Merge pull request #234 from bitfinity-network/fix_wrong_cast

Fix wrong cast that could lead to a panic

ic-stable-structures/src/structure/cache/multimap.rs

@@ -100,7 +100,7 @@ where
         Some(res)
     }
 
-    fn len(&self) -> usize {
+    fn len(&self) -> u64 {
         self.inner.len()
     }
 

ic-stable-structures/src/structure/mod.rs

@@ -134,7 +134,7 @@ pub trait MultimapStructure<K1, K2, V> {
     fn pop_last(&mut self) -> Option<((K1, K2), V)>;
 
     /// Items count.
-    fn len(&self) -> usize;
+    fn len(&self) -> u64;
 
     /// Is map empty.
     fn is_empty(&self) -> bool;

ic-stable-structures/src/structure/stable_storage/multimap.rs

@@ -76,8 +76,8 @@ where
         self.0.pop_last()
     }
 
-    fn len(&self) -> usize {
-        self.0.len() as usize
+    fn len(&self) -> u64 {
+        self.0.len()
     }
 
     fn is_empty(&self) -> bool {

ic-stable-structures/tests/dummy_canister/src/canister/service.rs

@@ -199,7 +199,7 @@ impl Service {
 
     pub fn insert_tx_to_multimap(transaction: BoundedTransaction) -> u64 {
         TX_MULTIMAP.with(|storage| {
-            let new_key = storage.borrow().len() as u64;
+            let new_key = storage.borrow().len();
             storage
                 .borrow_mut()
                 .insert(&new_key, &(new_key + 1), transaction);