Method ReadBase

r/src/io.cpp:266–290

Define the logic here because multiple inheritance makes it difficult for this base class, the InputStream and the RandomAccessFile interfaces to co-exist.

  // for this base class, the InputStream and the RandomAccessFile
  // interfaces to co-exist.
  arrow::Result<int64_t> ReadBase(int64_t nbytes, void* out) {
    if (closed()) {
      return arrow::Status::IOError("R connection is closed");
    }

    if (nbytes > std::numeric_limits<int>::max()) {
      return arrow::Status::Invalid(
          "Can't read more than INT_MAX bytes from an R connection");
    }

    return SafeCallIntoR<int64_t>(
        [&] {
          cpp11::function read_bin = cpp11::package("base")["readBin"];
          cpp11::writable::raws ptype(static_cast<R_xlen_t>(0));
          cpp11::integers n = cpp11::as_sexp<int>(static_cast<int>(nbytes));

          cpp11::sexp result = read_bin(connection_sexp_, ptype, n);

          int64_t result_size = cpp11::safe[Rf_xlength](result);
          memcpy(out, cpp11::safe[RAW](result), result_size);
          bytes_read_++;
          return result_size;
        },
        "readBin() on R connection");
  }

  arrow::Result<std::shared_ptr<arrow::Buffer>> ReadBase(int64_t nbytes) {
    arrow::BufferBuilder builder;