//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <errno.h>
#if defined(ROCKSDB_IOURING_PRESENT)
#include <liburing.h>
#include <sys/uio.h>
#endif
#include <unistd.h>
#include <atomic>
#include <string>
#include "rocksdb/env.h"
#include "util/thread_local.h"
#include "rocksdb/file_system.h"
#include "rocksdb/io_status.h"

// For non linux platform, the following macros are used only as place
// holder.
#if !(defined OS_LINUX) && !(defined CYGWIN) && !(defined OS_AIX)
#define POSIX_FADV_NORMAL 0     /* [MC1] no further special treatment */
#define POSIX_FADV_RANDOM 1     /* [MC1] expect random page refs */
#define POSIX_FADV_SEQUENTIAL 2 /* [MC1] expect sequential page refs */
#define POSIX_FADV_WILLNEED 3   /* [MC1] will need these pages */
#define POSIX_FADV_DONTNEED 4   /* [MC1] dont need these pages */
#endif

namespace rocksdb {
static std::string IOErrorMsg(const std::string& context,
                              const std::string& file_name) {
  if (file_name.empty()) {
    return context;
  }
  return context + ": " + file_name;
}

// file_name can be left empty if it is not unkown.
static IOStatus IOError(const std::string& context,
                        const std::string& file_name, int err_number) {
  switch (err_number) {
    case ENOSPC: {
      IOStatus s = IOStatus::NoSpace(IOErrorMsg(context, file_name),
                                     strerror(err_number));
      s.SetRetryable(true);
      return s;
    }
  case ESTALE:
    return IOStatus::IOError(IOStatus::kStaleFile);
  case ENOENT:
    return IOStatus::PathNotFound(IOErrorMsg(context, file_name),
                                  strerror(err_number));
  default:
    return IOStatus::IOError(IOErrorMsg(context, file_name),
                             strerror(err_number));
  }
}

class PosixHelper {
 public:
  static size_t GetUniqueIdFromFile(int fd, char* id, size_t max_size);
};

class PosixSequentialFile : public FSSequentialFile {
 private:
  std::string filename_;
  FILE* file_;
  int fd_;
  bool use_direct_io_;
  size_t logical_sector_size_;

 public:
  PosixSequentialFile(const std::string& fname, FILE* file, int fd,
                      const EnvOptions& options);
  virtual ~PosixSequentialFile();

  virtual IOStatus Read(size_t n, const IOOptions& opts, Slice* result,
                        char* scratch, IODebugContext* dbg) override;
  virtual IOStatus PositionedRead(uint64_t offset, size_t n,
                                  const IOOptions& opts, Slice* result,
                                  char* scratch, IODebugContext* dbg) override;
  virtual IOStatus Skip(uint64_t n) override;
  virtual IOStatus InvalidateCache(size_t offset, size_t length) override;
  virtual bool use_direct_io() const override { return use_direct_io_; }
  virtual size_t GetRequiredBufferAlignment() const override {
    return logical_sector_size_;
  }
};

#if defined(ROCKSDB_IOURING_PRESENT)
// io_uring instance queue depth
const unsigned int kIoUringDepth = 256;

inline void DeleteIOUring(void* p) {
  struct io_uring* iu = static_cast<struct io_uring*>(p);
  delete iu;
}

inline struct io_uring* CreateIOUring() {
  struct io_uring* new_io_uring = new struct io_uring;
  int ret = io_uring_queue_init(kIoUringDepth, new_io_uring, 0);
  if (ret) {
    delete new_io_uring;
    new_io_uring = nullptr;
  }
  return new_io_uring;
}
#endif  // defined(ROCKSDB_IOURING_PRESENT)

class PosixRandomAccessFile : public FSRandomAccessFile {
 protected:
  std::string filename_;
  int fd_;
  bool use_direct_io_;
  size_t logical_sector_size_;
#if defined(ROCKSDB_IOURING_PRESENT)
  ThreadLocalPtr* thread_local_io_urings_;
#endif

 public:
  PosixRandomAccessFile(const std::string& fname, int fd,
                        const EnvOptions& options
#if defined(ROCKSDB_IOURING_PRESENT)
                        ,
                        ThreadLocalPtr* thread_local_io_urings
#endif
  );
  virtual ~PosixRandomAccessFile();

  virtual IOStatus Read(uint64_t offset, size_t n, const IOOptions& opts,
                        Slice* result, char* scratch,
                        IODebugContext* dbg) const override;

  virtual IOStatus MultiRead(FSReadRequest* reqs, size_t num_reqs,
                             const IOOptions& options,
                             IODebugContext* dbg) override;

  virtual IOStatus Prefetch(uint64_t offset, size_t n, const IOOptions& opts,
                            IODebugContext* dbg) override;

#if defined(OS_LINUX) || defined(OS_MACOSX) || defined(OS_AIX)
  virtual size_t GetUniqueId(char* id, size_t max_size) const override;
#endif
  virtual void Hint(AccessPattern pattern) override;
  virtual IOStatus InvalidateCache(size_t offset, size_t length) override;
  virtual bool use_direct_io() const override { return use_direct_io_; }
  virtual size_t GetRequiredBufferAlignment() const override {
    return logical_sector_size_;
  }
};

class PosixWritableFile : public FSWritableFile {
 protected:
  const std::string filename_;
  const bool use_direct_io_;
  int fd_;
  uint64_t filesize_;
  size_t logical_sector_size_;
#ifdef ROCKSDB_FALLOCATE_PRESENT
  bool allow_fallocate_;
  bool fallocate_with_keep_size_;
#endif
#ifdef ROCKSDB_RANGESYNC_PRESENT
  // Even if the syscall is present, the filesystem may still not properly
  // support it, so we need to do a dynamic check too.
  bool sync_file_range_supported_;
#endif  // ROCKSDB_RANGESYNC_PRESENT

 public:
  explicit PosixWritableFile(const std::string& fname, int fd,
                             const EnvOptions& options);
  virtual ~PosixWritableFile();

  // Need to implement this so the file is truncated correctly
  // with direct I/O
  virtual IOStatus Truncate(uint64_t size, const IOOptions& opts,
                            IODebugContext* dbg) override;
  virtual IOStatus Close(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Append(const Slice& data, const IOOptions& opts,
                          IODebugContext* dbg) override;
  virtual IOStatus PositionedAppend(const Slice& data, uint64_t offset,
                                    const IOOptions& opts,
                                    IODebugContext* dbg) override;
  virtual IOStatus Flush(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Sync(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Fsync(const IOOptions& opts, IODebugContext* dbg) override;
  virtual bool IsSyncThreadSafe() const override;
  virtual bool use_direct_io() const override { return use_direct_io_; }
  virtual void SetWriteLifeTimeHint(Env::WriteLifeTimeHint hint) override;
  virtual uint64_t GetFileSize(const IOOptions& opts,
                               IODebugContext* dbg) override;
  virtual IOStatus InvalidateCache(size_t offset, size_t length) override;
  virtual size_t GetRequiredBufferAlignment() const override {
    return logical_sector_size_;
  }
#ifdef ROCKSDB_FALLOCATE_PRESENT
  virtual IOStatus Allocate(uint64_t offset, uint64_t len,
                            const IOOptions& opts,
                            IODebugContext* dbg) override;
#endif
  virtual IOStatus RangeSync(uint64_t offset, uint64_t nbytes,
                             const IOOptions& opts,
                             IODebugContext* dbg) override;
#ifdef OS_LINUX
  virtual size_t GetUniqueId(char* id, size_t max_size) const override;
#endif
};

// mmap() based random-access
class PosixMmapReadableFile : public FSRandomAccessFile {
 private:
  int fd_;
  std::string filename_;
  void* mmapped_region_;
  size_t length_;

 public:
  PosixMmapReadableFile(const int fd, const std::string& fname, void* base,
                        size_t length, const EnvOptions& options);
  virtual ~PosixMmapReadableFile();
  virtual IOStatus Read(uint64_t offset, size_t n, const IOOptions& opts,
                        Slice* result, char* scratch,
                        IODebugContext* dbg) const override;
  virtual IOStatus InvalidateCache(size_t offset, size_t length) override;
};

class PosixMmapFile : public FSWritableFile {
 private:
  std::string filename_;
  int fd_;
  size_t page_size_;
  size_t map_size_;       // How much extra memory to map at a time
  char* base_;            // The mapped region
  char* limit_;           // Limit of the mapped region
  char* dst_;             // Where to write next  (in range [base_,limit_])
  char* last_sync_;       // Where have we synced up to
  uint64_t file_offset_;  // Offset of base_ in file
#ifdef ROCKSDB_FALLOCATE_PRESENT
  bool allow_fallocate_;  // If false, fallocate calls are bypassed
  bool fallocate_with_keep_size_;
#endif

  // Roundup x to a multiple of y
  static size_t Roundup(size_t x, size_t y) { return ((x + y - 1) / y) * y; }

  size_t TruncateToPageBoundary(size_t s) {
    s -= (s & (page_size_ - 1));
    assert((s % page_size_) == 0);
    return s;
  }

  IOStatus MapNewRegion();
  IOStatus UnmapCurrentRegion();
  IOStatus Msync();

 public:
  PosixMmapFile(const std::string& fname, int fd, size_t page_size,
                const EnvOptions& options);
  ~PosixMmapFile();

  // Means Close() will properly take care of truncate
  // and it does not need any additional information
  virtual IOStatus Truncate(uint64_t /*size*/, const IOOptions& /*opts*/,
                            IODebugContext* /*dbg*/) override {
    return IOStatus::OK();
  }
  virtual IOStatus Close(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Append(const Slice& data, const IOOptions& opts,
                          IODebugContext* dbg) override;
  virtual IOStatus Flush(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Sync(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Fsync(const IOOptions& opts, IODebugContext* dbg) override;
  virtual uint64_t GetFileSize(const IOOptions& opts,
                               IODebugContext* dbg) override;
  virtual IOStatus InvalidateCache(size_t offset, size_t length) override;
#ifdef ROCKSDB_FALLOCATE_PRESENT
  virtual IOStatus Allocate(uint64_t offset, uint64_t len,
                            const IOOptions& opts,
                            IODebugContext* dbg) override;
#endif
};

class PosixRandomRWFile : public FSRandomRWFile {
 public:
  explicit PosixRandomRWFile(const std::string& fname, int fd,
                             const EnvOptions& options);
  virtual ~PosixRandomRWFile();

  virtual IOStatus Write(uint64_t offset, const Slice& data,
                         const IOOptions& opts, IODebugContext* dbg) override;

  virtual IOStatus Read(uint64_t offset, size_t n, const IOOptions& opts,
                        Slice* result, char* scratch,
                        IODebugContext* dbg) const override;

  virtual IOStatus Flush(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Sync(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Fsync(const IOOptions& opts, IODebugContext* dbg) override;
  virtual IOStatus Close(const IOOptions& opts, IODebugContext* dbg) override;

 private:
  const std::string filename_;
  int fd_;
};

struct PosixMemoryMappedFileBuffer : public MemoryMappedFileBuffer {
  PosixMemoryMappedFileBuffer(void* _base, size_t _length)
      : MemoryMappedFileBuffer(_base, _length) {}
  virtual ~PosixMemoryMappedFileBuffer();
};

class PosixDirectory : public FSDirectory {
 public:
  explicit PosixDirectory(int fd) : fd_(fd) {}
  ~PosixDirectory();
  virtual IOStatus Fsync(const IOOptions& opts, IODebugContext* dbg) override;

 private:
  int fd_;
};

}  // namespace rocksdb