added directory listing cache

TODO.txt

@@ -1,5 +1,4 @@
 * add disk quota
   * preload: dont load file if quota exceeded
 * add LRU cache
-* implement directory listing cache
 * clear cache if file sizes differ and > 0

pkg/fs/dir.go

@@ -3,12 +3,47 @@
 package fs
 
 import (
+	"errors"
 	"io"
 	"os"
+	"sync"
+	"time"
 )
 
+var NoCacheEntry = errors.New("no cache entry")
+
+type DirCacheEntry struct {
+	mtime time.Time
+	fi    []os.FileInfo
+}
+
+type DirCache struct {
+	mu sync.RWMutex
+	m  map[string]*DirCacheEntry
+}
+
+func NewDirCache() *DirCache {
+	return &DirCache{m: make(map[string]*DirCacheEntry)}
+}
+
+func (dc *DirCache) Get(name string) (*DirCacheEntry, error) {
+	dc.mu.RLock()
+	defer dc.mu.RUnlock()
+	if dce, ok := dc.m[name]; ok {
+		return dce, nil
+	}
+	return nil, NoCacheEntry
+}
+
+func (dc *DirCache) Set(name string, dce *DirCacheEntry) {
+	dc.mu.Lock()
+	defer dc.mu.Unlock()
+	dc.m[name] = dce
+}
+
 type Dir struct {
 	f  *os.File
+	dc *DirCache
 }
 
 func (f *Dir) Read(_ []byte) (int, error) {
@@ -19,8 +54,23 @@ func (f *Dir) Seek(_ int64, _ int) (int64, error) {
 	return 0, io.EOF
 }
 
-func (f *Dir) Readdir(count int) ([]os.FileInfo, error) {
+func (f *Dir) Readdir(_ int) (fi []os.FileInfo, err error) {
-	return f.f.Readdir(count)
+	i, err := f.Stat()
+	if err != nil {
+		return
+	}
+	name := f.f.Name()
+	dce, err := f.dc.Get(name)
+	if err == NoCacheEntry || i.ModTime().After(dce.mtime) {
+		fi, err = f.f.Readdir(0)
+		if err != nil {
+			return
+		}
+		dce = &DirCacheEntry{i.ModTime(), fi}
+		f.dc.Set(name, dce)
+	}
+	fi = dce.fi
+	return
 }
 
 func (f *Dir) Stat() (os.FileInfo, error) {

pkg/fs/fs.go

@@ -28,6 +28,7 @@ type FS struct {
 	dst     string
 	mdf     *os.File
 	jenc    *json.Encoder
+	dc      *DirCache
 	mm      map[string]*Metadata
 	prem    map[string]func()
 	cancel  func()
@@ -56,6 +57,7 @@ func NewFS(src, dst, metadata string, log logr.Logger) (fs *FS, err error) {
 		src:     src,
 		dst:     dst,
 		mdf:     mdf,
+		dc:      NewDirCache(),
 		mm:      make(map[string]*Metadata),
 		prem:    make(map[string]func()),
 		jenc:    json.NewEncoder(mdf),
@@ -197,7 +199,7 @@ func (fs *FS) Open(name string) (f http.File, err error) {
 			offline = true
 			log.V(2).Info("dir offline mode", "path", dp)
 		}
-		return &Dir{f: sf}, err
+		return &Dir{f: sf, dc: fs.dc}, err
 	}
 	md := fs.metadata(name, sfi.Size())
 	return &File{

pkg/srv/srv.go

@@ -67,10 +67,10 @@ func (fs *FileServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if !d.IsDir() {
-		if option == "p" || option == "sp" {
+		if option == "p" || option == "s" {
 			if option == "p" {
 				fs.fs.Preload(p)
-			} else {
+			} else if option == "s" {
 				fs.fs.CancelPreload(p)
 			}
 			rdir := "/"

pkg/srv/templates.go

@@ -30,7 +30,7 @@ var (
 {{end -}}
 {{range $s := .Files -}}
     <tr><td><a id="{{$s.Anchor}}" href="{{$s.Name}}">{{$s.Name}}</a></td>
-    <td><a href="{{$s.Name}}?o=v">[v]</a>&nbsp;<a href="{{$s.Name}}?o=n">[n]</a>&nbsp;<a href="{{$s.Name}}?o=p">[p]</a>&nbsp;<a href="{{$s.Name}}?o=sp">[sp]</a>&nbsp;{{if ge $s.Status 0}}{{$s.Status}}%{{end}}</td></tr>
+    <td><a href="{{$s.Name}}?o=v">[v]</a>&nbsp;<a href="{{$s.Name}}?o=n">[n]</a>&nbsp;<a href="{{$s.Name}}?o=p">[p]</a>&nbsp;<a href="{{$s.Name}}?o=s">[s]</a>&nbsp;{{if ge $s.Status 0}}{{$s.Status}}%{{end}}</td></tr>
 {{end -}}
   </table>
   </article>