Introduce IgnoredIssuance into Gilts (#8299)

* IgnoredIssuance

* Fixes

* Fixes

substrate/bin/node/runtime/src/lib.rs

@@ -1046,6 +1046,7 @@ impl pallet_assets::Config for Runtime {
 }
 
 parameter_types! {
+	pub IgnoredIssuance: Balance = Treasury::pot();
 	pub const QueueCount: u32 = 300;
 	pub const MaxQueueLen: u32 = 1000;
 	pub const FifoQueueLen: u32 = 500;
@@ -1061,6 +1062,7 @@ impl pallet_gilt::Config for Runtime {
 	type AdminOrigin = frame_system::EnsureRoot<AccountId>;
 	type Deficit = ();
 	type Surplus = ();
+	type IgnoredIssuance = IgnoredIssuance;
 	type QueueCount = QueueCount;
 	type MaxQueueLen = MaxQueueLen;
 	type FifoQueueLen = FifoQueueLen;

substrate/frame/gilt/src/lib.rs

@@ -109,6 +109,10 @@ pub mod pallet {
 		/// over freezing period).
 		type Surplus: OnUnbalanced<NegativeImbalanceOf<Self>>;
 
+		/// The issuance to ignore. This is subtracted from the `Currency`'s `total_issuance` to get
+		/// the issuance by which we inflate or deflate the gilt.
+		type IgnoredIssuance: Get<BalanceOf<Self>>;
+
 		/// Number of duration queues in total. This sets the maximum duration supported, which is
 		/// this value multiplied by `Period`.
 		#[pallet::constant]
@@ -191,7 +195,9 @@ pub mod pallet {
 	/// The way of determining the net issuance (i.e. after factoring in all maturing frozen funds)
 	/// is:
 	///
-	/// `total_issuance - frozen + proportion * total_issuance`
+	/// `issuance - frozen + proportion * issuance`
+	///
+	/// where `issuance = total_issuance - IgnoredIssuance`
 	#[derive(Clone, Eq, PartialEq, Default, Encode, Decode, RuntimeDebug)]
 	pub struct ActiveGiltsTotal<Balance> {
 		/// The total amount of funds held in reserve for all active gilts.
@@ -440,7 +446,7 @@ pub mod pallet {
 			Active::<T>::remove(index);
 
 			// Multiply the proportion it is by the total issued.
-			let total_issuance = T::Currency::total_issuance();
+			let total_issuance = T::Currency::total_issuance().saturating_sub(T::IgnoredIssuance::get());
 			ActiveTotal::<T>::mutate(|totals| {
 				let nongilt_issuance: u128 = total_issuance.saturating_sub(totals.frozen)
 					.saturated_into();
@@ -490,7 +496,7 @@ pub mod pallet {
 			if totals.proportion < totals.target {
 				let missing = totals.target.saturating_sub(totals.proportion);
 
-				let total_issuance = T::Currency::total_issuance();
+				let total_issuance = T::Currency::total_issuance().saturating_sub(T::IgnoredIssuance::get());
 				let nongilt_issuance: u128 = total_issuance.saturating_sub(totals.frozen)
 					.saturated_into();
 				let effective_issuance = totals.proportion.left_from_one()
@@ -515,7 +521,7 @@ pub mod pallet {
 			amount: BalanceOf<T>,
 			max_bids: u32,
 		) -> (u32, u32) {
-			let total_issuance = T::Currency::total_issuance();
+			let total_issuance = T::Currency::total_issuance().saturating_sub(T::IgnoredIssuance::get());
 			let mut remaining = amount;
 			let mut bids_taken = 0;
 			let mut queues_hit = 0;

substrate/frame/gilt/src/mock.rs

@@ -20,7 +20,8 @@
 use crate as pallet_gilt;
 
 use frame_support::{
-	parameter_types, ord_parameter_types, traits::{OnInitialize, OnFinalize, GenesisBuild},
+	parameter_types, ord_parameter_types,
+	traits::{OnInitialize, OnFinalize, GenesisBuild, Currency},
 };
 use sp_core::H256;
 use sp_runtime::{traits::{BlakeTwo256, IdentityLookup}, testing::Header};
@@ -86,6 +87,7 @@ impl pallet_balances::Config for Test {
 }
 
 parameter_types! {
+	pub IgnoredIssuance: u64 = Balances::total_balance(&0); // Account zero is ignored.
 	pub const QueueCount: u32 = 3;
 	pub const MaxQueueLen: u32 = 3;
 	pub const FifoQueueLen: u32 = 1;
@@ -104,6 +106,7 @@ impl pallet_gilt::Config for Test {
 	type AdminOrigin = frame_system::EnsureSignedBy<One, Self::AccountId>;
 	type Deficit = ();
 	type Surplus = ();
+	type IgnoredIssuance = IgnoredIssuance;
 	type QueueCount = QueueCount;
 	type MaxQueueLen = MaxQueueLen;
 	type FifoQueueLen = FifoQueueLen;

substrate/frame/gilt/src/tests.rs

@@ -322,6 +322,30 @@ fn thaw_when_issuance_higher_works() {
 	});
 }
 
+#[test]
+fn thaw_with_ignored_issuance_works() {
+	new_test_ext().execute_with(|| {
+		run_to_block(1);
+		// Give account zero some balance.
+		Balances::make_free_balance_be(&0, 200);
+
+		assert_ok!(Gilt::place_bid(Origin::signed(1), 100, 1));
+		Gilt::enlarge(100, 1);
+
+		// Account zero transfers 50 into everyone else's accounts.
+		assert_ok!(Balances::transfer(Origin::signed(0), 2, 50));
+		assert_ok!(Balances::transfer(Origin::signed(0), 3, 50));
+		assert_ok!(Balances::transfer(Origin::signed(0), 4, 50));
+
+		run_to_block(4);
+		assert_ok!(Gilt::thaw(Origin::signed(1), 0));
+
+		// Account zero changes have been ignored.
+		assert_eq!(Balances::free_balance(1), 150);
+		assert_eq!(Balances::reserved_balance(1), 0);
+	});
+}
+
 #[test]
 fn thaw_when_issuance_lower_works() {
 	new_test_ext().execute_with(|| {