Optimize test_vm get_actor (#585)

* Optimize test_vm get_actor

Improves extend_sector_with_deals by 40%

Signed-off-by: Jakub Sztandera <kubuxu@protocol.ai>

* Keep the cache across invocations

Gives another 32%

Signed-off-by: Jakub Sztandera <kubuxu@protocol.ai>

Signed-off-by: Jakub Sztandera <kubuxu@protocol.ai>

test_vm/src/lib.rs

@@ -328,7 +328,11 @@ impl<'bs> VM<'bs> {
             self.store,
         )
         .unwrap();
-        actors.get(&addr.to_bytes()).unwrap().cloned()
+        let actor = actors.get(&addr.to_bytes()).unwrap().cloned();
+        actor.iter().for_each(|a| {
+            self.actors_cache.borrow_mut().insert(addr, a.clone());
+        });
+        actor
     }
 
     // blindly overwrite the actor at this address whether it previously existed or not
@@ -348,8 +352,8 @@ impl<'bs> VM<'bs> {
             actors.set(addr.to_bytes().into(), act.clone()).unwrap();
         }
 
-        // roll "back" to latest head, flushing cache
-        self.rollback(actors.flush().unwrap());
+        self.state_root.replace(actors.flush().unwrap());
+        self.actors_dirty.replace(false);
         *self.state_root.borrow()
     }