pallet-staking: Reorg migration, pallet and pallet impls (#9410)

* Reorg migration and pallet and pallet impls

* Fix imports in untouched modules

* Add file headers

* Add header for migrations

* Improve comment

* Move OnOffenceHandler impl for Pallet to impl.rs

* fmt

substrate/frame/staking/src/benchmarking.rs

@@ -21,11 +21,22 @@ use super::*;
 use crate::Pallet as Staking;
 use testing_utils::*;
 
+use frame_support::{
+	pallet_prelude::*,
+	traits::{Currency, Get, Imbalance},
+};
+use sp_runtime::{
+	traits::{StaticLookup, Zero},
+	Perbill, Percent,
+};
+use sp_staking::SessionIndex;
+use sp_std::prelude::*;
+
 pub use frame_benchmarking::{
 	account, benchmarks, impl_benchmark_test_suite, whitelist_account, whitelisted_caller,
 };
 use frame_system::RawOrigin;
-use sp_runtime::traits::One;
+use sp_runtime::traits::{Bounded, One};
 
 const SEED: u32 = 0;
 const MAX_SPANS: u32 = 100;

substrate/frame/staking/src/migrations.rs

@@ -0,0 +1,86 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2020-2021 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+
+//! Storage migrations for the Staking pallet.
+
+use super::*;
+
+pub mod v7 {
+	use super::*;
+
+	pub fn pre_migrate<T: Config>() -> Result<(), &'static str> {
+		assert!(CounterForValidators::<T>::get().is_zero(), "CounterForValidators already set.");
+		assert!(CounterForNominators::<T>::get().is_zero(), "CounterForNominators already set.");
+		assert!(StorageVersion::<T>::get() == Releases::V6_0_0);
+		Ok(())
+	}
+
+	pub fn migrate<T: Config>() -> Weight {
+		log!(info, "Migrating staking to Releases::V7_0_0");
+		let validator_count = Validators::<T>::iter().count() as u32;
+		let nominator_count = Nominators::<T>::iter().count() as u32;
+
+		CounterForValidators::<T>::put(validator_count);
+		CounterForNominators::<T>::put(nominator_count);
+
+		StorageVersion::<T>::put(Releases::V7_0_0);
+		log!(info, "Completed staking migration to Releases::V7_0_0");
+
+		T::DbWeight::get().reads_writes(validator_count.saturating_add(nominator_count).into(), 2)
+	}
+}
+
+pub mod v6 {
+	use super::*;
+	use frame_support::{generate_storage_alias, traits::Get, weights::Weight};
+
+	// NOTE: value type doesn't matter, we just set it to () here.
+	generate_storage_alias!(Staking, SnapshotValidators => Value<()>);
+	generate_storage_alias!(Staking, SnapshotNominators => Value<()>);
+	generate_storage_alias!(Staking, QueuedElected => Value<()>);
+	generate_storage_alias!(Staking, QueuedScore => Value<()>);
+	generate_storage_alias!(Staking, EraElectionStatus => Value<()>);
+	generate_storage_alias!(Staking, IsCurrentSessionFinal => Value<()>);
+
+	/// check to execute prior to migration.
+	pub fn pre_migrate<T: Config>() -> Result<(), &'static str> {
+		// these may or may not exist.
+		log!(info, "SnapshotValidators.exits()? {:?}", SnapshotValidators::exists());
+		log!(info, "SnapshotNominators.exits()? {:?}", SnapshotNominators::exists());
+		log!(info, "QueuedElected.exits()? {:?}", QueuedElected::exists());
+		log!(info, "QueuedScore.exits()? {:?}", QueuedScore::exists());
+		// these must exist.
+		assert!(IsCurrentSessionFinal::exists(), "IsCurrentSessionFinal storage item not found!");
+		assert!(EraElectionStatus::exists(), "EraElectionStatus storage item not found!");
+		Ok(())
+	}
+
+	/// Migrate storage to v6.
+	pub fn migrate<T: Config>() -> Weight {
+		log!(info, "Migrating staking to Releases::V6_0_0");
+
+		SnapshotValidators::kill();
+		SnapshotNominators::kill();
+		QueuedElected::kill();
+		QueuedScore::kill();
+		EraElectionStatus::kill();
+		IsCurrentSessionFinal::kill();
+
+		StorageVersion::<T>::put(Releases::V6_0_0);
+		log!(info, "Done.");
+		T::DbWeight::get().writes(6 + 1)
+	}
+}

substrate/frame/staking/src/mock.rs

@@ -22,7 +22,10 @@ use crate::*;
 use frame_election_provider_support::onchain;
 use frame_support::{
 	assert_ok, parameter_types,
-	traits::{Currency, FindAuthor, Get, OnInitialize, OneSessionHandler},
+	traits::{
+		Currency, FindAuthor, GenesisBuild, Get, Hooks, Imbalance, OnInitialize, OnUnbalanced,
+		OneSessionHandler,
+	},
 	weights::constants::RocksDbWeight,
 };
 use sp_core::H256;

substrate/frame/staking/src/slashing.rs

@@ -49,7 +49,7 @@
 //!
 //! Based on research at <https://w3f-research.readthedocs.io/en/latest/polkadot/slashing/npos.html>
 
-use super::{
+use crate::{
 	BalanceOf, Config, EraIndex, Error, Exposure, NegativeImbalanceOf, Pallet, Perbill,
 	SessionInterface, Store, UnappliedSlash,
 };

substrate/frame/staking/src/testing_utils.rs

@@ -27,6 +27,10 @@ use rand_chacha::{
 };
 use sp_io::hashing::blake2_256;
 
+use frame_support::{pallet_prelude::*, traits::Currency};
+use sp_runtime::{traits::StaticLookup, Perbill};
+use sp_std::prelude::*;
+
 const SEED: u32 = 0;
 
 /// This function removes all validators and nominators from storage.

substrate/frame/staking/src/tests.rs

@@ -18,10 +18,12 @@
 //! Tests for the module.
 
 use super::{Event, *};
-use frame_election_provider_support::Support;
+use frame_election_provider_support::{ElectionProvider, Support};
 use frame_support::{
 	assert_noop, assert_ok,
-	traits::{Currency, OnInitialize, ReservableCurrency},
+	dispatch::WithPostDispatchInfo,
+	pallet_prelude::*,
+	traits::{Currency, Get, OnInitialize, ReservableCurrency},
 	weights::{extract_actual_weight, GetDispatchInfo},
 };
 use mock::*;
@@ -29,8 +31,13 @@ use pallet_balances::Error as BalancesError;
 use sp_runtime::{
 	assert_eq_error_rate,
 	traits::{BadOrigin, Dispatchable},
+	Perbill, Percent,
 };
-use sp_staking::offence::OffenceDetails;
+use sp_staking::{
+	offence::{OffenceDetails, OnOffenceHandler},
+	SessionIndex,
+};
+use sp_std::prelude::*;
 use substrate_test_utils::assert_eq_uvec;
 
 #[test]