start replacing engine

src/login/mod.rs

@@ -109,8 +109,8 @@ impl Region {
 
 
 impl Credentials {
-    pub fn k2v_client(&self) -> Result<K2vClient> {
-        self.storage.k2v_client()
+    pub fn k2v_client(&self) -> Result<RowStore, Error> {
+        self.storage.row.row_store()
     }
     pub fn s3_client(&self) -> Result<S3Client> {
         self.storage.s3_client()

src/storage/garage.rs

@@ -7,7 +7,7 @@ pub struct GrgRef {}
 pub struct GrgValue {}
 
 impl IRowBuilder for GrgCreds {
-    fn row_store(&self) -> RowStore {
+    fn row_store(&self) -> Result<RowStore, Error> {
         unimplemented!();
     }
 }

src/storage/in_memory.rs

@@ -8,7 +8,7 @@ pub struct MemRef {}
 pub struct MemValue {}
 
 impl IRowBuilder for MemCreds {
-    fn row_store(&self) -> RowStore {
+    fn row_store(&self) -> Result<RowStore, Error> {
         unimplemented!();
     }
 }

src/storage/mod.rs

@@ -54,7 +54,7 @@ pub type AsyncResult<'a, T> = BoxFuture<'a, Result<T, Error>>;
 // ------ Row Builder
 pub trait IRowBuilder
 {
-    fn row_store(&self) -> RowStore;
+    fn row_store(&self) -> Result<RowStore, Error>;
 }
 pub type RowBuilder = Box<dyn IRowBuilder + Send + Sync>;
 
@@ -63,7 +63,7 @@ pub trait IRowStore
 {
     fn new_row(&self, partition: &str, sort: &str) -> RowRef;
 }
-type RowStore = Box<dyn IRowStore>;
+pub type RowStore = Box<dyn IRowStore>;
 
 // ------- Row Item
 pub trait IRowRef