switch to a breadth first traversal

kittens/choose_files/scan.go

@@ -66,7 +66,7 @@ type FileSystemScanner struct {
 	root_dir                string
 	mutex                   sync.Mutex
 	results                 []ResultItem
-	dir_reader              func(path string, level int) ([]fs.DirEntry, error)
+	dir_reader              func(path string) ([]fs.DirEntry, error)
 	err                     error
 }
 
@@ -74,9 +74,7 @@ func NewFileSystemScanner(root_dir string, notify chan int) (fss *FileSystemScan
 	ans := &FileSystemScanner{root_dir: root_dir, listeners: []chan int{notify}, results: make([]ResultItem, 0, 1024)}
 	ans.in_progress.Store(true)
 	ans.keep_going.Store(true)
-	ans.dir_reader = func(path string, level int) ([]fs.DirEntry, error) {
+	ans.dir_reader = os.ReadDir
-		return os.ReadDir(path)
-	}
 	return ans
 }
 
@@ -147,22 +145,25 @@ func (fss *FileSystemScanner) worker() {
 			close(l)
 		}
 	}()
-	var scan_dir func(string, int)
 	seen_dirs := make(map[string]bool)
-	scan_dir = func(dir string, level int) {
+	dir := fss.root_dir
-		if !fss.keep_going.Load() || seen_dirs[dir] {
+	pos := 0
-			return
+	// do a breadth first traversal of the filesystem
+	for dir != "" {
+		if !fss.keep_going.Load() {
+			break
 		}
+		if !seen_dirs[dir] {
 			seen_dirs[dir] = true
-		entries, err := fss.dir_reader(dir, level)
+			entries, err := fss.dir_reader(dir)
 			if err != nil {
-			if level == 0 {
+				if dir == fss.root_dir {
 					fss.keep_going.Store(false)
 					fss.mutex.Lock()
 					fss.err = err
 					fss.mutex.Unlock()
 				}
-			return
+				break
 			}
 			ns := fss.results
 			new_sz := len(ns) + len(entries)
@@ -203,14 +204,16 @@ func (fss *FileSystemScanner) worker() {
 				default:
 				}
 			}
-		for _, x := range new_items {
+		}
-			if x.ftype.IsDir() {
+		dir = ""
-				scan_dir(x.abspath, level+1)
+		for pos < len(fss.results) && dir == "" {
+			if fss.results[pos].ftype.IsDir() {
+				dir = fss.results[pos].abspath
+			}
+			pos++
 		}
 	}
 }
-	scan_dir(fss.root_dir, 0)
-}
 
 type FileSystemScorer struct {
 	scanner                 Scanner
@@ -271,7 +274,7 @@ func (fss *FileSystemScorer) worker(on_results chan int, worker_wait *sync.WaitG
 			}
 		} else {
 			if fss.keep_going.Load() {
-				fss.on_results(nil, true)
+				fss.on_results(fss.scanner.Error(), true)
 			}
 		}
 	}()