bump buntdb to v1.2.3

Potentially fixes the database corruption seen on #1603

vendor/github.com/tidwall/rtred/base/knn.go

@@ -0,0 +1,98 @@
+package base
+
+import (
+	"github.com/tidwall/tinyqueue"
+)
+
+type queueItem struct {
+	node   *treeNode
+	isItem bool
+	dist   float64
+}
+
+func (item *queueItem) Less(b tinyqueue.Item) bool {
+	return item.dist < b.(*queueItem).dist
+}
+
+// KNN returns items nearest to farthest. The dist param is the "box distance".
+func (tr *RTree) KNN(min, max []float64, center bool, iter func(item interface{}, dist float64) bool) bool {
+	var isBox bool
+	knnPoint := make([]float64, tr.dims)
+
+	bbox := &treeNode{min: min, max: max}
+
+	for i := 0; i < tr.dims; i++ {
+		knnPoint[i] = (bbox.min[i] + bbox.max[i]) / 2
+		if !isBox && bbox.min[i] != bbox.max[i] {
+			isBox = true
+		}
+	}
+	node := tr.data
+	queue := tinyqueue.New(nil)
+	for node != nil {
+		for i := 0; i < node.count; i++ {
+			child := node.children[i]
+			var dist float64
+			if isBox {
+				dist = boxDistRect(bbox, child)
+			} else {
+				dist = boxDistPoint(knnPoint, child)
+			}
+			queue.Push(&queueItem{node: child, isItem: node.leaf, dist: dist})
+		}
+		for queue.Len() > 0 && queue.Peek().(*queueItem).isItem {
+			item := queue.Pop().(*queueItem)
+			if !iter(item.node.unsafeItem().item, item.dist) {
+				return false
+			}
+		}
+		last := queue.Pop()
+		if last != nil {
+			node = (*treeNode)(last.(*queueItem).node)
+		} else {
+			node = nil
+		}
+	}
+	return true
+}
+
+func boxDistRect(a, b *treeNode) float64 {
+	var dist float64
+	for i := 0; i < len(a.min); i++ {
+		var min, max float64
+		if a.min[i] > b.min[i] {
+			min = a.min[i]
+		} else {
+			min = b.min[i]
+		}
+		if a.max[i] < b.max[i] {
+			max = a.max[i]
+		} else {
+			max = b.max[i]
+		}
+		squared := min - max
+		if squared > 0 {
+			dist += squared * squared
+		}
+	}
+	return dist
+}
+
+func boxDistPoint(point []float64, childBox *treeNode) float64 {
+	var dist float64
+	for i := 0; i < len(point); i++ {
+		d := axisDist(point[i], childBox.min[i], childBox.max[i])
+		dist += d * d
+	}
+	return dist
+}
+
+func axisDist(k, min, max float64) float64 {
+	if k < min {
+		return min - k
+	}
+	if k <= max {
+		return 0
+	}
+	return k - max
+}