faster update

pkg/hnsw/heap.go

@@ -13,13 +13,13 @@ var EmptyHeapError = fmt.Errorf("Empty Heap")
 
 type DistHeap struct {
 	items   []*Item
-	visited map[Id]bool
+	visited map[Id]int
 }
 
 func NewDistHeap() *DistHeap {
 	d := &DistHeap{
 		items:   make([]*Item, 0),
-		visited: make(map[Id]bool),
+		visited: make(map[Id]int),
 	}
 	return d
 }
@@ -86,20 +86,19 @@ func (d *DistHeap) PopMaxItem() (*Item, error) {
 	return d.Pop(), nil
 }
 func (d *DistHeap) Insert(id Id, dist float32) {
-	if d.visited[id] {
-		for idx, item := range d.items {
-			if item.id == id {
-				item.dist = dist
-				d.Fix(idx)
-				return
-			}
-		}
-	} else {
+	index, ok := d.visited[id]
+
+	if !ok {
 		d.Push(&Item{id: id, dist: dist})
+		d.visited[id] = d.Len() - 1
 		d.up(d.Len() - 1)
-		d.visited[id] = true
+		return
 	}
+
+	d.items[index].dist = dist
+	d.Fix(index)
 }
+
 func (d *DistHeap) Fix(i int) {
 	if !d.down(i, d.Len()) {
 		d.up(i)
@@ -109,7 +108,10 @@ func (d *DistHeap) Fix(i int) {
 func (d DistHeap) IsEmpty() bool      { return len(d.items) == 0 }
 func (d DistHeap) Len() int           { return len(d.items) }
 func (d DistHeap) Less(i, j int) bool { return d.items[i].dist < d.items[j].dist }
-func (d DistHeap) Swap(i, j int)      { d.items[i], d.items[j] = d.items[j], d.items[i] }
+func (d DistHeap) Swap(i, j int) {
+	d.visited[d.items[i].id], d.visited[d.items[j].id] = j, i
+	d.items[i], d.items[j] = d.items[j], d.items[i]
+}
 func (d *DistHeap) Push(x *Item) {
 	(*d).items = append((*d).items, x)
 }
@@ -118,5 +120,6 @@ func (d *DistHeap) Pop() *Item {
 	n := len(old)
 	x := old[n-1]
 	(*d).items = old[0 : n-1]
+	delete(d.visited, x.id)
 	return x
 }