fix: reduce the scope of map lock

trie/triedb/pathdb/layertree.go

@@ -123,8 +123,6 @@ func (tree *layerTree) cap(root common.Hash, layers int) error {
 	if !ok {
 		return fmt.Errorf("triedb layer [%#x] is disk layer", root)
 	}
-	tree.lock.Lock()
-	defer tree.lock.Unlock()
 
 	// If full commit was requested, flatten the diffs and merge onto disk
 	if layers == 0 {
@@ -133,7 +131,9 @@ func (tree *layerTree) cap(root common.Hash, layers int) error {
 			return err
 		}
 		// Replace the entire layer tree with the flat base
+		tree.lock.Lock()
 		tree.layers = map[common.Hash]layer{base.rootHash(): base}
+		tree.lock.Unlock()
 		return nil
 	}
 	// Dive until we run out of layers or reach the persistent database
@@ -162,14 +162,20 @@ func (tree *layerTree) cap(root common.Hash, layers int) error {
 			diff.lock.Unlock()
 			return err
 		}
+		tree.lock.Lock()
 		tree.layers[base.rootHash()] = base
+		tree.lock.Unlock()
+
 		diff.parent = base
 
 		diff.lock.Unlock()
 
 	default:
 		panic(fmt.Sprintf("unknown data layer in triedb: %T", parent))
 	}
+
+	tree.lock.Lock()
+	defer tree.lock.Unlock()
 	// Remove any layer that is stale or links into a stale layer
 	children := make(map[common.Hash][]common.Hash)
 	for root, layer := range tree.layers {
@@ -196,18 +202,17 @@ func (tree *layerTree) cap(root common.Hash, layers int) error {
 
 // bottom returns the bottom-most disk layer in this tree.
 func (tree *layerTree) bottom() *diskLayer {
-	tree.lock.RLock()
-	defer tree.lock.RUnlock()
-
-	if len(tree.layers) == 0 {
+	if tree.len() == 0 {
 		return nil // Shouldn't happen, empty tree
 	}
 	// pick a random one as the entry point
 	var current layer
+	tree.lock.RLock()
 	for _, layer := range tree.layers {
 		current = layer
 		break
 	}
+	tree.lock.RUnlock()
 	for current.parentLayer() != nil {
 		current = current.parentLayer()
 	}