Method GetBuffer

be/src/exec/scanner-context.cc:216–261

}

Status ScannerContext::Stream::GetBuffer(bool peek, uint8_t** out_buffer, int64_t* len) {
  *out_buffer = nullptr;
  *len = 0;
  if (eosr()) return Status::OK();

  if (UNLIKELY(parent_->cancelled())) {
    DCHECK(*out_buffer == nullptr);
    return CONTEXT_CANCELLED;
  }

  if (boundary_buffer_bytes_left_ > 0) {
    DCHECK(ValidateBufferPointers());
    DCHECK_EQ(output_buffer_bytes_left_, &boundary_buffer_bytes_left_);
    *out_buffer = boundary_buffer_pos_;
    // Don't return more bytes past eosr
    *len = min(boundary_buffer_bytes_left_, bytes_left());
    DCHECK_GE(*len, 0);
    if (!peek) {
      AdvanceBufferPos(*len, &boundary_buffer_pos_, &boundary_buffer_bytes_left_);
      total_bytes_returned_ += *len;
    }
    return Status::OK();
  }

  if (io_buffer_bytes_left_ == 0) {
    // We're at the end of the boundary buffer and the current IO buffer. Get a new IO
    // buffer and set the current buffer to it.
    RETURN_IF_ERROR(GetNextBuffer());
    // Check that we're not pointing to the IO buffer if there are bytes left in the
    // boundary buffer.
    DCHECK_EQ(boundary_buffer_bytes_left_, 0);
    output_buffer_pos_ = &io_buffer_pos_;
    output_buffer_bytes_left_ = &io_buffer_bytes_left_;
  }
  DCHECK(io_buffer_ != nullptr);

  *out_buffer = io_buffer_pos_;
  *len = io_buffer_bytes_left_;
  if (!peek) {
    AdvanceBufferPos(*len, &io_buffer_pos_, &io_buffer_bytes_left_);
    total_bytes_returned_ += *len;
  }
  DCHECK_GE(bytes_left(), 0);
  DCHECK(ValidateBufferPointers());
  return Status::OK();
}

Status ScannerContext::Stream::GetBytesInternal(int64_t requested_len,
    uint8_t** out_buffer, bool peek, int64_t* out_len) {