more async improvements and crypto bugfix

pkg/fs/metadata.go

@@ -29,13 +29,14 @@ func now() int64 {
 }
 
 type MetadataHandler struct {
-	mu  sync.RWMutex
-	log logr.Logger
-	md  map[string]*Metadata
-	fs  *FS
-	dst string
-	f   *os.File
-	enc *json.Encoder
+	mu   sync.RWMutex
+	done chan struct{}
+	log  logr.Logger
+	md   map[string]*Metadata
+	fs   *FS
+	dst  string
+	f    *os.File
+	enc  *json.Encoder
 }
 
 func MetadataGenerator(file string, dst provider.FS, fstat, encrypted bool) error {
@@ -109,10 +110,11 @@ func NewMetadataHandler(ctx context.Context, fs *FS, file, dst string, log logr.
 		return nil, errors.New("metadata path is not absolute")
 	}
 	mh = &MetadataHandler{
-		log: log,
-		md:  make(map[string]*Metadata),
-		fs:  fs,
-		dst: dst,
+		log:  log,
+		done: make(chan struct{}),
+		md:   make(map[string]*Metadata),
+		fs:   fs,
+		dst:  dst,
 	}
 	mh.f, err = os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0o640)
 	if err != nil {
@@ -230,6 +232,7 @@ func (mh *MetadataHandler) flusher(ctx context.Context) {
 		select {
 		case <-ctx.Done():
 			mh.close()
+			close(mh.done)
 			return
 		case <-time.After(time.Minute * 5):
 		}
@@ -302,6 +305,7 @@ func (mh *MetadataHandler) close() {
 	mh.mu.Lock()
 	for _, md := range mh.md {
 		if md.f != nil {
+			close(md.wc)
 			md.f.Sync()
 			md.f.Close()
 		}
@@ -309,7 +313,10 @@ func (mh *MetadataHandler) close() {
 	mh.mu.Unlock()
 	mh.flush()
 	mh.f.Close()
-	close(mh.fs.done)
+}
+
+func (mh *MetadataHandler) Done() <-chan struct{} {
+	return mh.done
 }
 
 type Error string
@@ -341,6 +348,8 @@ type Metadata struct {
 	mu     sync.RWMutex  `json:"-"`
 	fs     *FS           `json:"-"`
 	f      provider.File `json:"-"`
+	wc     chan writeAt  `json:"-"`
+	err    error         `json:"-"`
 	name   string        `json:"-"`
 	Size   int64         `json:"s"`
 	Atime  int64         `json:"a"`
@@ -350,6 +359,7 @@ type Metadata struct {
 func (md *Metadata) Close() error {
 	md.mu.Lock()
 	defer md.mu.Unlock()
+	close(md.wc)
 	err := md.f.Close()
 	md.f = nil
 	return err
@@ -359,6 +369,7 @@ func (md *Metadata) Delete() error {
 	md.mu.Lock()
 	defer md.mu.Unlock()
 	md.Chunks = chunk.Chunks{}
+	close(md.wc)
 	md.f.Close()
 	md.f = nil
 	atomic.StoreInt64(&md.Atime, now())
@@ -383,7 +394,7 @@ func (md *Metadata) ChunkSize() int64 {
 	return md.Chunks.Size()
 }
 
-func (md *Metadata) AddChunk(off int64, n int) {
+func (md *Metadata) addChunk(off int64, n int) {
 	md.mu.Lock()
 	defer md.mu.Unlock()
 	md.Chunks.Add(off, n)
@@ -400,16 +411,39 @@ func (md *Metadata) AddChunk(off int64, n int) {
 //	return md.f.ReadAt(p, pos)
 //}
 
+type writeAt struct {
+	pos  int64
+	data []byte
+}
+
+func (md *Metadata) writer() {
+	md.wc = make(chan writeAt, 10)
+	go func() {
+		for wa := range md.wc {
+			atomic.StoreInt64(&md.Atime, now())
+			n, err := md.f.WriteAt(wa.data, wa.pos)
+			if err == nil {
+				md.addChunk(wa.pos, n)
+				md.fs.q.Add(n)
+			} else {
+				md.err = err
+			}
+		}
+	}()
+}
+
 func (md *Metadata) WriteAt(data []byte, pos int64) (int, error) {
+	if md.err != nil {
+		return 0, md.err
+	}
 	if md.f == nil {
 		err := md.openCacheFile()
 		if err != nil {
 			return 0, err
 		}
 	}
-	atomic.StoreInt64(&md.Atime, now())
-	md.fs.q.Add(len(data))
-	return md.f.WriteAt(data, pos)
+	md.wc <- writeAt{pos, data}
+	return len(data), nil
 }
 
 func (md *Metadata) openCacheFile() error {
@@ -419,8 +453,12 @@ func (md *Metadata) openCacheFile() error {
 		return nil
 	}
 	f, err := md.fs.openCacheFile(md.name, md.Size)
+	if err != nil {
+		return err
+	}
 	md.f = f
-	return err
+	md.writer()
+	return nil
 }
 
 func (md *Metadata) Stat() (os.FileInfo, error) {