file_handle.hpp

/*
 * Copyright (c) 2021-2025, NVIDIA CORPORATION.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 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.
 */
#pragma once
 
#include <sys/stat.h>
#include <sys/types.h>
 
#include <cstddef>
#include <cstdlib>
#include <stdexcept>
#include <system_error>
#include <utility>
 
#include <kvikio/buffer.hpp>
#include <kvikio/cufile/config.hpp>
#include <kvikio/defaults.hpp>
#include <kvikio/error.hpp>
#include <kvikio/parallel_operation.hpp>
#include <kvikio/posix_io.hpp>
#include <kvikio/shim/cufile.hpp>
#include <kvikio/stream.hpp>
#include <kvikio/utils.hpp>
 
namespace kvikio {
 
class FileHandle {
 private:
  // We use two file descriptors, one opened with the O_DIRECT flag and one without.
  int _fd_direct_on{-1};
  int _fd_direct_off{-1};
  bool _initialized{false};
  CompatMode _compat_mode{CompatMode::AUTO};
  mutable std::size_t _nbytes{0};  // The size of the underlying file, zero means unknown.
  CUfileHandle_t _handle{};
 
  bool is_compat_mode_preferred_for_async(CompatMode requested_compat_mode);
 
 public:
  static constexpr mode_t m644 = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH;
  FileHandle() noexcept        = default;
 
  FileHandle(const std::string& file_path,
             const std::string& flags = "r",
             mode_t mode              = m644,
             CompatMode compat_mode   = defaults::compat_mode());
 
  FileHandle(const FileHandle&)            = delete;
  FileHandle& operator=(FileHandle const&) = delete;
  FileHandle(FileHandle&& o) noexcept;
  FileHandle& operator=(FileHandle&& o) noexcept;
  ~FileHandle() noexcept;
 
  [[nodiscard]] bool closed() const noexcept;
 
  void close() noexcept;
 
  [[nodiscard]] CUfileHandle_t handle();
 
  [[nodiscard]] int fd() const noexcept;
 
  [[nodiscard]] int fd_open_flags() const;
 
  [[nodiscard]] std::size_t nbytes() const;
 
  std::size_t read(void* devPtr_base,
                   std::size_t size,
                   std::size_t file_offset,
                   std::size_t devPtr_offset,
                   bool sync_default_stream = true);
 
  std::size_t write(const void* devPtr_base,
                    std::size_t size,
                    std::size_t file_offset,
                    std::size_t devPtr_offset,
                    bool sync_default_stream = true);
 
  std::future<std::size_t> pread(void* buf,
                                 std::size_t size,
                                 std::size_t file_offset   = 0,
                                 std::size_t task_size     = defaults::task_size(),
                                 std::size_t gds_threshold = defaults::gds_threshold(),
                                 bool sync_default_stream  = true);
 
  std::future<std::size_t> pwrite(const void* buf,
                                  std::size_t size,
                                  std::size_t file_offset   = 0,
                                  std::size_t task_size     = defaults::task_size(),
                                  std::size_t gds_threshold = defaults::gds_threshold(),
                                  bool sync_default_stream  = true);
 
  void read_async(void* devPtr_base,
                  std::size_t* size_p,
                  off_t* file_offset_p,
                  off_t* devPtr_offset_p,
                  ssize_t* bytes_read_p,
                  CUstream stream);
 
  [[nodiscard]] StreamFuture read_async(void* devPtr_base,
                                        std::size_t size,
                                        off_t file_offset   = 0,
                                        off_t devPtr_offset = 0,
                                        CUstream stream     = nullptr);
 
  void write_async(void* devPtr_base,
                   std::size_t* size_p,
                   off_t* file_offset_p,
                   off_t* devPtr_offset_p,
                   ssize_t* bytes_written_p,
                   CUstream stream);
 
  [[nodiscard]] StreamFuture write_async(void* devPtr_base,
                                         std::size_t size,
                                         off_t file_offset   = 0,
                                         off_t devPtr_offset = 0,
                                         CUstream stream     = nullptr);
 
  [[nodiscard]] bool is_compat_mode_preferred() const noexcept;
 
  [[nodiscard]] bool is_compat_mode_preferred_for_async() const noexcept;
};
 
}  // namespace kvikio