fix: replace the lock with an RW lock to only lock the read on list a…

…nd fetch

api/tech/oras/client.go

@@ -24,7 +24,7 @@ type Client struct {
 	client    *auth.Client
 	plainHTTP bool
 	ref       string
-	mu        sync.Mutex
+	mu        sync.RWMutex
 }
 
 var (
@@ -38,10 +38,34 @@ func New(opts ClientOptions) *Client {
 	return &Client{client: opts.Client, plainHTTP: opts.PlainHTTP}
 }
 
-func (c *Client) Resolve(ctx context.Context, ref string) (string, ociv1.Descriptor, error) {
+func (c *Client) Fetcher(ctx context.Context, ref string) (Fetcher, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.ref = ref
+	return c, nil
+}
+
+func (c *Client) Pusher(ctx context.Context, ref string) (Pusher, error) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
+	c.ref = ref
+	return c, nil
+}
+
+func (c *Client) Lister(ctx context.Context, ref string) (Lister, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.ref = ref
+	return c, nil
+}
+
+func (c *Client) Resolve(ctx context.Context, ref string) (string, ociv1.Descriptor, error) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
 	src, err := c.createRepository(ref)
 	if err != nil {
 		return "", ociv1.Descriptor{}, err
@@ -64,33 +88,9 @@ func (c *Client) Resolve(ctx context.Context, ref string) (string, ociv1.Descrip
 	return "", desc, nil
 }
 
-func (c *Client) Fetcher(ctx context.Context, ref string) (Fetcher, error) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
-	c.ref = ref
-	return c, nil
-}
-
-func (c *Client) Pusher(ctx context.Context, ref string) (Pusher, error) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
-	c.ref = ref
-	return c, nil
-}
-
-func (c *Client) Lister(ctx context.Context, ref string) (Lister, error) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-
-	c.ref = ref
-	return c, nil
-}
-
 func (c *Client) Push(ctx context.Context, d ociv1.Descriptor, src Source) error {
-	c.mu.Lock()
-	defer c.mu.Unlock()
+	c.mu.RLock()
+	defer c.mu.RUnlock()
 
 	reader, err := src.Reader()
 	if err != nil {
@@ -124,8 +124,8 @@ func (c *Client) Push(ctx context.Context, d ociv1.Descriptor, src Source) error
 }
 
 func (c *Client) Fetch(ctx context.Context, desc ociv1.Descriptor) (io.ReadCloser, error) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
+	c.mu.RLock()
+	defer c.mu.RUnlock()
 
 	src, err := c.createRepository(c.ref)
 	if err != nil {
@@ -167,8 +167,8 @@ func (c *Client) Fetch(ctx context.Context, desc ociv1.Descriptor) (io.ReadClose
 }
 
 func (c *Client) List(ctx context.Context) ([]string, error) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
+	c.mu.RLock()
+	defer c.mu.RUnlock()
 
 	src, err := c.createRepository(c.ref)
 	if err != nil {