API for registering inactive funds (#12813)

* API for registering inactive funds

* Build fixes.

* Update frame/treasury/src/lib.rs

* Fix

* Fixes

* Fixes

substrate/frame/balances/src/lib.rs

@@ -156,6 +156,7 @@
 #[macro_use]
 mod tests;
 mod benchmarking;
+pub mod migration;
 mod tests_composite;
 mod tests_local;
 #[cfg(test)]
@@ -497,6 +498,13 @@ pub mod pallet {
 	#[pallet::whitelist_storage]
 	pub type TotalIssuance<T: Config<I>, I: 'static = ()> = StorageValue<_, T::Balance, ValueQuery>;
 
+	/// The total units of outstanding deactivated balance in the system.
+	#[pallet::storage]
+	#[pallet::getter(fn inactive_issuance)]
+	#[pallet::whitelist_storage]
+	pub type InactiveIssuance<T: Config<I>, I: 'static = ()> =
+		StorageValue<_, T::Balance, ValueQuery>;
+
 	/// The Balances pallet example of storing the balance of an account.
 	///
 	/// # Example
@@ -1067,6 +1075,9 @@ impl<T: Config<I>, I: 'static> fungible::Inspect<T::AccountId> for Pallet<T, I>
 	fn total_issuance() -> Self::Balance {
 		TotalIssuance::<T, I>::get()
 	}
+	fn active_issuance() -> Self::Balance {
+		TotalIssuance::<T, I>::get().saturating_sub(InactiveIssuance::<T, I>::get())
+	}
 	fn minimum_balance() -> Self::Balance {
 		T::ExistentialDeposit::get()
 	}
@@ -1145,6 +1156,14 @@ impl<T: Config<I>, I: 'static> fungible::Transfer<T::AccountId> for Pallet<T, I>
 		let er = if keep_alive { KeepAlive } else { AllowDeath };
 		<Self as Currency<T::AccountId>>::transfer(source, dest, amount, er).map(|_| amount)
 	}
+
+	fn deactivate(amount: Self::Balance) {
+		InactiveIssuance::<T, I>::mutate(|b| b.saturating_accrue(amount));
+	}
+
+	fn reactivate(amount: Self::Balance) {
+		InactiveIssuance::<T, I>::mutate(|b| b.saturating_reduce(amount));
+	}
 }
 
 impl<T: Config<I>, I: 'static> fungible::Unbalanced<T::AccountId> for Pallet<T, I> {
@@ -1418,7 +1437,19 @@ where
 	}
 
 	fn total_issuance() -> Self::Balance {
-		<TotalIssuance<T, I>>::get()
+		TotalIssuance::<T, I>::get()
+	}
+
+	fn active_issuance() -> Self::Balance {
+		<Self as fungible::Inspect<T::AccountId>>::active_issuance()
+	}
+
+	fn deactivate(amount: Self::Balance) {
+		<Self as fungible::Transfer<T::AccountId>>::deactivate(amount);
+	}
+
+	fn reactivate(amount: Self::Balance) {
+		<Self as fungible::Transfer<T::AccountId>>::reactivate(amount);
 	}
 
 	fn minimum_balance() -> Self::Balance {

substrate/frame/balances/src/migration.rs

@@ -0,0 +1,51 @@
+// Copyright 2017-2020 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::*;
+use frame_support::{pallet_prelude::*, traits::OnRuntimeUpgrade, weights::Weight};
+
+// NOTE: This must be used alongside the account whose balance is expected to be inactive.
+// Generally this will be used for the XCM teleport checking account.
+pub struct MigrateToTrackInactive<T: Config, A: Get<T::AccountId>>(
+	sp_std::marker::PhantomData<(T, A)>,
+);
+impl<T: Config, A: Get<T::AccountId>> OnRuntimeUpgrade for MigrateToTrackInactive<T, A> {
+	fn on_runtime_upgrade() -> Weight {
+		let current_version = Pallet::<T>::current_storage_version();
+		let onchain_version = Pallet::<T>::on_chain_storage_version();
+
+		if onchain_version == 0 && current_version == 1 {
+			let b = Pallet::<T>::total_balance(&A::get());
+			Pallet::<T>::deactivate(b);
+			current_version.put::<Pallet<T>>();
+			log::info!(target: "runtime::balances", "Storage to version {:?}", current_version);
+			T::DbWeight::get().reads_writes(3, 3)
+		} else {
+			log::info!(target: "runtime::balances",  "Migration did not execute. This probably should be removed");
+			T::DbWeight::get().reads(2)
+		}
+	}
+
+	#[cfg(feature = "try-runtime")]
+	fn pre_upgrade() -> Result<Vec<u8>, &'static str> {
+		Ok(vec![])
+	}
+
+	#[cfg(feature = "try-runtime")]
+	fn post_upgrade(total: Vec<u8>) -> Result<(), &'static str> {
+		Ok(())
+	}
+}