added bounded tree to track exploration boundary

1 files changed, 129 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..fa172a764
--- /dev/null
+++ b/weed/util/bounded_tree/bounded_tree.go
@@ -0,0 +1,129 @@
+package bounded_tree
+
+import (
+	"fmt"
+
+	"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
+}
+
+func NewBoundedTree() *BoundedTree {
+	return &BoundedTree{
+		root: &Node{
+			Name: "/",
+		},
+	}
+}
+
+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) {
+	println()
+	println("EnsureVisited", p)
+
+	if t.root == nil {
+		return
+	}
+	components := p.Split()
+	fmt.Printf("components %v %d\n", components, len(components))
+	if canDelete := t.ensureVisited(t.root, util.FullPath("/"), components, 0, visitFn); canDelete {
+		t.root = nil
+	}
+}
+
+func (t *BoundedTree) ensureVisited(n *Node, currentPath util.FullPath, components []string, i int, visitFn VisitNodeFunc) (canDeleteNode bool) {
+
+	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
+		}
+
+		if len(children) == 0 {
+			fmt.Printf("  canDelete %v without children\n", currentPath)
+			return true
+		}
+
+		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)
+
+	if canDelete := t.ensureVisited(toVisitNode, currentPath.Child(components[i]), components, i+1, visitFn); 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
+		}
+	}
+
+	return false
+
+}
+
+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
+}