Move search() method into Search

src/lib.rs

@@ -13,7 +13,7 @@ use serde::{Deserialize, Serialize};
 
 mod types;
 pub use types::PointId;
-use types::{Candidate, LayerId, NearestIter, UpperNode, Visited, ZeroNode};
+use types::{Candidate, Layer, LayerId, UpperNode, Visited, ZeroNode};
 
 /// Parameters for building the `Hnsw`
 pub struct Builder {
@@ -260,11 +260,11 @@ where
                         search.ef = if cur <= layer { ef_construction } else { 1 };
                         match cur > layer {
                             true => {
-                                layers[cur.0 - 1].search(point, search, &points, num);
+                                search.search(point, &layers[cur.0 - 1], &points, num);
                                 search.cull();
                             }
                             false => {
-                                zero.search(point, search, &points, num);
+                                search.search(point, &zero, &points, num);
                                 break;
                             }
                         }
@@ -347,8 +347,8 @@ where
 
             search.ef = ef;
             match cur.0 {
-                0 => self.zero.search(point, search, &self.points, num),
+                0 => search.search(point, &self.zero, &self.points, num),
-                l => self.layers[l - 1].search(point, search, &self.points, num),
+                l => search.search(point, &self.layers[l - 1], &self.points, num),
             }
 
             if !cur.is_zero() {
@@ -410,7 +410,7 @@ fn insert<P: Point>(
             insertion.reset();
             let candidate_point = &points[pid];
             insertion.push(new, candidate_point, points);
-            for hop in layer.nearest_iter(pid) {
+            for hop in (&*layer).nearest_iter(pid) {
                 insertion.push(hop, candidate_point, points);
             }
 
@@ -484,37 +484,6 @@ impl SearchPool {
     }
 }
 
-trait Layer {
-    /// Search this layer for nodes near the given `point`
-    ///
-    /// This contains the loops from the paper's algorithm 2. `point` represents `q`, the query
-    /// element; `search.candidates` contains the enter points `ep`. `points` contains all the
-    /// points, which is required to calculate distances between two points.
-    ///
-    /// The `links` argument represents the number of links from each candidate to consider. This
-    /// function may be called for a higher layer (with M links per node) or the zero layer (with
-    /// M * 2 links per node), but for performance reasons we often call this function on the data
-    /// representation matching the zero layer even when we're referring to a higher layer. In that
-    /// case, we use `links` to constrain the number of per-candidate links we consider for search.
-    fn search<P: Point>(&self, point: &P, search: &mut Search, points: &[P], links: usize) {
-        while let Some(Reverse(candidate)) = search.candidates.pop() {
-            if let Some(furthest) = search.nearest.last() {
-                if candidate.distance > furthest.distance {
-                    break;
-                }
-            }
-
-            for pid in self.nearest_iter(candidate.pid).take(links) {
-                search.push(pid, point, points);
-            }
-        }
-
-        search.nearest.truncate(search.ef);
-    }
-
-    fn nearest_iter(&self, pid: PointId) -> NearestIter<'_>;
-}
-
 /// Keeps mutable state for searching a point's nearest neighbors
 ///
 /// In particular, this contains most of the state used in algorithm 2. The structure is
@@ -543,6 +512,33 @@ impl Search {
         }
     }
 
+    /// Search the given layer for nodes near the given `point`
+    ///
+    /// This contains the loops from the paper's algorithm 2. `point` represents `q`, the query
+    /// element; `search.candidates` contains the enter points `ep`. `points` contains all the
+    /// points, which is required to calculate distances between two points.
+    ///
+    /// The `links` argument represents the number of links from each candidate to consider. This
+    /// function may be called for a higher layer (with M links per node) or the zero layer (with
+    /// M * 2 links per node), but for performance reasons we often call this function on the data
+    /// representation matching the zero layer even when we're referring to a higher layer. In that
+    /// case, we use `links` to constrain the number of per-candidate links we consider for search.
+    fn search<L: Layer, P: Point>(&mut self, point: &P, layer: L, points: &[P], links: usize) {
+        while let Some(Reverse(candidate)) = self.candidates.pop() {
+            if let Some(furthest) = self.nearest.last() {
+                if candidate.distance > furthest.distance {
+                    break;
+                }
+            }
+
+            for pid in layer.nearest_iter(candidate.pid).take(links) {
+                self.push(pid, point, points);
+            }
+        }
+
+        self.nearest.truncate(self.ef);
+    }
+
     /// Resets the state to be ready for a new search
     fn reset(&mut self) {
         let Search {
@@ -568,7 +564,7 @@ impl Search {
 
     fn select_heuristic<P: Point>(
         &mut self,
-        layer: &[ZeroNode],
+        layer: &Vec<ZeroNode>,
         num: usize,
         point: &P,
         points: &[P],

src/types.rs

@@ -7,7 +7,7 @@ use rand::Rng;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
-use crate::{Hnsw, Layer, Point, M};
+use crate::{Hnsw, Point, M};
 
 pub(crate) struct Visited {
     store: Vec<u8>,
@@ -66,7 +66,7 @@ pub(crate) struct UpperNode {
     pub(crate) nearest: [PointId; M],
 }
 
-impl Layer for [UpperNode] {
+impl Layer for &Vec<UpperNode> {
     fn nearest_iter(&self, pid: PointId) -> NearestIter<'_> {
         NearestIter {
             nearest: &self[pid.0 as usize].nearest,
@@ -91,7 +91,7 @@ impl Default for ZeroNode {
     }
 }
 
-impl Layer for [ZeroNode] {
+impl Layer for &Vec<ZeroNode> {
     fn nearest_iter(&self, pid: PointId) -> NearestIter<'_> {
         NearestIter {
             nearest: &self[pid.0 as usize].nearest,
@@ -99,6 +99,10 @@ impl Layer for [ZeroNode] {
     }
 }
 
+pub(crate) trait Layer {
+    fn nearest_iter(&self, pid: PointId) -> NearestIter<'_>;
+}
+
 pub(crate) struct NearestIter<'a> {
     nearest: &'a [PointId],
 }