Re-add the async buffer on seek - fixes #1137

fs/accounting.go

@@ -343,12 +343,8 @@ func NewAccount(in io.ReadCloser, obj Object) *Account {
 	return NewAccountSizeName(in, obj.Size(), obj.Remote())
 }
 
-// NewAccountSizeNameWithBuffer makes a Account reader for an io.ReadCloser of
-// the given size and name
-//
-// If the file is above a certain size it adds an Async reader
-func NewAccountSizeNameWithBuffer(in io.ReadCloser, size int64, name string) *Account {
-	const bufSize = 1024 * 1024
+// bufferReadCloser returns a buffered version of in if necessary
+func bufferReadCloser(in io.ReadCloser, size int64, name string) io.ReadCloser {
 	var buffers int
 	if size >= int64(Config.BufferSize) {
 		buffers = int(int64(Config.BufferSize) / asyncBufferSize)
@@ -364,7 +360,15 @@ func NewAccountSizeNameWithBuffer(in io.ReadCloser, size int64, name string) *Ac
 			in = newIn
 		}
 	}
-	return NewAccountSizeName(in, size, name)
+	return in
+}
+
+// NewAccountSizeNameWithBuffer makes a Account reader for an io.ReadCloser of
+// the given size and name
+//
+// If the file is above a certain size it adds an Async reader
+func NewAccountSizeNameWithBuffer(in io.ReadCloser, size int64, name string) *Account {
+	return NewAccountSizeName(bufferReadCloser(in, size, name), size, name)
 }
 
 // NewAccountWithBuffer makes a Account reader for an object
@@ -384,7 +388,10 @@ func (acc *Account) GetReader() io.ReadCloser {
 // UpdateReader updates the underlying io.ReadCloser
 func (acc *Account) UpdateReader(in io.ReadCloser) {
 	acc.mu.Lock()
-	acc.in = in
+	if asyncIn, ok := acc.in.(*asyncReader); ok {
+		asyncIn.Abandon()
+	}
+	acc.in = bufferReadCloser(in, acc.size, acc.name)
 	acc.mu.Unlock()
 }
 

fs/buffer.go

@@ -152,9 +152,10 @@ func (a *asyncReader) WriteTo(w io.Writer) (n int64, err error) {
 	}
 }
 
-// Close will ensure that the underlying async reader is shut down.
-// It will also close the input supplied on newAsyncReader.
-func (a *asyncReader) Close() (err error) {
+// close will ensure that the underlying async reader is shut down.
+// If closeIn is set it will also close the input supplied on
+// newAsyncReader.
+func (a *asyncReader) close(closeIn bool) (err error) {
 	// Return if already closed
 	select {
 	case <-a.exit:
@@ -171,7 +172,22 @@ func (a *asyncReader) Close() (err error) {
 	for b := range a.ready {
 		a.putBuffer(b)
 	}
-	return a.in.Close()
+	if closeIn {
+		return a.in.Close()
+	}
+	return nil
+}
+
+// Close will ensure that the underlying async reader is shut down.
+// It will also close the input supplied on newAsyncReader.
+func (a *asyncReader) Close() (err error) {
+	return a.close(true)
+}
+
+// Abandon will ensure that the underlying async reader is shut down.
+// It will NOT close the input supplied on newAsyncReader.
+func (a *asyncReader) Abandon() {
+	_ = a.close(false)
 }
 
 // Internal buffer