AlignedVector(AlignedVector<T> &&vec) noexcept
  : data_begin(vec.data_begin)
  , data_end(vec.data_end)
  , allocated_end(vec.allocated_end)
{
  vec.data_begin    = nullptr;
  vec.data_end      = nullptr;
  vec.allocated_end = nullptr;
}



template <class T>
inline AlignedVector<T> &
AlignedVector<T>::operator=(const AlignedVector<T> &vec)
{
  resize(0);
  resize_fast(vec.data_end - vec.data_begin);
  internal::AlignedVectorCopy<T>(vec.data_begin, vec.data_end, data_begin);
  return *this;
}



template <class T>
inline AlignedVector<T> &
AlignedVector<T>::operator=(AlignedVector<T> &&vec) noexcept
{
  clear();

  data_begin    = vec.data_begin;
  data_end      = vec.data_end;
  allocated_end = vec.allocated_end;

  vec.data_begin    = nullptr;
  vec.data_end      = nullptr;
  vec.allocated_end = nullptr;

  return *this;
}



template <class T>
inline void
AlignedVector<T>::resize_fast(const size_type size_in)
{
  const size_type old_size = size();
  if (std::is_trivial<T>::value == false && size_in < old_size)
    {
      // call destructor on fields that are released. doing it backward
      // releases the elements in reverse order as compared to how they were
      // created
      while (data_end != data_begin + size_in)
        (--data_end)->~T();
    }
  reserve(size_in);
  data_end = data_begin + size_in;

  // need to still set the values in case the class is non-trivial because
  // virtual classes etc. need to run their (default) constructor
  if (std::is_trivial<T>::value == false && size_in > old_size)
    ::internal::AlignedVectorDefaultInitialize<T, true>(
      size_in - old_size, data_begin + old_size);
}



template <class T>
inline void
AlignedVector<T>::resize(const size_type size_in)
{
  const size_type old_size = size();
  if (std::is_trivial<T>::value == false && size_in < old_size)
    {
      // call destructor on fields that are released. doing it backward
      // releases the elements in reverse order as compared to how they were
      // created
      while (data_end != data_begin + size_in)
        (--data_end)->~T();
    }
  reserve(size_in);
  data_end = data_begin + size_in;

  // finally set the desired init values
  if (size_in > old_size)
    ::internal::AlignedVectorDefaultInitialize<T, true>(
      size_in - old_size, data_begin + old_size);
}



template <class T>
inline void
AlignedVector<T>::resize(const size_type size_in, const T &init)
{
  const size_type old_size = size();
  if (std::is_trivial<T>::value == false && size_in < old_size)
    {
      // call destructor on fields that are released. doing it backward
      // releases the elements in reverse order as compared to how they were
      // created
      while (data_end != data_begin + size_in)
        (--data_end)->~T();
    }
  reserve(size_in);
  data_end = data_begin + size_in;

  // finally set the desired init values
  if (size_in > old_size)
    ::internal::AlignedVectorSet<T, true>(size_in - old_size,
                                                init,
                                                data_begin + old_size);
}



template <class T>
inline void
AlignedVector<T>::reserve(const size_type size_alloc)
{
  const size_type old_size       = data_end - data_begin;
  const size_type allocated_size = allocated_end - data_begin;
  if (size_alloc > allocated_size)
    {
      // if we continuously increase the size of the vector, we might be
      // reallocating a lot of times. therefore, try to increase the size more
      // aggressively
      size_type new_size = size_alloc;
      if (size_alloc < (2 * allocated_size))
        new_size = 2 * allocated_size;

      const size_type size_actual_allocate = new_size * sizeof(T);

      // allocate and align along 64-byte boundaries (this is enough for all
      // levels of vectorization currently supported by deal.II)
      T *new_data;
      Utilities::System::posix_memalign(reinterpret_cast<void **>(&new_data),
                                        64,
                                        size_actual_allocate);

      // copy data in case there was some content before and release the old
      // memory with the function corresponding to the one used for allocating
      std::swap(data_begin, new_data);
      data_end      = data_begin + old_size;
      allocated_end = data_begin + new_size;
      if (data_end != data_begin)
        {
          ::internal::AlignedVectorMove<T>(new_data,
                                                 new_data + old_size,
                                                 data_begin);
          free(new_data);
        }
      else
        Assert(new_data == nullptr, ExcInternalError());
    }
  else if (size_alloc == 0)
    clear();
}



template <class T>
inline void
AlignedVector<T>::clear()
{
  if (data_begin != nullptr)
    {
      if (std::is_trivial<T>::value == false)
        while (data_end != data_begin)
          (--data_end)->~T();

      free(data_begin);
    }
  data_begin    = nullptr;
  data_end      = nullptr;
  allocated_end = nullptr;
}



template <class T>
inline void
AlignedVector<T>::push_back(const T in_data)
{
  Assert(data_end <= allocated_end, ExcInternalError());
  if (data_end == allocated_end)
    reserve(std::max(2 * capacity(), static_cast<size_type>(16)));
  if (std::is_trivial<T>::value == false)
    new (data_end++) T(in_data);
  else
    *data_end++ = in_data;
}



template <class T>
inline typename AlignedVector<T>::reference
AlignedVector<T>::back()
{
  AssertIndexRange(0, size());
  T *field = data_end - 1;
  return *field;
}



template <class T>
inline typename AlignedVector<T>::const_reference
AlignedVector<T>::back() const
{
  AssertIndexRange(0, size());
  const T *field = data_end - 1;
  return *field;
}



template <class T>
template <typename ForwardIterator>
inline void
AlignedVector<T>::insert_back(ForwardIterator begin, ForwardIterator end)
{
  const unsigned int old_size = size();
  reserve(old_size + (end - begin));
  for (; begin != end; ++begin, ++data_end)
    {
      if (std::is_trivial<T>::value == false)
        new (data_end) T;
      *data_end = *begin;
    }
}



template <class T>
inline void
AlignedVector<T>::fill()
{
  ::internal::AlignedVectorDefaultInitialize<T, false>(size(),
                                                             data_begin);
}



template <class T>
inline void
AlignedVector<T>::fill(const T &value)
{
  ::internal::AlignedVectorSet<T, false>(size(), value, data_begin);
}



template <class T>
inline void
AlignedVector<T>::swap(AlignedVector<T> &vec)
{
  std::swap(data_begin, vec.data_begin);
  std::swap(data_end, vec.data_end);
  std::swap(allocated_end, vec.allocated_end);
}



template <class T>
inline bool
AlignedVector<T>::empty() const
{
  return data_end == data_begin;
}



template <class T>
inline typename AlignedVector<T>::size_type
AlignedVector<T>::size() const
{
  return data_end - data_begin;
}



template <class T>
inline typename AlignedVector<T>::size_type
AlignedVector<T>::capacity() const
{
  return allocated_end - data_begin;
}



template <class T>
inline typename AlignedVector<T>::reference AlignedVector<T>::
                                            operator[](const size_type index)
{
  AssertIndexRange(index, size());
  return data_begin[index];
}



template <class T>
inline typename AlignedVector<T>::const_reference AlignedVector<T>::
                                                  operator[](const size_type index) const
{
  AssertIndexRange(index, size());
  return data_begin[index];
}



template <typename T>
inline typename AlignedVector<T>::pointer
AlignedVector<T>::data()
{
  return data_begin;
}



template <typename T>
inline typename AlignedVector<T>::const_pointer
AlignedVector<T>::data() const
{
  return data_begin;
}



template <class T>
inline typename AlignedVector<T>::iterator
AlignedVector<T>::begin()
{
  return data_begin;
}



template <class T>
inline typename AlignedVector<T>::iterator
AlignedVector<T>::end()
{
  return data_end;
}



template <class T>
inline typename AlignedVector<T>::const_iterator
AlignedVector<T>::begin() const
{
  return data_begin;
}



template <class T>
inline typename AlignedVector<T>::const_iterator
AlignedVector<T>::end() const
{
  return data_end;
}



template <class T>
template <class Archive>
inline void
AlignedVector<T>::save(Archive &ar, const unsigned int) const
{
  size_type vec_size(size());
  ar &      vec_size;
  if (vec_size > 0)
    ar &boost::serialization::make_array(data_begin, vec_size);
}



template <class T>
template <class Archive>
inline void
AlignedVector<T>::load(Archive &ar, const unsigned int)
{
  size_type vec_size = 0;
  ar &      vec_size;

  if (vec_size > 0)
    {
      reserve(vec_size);
      ar &boost::serialization::make_array(data_begin, vec_size);
      data_end = data_begin + vec_size;
    }
}



template <class T>
inline typename AlignedVector<T>::size_type
AlignedVector<T>::memory_consumption() const
{
  size_type memory = sizeof(*this);
  for (const T *t = data_begin; t != data_end; ++t)
    memory += ::MemoryConsumption::memory_consumption(*t);
  memory += sizeof(T) * (allocated_end - data_end);
  return memory;
}


#endif // ifndef DOXYGEN


template <class T>
bool
operator==(const AlignedVector<T> &lhs, const AlignedVector<T> &rhs)
{
  if (lhs.size() != rhs.size())
    return false;
  for (typename AlignedVector<T>::const_iterator lit = lhs.begin(),
                                                 rit = rhs.begin();
       lit != lhs.end();
       ++lit, ++rit)
    if (*lit != *rit)
      return false;
  return true;
}



template <class T>
bool
operator!=(const AlignedVector<T> &lhs, const AlignedVector<T> &rhs)
{
  return !(operator==(lhs, rhs));
}


DEAL_II_NAMESPACE_CLOSE

#endif