lib/memfs: re-scan directory content on Node's Update

Previously, only node content get updated.
In case in the MemFS, user set "Options.TryDirect" to true, the directory
content should be updated too on "MemFS.Get".

lib/memfs/dirwatcher_example_test.go

@@ -57,16 +57,14 @@ func ExampleDirWatcher() {
 	fmt.Println(`--`, ns.State, ns.Node.Path)
 
 	// Create the root directory back with sub directory
-	// This will trigger two FileStateCreated events, one for "/" and one
-	// for "/assets".
+	// This will trigger one FileStateCreated event, for "/".
 	fmt.Println(`Re-create root directory with sub-directory:`)
 	var dirAssets = filepath.Join(rootDir, `assets`)
 	err = os.MkdirAll(dirAssets, 0770)
 	if err != nil {
 		log.Fatal(err)
 	}
-	ns = <-dw.C
-	fmt.Println(`--`, ns.State, ns.Node.Path)
+
 	ns = <-dw.C
 	fmt.Println(`--`, ns.State, ns.Node.Path)
 
@@ -149,7 +147,6 @@ func ExampleDirWatcher() {
 	//-- FileStateDeleted /
 	//Re-create root directory with sub-directory:
 	//-- FileStateCreated /
-	//-- FileStateCreated /assets
 	//Chmod on root directory:
 	//-- FileStateUpdateMode / drwx------
 	//Create new file on root directory: /new.adoc

lib/memfs/node.go

@@ -15,6 +15,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"sort"
 	"time"
 
 	"github.com/shuLhan/share/lib/ascii"
@@ -492,17 +493,31 @@ func (node *Node) Update(newInfo os.FileInfo, maxFileSize int64) (err error) {
 		return nil
 	}
 
+	var doUpdate = false
+	if newInfo.ModTime().After(node.modTime) {
+		doUpdate = true
+	} else if !newInfo.IsDir() {
+		if newInfo.Size() != node.size {
+			doUpdate = true
+		}
+	}
+
+	if !doUpdate {
+		return nil
+	}
+
 	node.modTime = newInfo.ModTime()
 	node.size = newInfo.Size()
 
 	if newInfo.IsDir() {
-		return nil
+		err = node.updateDir(maxFileSize)
+	} else {
+		err = node.updateContent(maxFileSize)
 	}
-
-	err = node.updateContent(maxFileSize)
 	if err != nil {
 		return fmt.Errorf("%s %s: %w", logp, node.SysPath, err)
 	}
+
 	return nil
 }
 
@@ -511,7 +526,8 @@ func (node *Node) updateContent(maxFileSize int64) (err error) {
 	if maxFileSize < 0 {
 		// Negative maxFileSize means content will not be read.
 		return nil
-	} else if maxFileSize == 0 {
+	}
+	if maxFileSize == 0 {
 		maxFileSize = defaultMaxFileSize
 	}
 	if node.size > maxFileSize {
@@ -533,6 +549,81 @@ func (node *Node) updateContent(maxFileSize int64) (err error) {
 	return nil
 }
 
+// updateDir update the childs node by reading content of directory.
+func (node *Node) updateDir(maxFileSize int64) (err error) {
+	var (
+		currChilds = make(map[string]*Node, len(node.Childs))
+		child      *Node
+	)
+
+	// Store the current childs as map first so we can use it later.
+	for _, child = range node.Childs {
+		currChilds[child.name] = child
+	}
+
+	var dir *os.File
+
+	dir, err = os.Open(node.SysPath)
+	if err != nil {
+		if os.IsPermission(err) {
+			// Ignore error due to permission.
+			return nil
+		}
+		return fmt.Errorf(`%q: %w`, node.SysPath, err)
+	}
+
+	var fis []os.FileInfo
+
+	fis, err = dir.Readdir(0)
+	if err != nil {
+		return fmt.Errorf(`%q: %w`, node.SysPath, err)
+	}
+
+	sort.SliceStable(fis, func(x, y int) bool {
+		return fis[x].Name() < fis[y].Name()
+	})
+
+	var fi os.FileInfo
+
+	node.Childs = nil
+	for _, fi = range fis {
+		child = currChilds[fi.Name()]
+		if child == nil {
+			// New node found in directory.
+			child, err = NewNode(node, fi, maxFileSize)
+			if err != nil {
+				if os.IsPermission(err) {
+					// Ignore error due to permission.
+					continue
+				}
+				return err
+			}
+
+			child.SysPath = filepath.Join(node.SysPath, child.name)
+		} else {
+			delete(currChilds, fi.Name())
+		}
+
+		node.Childs = append(node.Childs, child)
+
+		if !child.IsDir() {
+			continue
+		}
+
+		// If node exist and its a directory, try to update their
+		// childs too.
+		err = child.Update(nil, maxFileSize)
+		if err != nil {
+			if os.IsPermission(err) {
+				// Ignore error due to permission.
+				continue
+			}
+			return err
+		}
+	}
+	return nil
+}
+
 func (node *Node) updateContentType() error {
 	node.ContentType = mime.TypeByExtension(path.Ext(node.name))
 	if len(node.ContentType) > 0 {