Template

runtime/kusama/src/lib.rs

@@ -955,7 +955,78 @@ impl pallet_elections_phragmen::migrations_3_0_0::V2ToV3 for PhragmenElectionDep
 	type Balance = Balance;
 	type Module = ElectionsPhragmen;
 }
+
+type SanityState = (u32, u32, u32, u32, AccountId, Vec<AccountId>, Balance);
 impl frame_support::traits::OnRuntimeUpgrade for PhragmenElectionDepositRuntimeUpgrade {
+	#[cfg(feature = "std")]
+	fn pre_migration() -> Result<(), &'static str> {
+		let num_voters =
+			frame_support::migration::StorageKeyIterator::<AccountId, (Balance, Vec<AccountId>), frame_support::Twox64Concat>::new(
+				b"PhragmenElection",
+				b"Voting",
+			)
+			.count() as u32;
+		let num_candidates = frame_support::migration::get_storage_value::<Vec<AccountId>>(
+			b"PhragmenElection",
+			b"Candidates",
+			&[],
+		)
+		.unwrap_or_default() // we may actually have no candidates
+		.len() as u32;
+		let num_members = frame_support::migration::get_storage_value::<Vec<(AccountId, Balance)>>(
+			b"PhragmenElection",
+			b"Members",
+			&[],
+		)
+		.unwrap()
+		.len() as u32;
+		let num_runners_up =
+			frame_support::migration::get_storage_value::<Vec<(AccountId, Balance)>>(
+				b"PhragmenElection",
+				b"RunnersUp",
+				&[],
+			)
+			.unwrap()
+			.len() as u32;
+
+		// to ensure that votes etc stay persistent.
+		let (random_voter, (random_stake, random_votes)) =
+		frame_support::migration::StorageKeyIterator::<AccountId, (Balance, Vec<AccountId>), frame_support::Twox64Concat>::new(
+				b"PhragmenElection",
+				b"Voting",
+			)
+			.skip(5)
+			.take(1)
+			.collect::<Vec<_>>()
+			.pop()
+			.unwrap();
+
+		let data: SanityState =
+			(num_voters, num_candidates, num_members, num_runners_up, random_voter, random_votes, random_stake);
+
+		frame_support::storage::unhashed::put(b"migration_data_election_phragmen", &data);
+
+		Ok(())
+	}
+
+	#[cfg(feature = "std")]
+	fn post_migration() -> Result<(), &'static str> {
+		use frame_support::{IterableStorageMap, StorageMap, StorageValue};
+
+		let (num_voters, num_candidates, num_members, num_runners_up, random_voter, random_votes, random_stake): SanityState =
+			frame_support::storage::unhashed::get(b"migration_data_election_phragmen").unwrap();
+
+		assert_eq!(<pallet_elections_phragmen::Voting<Runtime>>::iter().count() as u32, num_voters);
+		assert_eq!(<pallet_elections_phragmen::Candidates<Runtime>>::get().len() as u32, num_candidates);
+		assert_eq!(<pallet_elections_phragmen::Members<Runtime>>::get().len() as u32, num_members);
+		assert_eq!(<pallet_elections_phragmen::RunnersUp<Runtime>>::get().len() as u32, num_runners_up);
+
+		assert_eq!(<pallet_elections_phragmen::Voting<Runtime>>::get(&random_voter).votes, random_votes);
+		assert_eq!(<pallet_elections_phragmen::Voting<Runtime>>::get(&random_voter).stake, random_stake);
+
+		Ok(())
+	}
+
 	fn on_runtime_upgrade() -> frame_support::weights::Weight {
 		pallet_elections_phragmen::migrations_3_0_0::apply::<Self>(5 * CENTS, DOLLARS)
 	}
@@ -1063,11 +1134,70 @@ pub type Executive = frame_executive::Executive<
 	frame_system::ChainContext<Runtime>,
 	Runtime,
 	AllModules,
-	(UpgradeSessionKeys, PhragmenElectionDepositRuntimeUpgrade)
+	CustomMigrations,
 >;
 /// The payload being signed in the transactions.
 pub type SignedPayload = generic::SignedPayload<Call, SignedExtra>;
 
+/// All custom runtime migrations that shall happen in an upcoming runtime upgrade.
+///
+/// The type alias should always be kept, change the internals
+pub type CustomMigrations = (PhragmenElectionDepositRuntimeUpgrade, UpgradeSessionKeys,);
+
+pub struct EnsureAccountsStayUntouched;
+
+/// An example of a migration that alters an existing storage item.
+pub struct DoubleAccountBalances;
+impl frame_support::traits::OnRuntimeUpgrade for DoubleAccountBalances {
+	fn on_runtime_upgrade() -> Weight {
+		use frame_support::StorageValue;
+
+		// NOTE: better to use StorageIterator, this is not really a `translate` op, but anyhow.
+		<frame_system::Account<Runtime>>::translate::<
+			frame_system::AccountInfo<Nonce, pallet_balances::AccountData<Balance>>,
+			_,
+		>(|_, mut info| {
+			info.data.free *= 2;
+			Some(info)
+		});
+		<pallet_balances::TotalIssuance<Runtime>>::mutate(|t| *t *= 2);
+
+		Default::default()
+	}
+
+	#[cfg(feature = "std")]
+	fn pre_migration() -> Result<(), &'static str> {
+		let num_accounts = <frame_system::Account<Runtime>>::iter().count() as u32;
+		let total_issuance = <pallet_balances::Module<Runtime>>::total_issuance();
+
+		let data = (num_accounts, total_issuance);
+		frame_support::storage::unhashed::put(b"migration_data", &data);
+
+		Ok(())
+	}
+
+	#[cfg(feature = "std")]
+	fn post_migration() -> Result<(), &'static str> {
+		let (num_accounts, total_issuance): (u32, u128) =
+			frame_support::storage::unhashed::get(b"migration_data").unwrap();
+		let total_issuance_computed = <frame_system::Account<Runtime>>::iter()
+			.fold(0 as Balance, |accumulator, (_acc, account)| {
+				accumulator.checked_add(account.data.total()).unwrap()
+			});
+
+		frame_support::ensure!(
+			<frame_system::Account<Runtime>>::iter().count() as u32 == num_accounts,
+			"invalid total_issuance post migration",
+		);
+		frame_support::ensure!(
+			total_issuance_computed == total_issuance,
+			"invalid total_issuance ",
+		);
+
+		Ok(())
+	}
+}
+
 #[cfg(not(feature = "disable-runtime-api"))]
 sp_api::impl_runtime_apis! {
 	impl sp_api::Core<Block> for Runtime {