small refactor*

server/pkg/ioutils/readerat.go

@@ -0,0 +1,49 @@
+package ioutils
+
+import (
+	"context"
+	"sync"
+
+	"github.com/royalcat/ctxio"
+)
+
+type ReaderReaderAtWrapper struct {
+	mu     sync.Mutex
+	rat    ctxio.ReaderAt
+	offset int64
+}
+
+func NewReaderReaderAtWrapper(rat ctxio.ReaderAt) *ReaderReaderAtWrapper {
+	return &ReaderReaderAtWrapper{
+		rat: rat,
+	}
+}
+
+var _ ctxio.Reader = (*ReaderReaderAtWrapper)(nil)
+var _ ctxio.ReaderAt = (*ReaderReaderAtWrapper)(nil)
+var _ ctxio.Closer = (*ReaderReaderAtWrapper)(nil)
+
+// Read implements Reader.
+func (r *ReaderReaderAtWrapper) Read(ctx context.Context, p []byte) (n int, err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	n, err = r.rat.ReadAt(ctx, p, r.offset)
+	r.offset += int64(n)
+	return n, err
+}
+
+// ReadAt implements ReaderAt.
+func (r *ReaderReaderAtWrapper) ReadAt(ctx context.Context, p []byte, off int64) (n int, err error) {
+	return r.rat.ReadAt(ctx, p, off)
+}
+
+// Close implements Closer.
+func (r *ReaderReaderAtWrapper) Close(ctx context.Context) (err error) {
+	if c, ok := r.rat.(ctxio.Closer); ok {
+		err = c.Close(ctx)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}