Add owner calls to the parachains pallet

Signed-off-by: Serban Iorga <serban@parity.io>

bridges/modules/parachains/src/lib.rs

@@ -80,6 +80,7 @@ struct UpdateParachainHeadArtifacts {
 #[frame_support::pallet]
 pub mod pallet {
 	use super::*;
+	use bp_runtime::{BasicOperatingMode, OwnedBridgeModule};
 	use frame_support::pallet_prelude::*;
 	use frame_system::pallet_prelude::*;
 
@@ -100,6 +101,8 @@ pub mod pallet {
 		StorageRootMismatch,
 		/// Failed to extract state root from given parachain head.
 		FailedToExtractStateRoot,
+		/// Error generated by the `OwnedBridgeModule` trait.
+		BridgeModule(bp_runtime::OwnedBridgeModuleError),
 	}
 
 	#[pallet::config]
@@ -138,6 +141,23 @@ pub mod pallet {
 		type HeadsToKeep: Get<u32>;
 	}
 
+	/// Optional pallet owner.
+	///
+	/// Pallet owner has a right to halt all pallet operations and then resume them. If it is
+	/// `None`, then there are no direct ways to halt/resume pallet operations, but other
+	/// runtime methods may still be used to do that (i.e. democracy::referendum to update halt
+	/// flag directly or call the `halt_operations`).
+	#[pallet::storage]
+	pub type PalletOwner<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, T::AccountId, OptionQuery>;
+
+	/// The current operating mode of the pallet.
+	///
+	/// Depending on the mode either all, or no transactions will be allowed.
+	#[pallet::storage]
+	pub type PalletOperatingMode<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, BasicOperatingMode, ValueQuery>;
+
 	/// Best parachain heads.
 	#[pallet::storage]
 	pub type BestParaHeads<T: Config<I>, I: 'static = ()> =
@@ -158,6 +178,13 @@ pub mod pallet {
 	#[pallet::without_storage_info]
 	pub struct Pallet<T, I = ()>(PhantomData<(T, I)>);
 
+	impl<T: Config<I>, I: 'static> OwnedBridgeModule<T> for Pallet<T, I> {
+		const LOG_TARGET: &'static str = LOG_TARGET;
+		type OwnerStorage = PalletOwner<T, I>;
+		type OperatingMode = BasicOperatingMode;
+		type OperatingModeStorage = PalletOperatingMode<T, I>;
+	}
+
 	#[pallet::call]
 	impl<T: Config<I>, I: 'static> Pallet<T, I>
 	where
@@ -185,6 +212,7 @@ pub mod pallet {
 			parachains: Vec<ParaId>,
 			parachain_heads_proof: ParaHeadsProof,
 		) -> DispatchResultWithPostInfo {
+			Self::ensure_not_halted().map_err(Error::<T, I>::BridgeModule)?;
 			// we'll need relay chain header to verify that parachains heads are always increasing.
 			let (relay_block_number, relay_block_hash) = at_relay_block;
 			let relay_block = pallet_bridge_grandpa::ImportedHeaders::<
@@ -266,6 +294,25 @@ pub mod pallet {
 
 			Ok(PostDispatchInfo { actual_weight: Some(actual_weight), pays_fee: Pays::Yes })
 		}
+
+		/// Change `PalletOwner`.
+		///
+		/// May only be called either by root, or by `PalletOwner`.
+		#[pallet::weight((T::DbWeight::get().reads_writes(1, 1), DispatchClass::Operational))]
+		pub fn set_owner(origin: OriginFor<T>, new_owner: Option<T::AccountId>) -> DispatchResult {
+			<Self as OwnedBridgeModule<_>>::set_owner(origin, new_owner)
+		}
+
+		/// Halt or resume all pallet operations.
+		///
+		/// May only be called either by root, or by `PalletOwner`.
+		#[pallet::weight((T::DbWeight::get().reads_writes(1, 1), DispatchClass::Operational))]
+		pub fn set_operating_mode(
+			origin: OriginFor<T>,
+			operating_mode: BasicOperatingMode,
+		) -> DispatchResult {
+			<Self as OwnedBridgeModule<_>>::set_operating_mode(origin, operating_mode)
+		}
 	}
 
 	impl<T: Config<I>, I: 'static> Pallet<T, I> {
@@ -404,7 +451,9 @@ mod tests {
 	};
 
 	use bp_runtime::BasicOperatingMode;
-	use bp_test_utils::{authority_list, make_default_justification};
+	use bp_test_utils::{
+		authority_list, generate_owned_bridge_module_tests, make_default_justification,
+	};
 	use frame_support::{
 		assert_noop, assert_ok,
 		dispatch::DispatchResultWithPostInfo,
@@ -412,6 +461,7 @@ mod tests {
 		traits::{Get, OnInitialize},
 		weights::Weight,
 	};
+	use sp_runtime::DispatchError;
 	use sp_trie::{
 		record_all_keys, trie_types::TrieDBMutV1, LayoutV1, MemoryDB, Recorder, TrieMut,
 	};
@@ -837,4 +887,6 @@ mod tests {
 			.0,
 		);
 	}
+
+	generate_owned_bridge_module_tests!(BasicOperatingMode::Normal, BasicOperatingMode::Halted);
 }