| 661 | } |
| 662 | |
| 663 | Status BufferedTupleStream::PinStream(bool* pinned) { |
| 664 | DCHECK(!closed_); |
| 665 | CHECK_CONSISTENCY_FULL(read_it_); |
| 666 | if (pinned_) { |
| 667 | *pinned = true; |
| 668 | return Status::OK(); |
| 669 | } |
| 670 | *pinned = false; |
| 671 | // First, make sure we have the reservation to pin all the pages for reading. |
| 672 | int64_t bytes_to_pin = 0; |
| 673 | for (Page& page : pages_) { |
| 674 | bytes_to_pin += (ExpectedPinCount(true, &page) - page.pin_count()) * page.len(); |
| 675 | } |
| 676 | |
| 677 | // Check if we have some reservation to restore. |
| 678 | bool restore_write_reservation = |
| 679 | NeedWriteReservation(false) && !NeedWriteReservation(true); |
| 680 | bool restore_read_reservation = |
| 681 | NeedReadReservation(false) && !NeedReadReservation(true); |
| 682 | int64_t increase_needed = bytes_to_pin |
| 683 | - (restore_write_reservation ? default_page_len_ : 0) |
| 684 | - (restore_read_reservation ? default_page_len_ : 0); |
| 685 | bool reservation_granted = |
| 686 | buffer_pool_client_->IncreaseReservationToFit(increase_needed); |
| 687 | if (!reservation_granted) return Status::OK(); |
| 688 | |
| 689 | // If there is no current write page we should have some saved reservation to use. |
| 690 | // Only continue saving it if the stream is empty and need it to pin the first page. |
| 691 | if (restore_write_reservation) { |
| 692 | buffer_pool_client_->RestoreReservation(&write_page_reservation_, default_page_len_); |
| 693 | } |
| 694 | if (restore_read_reservation) { |
| 695 | buffer_pool_client_->RestoreReservation(&read_page_reservation_, default_page_len_); |
| 696 | } |
| 697 | |
| 698 | // At this point success is guaranteed - go through to pin the pages we need to pin. |
| 699 | // If the page data was evicted from memory, the read I/O can happen in parallel |
| 700 | // because we defer calling GetBuffer() until NextReadPage(). |
| 701 | for (Page& page : pages_) RETURN_IF_ERROR(PinPageIfNeeded(&page, true)); |
| 702 | |
| 703 | pinned_ = true; |
| 704 | *pinned = true; |
| 705 | CHECK_CONSISTENCY_FULL(read_it_); |
| 706 | return Status::OK(); |
| 707 | } |
| 708 | |
| 709 | Status BufferedTupleStream::UnpinStream(UnpinMode mode) { |
| 710 | CHECK_CONSISTENCY_FULL(read_it_); |