Trait NullBitmap

source

pub trait NullBitmap:
    EstimateSize
    + Clone
    + PartialEq
    + Debug
    + Send
    + Sync
    + 'static {
    // Required methods
    fn empty() -> Self;
    fn is_empty(&self) -> bool;
    fn set_true(&mut self, idx: usize);
    fn contains(&self, x: usize) -> bool;
    fn is_subset(&self, other: &Self) -> bool;
    fn from_bool_vec<T: AsRef<[bool]> + IntoIterator<Item = bool>>(
        value: T,
    ) -> Self;
}

Expand description

We use a trait for NullBitmap so we can parameterize structs on it. This is because NullBitmap is used often, and we want it to occupy the minimal stack space.

§Example

use risingwave_common::hash::{NullBitmap, StackNullBitmap};
struct A<B: NullBitmap> {
    null_bitmap: B,
}

Then A<StackNullBitmap> occupies 64 bytes, and in cases which require it, A<HeapNullBitmap> will occupy 4 * usize bytes (on 64 bit arch that would be 256 bytes).