Implement Inactive balance tracking in Assets pallet

prdoc/pr_1747.prdoc

@@ -0,0 +1,13 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Implement Inactive balance tracking in Assets pallet 
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      The trait `fungibles::Unbalanced` provides methods to increase and decrease active issuance. 
+      This PR addresses the lack of this feature in Assets, by introducing a new field `inactive` in the `Asset` struct and implementing the methods accordingly.
+
+crates: 
+  - name: pallet-assets

substrate/frame/assets/src/functions.rs

@@ -713,6 +713,7 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 				admin: owner.clone(),
 				freezer: owner.clone(),
 				supply: Zero::zero(),
+				inactive: Zero::zero(),
 				deposit: Zero::zero(),
 				min_balance,
 				is_sufficient,

substrate/frame/assets/src/impl_fungibles.rs

@@ -164,7 +164,22 @@ impl<T: Config<I>, I: 'static> fungibles::Unbalanced<T::AccountId> for Pallet<T,
 		Ok(amount)
 	}
 
-	// TODO: #13196 implement deactivate/reactivate once we have inactive balance tracking.
+	fn deactivate(asset: Self::AssetId, amount: Self::Balance) {
+		Asset::<T, I>::mutate(&asset, |maybe_asset| match maybe_asset {
+			Some(ref mut asset) => {
+				// Inactive amount can't exceed supply
+				asset.inactive = asset.inactive.saturating_add(amount).max(asset.supply);
+			},
+			None => log::error!("Called deactivate for nonexistent asset {:?}", asset),
+		});
+	}
+
+	fn reactivate(asset: Self::AssetId, amount: Self::Balance) {
+		Asset::<T, I>::mutate(&asset, |maybe_asset| match maybe_asset {
+			Some(ref mut asset) => asset.inactive.saturating_reduce(amount),
+			None => log::error!("Called reactivate for nonexistent asset {:?}", asset),
+		});
+	}
 }
 
 impl<T: Config<I>, I: 'static> fungibles::Create<T::AccountId> for Pallet<T, I> {

substrate/frame/assets/src/lib.rs

@@ -218,8 +218,8 @@ pub mod pallet {
 	};
 	use frame_system::pallet_prelude::*;
 
-	/// The in-code storage version.
-	const STORAGE_VERSION: StorageVersion = StorageVersion::new(1);
+	/// The current storage version.
+	const STORAGE_VERSION: StorageVersion = StorageVersion::new(2);
 
 	#[pallet::pallet]
 	#[pallet::storage_version(STORAGE_VERSION)]
@@ -440,6 +440,7 @@ pub mod pallet {
 						admin: owner.clone(),
 						freezer: owner.clone(),
 						supply: Zero::zero(),
+						inactive: Zero::zero(),
 						deposit: Zero::zero(),
 						min_balance: *min_balance,
 						is_sufficient: *is_sufficient,
@@ -666,6 +667,7 @@ pub mod pallet {
 					admin: admin.clone(),
 					freezer: admin.clone(),
 					supply: Zero::zero(),
+					inactive: Zero::zero(),
 					deposit,
 					min_balance,
 					is_sufficient: false,

substrate/frame/assets/src/migration/mod.rs

@@ -0,0 +1,21 @@
+// This file is part of Substrate.
+
+// Copyright (C) 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
+// limitations under the License.
+
+/// Version 0 to 1.
+pub mod v1;
+/// Version 1 to 2.
+pub mod v2;