osrm-backend/include/util/mmap_file.hpp
2024-06-20 21:44:28 +02:00

88 lines
2.7 KiB
C++

#ifndef OSRM_UTIL_MMAP_FILE_HPP
#define OSRM_UTIL_MMAP_FILE_HPP
#include "util/exception.hpp"
#include "util/exception_utils.hpp"
#include "util/vector_view.hpp"
#include <boost/iostreams/device/mapped_file.hpp>
#include <filesystem>
namespace osrm::util
{
namespace detail
{
template <typename T, typename MmapContainerT>
util::vector_view<T> mmapFile(const std::filesystem::path &file, MmapContainerT &mmap_container)
{
try
{
auto path_string = file.string();
mmap_container.open(path_string);
std::size_t num_objects = mmap_container.size() / sizeof(T);
auto data_ptr = mmap_container.data();
BOOST_ASSERT(reinterpret_cast<uintptr_t>(data_ptr) % alignof(T) == 0);
return util::vector_view<T>(reinterpret_cast<T *>(data_ptr), num_objects);
}
catch (const std::exception &exc)
{
throw exception(
boost::str(boost::format("File %1% mapping failed: %2%") % file % exc.what()) +
SOURCE_REF);
}
}
template <typename T, typename MmapContainerT>
util::vector_view<T>
mmapFile(const std::filesystem::path &file, MmapContainerT &mmap_container, const std::size_t size)
{
try
{
// Create a new file with the given size in bytes
boost::iostreams::mapped_file_params params;
params.path = file.string();
params.flags = boost::iostreams::mapped_file::readwrite;
params.new_file_size = size;
mmap_container.open(params);
std::size_t num_objects = size / sizeof(T);
auto data_ptr = mmap_container.data();
BOOST_ASSERT(reinterpret_cast<uintptr_t>(data_ptr) % alignof(T) == 0);
return util::vector_view<T>(reinterpret_cast<T *>(data_ptr), num_objects);
}
catch (const std::exception &exc)
{
throw exception(
boost::str(boost::format("File %1% mapping failed: %2%") % file % exc.what()) +
SOURCE_REF);
}
}
} // namespace detail
template <typename T>
util::vector_view<const T> mmapFile(const std::filesystem::path &file,
boost::iostreams::mapped_file_source &mmap_container)
{
return detail::mmapFile<const T>(file, mmap_container);
}
template <typename T>
util::vector_view<T> mmapFile(const std::filesystem::path &file,
boost::iostreams::mapped_file &mmap_container)
{
return detail::mmapFile<T>(file, mmap_container);
}
template <typename T>
util::vector_view<T> mmapFile(const std::filesystem::path &file,
boost::iostreams::mapped_file &mmap_container,
std::size_t size)
{
return detail::mmapFile<T>(file, mmap_container, size);
}
} // namespace osrm::util
#endif