Struct LirePatcher 

pub struct LirePatcher<'a> {
    pub main: &'a mut HnswIndex,
    pub delta: &'a mut DeltaIndex,
    pub drift_threshold: f32,
}

SPFresh LIRE-style topology-aware local patcher.

Holds mutable references to both the main HNSW and the delta buffer so both can be updated atomically within a single flush.

Fields

main: &'a mut HnswIndex

Main HNSW graph that fresh vectors will be patched into.

delta: &'a mut DeltaIndex

Delta buffer whose fresh vectors (and tombstones) will be drained.

drift_threshold: f32

Drift threshold in [0.0, 1.0]. When the average neighbor-overlap fraction for a batch falls below this value the subgraph is flagged for deeper re-pruning. Default: 0.3.

Implementations

impl<'a> LirePatcher<'a>

pub fn new(main: &'a mut HnswIndex, delta: &'a mut DeltaIndex) -> Self

Create a patcher with the default drift threshold (0.3).

pub fn patch( &mut self, _k_neighbors: usize, _ef_construction: usize, ) -> Result<PatchStats, VectorError>

Flush the delta buffer into the main HNSW.

Steps

1. Drain tombstones → call HnswIndex::delete on each.
2. Drain fresh vectors → call HnswIndex::insert on each.
3. After each insert, estimate local topology drift for the newly assigned node and accumulate the overlap fraction.
4. If average overlap fraction < drift_threshold, increment drift_subgraphs.

k_neighbors and ef_construction are accepted for API completeness and forward-compatibility with future Vamana-style patchers; the current HNSW implementation derives its own neighbor count from HnswParams stored on the index, so these values are informational.