DataSynchronizeBuffer.cc

// -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
//-----------------------------------------------------------------------------
// Copyright 2000-2026 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
// See the top-level COPYRIGHT file for details.
// SPDX-License-Identifier: Apache-2.0
//-----------------------------------------------------------------------------
/*---------------------------------------------------------------------------*/
/* DataSynchronizeBuffer.cc                                    (C) 2000-2026 */
/*                                                                           */
/* Implementation of a generic buffer for data synchronization.              */
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
#include "arcane/impl/internal/DataSynchronizeBuffer.h"
 
#include "arcane/utils/FatalErrorException.h"
#include "arcane/utils/internal/MemoryBuffer.h"
 
#include "arcane/impl/DataSynchronizeInfo.h"
#include "arcane/impl/internal/IBufferCopier.h"
 
#include "arcane/accelerator/core/Runner.h"
#include "arcane/utils/FixedArray.h"
#include "arcane/utils/ITraceMng.h"
 
#include <cstddef>
#include <cstring>
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
namespace Arcane
{
 
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/*---------------------------------------------------------------------------*/
 
namespace
{
  constexpr Int64 ALIGNEMENT_SIZE = 64;
  Int64 _applyPadding(Int64 original_size)
  {
    Int64 modulo = original_size % ALIGNEMENT_SIZE;
    Int64 new_size = original_size;
    if (modulo != 0)
      new_size += (ALIGNEMENT_SIZE - modulo);
    if ((new_size % ALIGNEMENT_SIZE) != 0)
      ARCANE_FATAL("Bad padding");
    return new_size;
  }
  void _checkAlignment(const void* address)
  {
    auto a = reinterpret_cast<intptr_t>(address);
    intptr_t max_align = alignof(std::max_align_t);
    intptr_t modulo = a % max_align;
    if (modulo != 0)
      ARCANE_FATAL("Address '{0}' is not aligned (align={1}, modulo={2})", address, max_align, modulo);
  }
} // namespace
 
/*---------------------------------------------------------------------------*/
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void IDataSynchronizeBuffer::
copyAllSend()
{
  Int32 nb_rank = nbRank();
  for (Int32 i = 0; i < nb_rank; ++i)
    copySendAsync(i);
  barrier();
}
 
/*---------------------------------------------------------------------------*/
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void IDataSynchronizeBuffer::
copyAllReceive()
{
  Int32 nb_rank = nbRank();
  for (Int32 i = 0; i < nb_rank; ++i)
    copyReceiveAsync(i);
  barrier();
}
 
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/*---------------------------------------------------------------------------*/
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void DirectBufferCopier::
barrier()
{
  m_queue.barrier();
}
 
/*---------------------------------------------------------------------------*/
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void DataSynchronizeBufferBase::BufferInfo::
setGlobalBuffer(MutableMemoryView v)
{
  if (v.datatypeSize() != 1)
    ARCANE_FATAL("Global buffer has to use a datatype of size 1 (current={0})", v.datatypeSize());
  m_memory_view = v;
}
 
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Int64 DataSynchronizeBufferBase::BufferInfo::
displacement(Int32 rank_index) const
{
  return m_displacements[rank_index][0];
}
 
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Int64 DataSynchronizeBufferBase::BufferInfo::
localBufferSize(Int32 rank_index) const
{
  return m_local_buffer_size[rank_index];
}
 
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MutableMemoryView DataSynchronizeBufferBase::BufferInfo::
localBuffer(Int32 rank_index) const
{
  std::byte* data = m_memory_view.data();
  data += m_displacements[rank_index][0];
  const Int64 nb_byte = m_local_buffer_size[rank_index];
  return makeMutableMemoryView(data, 1, nb_byte);
}
 
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MutableMemoryView DataSynchronizeBufferBase::BufferInfo::
dataLocalBuffer(Int32 rank_index, Int32 data_index) const
{
  std::byte* data = m_memory_view.data();
  data += m_displacements[rank_index][data_index];
  const Int32 nb_item = m_buffer_info->nbItem(rank_index);
  return makeMutableMemoryView(data, m_datatype_sizes[data_index], nb_item);
}
 
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ConstArrayView<Int32> DataSynchronizeBufferBase::BufferInfo::
localIds(Int32 index) const
{
  return m_buffer_info->localIds(index);
}
 
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void DataSynchronizeBufferBase::BufferInfo::
initialize(ConstArrayView<Int32> datatype_sizes, const DataSynchronizeBufferInfoList* buffer_info)
{
  ARCANE_CHECK_POINTER(buffer_info);
  m_buffer_info = buffer_info;
  m_datatype_sizes = datatype_sizes;
  const Int32 nb_data = datatype_sizes.size();
  const Int32 nb_rank = buffer_info->nbRank();
  m_displacements.resize(nb_rank, nb_data);
  m_local_buffer_size.resize(nb_rank);
 
  // Calculates the offset for each data item from each rank
  // ensuring that the offset is a multiple of ALIGNMENT_SIZE
  Int64 data_offset = 0;
  m_total_size = 0;
  for (Int32 i = 0; i < nb_rank; ++i) {
    const Int32 nb_item = buffer_info->nbItem(i);
    Int64 local_buf_nb_byte = 0;
    for (Int32 d = 0; d < nb_data; ++d) {
      // Size needed for data \a d for rank \a i
      // Padding is applied to this size to achieve
      // a specific alignment.
      const Int64 nb_byte = _applyPadding(nb_item * datatype_sizes[d]);
      m_displacements[i][d] = data_offset;
      local_buf_nb_byte += nb_byte;
      data_offset += nb_byte;
    }
    m_local_buffer_size[i] = local_buf_nb_byte;
    m_total_size += local_buf_nb_byte;
  }
}
 
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/*---------------------------------------------------------------------------*/
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DataSynchronizeBufferBase::
DataSynchronizeBufferBase(DataSynchronizeInfo* sync_info, Ref<IBufferCopier> copier)
: m_sync_info(sync_info)
, m_buffer_copier(copier)
{
}
 
/*---------------------------------------------------------------------------*/
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Int32 DataSynchronizeBufferBase::
targetRank(Int32 index) const
{
  return m_sync_info->targetRank(index);
}
 
/*---------------------------------------------------------------------------*/
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void DataSynchronizeBufferBase::
barrier()
{
  m_buffer_copier->barrier();
}
 
/*---------------------------------------------------------------------------*/
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void DataSynchronizeBufferBase::
_compute(ConstArrayView<Int32> datatype_sizes)
{
  m_nb_rank = m_sync_info->size();
 
  m_ghost_buffer_info.initialize(datatype_sizes, &m_sync_info->receiveInfo());
  m_share_buffer_info.initialize(datatype_sizes, &m_sync_info->sendInfo());
  m_compare_sync_buffer_info.initialize(datatype_sizes, &m_sync_info->receiveInfo());
 
  _allocateBuffers();
}
 
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void DataSynchronizeBufferBase::
_allocateBuffers()
{
  const Int64 total_ghost_buffer = m_ghost_buffer_info.totalSize();
  const Int64 total_share_buffer = m_share_buffer_info.totalSize();
  Int64 total_compare_buffer = 0;
  if (m_is_compare_sync_values)
    total_compare_buffer = m_compare_sync_buffer_info.totalSize();
 
  Int64 total_size = total_ghost_buffer + total_share_buffer + total_compare_buffer;
  m_memory->resize(total_size);
 
  Int64 share_offset = total_ghost_buffer;
  Int64 check_sync_offset = share_offset + total_share_buffer;
 
  Span<std::byte> buffer_span = m_memory->bytes();
  auto s1 = buffer_span.subspan(0, share_offset);
  m_ghost_buffer_info.setGlobalBuffer(makeMutableMemoryView(s1.data(), 1, total_ghost_buffer));
  auto s2 = buffer_span.subspan(share_offset, total_share_buffer);
  m_share_buffer_info.setGlobalBuffer(makeMutableMemoryView(s2.data(), 1, total_share_buffer));
  if (m_is_compare_sync_values) {
    auto s3 = buffer_span.subspan(check_sync_offset, total_ghost_buffer);
    m_compare_sync_buffer_info.setGlobalBuffer(makeMutableMemoryView(s3.data(), 1, total_ghost_buffer));
  }
}
 
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void SingleDataSynchronizeBuffer::
copyReceiveAsync(Int32 index)
{
  m_ghost_buffer_info.checkValid();
 
  MutableMemoryView var_values = dataView();
  ConstArrayView<Int32> indexes = m_ghost_buffer_info.localIds(index);
  ConstMemoryView local_buffer = m_ghost_buffer_info.dataLocalBuffer(index, 0);
 
  m_buffer_copier->copyFromBufferAsync(indexes, local_buffer, var_values);
}
 
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void SingleDataSynchronizeBuffer::
copySendAsync(Int32 index)
{
  m_share_buffer_info.checkValid();
 
  ConstMemoryView var_values = dataView();
  ConstArrayView<Int32> indexes = m_share_buffer_info.localIds(index);
  MutableMemoryView local_buffer = m_share_buffer_info.dataLocalBuffer(index, 0);
  m_buffer_copier->copyToBufferAsync(indexes, local_buffer, var_values);
}
 
/*---------------------------------------------------------------------------*/
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void SingleDataSynchronizeBuffer::
prepareSynchronize(bool is_compare_sync)
{
  m_is_compare_sync_values = is_compare_sync;
 
  _compute(m_datatype_sizes.view());
 
  if (is_compare_sync) {
    // Recopy the current values of the ghost cells into the verification buffer.
    MutableMemoryView var_values = dataView();
    Int32 nb_rank = nbRank();
    for (Int32 i = 0; i < nb_rank; ++i) {
      ConstArrayView<Int32> indexes = m_compare_sync_buffer_info.localIds(i);
      MutableMemoryView local_buffer = m_compare_sync_buffer_info.dataLocalBuffer(i, 0);
      m_buffer_copier->copyToBufferAsync(indexes, local_buffer, var_values);
    }
    // Normally no need to perform a barrier, because there will be the
    // sends on the same queue and then a barrier.
  }
}
 
/*---------------------------------------------------------------------------*/
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DataSynchronizeResult SingleDataSynchronizeBuffer::
finalizeSynchronize()
{
  if (!m_is_compare_sync_values)
    return {};
  ConstMemoryView reference_buffer = m_compare_sync_buffer_info.globalBuffer();
  ConstMemoryView receive_buffer = m_ghost_buffer_info.globalBuffer();
  Span<const std::byte> reference_bytes = reference_buffer.bytes();
  Span<const std::byte> receive_bytes = receive_buffer.bytes();
  Int64 reference_size = reference_bytes.size();
  Int64 receive_size = receive_bytes.size();
  if (reference_size != receive_size)
    ARCANE_FATAL("Incoherent buffer size ref={0} receive={1}", reference_size, receive_size);
  // TODO: handle the case where memory is on the device
 
  DataSynchronizeResult result;
  bool is_same = std::memcmp(reference_bytes.data(), receive_bytes.data(), reference_size) == 0;
  result.setCompareStatus(is_same ? eDataSynchronizeCompareStatus::Same : eDataSynchronizeCompareStatus::Different);
  return result;
}
 
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/*---------------------------------------------------------------------------*/
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void MultiDataSynchronizeBuffer::
prepareSynchronize([[maybe_unused]] bool is_compare_sync)
{
  _compute(m_datatype_sizes);
}
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
void MultiDataSynchronizeBuffer::
copyReceiveAsync(Int32 rank_index)
{
  IBufferCopier* copier = m_buffer_copier.get();
  m_ghost_buffer_info.checkValid();
 
  ConstArrayView<Int32> local_ids = m_ghost_buffer_info.localIds(rank_index);
  Int32 data_index = 0;
  for (MutableMemoryView var_values : m_data_views) {
    ConstMemoryView local_buffer = m_ghost_buffer_info.dataLocalBuffer(rank_index, data_index);
    _checkAlignment(local_buffer.data());
    if (!local_buffer.bytes().empty())
      copier->copyFromBufferAsync(local_ids, local_buffer, var_values);
    ++data_index;
  }
}
 
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
 
void MultiDataSynchronizeBuffer::
copySendAsync(Int32 rank_index)
{
  IBufferCopier* copier = m_buffer_copier.get();
  m_ghost_buffer_info.checkValid();
 
  ConstArrayView<Int32> local_ids = m_share_buffer_info.localIds(rank_index);
  Int32 data_index = 0;
  for (ConstMemoryView var_values : m_data_views) {
    MutableMemoryView local_buffer = m_share_buffer_info.dataLocalBuffer(rank_index, data_index);
    _checkAlignment(local_buffer.data());
    if (!local_buffer.bytes().empty())
      copier->copyToBufferAsync(local_ids, local_buffer, var_values);
    ++data_index;
  }
}
 
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} // namespace Arcane
 
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