Improve call, and usage in pallet utility (#9418)

* WIP

* WIP

* WIP

* add some tests and limit

* remove wip test

* fmt

* Update bin/node/runtime/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* fmt

* use primitives allocation limit

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/frame/utility/src/lib.rs

@@ -112,13 +112,33 @@ pub mod pallet {
 		ItemCompleted,
 	}
 
+	#[pallet::extra_constants]
+	impl<T: Config> Pallet<T> {
+		/// The limit on the number of batched calls.
+		fn batched_calls_limit() -> u32 {
+			let allocator_limit = sp_core::MAX_POSSIBLE_ALLOCATION;
+			let call_size = core::mem::size_of::<<T as Config>::Call>() as u32;
+			// The margin to take into account vec doubling capacity.
+			let margin_factor = 3;
+
+			allocator_limit / margin_factor / call_size
+		}
+	}
+
+	#[pallet::error]
+	pub enum Error<T> {
+		/// Too many calls batched.
+		TooManyCalls,
+	}
+
 	#[pallet::call]
 	impl<T: Config> Pallet<T> {
 		/// Send a batch of dispatch calls.
 		///
 		/// May be called from any origin.
 		///
-		/// - `calls`: The calls to be dispatched from the same origin.
+		/// - `calls`: The calls to be dispatched from the same origin. The number of call must not
+		///   exceed the constant: `batched_calls_limit` (available in constant metadata).
 		///
 		/// If origin is root then call are dispatch without checking origin filter. (This includes
 		/// bypassing `frame_system::Config::BaseCallFilter`).
@@ -156,6 +176,8 @@ pub mod pallet {
 		) -> DispatchResultWithPostInfo {
 			let is_root = ensure_root(origin.clone()).is_ok();
 			let calls_len = calls.len();
+			ensure!(calls_len <= Self::batched_calls_limit() as usize, Error::<T>::TooManyCalls);
+
 			// Track the actual weight of each of the batch calls.
 			let mut weight: Weight = 0;
 			for (index, call) in calls.into_iter().enumerate() {
@@ -234,7 +256,8 @@ pub mod pallet {
 		///
 		/// May be called from any origin.
 		///
-		/// - `calls`: The calls to be dispatched from the same origin.
+		/// - `calls`: The calls to be dispatched from the same origin. The number of call must not
+		///   exceed the constant: `batched_calls_limit` (available in constant metadata).
 		///
 		/// If origin is root then call are dispatch without checking origin filter. (This includes
 		/// bypassing `frame_system::Config::BaseCallFilter`).
@@ -267,6 +290,8 @@ pub mod pallet {
 		) -> DispatchResultWithPostInfo {
 			let is_root = ensure_root(origin.clone()).is_ok();
 			let calls_len = calls.len();
+			ensure!(calls_len <= Self::batched_calls_limit() as usize, Error::<T>::TooManyCalls);
+
 			// Track the actual weight of each of the batch calls.
 			let mut weight: Weight = 0;
 			for (index, call) in calls.into_iter().enumerate() {

substrate/frame/utility/src/tests.rs

@@ -66,6 +66,9 @@ pub mod example {
 					Ok(end_weight.into())
 				}
 			}
+
+			#[weight = 0]
+			fn big_variant(_origin, _arg: [u8; 400]) {}
 		}
 	}
 }
@@ -588,3 +591,12 @@ fn batch_all_does_not_nest() {
 		assert_eq!(Balances::free_balance(2), 10);
 	});
 }
+
+#[test]
+fn batch_limit() {
+	new_test_ext().execute_with(|| {
+		let calls = vec![Call::System(SystemCall::remark(vec![])); 40_000];
+		assert_noop!(Utility::batch(Origin::signed(1), calls.clone()), Error::<Test>::TooManyCalls);
+		assert_noop!(Utility::batch_all(Origin::signed(1), calls), Error::<Test>::TooManyCalls);
+	});
+}