[#569] writecache: Do not wait modeMtx if mode changes

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/local_object_storage/writecache/delete.go

@@ -18,6 +18,7 @@ import (
 // Delete removes object from write-cache.
 //
 // Returns an error of type apistatus.ObjectNotFound if object is missing in write-cache.
+// Returns ErrNotInitialized if write-cache has not been initialized yet.
 func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
 	ctx, span := tracing.StartSpanFromContext(ctx, "writecache.Delete",
 		trace.WithAttributes(
@@ -32,7 +33,9 @@ func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
 		c.metrics.Delete(time.Since(startedAt), deleted, storageType)
 	}()
 
-	c.modeMtx.RLock()
+	if !c.modeMtx.TryRLock() {
+		return ErrNotInitialized
+	}
 	defer c.modeMtx.RUnlock()
 	if c.readOnly() {
 		return ErrReadOnly

pkg/local_object_storage/writecache/put.go

@@ -34,7 +34,9 @@ func (c *cache) Put(ctx context.Context, prm common.PutPrm) (common.PutRes, erro
 		c.metrics.Put(time.Since(startedAt), added, storageType)
 	}()
 
-	c.modeMtx.RLock()
+	if !c.modeMtx.TryRLock() {
+		return common.PutRes{}, ErrNotInitialized
+	}
 	defer c.modeMtx.RUnlock()
 	if c.readOnly() {
 		return common.PutRes{}, ErrReadOnly