}

Status ModularRandomAccessFile::Read(uint64 offset, size_t n,
                                     StringPiece* result, char* scratch) const {
  if (ops_->read == nullptr)
    return errors::Unimplemented(
        tensorflow::strings::StrCat("Read() not implemented for ", filename_));

  UniquePtrTo_TF_Status plugin_status(TF_NewStatus(), TF_DeleteStatus);
  int64_t read =

namespace tf_random_access_file {
using ReadFn =
    std::function<int64_t(const std::string& path, uint64_t offset, size_t n,
                          char* buffer, TF_Status* status)>;
typedef struct GCSFile {
  const std::string path;
  const bool is_cache_enable;
  const uint64_t buffer_size;
  ReadFn read_fn;
  absl::Mutex buffer_mutex;
  uint64_t buffer_start ABSL_GUARDED_BY(buffer_mutex);

  if (!status.ok()) GTEST_SKIP() << "CreateDir() not supported: " << status;

  uint64 size;
  status = env_->GetFileSize(dirpath, &size);
  EXPECT_PRED2(UnimplementedOrReturnsCode, status, Code::FAILED_PRECONDITION);
}

TEST_P(ModularFileSystemTest, TestGetFileSizeNotFound) {
  const std::string filepath = GetURIForPath("a_dir");
  uint64 size;
  Status status = env_->GetFileSize(filepath, &size);

  EXPECT_EQ(6 * TF_DataTypeSize(TF_UINT64), TF_TensorByteSize(a));
  EXPECT_EQ(6 * TF_DataTypeSize(TF_UINT64), TF_TensorByteSize(b));

  // Check that a write to one tensor shows up in the other.
  *(static_cast<int64_t*>(TF_TensorData(a))) = 4;
  EXPECT_EQ(4, *(static_cast<int64_t*>(TF_TensorData(b))));
  *(static_cast<int64_t*>(TF_TensorData(b))) = 6;
  EXPECT_EQ(6, *(static_cast<int64_t*>(TF_TensorData(a))));

                          char* buffer, TF_Status* status) -> int64_t {
    calls++;
    memset(buffer, 'x', n);
    TF_SetStatus(status, TF_OK, "");
    return n;
  };
  std::vector<char> out;
  // Our fake environment is initialized with the current timestamp.
  std::unique_ptr<NowSecondsEnv> env(new NowSecondsEnv);
  uint64 now = Env::Default()->NowSeconds();
  env->SetNowSeconds(now);

}

TF_CAPI_EXPORT extern uint64_t TF_NowNanos(void) {
  return ::tensorflow::Env::Default()->NowNanos();
}

// Returns the number of microseconds since the Unix epoch.
TF_CAPI_EXPORT extern uint64_t TF_NowMicros(void) {
  return ::tensorflow::Env::Default()->NowMicros();
}

// Returns the number of seconds since the Unix epoch.
TF_CAPI_EXPORT extern uint64_t TF_NowSeconds(void) {

  Status DeleteFile(const std::string& fname, TransactionToken* token) override;
  Status DeleteRecursively(const std::string& dirname, TransactionToken* token,
                           int64_t* undeleted_files,
                           int64_t* undeleted_dirs) override;
  Status DeleteDir(const std::string& dirname,
                   TransactionToken* token) override;
  Status RecursivelyCreateDir(const std::string& dirname,

    case TF_DataType::TF_INT8:
    case TF_DataType::TF_INT16:
    case TF_DataType::TF_INT32:
    case TF_DataType::TF_INT64:
      dtype.code = DLDataTypeCode::kDLInt;
      break;
    case TF_DataType::TF_UINT8:
    case TF_DataType::TF_UINT16:
    case TF_DataType::TF_UINT32:
    case TF_DataType::TF_UINT64:
      dtype.code = DLDataTypeCode::kDLUInt;
      break;
    case TF_DataType::TF_BFLOAT16:

    // `pread` returns a `ssize_t` on POSIX, but due to interface being
    // cross-platform, return type of `Read` is `int64_t`.
    int64_t r = int64_t{pread(posix_file->fd, dst, requested_read_length,
                              static_cast<off_t>(offset))};
    if (r > 0) {
      dst += r;
      offset += static_cast<uint64_t>(r);
      n -= r;  // safe as 0 < r <= n so n will never underflow
      read += r;
    } else if (r == 0) {

               tensorflow::uint64 send_device_incarnation);

// Return a RecvOp op `op_name` with the attributes `send_device`,
// `recv_device`, and `send_device_incarnation` set.
TFE_Op* RecvOp(TFE_Context* ctx, const std::string& op_name,
               const std::string& send_device, const std::string& recv_device,
               tensorflow::uint64 send_device_incarnation);