fuse: Add bandwidth accounting and buffering

This fixes rclone mount ignoring bwlimit and increases buffering which
should speed up transfers greatly.

Fixes #796
Fixes #690

cmd/mount/read.go

@@ -27,10 +27,11 @@ func newReadFileHandle(o fs.Object) (*ReadFileHandle, error) {
 	if err != nil {
 		return nil, err
 	}
-	return &ReadFileHandle{
+	fh := &ReadFileHandle{
-		r: r,
 		o: o,
-	}, nil
+		r: fs.NewAccount(r, o), // account and buffer the transfer
+	}
+	return fh, nil
 }
 
 // Check interface satisfied
@@ -63,7 +64,7 @@ func (fh *ReadFileHandle) seek(offset int64) error {
 		if err != nil {
 			fs.Debug(fh.o, "ReadFileHandle.Read seek close old failed: %v", err)
 		}
-		fh.r = r
+		fh.r = fs.NewAccount(r, fh.o) // account and buffer the transfer
 	}
 	fh.offset = offset
 	return nil

cmd/mount/write.go

@@ -38,8 +38,9 @@ func newWriteFileHandle(d *Dir, f *File, src fs.ObjectInfo) (*WriteFileHandle, e
 		file:   f,
 	}
 	fh.pipeReader, fh.pipeWriter = io.Pipe()
+	r := fs.NewAccountSizeName(fh.pipeReader, 0, src.Remote()) // account and buffer the transfer
 	go func() {
-		o, err := d.f.Put(fh.pipeReader, src)
+		o, err := d.f.Put(r, src)
 		fh.o = o
 		fh.result <- err
 	}()

fs/accounting.go

@@ -276,12 +276,28 @@ type Account struct {
 	wholeFileDisabled bool // disables the whole file when doing parts
 }
 
-// NewAccount makes a Account reader for an object
+// NewAccountSizeName makes a Account reader for an io.ReadCloser of
-func NewAccount(in io.ReadCloser, obj Object) *Account {
+// the given size and name
+//
+// If the file is above a certain size it adds an Async reader
+func NewAccountSizeName(in io.ReadCloser, size int64, name string) *Account {
+	// On big files add a buffer
+	if size > 10<<20 {
+		const memUsed = 16 * 1024 * 1024
+		const bufSize = 128 * 1024
+		const buffers = memUsed / bufSize
+		newIn, err := newAsyncReader(in, buffers, bufSize)
+		if err != nil {
+			ErrorLog(name, "Failed to make buffer: %v", err)
+		} else {
+			in = newIn
+		}
+	}
+
 	acc := &Account{
 		in:     in,
-		size:   obj.Size(),
+		size:   size,
-		name:   obj.Remote(),
+		name:   name,
 		exit:   make(chan struct{}),
 		avg:    ewma.NewMovingAverage(),
 		lpTime: time.Now(),
@@ -291,6 +307,11 @@ func NewAccount(in io.ReadCloser, obj Object) *Account {
 	return acc
 }
 
+// NewAccount makes a Account reader for an object
+func NewAccount(in io.ReadCloser, obj Object) *Account {
+	return NewAccountSizeName(in, obj.Size(), obj.Remote())
+}
+
 // disableWholeFileAccounting turns off the whole file accounting
 func (acc *Account) disableWholeFileAccounting() {
 	acc.mu.Lock()

fs/operations.go

@@ -264,12 +264,7 @@ func Copy(f Fs, dst Object, remote string, src Object) (err error) {
 			if err != nil {
 				err = errors.Wrap(err, "failed to open source object")
 			} else {
-				// On big files add a buffer
+				in := NewAccount(in0, src) // account and buffer the transfer
-				if src.Size() > 10<<20 {
-					in0, _ = newAsyncReader(in0, 4, 4<<20)
-				}
-
-				in := NewAccount(in0, src) // account the transfer
 
 				wrappedSrc := &overrideRemoteObject{Object: src, remote: remote}
 				if doUpdate {
@@ -1131,7 +1126,7 @@ func Cat(f Fs, w io.Writer) error {
 				ErrorLog(o, "Failed to close: %v", err)
 			}
 		}()
-		inAccounted := NewAccount(in, o) // account the transfer
+		inAccounted := NewAccount(in, o) // account and buffer the transfer
 		_, err = io.Copy(w, inAccounted)
 		if err != nil {
 			Stats.Error()