1 files changed, 182 insertions, 0 deletions
diff --git a/weed/util/bounded_tree/bounded_tree.go b/weed/util/bounded_tree/bounded_tree.go
new file mode 100644
index 000000000..3a8a22a9c
--- /dev/null
+++ b/weed/util/bounded_tree/bounded_tree.go
@@ -0,0 +1,182 @@
+package bounded_tree
+
+import (
+	"sync"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/util"
+)
+
+type Node struct {
+	Parent   *Node
+	Name     string
+	Children map[string]*Node
+}
+
+type BoundedTree struct {
+	root *Node
+	sync.RWMutex
+	baseDir util.FullPath
+}
+
+func NewBoundedTree(baseDir util.FullPath) *BoundedTree {
+	return &BoundedTree{
+		root: &Node{
+			Name: "/",
+		},
+		baseDir: baseDir,
+	}
+}
+
+type VisitNodeFunc func(path util.FullPath) (childDirectories []string, err error)
+
+// If the path is not visited, call the visitFn for each level of directory
+// No action if the directory has been visited before or does not exist.
+// A leaf node, which has no children, represents a directory not visited.
+// A non-leaf node or a non-existing node represents a directory already visited, or does not need to visit.
+func (t *BoundedTree) EnsureVisited(p util.FullPath, visitFn VisitNodeFunc) (visitErr error) {
+	t.Lock()
+	defer t.Unlock()
+
+	if t.root == nil {
+		return
+	}
+	if t.baseDir != "/" {
+		p = p[len(t.baseDir):]
+	}
+	components := p.Split()
+	// fmt.Printf("components %v %d\n", components, len(components))
+	canDelete, err := t.ensureVisited(t.root, t.baseDir, components, 0, visitFn)
+	if err != nil {
+		return err
+	}
+	if canDelete {
+		t.root = nil
+	}
+	return nil
+}
+
+func (t *BoundedTree) ensureVisited(n *Node, currentPath util.FullPath, components []string, i int, visitFn VisitNodeFunc) (canDeleteNode bool, visitErr error) {
+
+	// println("ensureVisited", currentPath, i)
+
+	if n == nil {
+		// fmt.Printf("%s null\n", currentPath)
+		return
+	}
+
+	if n.isVisited() {
+		// fmt.Printf("%s visited %v\n", currentPath, n.Name)
+	} else {
+		// fmt.Printf("ensure %v\n", currentPath)
+
+		children, err := visitFn(currentPath)
+		if err != nil {
+			glog.V(0).Infof("failed to visit %s: %v", currentPath, err)
+			return false, err
+		}
+
+		if len(children) == 0 {
+			// fmt.Printf("  canDelete %v without children\n", currentPath)
+			return true, nil
+		}
+
+		n.Children = make(map[string]*Node)
+		for _, child := range children {
+			// fmt.Printf("  add child %v %v\n", currentPath, child)
+			n.Children[child] = &Node{
+				Name: child,
+			}
+		}
+	}
+
+	if i >= len(components) {
+		return
+	}
+
+	// fmt.Printf("  check child %v %v\n", currentPath, components[i])
+
+	toVisitNode, found := n.Children[components[i]]
+	if !found {
+		// fmt.Printf("  did not find child %v %v\n", currentPath, components[i])
+		return
+	}
+
+	// fmt.Printf("  ensureVisited %v %v\n", currentPath, toVisitNode.Name)
+	canDelete, childVisitErr := t.ensureVisited(toVisitNode, currentPath.Child(components[i]), components, i+1, visitFn)
+	if childVisitErr != nil {
+		return false, childVisitErr
+	}
+	if canDelete {
+
+		// fmt.Printf("  delete %v %v\n", currentPath, components[i])
+		delete(n.Children, components[i])
+
+		if len(n.Children) == 0 {
+			// fmt.Printf("  canDelete %v\n", currentPath)
+			return true, nil
+		}
+	}
+
+	return false, nil
+
+}
+
+func (n *Node) isVisited() bool {
+	if n == nil {
+		return true
+	}
+	if len(n.Children) > 0 {
+		return true
+	}
+	return false
+}
+
+func (n *Node) getChild(childName string) *Node {
+	if n == nil {
+		return nil
+	}
+	if len(n.Children) > 0 {
+		return n.Children[childName]
+	}
+	return nil
+}
+
+func (t *BoundedTree) HasVisited(p util.FullPath) bool {
+
+	t.RLock()
+	defer t.RUnlock()
+
+	if t.root == nil {
+		return true
+	}
+
+	components := p.Split()
+	// fmt.Printf("components %v %d\n", components, len(components))
+	return t.hasVisited(t.root, util.FullPath("/"), components, 0)
+}
+
+func (t *BoundedTree) hasVisited(n *Node, currentPath util.FullPath, components []string, i int) bool {
+
+	if n == nil {
+		return true
+	}
+
+	if !n.isVisited() {
+		return false
+	}
+
+	// fmt.Printf("  hasVisited child %v %+v %d\n", currentPath, components, i)
+
+	if i >= len(components) {
+		return true
+	}
+
+	toVisitNode, found := n.Children[components[i]]
+	if !found {
+		return true
+	}
+
+	return t.hasVisited(toVisitNode, currentPath.Child(components[i]), components, i+1)
+
+}