tree stats

pmap.go

@@ -209,3 +209,79 @@ func insert(n interface{}, shift, hash uint32, key Key, val Value, hashFn hashFu
 	newNode = _insert(n, shift)
 	return
 }
+
+type stats struct {
+	count          int
+	maxHeight      int
+	avgHeight      float64
+	avgDegree      float64
+	nodeCount      int
+	leafCount      int
+	collisionCount int
+	collidedKeys   int
+	emptySlots     int
+}
+
+func (p pmap) stats() stats {
+	var s stats
+	var th float64
+	var td float64
+	var visit func(n interface{}, h int)
+	visit = func(n interface{}, h int) {
+		switch n := n.(type) {
+		case leaf:
+			s.count++
+			s.leafCount++
+			th += float64(h)
+			if s.maxHeight < h {
+				s.maxHeight = h
+			}
+		case *node:
+			s.count++
+			s.nodeCount++
+			s.emptySlots += bits.OnesCount32(^n.bitmap)
+			td += float64(bits.OnesCount32(n.bitmap))
+			for i := range n.child {
+				if n.child[i] != nil {
+					visit(n.child[i], h+1)
+				}
+			}
+		case *collision:
+			s.collisionCount++
+			s.collidedKeys += len(n.leaf)
+		default:
+			panic("pmap: unhandled case in stats")
+		}
+	}
+	visit(p.root, 1)
+	if s.leafCount > 0 {
+		s.avgHeight = th / float64(s.leafCount)
+	}
+	if s.nodeCount > 0 {
+		s.avgDegree = td / float64(s.nodeCount)
+	}
+	return s
+}
+
+func (s stats) String() string {
+	return fmt.Sprintf(
+		"count          = %d\n"+
+			"maxHeight      = %d\n"+
+			"avgHeight      = %g\n"+
+			"avgDegree      = %g\n"+
+			"nodeCount      = %d\n"+
+			"leafCount      = %d\n"+
+			"collisionCount = %d\n"+
+			"collidedKeys   = %d\n"+
+			"emptySlots     = %d\n",
+		s.count,
+		s.maxHeight,
+		s.avgHeight,
+		s.avgDegree,
+		s.nodeCount,
+		s.leafCount,
+		s.collisionCount,
+		s.collidedKeys,
+		s.emptySlots,
+	)
+}

pmap_test.go

@@ -1,6 +1,9 @@
 package pmap
 
-import "testing"
+import (
+	"fmt"
+	"testing"
+)
 
 func TestPmap(t *testing.T) {
 	p := New()
@@ -17,6 +20,7 @@ func TestPmap(t *testing.T) {
 			t.Errorf("Get(%d) = %v %v, want %v %v", i, v, ok, i, true)
 		}
 	}
+	fmt.Print(p.(pmap).stats())
 }
 
 func BenchmarkGet(b *testing.B) {