feat: add Len API to track the number of route in the router

fox.go

@@ -305,6 +305,12 @@ func (fox *Router) Lookup(w ResponseWriter, r *http.Request) (route *Route, cc C
 	return nil, nil, tsr
 }
 
+// Len returns the number of registered route.
+func (fox *Router) Len() int {
+	tree := fox.getRoot()
+	return tree.size
+}
+
 // Iter returns a collection of range iterators for traversing registered methods and routes. It creates a
 // point-in-time snapshot of the routing tree. Therefore, all iterators returned by Iter will not observe subsequent
 // write on the router. This function is safe for concurrent use by multiple goroutine and while mutation on

fox_test.go

@@ -643,6 +643,8 @@ func TestStaticRoute(t *testing.T) {
 		require.Equal(t, http.StatusOK, w.Code)
 		assert.Equal(t, route.path, w.Body.String())
 	}
+
+	assert.Equal(t, iterutil.Len2(f.Iter().All()), f.Len())
 }
 
 func TestStaticRouteTxn(t *testing.T) {
@@ -664,6 +666,8 @@ func TestStaticRouteTxn(t *testing.T) {
 		require.Equal(t, http.StatusOK, w.Code)
 		assert.Equal(t, route.path, w.Body.String())
 	}
+
+	assert.Equal(t, iterutil.Len2(f.Iter().All()), f.Len())
 }
 
 func TestStaticRouteWithStaticDomain(t *testing.T) {
@@ -681,6 +685,8 @@ func TestStaticRouteWithStaticDomain(t *testing.T) {
 		require.Equal(t, http.StatusOK, w.Code)
 		assert.Equal(t, route.path, w.Body.String())
 	}
+
+	assert.Equal(t, iterutil.Len2(f.Iter().All()), f.Len())
 }
 
 func TestStaticRouteWithStaticDomainTxn(t *testing.T) {
@@ -703,6 +709,8 @@ func TestStaticRouteWithStaticDomainTxn(t *testing.T) {
 		require.Equal(t, http.StatusOK, w.Code)
 		assert.Equal(t, route.path, w.Body.String())
 	}
+
+	assert.Equal(t, iterutil.Len2(f.Iter().All()), f.Len())
 }
 
 func TestStaticRouteMalloc(t *testing.T) {

tree.go

@@ -19,6 +19,7 @@ type iTree struct {
 	ctx       sync.Pool
 	fox       *Router
 	root      roots
+	size      int
 	maxParams uint32
 	depth     uint32
 }
@@ -27,6 +28,7 @@ func (t *iTree) txn(cache bool) *tXn {
 	return &tXn{
 		tree:      t,
 		root:      t.root,
+		size:      t.size,
 		maxParams: t.maxParams,
 		depth:     t.depth,
 		cache:     cache,
@@ -46,6 +48,7 @@ type tXn struct {
 	tree      *iTree
 	writable  *simplelru.LRU[*node, any]
 	root      roots
+	size      int
 	maxParams uint32
 	depth     uint32
 	cache     bool
@@ -55,6 +58,7 @@ func (t *tXn) commit() *iTree {
 	nt := &iTree{
 		root:      t.root,
 		fox:       t.tree.fox,
+		size:      t.size,
 		maxParams: t.maxParams,
 		depth:     t.depth,
 	}
@@ -76,6 +80,7 @@ func (t *tXn) clone() *tXn {
 	tx := &tXn{
 		tree:      t.tree,
 		root:      t.root,
+		size:      t.size,
 		maxParams: t.maxParams,
 		depth:     t.depth,
 	}
@@ -204,6 +209,7 @@ func (t *tXn) insert(method string, route *Route, paramsN uint32) error {
 			result.matched.wildcardChildIndex,
 		)
 
+		t.size++
 		t.updateMaxParams(paramsN)
 		result.p.updateEdge(n)
 	case keyEndMidEdge:
@@ -244,6 +250,7 @@ func (t *tXn) insert(method string, route *Route, paramsN uint32) error {
 			[]*node{child},
 		)
 
+		t.size++
 		t.updateMaxParams(paramsN)
 		t.updateMaxDepth(result.depth + 1)
 		result.p.updateEdge(parent)
@@ -287,6 +294,7 @@ func (t *tXn) insert(method string, route *Route, paramsN uint32) error {
 			edges,
 		)
 
+		t.size++
 		t.updateMaxDepth(result.depth + addDepth)
 		t.updateMaxParams(paramsN)
 
@@ -375,6 +383,7 @@ func (t *tXn) insert(method string, route *Route, paramsN uint32) error {
 		// n3 children never start with a param
 		n3 := newNode(cPrefix, nil, []*node{n1, n2}) // intermediary node
 
+		t.size++
 		t.updateMaxDepth(result.depth + addDepth)
 		t.updateMaxParams(paramsN)
 		result.p.updateEdge(n3)
@@ -427,6 +436,7 @@ func (t *tXn) remove(method, path string) bool {
 		return false
 	}
 
+	t.size--
 	if len(result.matched.children) > 1 {
 		n := newNodeFromRef(
 			result.matched.key,

txn.go

@@ -226,6 +226,11 @@ func (txn *Txn) Iter() Iter {
 	}
 }
 
+// Len returns the number of registered route.
+func (txn *Txn) Len() int {
+	return txn.rootTxn.size
+}
+
 // Commit finalize the transaction. This is a noop for read transactions, already aborted or
 // committed transactions. This function is NOT thread-safe and should be run serially,
 // along with all other [Txn] APIs.

txn_test.go

@@ -237,6 +237,27 @@ func TestTxn_Isolation(t *testing.T) {
 		assert.Equal(t, err, want)
 		assert.Equal(t, len(staticRoutes), iterutil.Len2(f.Iter().All()))
 	})
+
+	t.Run("track registered route", func(t *testing.T) {
+		f := New()
+		require.NoError(t, f.Updates(func(txn *Txn) error {
+			for _, rte := range staticRoutes {
+				if _, err := txn.Handle(rte.method, "example.com"+rte.path, emptyHandler); err != nil {
+					return err
+				}
+			}
+			assert.Equal(t, len(staticRoutes), txn.Len())
+
+			for _, rte := range staticRoutes {
+				if err := txn.Delete(rte.method, "example.com"+rte.path); err != nil {
+					return err
+				}
+			}
+			assert.Zero(t, txn.Len())
+
+			return nil
+		}))
+	})
 }
 
 func TestTxn_WriteOnReadTransaction(t *testing.T) {