Add rclone mount --dir-cache-time to control caching of directory entries - fixes #680

cmd/mount/dir.go

@@ -30,7 +30,7 @@ type Dir struct {
 	f     fs.Fs
 	path  string
 	mu    sync.RWMutex // protects the following
-	read  bool
+	read  time.Time    // time directory entry last read
 	items map[string]*DirEntry
 }
 
@@ -66,9 +66,16 @@ func (d *Dir) delObject(leaf string) {
 func (d *Dir) readDir() error {
 	d.mu.Lock()
 	defer d.mu.Unlock()
-	if d.read {
+	when := time.Now()
+	if d.read.IsZero() {
+		fs.Debug(d.path, "Reading directory")
+	} else {
+		age := when.Sub(d.read)
+		if age < dirCacheTime {
 			return nil
 		}
+		fs.Debug(d.path, "Re-reading directory (%v old)", age)
+	}
 	objs, dirs, err := fs.NewLister().SetLevel(1).Start(d.f, d.path).GetAll()
 	if err == fs.ErrorDirNotFound {
 		// We treat directory not found as empty because we
@@ -76,6 +83,13 @@ func (d *Dir) readDir() error {
 	} else if err != nil {
 		return err
 	}
+	// NB when we re-read a directory after its cache has expired
+	// we drop the old files which should lead to correct
+	// behaviour but may not be very efficient.
+
+	// Keep a note of the previous contents of the directory
+	oldItems := d.items
+
 	// Cache the items by name
 	d.items = make(map[string]*DirEntry, len(objs)+len(dirs))
 	for _, obj := range objs {
@@ -87,12 +101,19 @@ func (d *Dir) readDir() error {
 	}
 	for _, dir := range dirs {
 		name := path.Base(dir.Remote())
+		// Use old dir value if it exists
+		if oldItem, ok := oldItems[name]; ok {
+			if _, ok := oldItem.o.(*fs.Dir); ok {
+				d.items[name] = oldItem
+				continue
+			}
+		}
 		d.items[name] = &DirEntry{
 			o:    dir,
 			node: nil,
 		}
 	}
-	d.read = true
+	d.read = when
 	return nil
 }
 

cmd/mount/mount.go

@@ -7,6 +7,7 @@ package mount
 import (
 	"log"
 	"os"
+	"time"
 
 	"bazil.org/fuse"
 	"github.com/ncw/rclone/cmd"
@@ -21,6 +22,7 @@ var (
 	noModTime    = false
 	debugFUSE    = false
 	noSeek       = false
+	dirCacheTime = 5 * 60 * time.Second
 	// mount options
 	readOnly                         = false
 	allowNonEmpty                    = false
@@ -45,6 +47,7 @@ func init() {
 	mountCmd.Flags().BoolVarP(&noModTime, "no-modtime", "", noModTime, "Don't read the modification time (can speed things up).")
 	mountCmd.Flags().BoolVarP(&debugFUSE, "debug-fuse", "", debugFUSE, "Debug the FUSE internals - needs -v.")
 	mountCmd.Flags().BoolVarP(&noSeek, "no-seek", "", noSeek, "Don't allow seeking in files.")
+	mountCmd.Flags().DurationVarP(&dirCacheTime, "dir-cache-time", "", dirCacheTime, "Time to cache directory entries for.")
 	// mount options
 	mountCmd.Flags().BoolVarP(&readOnly, "read-only", "", readOnly, "Mount read-only.")
 	mountCmd.Flags().BoolVarP(&allowNonEmpty, "allow-non-empty", "", allowNonEmpty, "Allow mounting over a non-empty directory.")