Struct TwoLevelIterator 

pub struct TwoLevelIterator {
    table: Arc<Table>,
    read_options: ReadOptions,
    index_block_iter: BlockIter<InternalKey>,
    maybe_data_block_iter: Option<BlockIter<InternalKey>>,
    data_block_handle: Option<BlockHandle>,
}

A two-level iterator that first iterates the index block and then iterates a corresponding data block. NOTE: This iterator is initially invalid until an operation is performed with it.

This iterator yields the concatenation of all key-value pairs in a sequence of blocks (e.g. in a table file).

Fields

table: Arc<Table>

The table the iterator is for.

read_options: ReadOptions

Options for configuring the behavior of reads done by the iterator.

index_block_iter: BlockIter<InternalKey>

Iterator for the index block.

maybe_data_block_iter: Option<BlockIter<InternalKey>>

Iterator for a data block.

data_block_handle: Option<BlockHandle>

The block handle used to get the data block in the [TwoLevelIterator::data_block] field.

Implementations

impl TwoLevelIterator

Private methods

fn new(table: Arc<Table>, read_options: ReadOptions) -> Self

Create a new instance of TwoLevelIterator.

fn init_data_block(&mut self) -> Result<(), ReadError>

fn skip_empty_data_blocks_forward(&mut self) -> Result<(), ReadError>

Move the index iterator and data iterator forward until we find a non-empty block.

fn skip_empty_data_blocks_backward(&mut self) -> Result<(), ReadError>

Move the index iterator and data iterator backward until we find a non-empty block.

If a data block is found, this will set the data block iterator to the last entry of the data block.

Trait Implementations

impl RainDbIterator for TwoLevelIterator

type Key = InternalKey

The type of key that is iterated over.

type Error = RainDBError

The type of error returned when there is an error during iteration.

fn is_valid(&self) -> bool

The iterator is only valid if the cursor is currently positioned at a key-value pair.

fn seek(&mut self, target: &Self::Key) -> Result<(), Self::Error>

Position cursor to the first key that is at or past the target.

fn seek_to_first(&mut self) -> Result<(), Self::Error>

Position cursor to the first element.

fn seek_to_last(&mut self) -> Result<(), Self::Error>

Position cursor to the last element.

fn next(&mut self) -> Option<(&Self::Key, &Vec<u8>)>

Move to the next element.

fn prev(&mut self) -> Option<(&Self::Key, &Vec<u8>)>

Move to the previous element.

fn current(&self) -> Option<(&Self::Key, &Vec<u8>)>

Return the key and value at the current cursor position.