LammpsLoader.h

Go to the documentation of this file.

/*
** This file is part of eOn.
**
** SPDX-License-Identifier: BSD-3-Clause
**
** Copyright (c) 2010--present, eOn Development Team
** All rights reserved.
**
** Repo:
** https://github.com/TheochemUI/eOn
*/
#pragma once

 
#include "eon/DynLib.h"
 
#include <stdexcept>
#include <string>
 
#ifdef EONMPI
#include <mpi.h>
#endif
 
namespace eonc {
 
// ---------------------------------------------------------------------------
// ILammpsLoader: injectable ABI. Production uses LammpsLoader::instance().
// ---------------------------------------------------------------------------
class ILammpsLoader {
public:
  // LAMMPS C API function pointer types (from library.h)
  using open_no_mpi_fn = void *(*)(int, char **, void **);
  using close_fn = void (*)(void *);
  using command_fn = char *(*)(void *, const char *);
  using file_fn = void (*)(void *, const char *);
  using scatter_atoms_fn = void (*)(void *, const char *, int, int, void *);
  using extract_var_fn = void *(*)(void *, const char *, const char *);
#ifdef EONMPI
  using open_mpi_fn = void *(*)(int, char **, MPI_Comm, void **);
#endif
 
  open_no_mpi_fn open_no_mpi{nullptr};
  close_fn close{nullptr};
  command_fn command{nullptr};
  file_fn file{nullptr};
  scatter_atoms_fn scatter_atoms{nullptr};
  extract_var_fn extract_variable{nullptr};
#ifdef EONMPI
  open_mpi_fn open_mpi{nullptr};
#endif
 
  virtual ~ILammpsLoader() = default;
  virtual void require_loaded() = 0;
  [[nodiscard]] virtual bool is_loaded() const noexcept = 0;
  [[nodiscard]] virtual bool available() const = 0;
  [[nodiscard]] virtual const std::string &last_error() const noexcept = 0;
 
  ILammpsLoader(const ILammpsLoader &) = delete;
  ILammpsLoader &operator=(const ILammpsLoader &) = delete;
 
protected:
  ILammpsLoader() = default;
};
 
// ---------------------------------------------------------------------------
// LammpsLoader: process-default loader (Meyer's singleton). Does not dlopen
// until require_loaded().
// ---------------------------------------------------------------------------
class LammpsLoader : public ILammpsLoader {
public:
  static LammpsLoader &instance();
 
  [[nodiscard]] bool is_loaded() const noexcept override { return m_loaded; }

  [[nodiscard]] bool available() const override;

  [[nodiscard]] const std::string &last_error() const noexcept override {
    return m_last_error;
  }

  void require_loaded() override;
 
  LammpsLoader(const LammpsLoader &) = delete;
  LammpsLoader &operator=(const LammpsLoader &) = delete;
 
private:
  LammpsLoader() = default;
  ~LammpsLoader() override;
 
  void ensure_loaded();
 
  bool m_loaded{false};
  bool m_tried{false};
  dynlib::Handle m_handle{};
  std::string m_last_error{};

  template <typename Fn> Fn load_sym(const char *name) {
    return reinterpret_cast<Fn>(dynlib::sym(m_handle, name));
  }
};
 
} // namespace eonc