[Feature] Add a migration that drains and refunds stored calls

frame/multisig/Cargo.toml

@@ -22,6 +22,9 @@ sp-io = { version = "6.0.0", default-features = false, path = "../../primitives/
 sp-runtime = { version = "6.0.0", default-features = false, path = "../../primitives/runtime" }
 sp-std = { version = "4.0.0", default-features = false, path = "../../primitives/std" }
 
+# third party
+log = { version = "0.4.17", default-features = false }
+
 [dev-dependencies]
 pallet-balances = { version = "4.0.0-dev", path = "../balances" }
 sp-core = { version = "6.0.0", path = "../../primitives/core" }

frame/multisig/src/lib.rs

@@ -47,6 +47,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
 mod benchmarking;
+pub mod migrations;
 mod tests;
 pub mod weights;
 
@@ -58,7 +59,7 @@ use frame_support::{
 	},
 	ensure,
 	traits::{Currency, Get, ReservableCurrency},
-	weights::{GetDispatchInfo, Weight},
+	weights::Weight,
 	RuntimeDebug,
 };
 use frame_system::{self as system, RawOrigin};
@@ -73,6 +74,20 @@ pub use weights::WeightInfo;
 
 pub use pallet::*;
 
+/// The log target of this pallet.
+pub const LOG_TARGET: &'static str = "runtime::multisig";
+
+// syntactic sugar for logging.
+#[macro_export]
+macro_rules! log {
+	($level:tt, $patter:expr $(, $values:expr)* $(,)?) => {
+		log::$level!(
+			target: crate::LOG_TARGET,
+			concat!("[{:?}] ✍️ ", $patter), <frame_system::Pallet<T>>::block_number() $(, $values)*
+		)
+	};
+}
+
 type BalanceOf<T> =
 	<<T as Config>::Currency as Currency<<T as frame_system::Config>::AccountId>>::Balance;
 
@@ -103,7 +118,7 @@ pub struct Multisig<BlockNumber, Balance, AccountId> {
 type CallHash = [u8; 32];
 
 enum CallOrHash<T: Config> {
-	Call(<T as Config>::Call),
+	Call(<T as Config>::RuntimeCall),
 	Hash([u8; 32]),
 }
 
@@ -150,9 +165,13 @@ pub mod pallet {
 		type WeightInfo: WeightInfo;
 	}
 
+	/// The current storage version.
+	const STORAGE_VERSION: StorageVersion = StorageVersion::new(1);
+
 	#[pallet::pallet]
 	#[pallet::generate_store(pub(super) trait Store)]
 	#[pallet::without_storage_info]
+	#[pallet::storage_version(STORAGE_VERSION)]
 	pub struct Pallet<T>(_);
 
 	/// The set of open multisig operations.
@@ -356,7 +375,7 @@ pub mod pallet {
 			threshold: u16,
 			other_signatories: Vec<T::AccountId>,
 			maybe_timepoint: Option<Timepoint<T::BlockNumber>>,
-			call: Box<<T as Config>::Call>,
+			call: Box<<T as Config>::RuntimeCall>,
 			max_weight: Weight,
 		) -> DispatchResultWithPostInfo {
 			let who = ensure_signed(origin)?;

frame/multisig/src/migrations.rs

@@ -0,0 +1,69 @@
+use super::*;
+use frame_support::{
+	dispatch::GetStorageVersion,
+	traits::{OnRuntimeUpgrade, WrapperKeepOpaque},
+	Identity,
+};
+
+#[cfg(feature = "try-runtime")]
+use frame_support::ensure;
+
+pub mod v1 {
+	use super::*;
+
+	type OpaqueCall<T> = WrapperKeepOpaque<<T as Config>::RuntimeCall>;
+
+	#[frame_support::storage_alias]
+	type Calls<T: Config> = StorageMap<
+		Pallet<T>,
+		Identity,
+		[u8; 32],
+		(OpaqueCall<T>, <T as frame_system::Config>::AccountId, BalanceOf<T>),
+	>;
+
+	pub struct MigrateToV1<T>(sp_std::marker::PhantomData<T>);
+	impl<T: Config> OnRuntimeUpgrade for MigrateToV1<T> {
+		#[cfg(feature = "try-runtime")]
+		fn pre_upgrade() -> Result<(), &'static str> {
+			let onchain = Pallet::<T>::on_chain_storage_version();
+
+			ensure!(onchain < 1, "this migration can be deleted");
+
+			log!(info, "Number of calls to refund and delete: {}", Calls::<T>::iter().count());
+
+			Ok(())
+		}
+
+		fn on_runtime_upgrade() -> Weight {
+			let current = Pallet::<T>::current_storage_version();
+			let onchain = Pallet::<T>::on_chain_storage_version();
+
+			if onchain > 0 {
+				log!(info, "MigrateToV1 should be removed");
+				return T::DbWeight::get().reads(1)
+			}
+
+			// TODO: Assuming this is one write and a read per record
+			Calls::<T>::drain().for_each(|(_call_hash, (_data, caller, deposit))| {
+				//TODO: What's the weight of one unreserve?
+				T::Currency::unreserve(&caller, deposit);
+			});
+
+			current.put::<Pallet<T>>();
+
+			<T as frame_system::Config>::BlockWeights::get().max_block
+		}
+
+		#[cfg(feature = "try-runtime")]
+		fn post_upgrade() -> Result<(), &'static str> {
+			let onchain = Pallet::<T>::on_chain_storage_version();
+
+			ensure!(onchain > 0, "this migration needs to be run");
+			ensure!(
+				Calls::<T>::iter().count() == 0,
+				"there are some dangling calls that need to be destroyed and refunded"
+			);
+			Ok(())
+		}
+	}
+}