heap.hpp

// Copyright 2020-2025 UnoDB contributors
#ifndef UNODB_DETAIL_HEAP_HPP
#define UNODB_DETAIL_HEAP_HPP

/// \file
/// Aligned heap memory allocation.

// Should be the first include
#include "global.hpp"

#include <algorithm>
#ifndef NDEBUG
#include <cerrno>
#endif
#include <cstdlib>
#include <new>

#ifdef _MSC_VER
#include <malloc.h>
#endif

#include "assert.hpp"
#include "test_heap.hpp"

namespace unodb::detail {

/// Get minimum alignment to use when allocating objects of type \a T.
template <typename T>
[[nodiscard]] consteval std::size_t alignment_for_new() noexcept {
  return std::max(alignof(T),
                  static_cast<std::size_t>(__STDCPP_DEFAULT_NEW_ALIGNMENT__));
}

/// Allocate aligned heap memory.
///
/// The allocated block should be freed with free_aligned(). In debug builds,
/// the allocation failure injector is hooked.
///
/// \param size Size of memory to allocate in bytes
/// \param alignment Memory alignment boundary
/// \return Pointer to allocated memory block
/// \throws `std::bad_alloc` if the allocation fails
[[nodiscard]] inline void* allocate_aligned(
    std::size_t size,
    std::size_t alignment = __STDCPP_DEFAULT_NEW_ALIGNMENT__) {
#ifndef NDEBUG
  unodb::test::allocation_failure_injector::maybe_fail();
#endif

  void* result;

#ifndef _MSC_VER
  const auto err = posix_memalign(&result, alignment, size);
  if (UNODB_DETAIL_UNLIKELY(err != 0)) result = nullptr;
#else
  result = _aligned_malloc(size, alignment);
#ifndef NDEBUG
  const auto err = UNODB_DETAIL_LIKELY(result != nullptr) ? 0 : errno;
#endif
#endif

  UNODB_DETAIL_ASSERT(err != EINVAL);
  // NOLINTNEXTLINE(readability-simplify-boolean-expr)
  UNODB_DETAIL_ASSERT(result != nullptr || err == ENOMEM);

  if (UNODB_DETAIL_UNLIKELY(result == nullptr)) {
    throw std::bad_alloc{};  // LCOV_EXCL_LINE
  }

  return result;
}

/// Free heap memory allocated with allocate_aligned().
inline void free_aligned(void* ptr) noexcept {
#ifndef _MSC_VER
  // NOLINTNEXTLINE(cppcoreguidelines-no-malloc,cppcoreguidelines-owning-memory,hicpp-no-malloc)
  free(ptr);
#else
  _aligned_free(ptr);
#endif
}

}  // namespace unodb::detail

#endif  // UNODB_DETAIL_HEAP_HPP