////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2014-2019, Lawrence Livermore National Security, LLC.
// Produced at the Lawrence Livermore National Laboratory.
// Written by the LBANN Research Team (B. Van Essen, et al.) listed in
// the CONTRIBUTORS file. <lbann-dev@llnl.gov>
//
// LLNL-CODE-697807.
// All rights reserved.
//
// This file is part of LBANN: Livermore Big Artificial Neural Network
// Toolkit. For details, see http://software.llnl.gov/LBANN or
// https://github.com/LLNL/LBANN.
//
// Licensed under the Apache License, Version 2.0 (the "Licensee"); you
// may not use this file except in compliance with the License.  You may
// obtain a copy of the License at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the license.
////////////////////////////////////////////////////////////////////////////////

#ifndef LBANN_UNIT_TEST_MPI_TEST_HELPERS_HPP_
#define LBANN_UNIT_TEST_MPI_TEST_HELPERS_HPP_

#include <lbann/comm.hpp>
#include <lbann/utils/exception.hpp>

#include <stdexcept>
#include <string>

#define LBANN_ASSERT_POINTER(ptr)                                       \
  do {                                                                  \
  if (!ptr)                                                             \
    throw ::unit_test::utilities::BadPointer(                           \
      __FILE__, __LINE__, #ptr);                                        \
  } while (false)

namespace unit_test {
namespace utilities {

struct BadPointer : std::runtime_error
{
  BadPointer(std::string const& file, unsigned int line,
             std::string const& var_name)
    : std::runtime_error{
      lbann::build_string(
        file, ":", line, ": \"", var_name, "\" is null.")}
  {}
};

/** @brief Get the world communicator for this MPI session. */
lbann::lbann_comm& current_world_comm();

// Sizes are not signed.
template <typename T>
size_t as_size(T const& size) noexcept { return static_cast<size_t>(size); }

/** @brief Expert-only methods */
namespace expert {

/** @brief Set the world communicator for this session.
 *
 *  @warning This may only be called in main().
 */
void register_world_comm(lbann::lbann_comm& comm) noexcept;

/** @brief Clear the world communicator for this session.
 *
 *  @warning This may only be called in main().
 */
void reset_world_comm() noexcept;
} // namespace expert
} // namespace utilities
} // namespace unit_test
#endif // LBANN_UNIT_TEST_MPI_TEST_HELPERS_HPP_
