refactor: Transaction-Payment module (#3816)

* Initial draft that compiles

* Extract payment stuff from balances

* Extract multiplier update stuff from system

* Some fixes.

* Update len-fee as well

* some review comments.

* Remove todo

* bump

substrate/srml/assets/src/lib.rs

@@ -271,7 +271,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/aura/src/mock.rs

@@ -54,7 +54,6 @@ impl system::Trait for Test {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/authority-discovery/src/lib.rs

@@ -204,7 +204,6 @@ mod tests {
 		type AccountId = AuthorityId;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/authorship/src/lib.rs

@@ -442,7 +442,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/babe/src/mock.rs

@@ -62,7 +62,6 @@ impl system::Trait for Test {
 	type AccountId = DummyValidatorId;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/balances/Cargo.toml

@@ -17,6 +17,7 @@ system = { package = "srml-system", path = "../system", default-features = false
 [dev-dependencies]
 runtime-io = { package = "sr-io", path = "../../core/sr-io" }
 primitives = { package = "substrate-primitives",  path = "../../core/primitives" }
+transaction-payment = { package = "srml-transaction-payment", path = "../transaction-payment" }
 
 [features]
 default = ["std"]

substrate/srml/balances/src/lib.rs

@@ -86,17 +86,6 @@
 //!
 //! - `vesting_balance` - Get the amount that is currently being vested and cannot be transferred out of this account.
 //!
-//! ### Signed Extensions
-//!
-//! The balances module defines the following extensions:
-//!
-//!   - [`TakeFees`]: Consumes fees proportional to the length and weight of the transaction.
-//!     Additionally, it can contain a single encoded payload as a `tip`. The inclusion priority
-//!     is increased proportional to the tip.
-//!
-//! Lookup the runtime aggregator file (e.g. `node/runtime`) to see the full list of signed
-//! extensions included in a chain.
-//!
 //! ## Usage
 //!
 //! The following examples show how to use the Balances module in your custom module.
@@ -171,15 +160,11 @@ use support::{
 	dispatch::Result,
 };
 use sr_primitives::{
-	transaction_validity::{
-		TransactionPriority, ValidTransaction, InvalidTransaction, TransactionValidityError,
-		TransactionValidity,
-	},
 	traits::{
 		Zero, SimpleArithmetic, StaticLookup, Member, CheckedAdd, CheckedSub, MaybeSerializeDebug,
-		Saturating, Bounded, SignedExtension, SaturatedConversion, Convert,
+		Saturating, Bounded,
 	},
-	weights::{DispatchInfo, SimpleDispatchInfo, Weight},
+	weights::SimpleDispatchInfo,
 };
 use system::{IsDeadAccount, OnNewAccount, ensure_signed, ensure_root};
 
@@ -210,15 +195,6 @@ pub trait Subtrait<I: Instance = DefaultInstance>: system::Trait {
 
 	/// The fee required to create an account.
 	type CreationFee: Get<Self::Balance>;
-
-	/// The fee to be paid for making a transaction; the base.
-	type TransactionBaseFee: Get<Self::Balance>;
-
-	/// The fee to be paid for making a transaction; the per-byte portion.
-	type TransactionByteFee: Get<Self::Balance>;
-
-	/// Convert a weight value into a deductible fee based on the currency type.
-	type WeightToFee: Convert<Weight, Self::Balance>;
 }
 
 pub trait Trait<I: Instance = DefaultInstance>: system::Trait {
@@ -235,9 +211,6 @@ pub trait Trait<I: Instance = DefaultInstance>: system::Trait {
 	/// Handler for when a new account is created.
 	type OnNewAccount: OnNewAccount<Self::AccountId>;
 
-	/// Handler for the unbalanced reduction when taking transaction fees.
-	type TransactionPayment: OnUnbalanced<NegativeImbalance<Self, I>>;
-
 	/// Handler for the unbalanced reduction when taking fees associated with balance
 	/// transfer (which may also include account creation).
 	type TransferPayment: OnUnbalanced<NegativeImbalance<Self, I>>;
@@ -256,15 +229,6 @@ pub trait Trait<I: Instance = DefaultInstance>: system::Trait {
 
 	/// The fee required to create an account.
 	type CreationFee: Get<Self::Balance>;
-
-	/// The fee to be paid for making a transaction; the base.
-	type TransactionBaseFee: Get<Self::Balance>;
-
-	/// The fee to be paid for making a transaction; the per-byte portion.
-	type TransactionByteFee: Get<Self::Balance>;
-
-	/// Convert a weight value into a deductible fee based on the currency type.
-	type WeightToFee: Convert<Weight, Self::Balance>;
 }
 
 impl<T: Trait<I>, I: Instance> Subtrait<I> for T {
@@ -274,9 +238,6 @@ impl<T: Trait<I>, I: Instance> Subtrait<I> for T {
 	type ExistentialDeposit = T::ExistentialDeposit;
 	type TransferFee = T::TransferFee;
 	type CreationFee = T::CreationFee;
-	type TransactionBaseFee = T::TransactionBaseFee;
-	type TransactionByteFee = T::TransactionByteFee;
-	type WeightToFee = T::WeightToFee;
 }
 
 decl_event!(
@@ -414,12 +375,6 @@ decl_module! {
 		/// The fee required to create an account.
 		const CreationFee: T::Balance = T::CreationFee::get();
 
-		/// The fee to be paid for making a transaction; the base.
-		const TransactionBaseFee: T::Balance = T::TransactionBaseFee::get();
-
-		/// The fee to be paid for making a transaction; the per-byte portion.
-		const TransactionByteFee: T::Balance = T::TransactionByteFee::get();
-
 		fn deposit_event() = default;
 
 		/// Transfer some liquid free balance to another account.
@@ -776,7 +731,7 @@ mod imbalances {
 // This works as long as `increase_total_issuance_by` doesn't use the Imbalance
 // types (basically for charging fees).
 // This should eventually be refactored so that the three type items that do
-// depend on the Imbalance type (TransactionPayment, TransferPayment, DustRemoval)
+// depend on the Imbalance type (TransferPayment, DustRemoval)
 // are placed in their own SRML module.
 struct ElevatedTrait<T: Subtrait<I>, I: Instance>(T, I);
 impl<T: Subtrait<I>, I: Instance> Clone for ElevatedTrait<T, I> {
@@ -796,7 +751,6 @@ impl<T: Subtrait<I>, I: Instance> system::Trait for ElevatedTrait<T, I> {
 	type AccountId = T::AccountId;
 	type Lookup = T::Lookup;
 	type Header = T::Header;
-	type WeightMultiplierUpdate = T::WeightMultiplierUpdate;
 	type Event = ();
 	type BlockHashCount = T::BlockHashCount;
 	type MaximumBlockWeight = T::MaximumBlockWeight;
@@ -809,15 +763,11 @@ impl<T: Subtrait<I>, I: Instance> Trait<I> for ElevatedTrait<T, I> {
 	type OnFreeBalanceZero = T::OnFreeBalanceZero;
 	type OnNewAccount = T::OnNewAccount;
 	type Event = ();
-	type TransactionPayment = ();
 	type TransferPayment = ();
 	type DustRemoval = ();
 	type ExistentialDeposit = T::ExistentialDeposit;
 	type TransferFee = T::TransferFee;
 	type CreationFee = T::CreationFee;
-	type TransactionBaseFee = T::TransactionBaseFee;
-	type TransactionByteFee = T::TransactionByteFee;
-	type WeightToFee = T::WeightToFee;
 }
 
 impl<T: Trait<I>, I: Instance> Currency<T::AccountId> for Module<T, I>
@@ -1194,91 +1144,6 @@ where
 	}
 }
 
-/// Require the transactor pay for themselves and maybe include a tip to gain additional priority
-/// in the queue.
-#[derive(Encode, Decode, Clone, Eq, PartialEq)]
-pub struct TakeFees<T: Trait<I>, I: Instance = DefaultInstance>(#[codec(compact)] T::Balance);
-
-impl<T: Trait<I>, I: Instance> TakeFees<T, I> {
-	/// utility constructor. Used only in client/factory code.
-	pub fn from(fee: T::Balance) -> Self {
-		Self(fee)
-	}
-
-	/// Compute the final fee value for a particular transaction.
-	///
-	/// The final fee is composed of:
-	///   - _length-fee_: This is the amount paid merely to pay for size of the transaction.
-	///   - _weight-fee_: This amount is computed based on the weight of the transaction. Unlike
-	///      size-fee, this is not input dependent and reflects the _complexity_ of the execution
-	///      and the time it consumes.
-	///   - (optional) _tip_: if included in the transaction, it will be added on top. Only signed
-	///      transactions can have a tip.
-	fn compute_fee(len: usize, info: DispatchInfo, tip: T::Balance) -> T::Balance {
-		let len_fee = if info.pay_length_fee() {
-			let len = T::Balance::from(len as u32);
-			let base = T::TransactionBaseFee::get();
-			let per_byte = T::TransactionByteFee::get();
-			base.saturating_add(per_byte.saturating_mul(len))
-		} else {
-			Zero::zero()
-		};
-
-		let weight_fee = {
-			// cap the weight to the maximum defined in runtime, otherwise it will be the `Bounded`
-			// maximum of its data type, which is not desired.
-			let capped_weight = info.weight.min(<T as system::Trait>::MaximumBlockWeight::get());
-			let weight_update = <system::Module<T>>::next_weight_multiplier();
-			let adjusted_weight = weight_update.apply_to(capped_weight);
-			T::WeightToFee::convert(adjusted_weight)
-		};
-
-		len_fee.saturating_add(weight_fee).saturating_add(tip)
-	}
-}
-
-#[cfg(feature = "std")]
-impl<T: Trait<I>, I: Instance> rstd::fmt::Debug for TakeFees<T, I> {
-	fn fmt(&self, f: &mut rstd::fmt::Formatter) -> rstd::fmt::Result {
-		self.0.fmt(f)
-	}
-}
-
-impl<T: Trait<I>, I: Instance + Clone + Eq> SignedExtension for TakeFees<T, I> {
-	type AccountId = T::AccountId;
-	type Call = T::Call;
-	type AdditionalSigned = ();
-	type Pre = ();
-	fn additional_signed(&self) -> rstd::result::Result<(), TransactionValidityError> { Ok(()) }
-
-	fn validate(
-		&self,
-		who: &Self::AccountId,
-		_call: &Self::Call,
-		info: DispatchInfo,
-		len: usize,
-	) -> TransactionValidity {
-		// pay any fees.
-		let fee = Self::compute_fee(len, info, self.0);
-		let imbalance = match <Module<T, I>>::withdraw(
-			who,
-			fee,
-			WithdrawReason::TransactionPayment,
-			ExistenceRequirement::KeepAlive,
-		) {
-			Ok(imbalance) => imbalance,
-			Err(_) => return InvalidTransaction::Payment.into(),
-		};
-		T::TransactionPayment::on_unbalanced(imbalance);
-
-		let mut r = ValidTransaction::default();
-		// NOTE: we probably want to maximize the _fee (of any type) per weight unit_ here, which
-		// will be a bit more than setting the priority to tip. For now, this is enough.
-		r.priority = fee.saturated_into::<TransactionPriority>();
-		Ok(r)
-	}
-}
-
 impl<T: Trait<I>, I: Instance> IsDeadAccount<T::AccountId> for Module<T, I>
 where
 	T::Balance: MaybeSerializeDebug

substrate/srml/balances/src/mock.rs

@@ -18,7 +18,7 @@
 
 #![cfg(test)]
 
-use sr_primitives::{Perbill, traits::{Convert, IdentityLookup}, testing::Header,
+use sr_primitives::{Perbill, traits::{ConvertInto, IdentityLookup}, testing::Header,
 	weights::{DispatchInfo, Weight}};
 use primitives::H256;
 use runtime_io;
@@ -35,10 +35,6 @@ thread_local! {
 	static EXISTENTIAL_DEPOSIT: RefCell<u64> = RefCell::new(0);
 	static TRANSFER_FEE: RefCell<u64> = RefCell::new(0);
 	static CREATION_FEE: RefCell<u64> = RefCell::new(0);
-	static TRANSACTION_BASE_FEE: RefCell<u64> = RefCell::new(0);
-	static TRANSACTION_BYTE_FEE: RefCell<u64> = RefCell::new(1);
-	static TRANSACTION_WEIGHT_FEE: RefCell<u64> = RefCell::new(1);
-	static WEIGHT_TO_FEE: RefCell<u64> = RefCell::new(1);
 }
 
 pub struct ExistentialDeposit;
@@ -56,23 +52,6 @@ impl Get<u64> for CreationFee {
 	fn get() -> u64 { CREATION_FEE.with(|v| *v.borrow()) }
 }
 
-pub struct TransactionBaseFee;
-impl Get<u64> for TransactionBaseFee {
-	fn get() -> u64 { TRANSACTION_BASE_FEE.with(|v| *v.borrow()) }
-}
-
-pub struct TransactionByteFee;
-impl Get<u64> for TransactionByteFee {
-	fn get() -> u64 { TRANSACTION_BYTE_FEE.with(|v| *v.borrow()) }
-}
-
-pub struct WeightToFee(u64);
-impl Convert<Weight, u64> for WeightToFee {
-	fn convert(t: Weight) -> u64 {
-		WEIGHT_TO_FEE.with(|v| *v.borrow() * (t as u64))
-	}
-}
-
 // Workaround for https://github.com/rust-lang/rust/issues/26925 . Remove when sorted.
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct Runtime;
@@ -92,7 +71,6 @@ impl system::Trait for Runtime {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;
@@ -100,26 +78,31 @@ impl system::Trait for Runtime {
 	type AvailableBlockRatio = AvailableBlockRatio;
 	type Version = ();
 }
+parameter_types! {
+	pub const TransactionBaseFee: u64 = 0;
+	pub const TransactionByteFee: u64 = 1;
+}
+impl transaction_payment::Trait for Runtime {
+	type Currency = Module<Runtime>;
+	type OnTransactionPayment = ();
+	type TransactionBaseFee = TransactionBaseFee;
+	type TransactionByteFee = TransactionByteFee;
+	type WeightToFee = ConvertInto;
+	type FeeMultiplierUpdate = ();
+}
 impl Trait for Runtime {
 	type Balance = u64;
 	type OnFreeBalanceZero = ();
 	type OnNewAccount = ();
 	type Event = ();
-	type TransactionPayment = ();
 	type DustRemoval = ();
 	type TransferPayment = ();
 	type ExistentialDeposit = ExistentialDeposit;
 	type TransferFee = TransferFee;
 	type CreationFee = CreationFee;
-	type TransactionBaseFee = TransactionBaseFee;
-	type TransactionByteFee = TransactionByteFee;
-	type WeightToFee = WeightToFee;
 }
 
 pub struct ExtBuilder {
-	transaction_base_fee: u64,
-	transaction_byte_fee: u64,
-	weight_to_fee: u64,
 	existential_deposit: u64,
 	transfer_fee: u64,
 	creation_fee: u64,
@@ -129,9 +112,6 @@ pub struct ExtBuilder {
 impl Default for ExtBuilder {
 	fn default() -> Self {
 		Self {
-			transaction_base_fee: 0,
-			transaction_byte_fee: 0,
-			weight_to_fee: 0,
 			existential_deposit: 0,
 			transfer_fee: 0,
 			creation_fee: 0,
@@ -141,12 +121,6 @@ impl Default for ExtBuilder {
 	}
 }
 impl ExtBuilder {
-	pub fn transaction_fees(mut self, base_fee: u64, byte_fee: u64, weight_fee: u64) -> Self {
-		self.transaction_base_fee = base_fee;
-		self.transaction_byte_fee = byte_fee;
-		self.weight_to_fee = weight_fee;
-		self
-	}
 	pub fn existential_deposit(mut self, existential_deposit: u64) -> Self {
 		self.existential_deposit = existential_deposit;
 		self
@@ -175,9 +149,6 @@ impl ExtBuilder {
 		EXISTENTIAL_DEPOSIT.with(|v| *v.borrow_mut() = self.existential_deposit);
 		TRANSFER_FEE.with(|v| *v.borrow_mut() = self.transfer_fee);
 		CREATION_FEE.with(|v| *v.borrow_mut() = self.creation_fee);
-		TRANSACTION_BASE_FEE.with(|v| *v.borrow_mut() = self.transaction_base_fee);
-		TRANSACTION_BYTE_FEE.with(|v| *v.borrow_mut() = self.transaction_byte_fee);
-		WEIGHT_TO_FEE.with(|v| *v.borrow_mut() = self.weight_to_fee);
 	}
 	pub fn build(self) -> runtime_io::TestExternalities {
 		self.set_associated_consts();
@@ -211,7 +182,6 @@ impl ExtBuilder {
 pub type System = system::Module<Runtime>;
 pub type Balances = Module<Runtime>;
 
-
 pub const CALL: &<Runtime as system::Trait>::Call = &();
 
 /// create a transaction info struct from weight. Handy to avoid building the whole struct.

substrate/srml/balances/src/tests.rs

@@ -20,12 +20,13 @@
 
 use super::*;
 use mock::{Balances, ExtBuilder, Runtime, System, info_from_weight, CALL};
+use sr_primitives::traits::SignedExtension;
 use support::{
 	assert_noop, assert_ok, assert_err,
 	traits::{LockableCurrency, LockIdentifier, WithdrawReason, WithdrawReasons,
 	Currency, ReservableCurrency}
 };
-use sr_primitives::weights::DispatchClass;
+use transaction_payment::ChargeTransactionPayment;
 use system::RawOrigin;
 
 const ID_1: LockIdentifier = *b"1       ";
@@ -115,7 +116,6 @@ fn lock_reasons_should_work() {
 	ExtBuilder::default()
 		.existential_deposit(1)
 		.monied(true)
-		.transaction_fees(0, 1, 0)
 		.build()
 		.execute_with(|| {
 			Balances::set_lock(ID_1, &1, 10, u64::max_value(), WithdrawReason::Transfer.into());
@@ -125,8 +125,8 @@ fn lock_reasons_should_work() {
 			);
 			assert_ok!(<Balances as ReservableCurrency<_>>::reserve(&1, 1));
 			// NOTE: this causes a fee payment.
-			assert!(<TakeFees<Runtime> as SignedExtension>::pre_dispatch(
-				TakeFees::from(1),
+			assert!(<ChargeTransactionPayment<Runtime> as SignedExtension>::pre_dispatch(
+				ChargeTransactionPayment::from(1),
 				&1,
 				CALL,
 				info_from_weight(1),
@@ -139,8 +139,8 @@ fn lock_reasons_should_work() {
 				<Balances as ReservableCurrency<_>>::reserve(&1, 1),
 				"account liquidity restrictions prevent withdrawal"
 			);
-			assert!(<TakeFees<Runtime> as SignedExtension>::pre_dispatch(
-				TakeFees::from(1),
+			assert!(<ChargeTransactionPayment<Runtime> as SignedExtension>::pre_dispatch(
+				ChargeTransactionPayment::from(1),
 				&1,
 				CALL,
 				info_from_weight(1),
@@ -150,8 +150,8 @@ fn lock_reasons_should_work() {
 			Balances::set_lock(ID_1, &1, 10, u64::max_value(), WithdrawReason::TransactionPayment.into());
 			assert_ok!(<Balances as Currency<_>>::transfer(&1, &2, 1));
 			assert_ok!(<Balances as ReservableCurrency<_>>::reserve(&1, 1));
-			assert!(<TakeFees<Runtime> as SignedExtension>::pre_dispatch(
-				TakeFees::from(1),
+			assert!(<ChargeTransactionPayment<Runtime> as SignedExtension>::pre_dispatch(
+				ChargeTransactionPayment::from(1),
 				&1,
 				CALL,
 				info_from_weight(1),
@@ -736,89 +736,6 @@ fn liquid_funds_should_transfer_with_delayed_vesting() {
 		});
 }
 
-#[test]
-fn signed_extension_take_fees_work() {
-	ExtBuilder::default()
-		.existential_deposit(10)
-		.transaction_fees(10, 1, 5)
-		.monied(true)
-		.build()
-		.execute_with(|| {
-			let len = 10;
-			assert!(
-				TakeFees::<Runtime>::from(0)
-					.pre_dispatch(&1, CALL, info_from_weight(5), len)
-					.is_ok()
-			);
-			assert_eq!(Balances::free_balance(&1), 100 - 20 - 25);
-			assert!(
-				TakeFees::<Runtime>::from(5 /* tipped */)
-					.pre_dispatch(&1, CALL, info_from_weight(3), len)
-					.is_ok()
-			);
-			assert_eq!(Balances::free_balance(&1), 100 - 20 - 25 - 20 - 5 - 15);
-		});
-}
-
-#[test]
-fn signed_extension_take_fees_is_bounded() {
-	ExtBuilder::default()
-		.existential_deposit(1000)
-		.transaction_fees(0, 0, 1)
-		.monied(true)
-		.build()
-		.execute_with(|| {
-			use sr_primitives::weights::Weight;
-
-			// maximum weight possible
-			assert!(
-				TakeFees::<Runtime>::from(0)
-					.pre_dispatch(&1, CALL, info_from_weight(Weight::max_value()), 10)
-					.is_ok()
-			);
-			// fee will be proportional to what is the actual maximum weight in the runtime.
-			assert_eq!(
-				Balances::free_balance(&1),
-				(10000 - <Runtime as system::Trait>::MaximumBlockWeight::get()) as u64
-			);
-		});
-}
-
-#[test]
-fn signed_extension_allows_free_transactions() {
-	ExtBuilder::default()
-		.transaction_fees(100, 1, 1)
-		.monied(false)
-		.build()
-		.execute_with(|| {
-			// 1 ain't have a penny.
-			assert_eq!(Balances::free_balance(&1), 0);
-
-			// like a FreeOperational
-			let operational_transaction = DispatchInfo {
-				weight: 0,
-				class: DispatchClass::Operational
-			};
-			let len = 100;
-			assert!(
-				TakeFees::<Runtime>::from(0)
-					.validate(&1, CALL, operational_transaction , len)
-					.is_ok()
-			);
-
-			// like a FreeNormal
-			let free_transaction = DispatchInfo {
-				weight: 0,
-				class: DispatchClass::Normal
-			};
-			assert!(
-				TakeFees::<Runtime>::from(0)
-					.validate(&1, CALL, free_transaction , len)
-					.is_err()
-			);
-		});
-}
-
 #[test]
 fn burn_must_work() {
 	ExtBuilder::default().monied(true).build().execute_with(|| {

substrate/srml/collective/src/lib.rs

@@ -406,7 +406,6 @@ mod tests {
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
 		type Event = Event;
-		type WeightMultiplierUpdate = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;
 		type MaximumBlockLength = MaximumBlockLength;

substrate/srml/contracts/src/lib.rs

@@ -442,7 +442,7 @@ where
 }
 
 /// The default dispatch fee computor computes the fee in the same way that
-/// the implementation of `TakeFees` for the Balances module does. Note that this only takes a fixed
+/// the implementation of `ChargeTransactionPayment` for the Balances module does. Note that this only takes a fixed
 /// fee based on size. Unlike the balances module, weight-fee is applied.
 pub struct DefaultDispatchFeeComputor<T: Trait>(PhantomData<T>);
 impl<T: Trait> ComputeDispatchFee<<T as Trait>::Call, BalanceOf<T>> for DefaultDispatchFeeComputor<T> {

substrate/srml/contracts/src/tests.rs

@@ -96,8 +96,6 @@ parameter_types! {
 	pub const BlockHashCount: u64 = 250;
 	pub const MaximumBlockWeight: u32 = 1024;
 	pub const MaximumBlockLength: u32 = 2 * 1024;
-	pub const BalancesTransactionBaseFee: u64 = 0;
-	pub const BalancesTransactionByteFee: u64 = 0;
 	pub const AvailableBlockRatio: Perbill = Perbill::one();
 }
 impl system::Trait for Test {
@@ -110,7 +108,6 @@ impl system::Trait for Test {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = MetaEvent;
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;
@@ -123,15 +120,11 @@ impl balances::Trait for Test {
 	type OnFreeBalanceZero = Contract;
 	type OnNewAccount = ();
 	type Event = MetaEvent;
-	type TransactionPayment = ();
 	type DustRemoval = ();
 	type TransferPayment = ();
 	type ExistentialDeposit = ExistentialDeposit;
 	type TransferFee = TransferFee;
 	type CreationFee = CreationFee;
-	type TransactionBaseFee = BalancesTransactionBaseFee;
-	type TransactionByteFee = BalancesTransactionByteFee;
-	type WeightToFee = ();
 }
 parameter_types! {
 	pub const MinimumPeriod: u64 = 1;

substrate/srml/council/src/lib.rs

@@ -114,7 +114,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = Event;
 		type Error = Error;
 		type BlockHashCount = BlockHashCount;
@@ -127,24 +126,18 @@ mod tests {
 		pub const ExistentialDeposit: u64 = 0;
 		pub const TransferFee: u64 = 0;
 		pub const CreationFee: u64 = 0;
-		pub const TransactionBaseFee: u64 = 1;
-		pub const TransactionByteFee: u64 = 0;
 	}
 	impl balances::Trait for Test {
 		type Balance = u64;
 		type OnNewAccount = ();
 		type OnFreeBalanceZero = ();
 		type Event = Event;
-		type TransactionPayment = ();
 		type TransferPayment = ();
 		type DustRemoval = ();
 		type Error = Error;
 		type ExistentialDeposit = ExistentialDeposit;
 		type TransferFee = TransferFee;
 		type CreationFee = CreationFee;
-		type TransactionBaseFee = TransactionBaseFee;
-		type TransactionByteFee = TransactionByteFee;
-		type WeightToFee = ();
 	}
 	parameter_types! {
 		pub const LaunchPeriod: u64 = 1;

substrate/srml/democracy/src/lib.rs

@@ -1015,7 +1015,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;
@@ -1027,23 +1026,17 @@ mod tests {
 		pub const ExistentialDeposit: u64 = 0;
 		pub const TransferFee: u64 = 0;
 		pub const CreationFee: u64 = 0;
-		pub const TransactionBaseFee: u64 = 0;
-		pub const TransactionByteFee: u64 = 0;
 	}
 	impl balances::Trait for Test {
 		type Balance = u64;
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
 		type Event = ();
-		type TransactionPayment = ();
 		type TransferPayment = ();
 		type DustRemoval = ();
 		type ExistentialDeposit = ExistentialDeposit;
 		type TransferFee = TransferFee;
 		type CreationFee = CreationFee;
-		type TransactionBaseFee = TransactionBaseFee;
-		type TransactionByteFee = TransactionByteFee;
-		type WeightToFee = ();
 	}
 	parameter_types! {
 		pub const LaunchPeriod: u64 = 2;

substrate/srml/elections-phragmen/src/lib.rs

@@ -616,7 +616,6 @@ mod tests {
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
 		type Event = Event;
-		type WeightMultiplierUpdate = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;
 		type MaximumBlockLength = MaximumBlockLength;
@@ -628,8 +627,6 @@ mod tests {
 		pub const ExistentialDeposit: u64 = 1;
 		pub const TransferFee: u64 = 0;
 		pub const CreationFee: u64 = 0;
-		pub const TransactionBaseFee: u64 = 0;
-		pub const TransactionByteFee: u64 = 0;
 	}
 
 	impl balances::Trait for Test {
@@ -637,15 +634,11 @@ mod tests {
 		type OnNewAccount = ();
 		type OnFreeBalanceZero = ();
 		type Event = Event;
-		type TransactionPayment = ();
 		type TransferPayment = ();
 		type DustRemoval = ();
 		type ExistentialDeposit = ExistentialDeposit;
 		type TransferFee = TransferFee;
 		type CreationFee = CreationFee;
-		type TransactionBaseFee = TransactionBaseFee;
-		type TransactionByteFee = TransactionByteFee;
-		type WeightToFee = ();
 	}
 
 	parameter_types! {

substrate/srml/elections/src/mock.rs

@@ -47,7 +47,6 @@ impl system::Trait for Test {
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
 	type Event = Event;
-	type WeightMultiplierUpdate = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;
 	type MaximumBlockLength = MaximumBlockLength;
@@ -59,23 +58,17 @@ parameter_types! {
 	pub const ExistentialDeposit: u64 = 0;
 	pub const TransferFee: u64 = 0;
 	pub const CreationFee: u64 = 0;
-	pub const TransactionBaseFee: u64 = 0;
-	pub const TransactionByteFee: u64 = 0;
 }
 impl balances::Trait for Test {
 	type Balance = u64;
 	type OnNewAccount = ();
 	type OnFreeBalanceZero = ();
 	type Event = Event;
-	type TransactionPayment = ();
 	type TransferPayment = ();
 	type DustRemoval = ();
 	type ExistentialDeposit = ExistentialDeposit;
 	type TransferFee = TransferFee;
 	type CreationFee = CreationFee;
-	type TransactionBaseFee = TransactionBaseFee;
-	type TransactionByteFee = TransactionByteFee;
-	type WeightToFee = ();
 }
 
 parameter_types! {

substrate/srml/example/src/lib.rs

@@ -667,7 +667,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;
@@ -679,23 +678,17 @@ mod tests {
 		pub const ExistentialDeposit: u64 = 0;
 		pub const TransferFee: u64 = 0;
 		pub const CreationFee: u64 = 0;
-		pub const TransactionBaseFee: u64 = 0;
-		pub const TransactionByteFee: u64 = 0;
 	}
 	impl balances::Trait for Test {
 		type Balance = u64;
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
 		type Event = ();
-		type TransactionPayment = ();
 		type TransferPayment = ();
 		type DustRemoval = ();
 		type ExistentialDeposit = ExistentialDeposit;
 		type TransferFee = TransferFee;
 		type CreationFee = CreationFee;
-		type TransactionBaseFee = TransactionBaseFee;
-		type TransactionByteFee = TransactionByteFee;
-		type WeightToFee = ();
 	}
 	impl Trait for Test {
 		type Event = ();

substrate/srml/executive/Cargo.toml

@@ -18,6 +18,7 @@ hex-literal = "0.2.1"
 primitives = { package = "substrate-primitives",  path = "../../core/primitives" }
 srml-indices = { path = "../indices" }
 balances = { package = "srml-balances", path = "../balances" }
+transaction-payment = { package = "srml-transaction-payment", path = "../transaction-payment" }
 
 [features]
 default = ["std"]

substrate/srml/executive/src/lib.rs

@@ -347,7 +347,6 @@ mod tests {
 		type Header = Header;
 		type Event = MetaEvent;
 		type BlockHashCount = BlockHashCount;
-		type WeightMultiplierUpdate = ();
 		type MaximumBlockWeight = MaximumBlockWeight;
 		type AvailableBlockRatio = AvailableBlockRatio;
 		type MaximumBlockLength = MaximumBlockLength;
@@ -357,23 +356,30 @@ mod tests {
 		pub const ExistentialDeposit: u64 = 0;
 		pub const TransferFee: u64 = 0;
 		pub const CreationFee: u64 = 0;
-		pub const TransactionBaseFee: u64 = 10;
-		pub const TransactionByteFee: u64 = 0;
 	}
 	impl balances::Trait for Runtime {
 		type Balance = u64;
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
 		type Event = MetaEvent;
-		type TransactionPayment = ();
 		type DustRemoval = ();
 		type TransferPayment = ();
 		type ExistentialDeposit = ExistentialDeposit;
 		type TransferFee = TransferFee;
 		type CreationFee = CreationFee;
+	}
+
+	parameter_types! {
+		pub const TransactionBaseFee: u64 = 10;
+		pub const TransactionByteFee: u64 = 0;
+	}
+	impl transaction_payment::Trait for Runtime {
+		type Currency = Balances;
+		type OnTransactionPayment = ();
 		type TransactionBaseFee = TransactionBaseFee;
 		type TransactionByteFee = TransactionByteFee;
 		type WeightToFee = ConvertInto;
+		type FeeMultiplierUpdate = ();
 	}
 
 	impl ValidateUnsigned for Runtime {
@@ -391,7 +397,7 @@ mod tests {
 		system::CheckEra<Runtime>,
 		system::CheckNonce<Runtime>,
 		system::CheckWeight<Runtime>,
-		balances::TakeFees<Runtime>
+		transaction_payment::ChargeTransactionPayment<Runtime>
 	);
 	type TestXt = sr_primitives::testing::TestXt<Call, SignedExtra>;
 	type Executive = super::Executive<Runtime, Block<TestXt>, system::ChainContext<Runtime>, Runtime, ()>;
@@ -401,7 +407,7 @@ mod tests {
 			system::CheckEra::from(Era::Immortal),
 			system::CheckNonce::from(nonce),
 			system::CheckWeight::new(),
-			balances::TakeFees::from(fee)
+			transaction_payment::ChargeTransactionPayment::from(fee)
 		)
 	}
 
@@ -450,7 +456,7 @@ mod tests {
 				header: Header {
 					parent_hash: [69u8; 32].into(),
 					number: 1,
-					state_root: hex!("a6378d7fdd31029d13718d54bdff10a370e75cc624aaf94a90e7e7d4a24e0bcc").into(),
+					state_root: hex!("f0d1d66255c2e5b40580eb8b93ddbe732491478487f85e358e1d167d369e398e").into(),
 					extrinsics_root: hex!("03170a2e7597b7b7e3d84c05391d139a62b157e78786d8c082f29dcf4c111314").into(),
 					digest: Digest { logs: vec![], },
 				},

substrate/srml/finality-tracker/src/lib.rs

@@ -298,7 +298,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<u64>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/generic-asset/src/lib.rs

@@ -1056,7 +1056,6 @@ impl<T: Subtrait> system::Trait for ElevatedTrait<T> {
 	type MaximumBlockWeight = T::MaximumBlockWeight;
 	type MaximumBlockLength = T::MaximumBlockLength;
 	type AvailableBlockRatio = T::AvailableBlockRatio;
-	type WeightMultiplierUpdate = ();
 	type BlockHashCount = T::BlockHashCount;
 	type Version = T::Version;
 }

substrate/srml/generic-asset/src/mock.rs

@@ -56,7 +56,6 @@ impl system::Trait for Test {
 	type Lookup = IdentityLookup<u64>;
 	type Header = Header;
 	type Event = TestEvent;
-	type WeightMultiplierUpdate = ();
 	type MaximumBlockWeight = MaximumBlockWeight;
 	type MaximumBlockLength = MaximumBlockLength;
 	type AvailableBlockRatio = AvailableBlockRatio;

substrate/srml/grandpa/src/mock.rs

@@ -57,7 +57,6 @@ impl system::Trait for Test {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = TestEvent;
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/im-online/src/mock.rs

@@ -111,7 +111,6 @@ impl system::Trait for Runtime {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/indices/src/mock.rs

@@ -81,7 +81,6 @@ impl system::Trait for Runtime {
 	type AccountId = u64;
 	type Lookup = Indices;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/membership/src/lib.rs

@@ -224,7 +224,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/offences/src/mock.rs

@@ -78,7 +78,6 @@ impl system::Trait for Runtime {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = TestEvent;
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/randomness-collective-flip/src/lib.rs

@@ -182,7 +182,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/scored-pool/src/mock.rs

@@ -52,8 +52,6 @@ parameter_types! {
 	pub const ExistentialDeposit: u64 = 0;
 	pub const TransferFee: u64 = 0;
 	pub const CreationFee: u64 = 0;
-	pub const TransactionBaseFee: u64 = 0;
-	pub const TransactionByteFee: u64 = 0;
 }
 
 impl system::Trait for Test {
@@ -66,7 +64,6 @@ impl system::Trait for Test {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;
@@ -80,15 +77,11 @@ impl balances::Trait for Test {
 	type OnFreeBalanceZero = ();
 	type OnNewAccount = ();
 	type Event = ();
-	type TransactionPayment = ();
 	type TransferPayment = ();
 	type DustRemoval = ();
 	type ExistentialDeposit = ExistentialDeposit;
 	type TransferFee = TransferFee;
 	type CreationFee = CreationFee;
-	type TransactionBaseFee = TransactionBaseFee;
-	type TransactionByteFee = TransactionByteFee;
-	type WeightToFee = ();
 }
 
 thread_local! {

substrate/srml/session/src/mock.rs

@@ -168,7 +168,6 @@ impl system::Trait for Test {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/staking/src/mock.rs

@@ -118,7 +118,6 @@ impl system::Trait for Test {
 	type AccountId = AccountId;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = ();
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;
@@ -129,23 +128,17 @@ impl system::Trait for Test {
 parameter_types! {
 	pub const TransferFee: Balance = 0;
 	pub const CreationFee: Balance = 0;
-	pub const TransactionBaseFee: u64 = 0;
-	pub const TransactionByteFee: u64 = 0;
 }
 impl balances::Trait for Test {
 	type Balance = Balance;
 	type OnFreeBalanceZero = Staking;
 	type OnNewAccount = ();
 	type Event = ();
-	type TransactionPayment = ();
 	type TransferPayment = ();
 	type DustRemoval = ();
 	type ExistentialDeposit = ExistentialDeposit;
 	type TransferFee = TransferFee;
 	type CreationFee = CreationFee;
-	type TransactionBaseFee = TransactionBaseFee;
-	type TransactionByteFee = TransactionByteFee;
-	type WeightToFee = ();
 }
 parameter_types! {
 	pub const Period: BlockNumber = 1;

substrate/srml/system/benches/bench.rs

@@ -68,7 +68,6 @@ impl system::Trait for Runtime {
 	type AccountId = u64;
 	type Lookup = IdentityLookup<Self::AccountId>;
 	type Header = Header;
-	type WeightMultiplierUpdate = ();
 	type Event = Event;
 	type BlockHashCount = BlockHashCount;
 	type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/system/src/lib.rs

@@ -97,13 +97,13 @@ use rstd::marker::PhantomData;
 use sr_version::RuntimeVersion;
 use sr_primitives::{
 	generic::{self, Era}, Perbill, ApplyError, ApplyOutcome, DispatchError,
-	weights::{Weight, DispatchInfo, DispatchClass, WeightMultiplier, SimpleDispatchInfo},
+	weights::{Weight, DispatchInfo, DispatchClass, SimpleDispatchInfo},
 	transaction_validity::{
 		ValidTransaction, TransactionPriority, TransactionLongevity, TransactionValidityError,
 		InvalidTransaction, TransactionValidity,
 	},
 	traits::{
-		self, CheckEqual, SimpleArithmetic, Zero, SignedExtension, Convert, Lookup, LookupError,
+		self, CheckEqual, SimpleArithmetic, Zero, SignedExtension, Lookup, LookupError,
 		SimpleBitOps, Hash, Member, MaybeDisplay, EnsureOrigin, SaturatedConversion,
 		MaybeSerializeDebugButNotDeserialize, MaybeSerializeDebug, StaticLookup, One, Bounded,
 	},
@@ -188,14 +188,6 @@ pub trait Trait: 'static + Eq + Clone {
 	/// (e.g. Indices module) may provide more functional/efficient alternatives.
 	type Lookup: StaticLookup<Target = Self::AccountId>;
 
-	/// Handler for updating the weight multiplier at the end of each block.
-	///
-	/// It receives the current block's weight as input and returns the next weight multiplier for next
-	/// block.
-	///
-	/// Note that passing `()` will keep the value constant.
-	type WeightMultiplierUpdate: Convert<(Weight, WeightMultiplier), WeightMultiplier>;
-
 	/// The block header.
 	type Header: Parameter + traits::Header<
 		Number = Self::BlockNumber,
@@ -381,9 +373,6 @@ decl_storage! {
 		AllExtrinsicsWeight: Option<Weight>;
 		/// Total length (in bytes) for all extrinsics put together, for the current block.
 		AllExtrinsicsLen: Option<u32>;
-		/// The next weight multiplier. This should be updated at the end of each block based on the
-		/// saturation level (weight).
-		pub NextWeightMultiplier get(next_weight_multiplier): WeightMultiplier = Default::default();
 		/// Map of block numbers to block hashes.
 		pub BlockHash get(block_hash) build(|_| vec![(T::BlockNumber::zero(), hash69())]): map T::BlockNumber => T::Hash;
 		/// Extrinsics data for the current block (maps an extrinsic's index to its data).
@@ -612,17 +601,6 @@ impl<T: Trait> Module<T> {
 		AllExtrinsicsLen::get().unwrap_or_default()
 	}
 
-	/// Update the next weight multiplier.
-	///
-	/// This should be called at then end of each block, before `all_extrinsics_weight` is cleared.
-	pub fn update_weight_multiplier() {
-		// update the multiplier based on block weight.
-		let current_weight = Self::all_extrinsics_weight();
-		NextWeightMultiplier::mutate(|fm| {
-			*fm = T::WeightMultiplierUpdate::convert((current_weight, *fm))
-		});
-	}
-
 	/// Start the execution of a particular block.
 	pub fn initialize(
 		number: &T::BlockNumber,
@@ -645,7 +623,6 @@ impl<T: Trait> Module<T> {
 	/// Remove temporary "environment" entries in storage.
 	pub fn finalize() -> T::Header {
 		ExtrinsicCount::kill();
-		Self::update_weight_multiplier();
 		AllExtrinsicsWeight::kill();
 		AllExtrinsicsLen::kill();
 
@@ -1118,7 +1095,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = u16;
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/timestamp/src/lib.rs

@@ -348,7 +348,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;

substrate/srml/transaction-payment/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "srml-transaction-payment"
+version = "2.0.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "1.0.0", default-features = false, features = ["derive"] }
+rstd = { package = "sr-std", path = "../../core/sr-std", default-features = false }
+sr-primitives = { path = "../../core/sr-primitives", default-features = false }
+support = { package = "srml-support", path = "../support", default-features = false }
+system = { package = "srml-system", path = "../system", default-features = false }
+
+[dev-dependencies]
+runtime-io = { package = "sr-io", path = "../../core/sr-io" }
+primitives = { package = "substrate-primitives",  path = "../../core/primitives" }
+balances = { package = "srml-balances", path = "../balances" }
+
+[features]
+default = ["std"]
+std = [
+	"codec/std",
+	"rstd/std",
+	"sr-primitives/std",
+	"support/std",
+	"system/std",
+]

substrate/srml/transaction-payment/src/lib.rs

@@ -0,0 +1,455 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate 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.
+
+// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! # Transaction Payment Module
+//!
+//! This module provides the basic logic needed to pay the absolute minimum amount needed for a
+//! transaction to be included. This includes:
+//!   - _weight fee_: A fee proportional to amount of weight a transaction consumes.
+//!   - _length fee_: A fee proportional to the encoded length of the transaction.
+//!   - _tip_: An optional tip. Tip increases the priority of the transaction, giving it a higher
+//!     chance to be included by the transaction queue.
+//!
+//! Additionally, this module allows one to configure:
+//!   - The mapping between one unit of weight to one unit of fee via [`WeightToFee`].
+//!   - A means of updating the fee for the next block, via defining a multiplier, based on the
+//!     final state of the chain at the end of the previous block. This can be configured via
+//!     [`FeeMultiplierUpdate`]
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use rstd::prelude::*;
+use codec::{Encode, Decode};
+use support::{
+	decl_storage, decl_module,
+	traits::{Currency, Get, OnUnbalanced, ExistenceRequirement, WithdrawReason},
+};
+use sr_primitives::{
+	Fixed64,
+	transaction_validity::{
+		TransactionPriority, ValidTransaction, InvalidTransaction, TransactionValidityError,
+		TransactionValidity,
+	},
+	traits::{Zero, Saturating, SignedExtension, SaturatedConversion, Convert},
+	weights::{Weight, DispatchInfo},
+};
+
+type Multiplier = Fixed64;
+type BalanceOf<T> =
+	<<T as Trait>::Currency as Currency<<T as system::Trait>::AccountId>>::Balance;
+type NegativeImbalanceOf<T> =
+	<<T as Trait>::Currency as Currency<<T as system::Trait>::AccountId>>::NegativeImbalance;
+
+pub trait Trait: system::Trait {
+	/// The currency type in which fees will be paid.
+	type Currency: Currency<Self::AccountId>;
+
+	/// Handler for the unbalanced reduction when taking transaction fees.
+	type OnTransactionPayment: OnUnbalanced<NegativeImbalanceOf<Self>>;
+
+	/// The fee to be paid for making a transaction; the base.
+	type TransactionBaseFee: Get<BalanceOf<Self>>;
+
+	/// The fee to be paid for making a transaction; the per-byte portion.
+	type TransactionByteFee: Get<BalanceOf<Self>>;
+
+	/// Convert a weight value into a deductible fee based on the currency type.
+	type WeightToFee: Convert<Weight, BalanceOf<Self>>;
+
+	/// Update the multiplier of the next block, based on the previous block's weight.
+	// TODO: maybe this does not need previous weight and can just read it
+	type FeeMultiplierUpdate: Convert<(Weight, Multiplier), Multiplier>;
+}
+
+decl_storage! {
+	trait Store for Module<T: Trait> as Balances {
+		NextFeeMultiplier get(next_fee_multiplier): Multiplier = Multiplier::from_parts(0);
+	}
+}
+
+decl_module! {
+	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
+		/// The fee to be paid for making a transaction; the base.
+		const TransactionBaseFee: BalanceOf<T> = T::TransactionBaseFee::get();
+
+		/// The fee to be paid for making a transaction; the per-byte portion.
+		const TransactionByteFee: BalanceOf<T> = T::TransactionByteFee::get();
+
+		fn on_finalize() {
+			let current_weight = <system::Module<T>>::all_extrinsics_weight();
+			NextFeeMultiplier::mutate(|fm| {
+				*fm = T::FeeMultiplierUpdate::convert((current_weight, *fm))
+			});
+		}
+	}
+}
+
+impl<T: Trait> Module<T> {}
+
+/// Require the transactor pay for themselves and maybe include a tip to gain additional priority
+/// in the queue.
+#[derive(Encode, Decode, Clone, Eq, PartialEq)]
+pub struct ChargeTransactionPayment<T: Trait + Send + Sync>(#[codec(compact)] BalanceOf<T>);
+
+impl<T: Trait + Send + Sync> ChargeTransactionPayment<T> {
+	/// utility constructor. Used only in client/factory code.
+	pub fn from(fee: BalanceOf<T>) -> Self {
+		Self(fee)
+	}
+
+	/// Compute the final fee value for a particular transaction.
+	///
+	/// The final fee is composed of:
+	///   - _length-fee_: This is the amount paid merely to pay for size of the transaction.
+	///   - _weight-fee_: This amount is computed based on the weight of the transaction. Unlike
+	///      size-fee, this is not input dependent and reflects the _complexity_ of the execution
+	///      and the time it consumes.
+	///   - (optional) _tip_: if included in the transaction, it will be added on top. Only signed
+	///      transactions can have a tip.
+	fn compute_fee(len: usize, info: DispatchInfo, tip: BalanceOf<T>) -> BalanceOf<T> {
+		let len_fee = if info.pay_length_fee() {
+			let len = <BalanceOf<T>>::from(len as u32);
+			let base = T::TransactionBaseFee::get();
+			let per_byte = T::TransactionByteFee::get();
+			base.saturating_add(per_byte.saturating_mul(len))
+		} else {
+			Zero::zero()
+		};
+
+		let weight_fee = {
+			// cap the weight to the maximum defined in runtime, otherwise it will be the `Bounded`
+			// maximum of its data type, which is not desired.
+			let capped_weight = info.weight.min(<T as system::Trait>::MaximumBlockWeight::get());
+			T::WeightToFee::convert(capped_weight)
+		};
+
+		// everything except for tip
+		let basic_fee = len_fee.saturating_add(weight_fee);
+		let fee_update = NextFeeMultiplier::get();
+		let adjusted_fee = fee_update.saturated_multiply_accumulate(basic_fee);
+
+		adjusted_fee.saturating_add(tip)
+	}
+}
+
+#[cfg(feature = "std")]
+impl<T: Trait + Send + Sync> rstd::fmt::Debug for ChargeTransactionPayment<T> {
+	fn fmt(&self, f: &mut rstd::fmt::Formatter) -> rstd::fmt::Result {
+		write!(f, "ChargeTransactionPayment<{:?}>", self.0)
+	}
+}
+
+impl<T: Trait + Send + Sync> SignedExtension for ChargeTransactionPayment<T>
+	where BalanceOf<T>: Send + Sync
+{
+	type AccountId = T::AccountId;
+	type Call = T::Call;
+	type AdditionalSigned = ();
+	type Pre = ();
+	fn additional_signed(&self) -> rstd::result::Result<(), TransactionValidityError> { Ok(()) }
+
+	fn validate(
+		&self,
+		who: &Self::AccountId,
+		_call: &Self::Call,
+		info: DispatchInfo,
+		len: usize,
+	) -> TransactionValidity {
+		// pay any fees.
+		let fee = Self::compute_fee(len, info, self.0);
+		let imbalance = match T::Currency::withdraw(
+			who,
+			fee,
+			WithdrawReason::TransactionPayment,
+			ExistenceRequirement::KeepAlive,
+		) {
+			Ok(imbalance) => imbalance,
+			Err(_) => return InvalidTransaction::Payment.into(),
+		};
+		T::OnTransactionPayment::on_unbalanced(imbalance);
+
+		let mut r = ValidTransaction::default();
+		// NOTE: we probably want to maximize the _fee (of any type) per weight unit_ here, which
+		// will be a bit more than setting the priority to tip. For now, this is enough.
+		r.priority = fee.saturated_into::<TransactionPriority>();
+		Ok(r)
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use support::{parameter_types, impl_outer_origin};
+	use primitives::H256;
+	use sr_primitives::{
+		Perbill,
+		testing::Header,
+		traits::{BlakeTwo256, IdentityLookup},
+		weights::DispatchClass,
+	};
+	use rstd::cell::RefCell;
+
+	const CALL: &<Runtime as system::Trait>::Call = &();
+
+	#[derive(Clone, PartialEq, Eq, Debug)]
+	pub struct Runtime;
+
+	impl_outer_origin!{
+		pub enum Origin for Runtime {}
+	}
+
+	parameter_types! {
+		pub const BlockHashCount: u64 = 250;
+		pub const MaximumBlockWeight: u32 = 1024;
+		pub const MaximumBlockLength: u32 = 2 * 1024;
+		pub const AvailableBlockRatio: Perbill = Perbill::one();
+	}
+
+	impl system::Trait for Runtime {
+		type Origin = Origin;
+		type Index = u64;
+		type BlockNumber = u64;
+		type Call = ();
+		type Hash = H256;
+		type Hashing = BlakeTwo256;
+		type AccountId = u64;
+		type Lookup = IdentityLookup<Self::AccountId>;
+		type Header = Header;
+		type Event = ();
+		type BlockHashCount = BlockHashCount;
+		type MaximumBlockWeight = MaximumBlockWeight;
+		type MaximumBlockLength = MaximumBlockLength;
+		type AvailableBlockRatio = AvailableBlockRatio;
+		type Version = ();
+	}
+
+	parameter_types! {
+		pub const TransferFee: u64 = 0;
+		pub const CreationFee: u64 = 0;
+		pub const ExistentialDeposit: u64 = 0;
+	}
+
+	impl balances::Trait for Runtime {
+		type Balance = u64;
+		type OnFreeBalanceZero = ();
+		type OnNewAccount = ();
+		type Event = ();
+		type TransferPayment = ();
+		type DustRemoval = ();
+		type ExistentialDeposit = ExistentialDeposit;
+		type TransferFee = TransferFee;
+		type CreationFee = CreationFee;
+	}
+
+	thread_local! {
+		static TRANSACTION_BASE_FEE: RefCell<u64> = RefCell::new(0);
+		static TRANSACTION_BYTE_FEE: RefCell<u64> = RefCell::new(1);
+		static WEIGHT_TO_FEE: RefCell<u64> = RefCell::new(1);
+	}
+
+	pub struct TransactionBaseFee;
+	impl Get<u64> for TransactionBaseFee {
+		fn get() -> u64 { TRANSACTION_BASE_FEE.with(|v| *v.borrow()) }
+	}
+
+	pub struct TransactionByteFee;
+	impl Get<u64> for TransactionByteFee {
+		fn get() -> u64 { TRANSACTION_BYTE_FEE.with(|v| *v.borrow()) }
+	}
+
+	pub struct WeightToFee(u64);
+	impl Convert<Weight, u64> for WeightToFee {
+		fn convert(t: Weight) -> u64 {
+			WEIGHT_TO_FEE.with(|v| *v.borrow() * (t as u64))
+		}
+	}
+
+	impl Trait for Runtime {
+		type Currency = balances::Module<Runtime>;
+		type OnTransactionPayment = ();
+		type TransactionBaseFee = TransactionBaseFee;
+		type TransactionByteFee = TransactionByteFee;
+		type WeightToFee = WeightToFee;
+		type FeeMultiplierUpdate = ();
+	}
+
+	type Balances = balances::Module<Runtime>;
+
+	pub struct ExtBuilder {
+		balance_factor: u64,
+		base_fee: u64,
+		byte_fee: u64,
+		weight_to_fee: u64
+	}
+
+	impl Default for ExtBuilder {
+		fn default() -> Self {
+			Self {
+				balance_factor: 1,
+				base_fee: 0,
+				byte_fee: 1,
+				weight_to_fee: 1,
+			}
+		}
+	}
+
+	impl ExtBuilder {
+		pub fn fees(mut self, base: u64, byte: u64, weight: u64) -> Self {
+			self.base_fee = base;
+			self.byte_fee = byte;
+			self.weight_to_fee = weight;
+			self
+		}
+		pub fn balance_factor(mut self, factor: u64) -> Self {
+			self.balance_factor = factor;
+			self
+		}
+		fn set_constants(&self) {
+			TRANSACTION_BASE_FEE.with(|v| *v.borrow_mut() = self.base_fee);
+			TRANSACTION_BYTE_FEE.with(|v| *v.borrow_mut() = self.byte_fee);
+			WEIGHT_TO_FEE.with(|v| *v.borrow_mut() = self.weight_to_fee);
+		}
+		pub fn build(self) -> runtime_io::TestExternalities {
+			self.set_constants();
+			let mut t = system::GenesisConfig::default().build_storage::<Runtime>().unwrap();
+			balances::GenesisConfig::<Runtime> {
+				balances: vec![
+					(1, 10 * self.balance_factor),
+					(2, 20 * self.balance_factor),
+					(3, 30 * self.balance_factor),
+					(4, 40 * self.balance_factor),
+					(5, 50 * self.balance_factor),
+					(6, 60 * self.balance_factor)
+				],
+				vesting: vec![],
+			}.assimilate_storage(&mut t).unwrap();
+			t.into()
+		}
+	}
+
+	/// create a transaction info struct from weight. Handy to avoid building the whole struct.
+	pub fn info_from_weight(w: Weight) -> DispatchInfo {
+		DispatchInfo { weight: w, ..Default::default() }
+	}
+
+	#[test]
+	fn signed_extension_transaction_payment_work() {
+			ExtBuilder::default()
+			.balance_factor(10) // 100
+			.fees(5, 1, 1) // 5 fixed, 1 per byte, 1 per weight
+			.build()
+			.execute_with(||
+		{
+			let len = 10;
+			assert!(
+				ChargeTransactionPayment::<Runtime>::from(0)
+					.pre_dispatch(&1, CALL, info_from_weight(5), len)
+					.is_ok()
+			);
+			assert_eq!(Balances::free_balance(&1), 100 - 5 - 5 - 10);
+
+			assert!(
+				ChargeTransactionPayment::<Runtime>::from(5 /* tipped */)
+					.pre_dispatch(&2, CALL, info_from_weight(3), len)
+					.is_ok()
+			);
+			assert_eq!(Balances::free_balance(&2), 200 - 5 - 10 - 3 - 5);
+		});
+	}
+
+	#[test]
+	fn signed_extension_transaction_payment_is_bounded() {
+			ExtBuilder::default()
+			.balance_factor(1000)
+			.fees(0, 0, 1)
+			.build()
+			.execute_with(||
+		{
+			use sr_primitives::weights::Weight;
+
+			// maximum weight possible
+			assert!(
+				ChargeTransactionPayment::<Runtime>::from(0)
+					.pre_dispatch(&1, CALL, info_from_weight(Weight::max_value()), 10)
+					.is_ok()
+			);
+			// fee will be proportional to what is the actual maximum weight in the runtime.
+			assert_eq!(
+				Balances::free_balance(&1),
+				(10000 - <Runtime as system::Trait>::MaximumBlockWeight::get()) as u64
+			);
+		});
+	}
+
+	#[test]
+	fn signed_extension_allows_free_transactions() {
+		ExtBuilder::default()
+			.fees(100, 1, 1)
+			.balance_factor(0)
+			.build()
+			.execute_with(||
+		{
+			// 1 ain't have a penny.
+			assert_eq!(Balances::free_balance(&1), 0);
+
+			// like a FreeOperational
+			let operational_transaction = DispatchInfo {
+				weight: 0,
+				class: DispatchClass::Operational
+			};
+			let len = 100;
+			assert!(
+				ChargeTransactionPayment::<Runtime>::from(0)
+					.validate(&1, CALL, operational_transaction , len)
+					.is_ok()
+			);
+
+			// like a FreeNormal
+			let free_transaction = DispatchInfo {
+				weight: 0,
+				class: DispatchClass::Normal
+			};
+			assert!(
+				ChargeTransactionPayment::<Runtime>::from(0)
+					.validate(&1, CALL, free_transaction , len)
+					.is_err()
+			);
+		});
+	}
+
+	#[test]
+	fn signed_ext_length_fee_is_also_updated_per_congestion() {
+		ExtBuilder::default()
+			.fees(5, 1, 1)
+			.balance_factor(10)
+			.build()
+			.execute_with(||
+		{
+			// all fees should be x1.5
+			NextFeeMultiplier::put(Fixed64::from_rational(1, 2));
+			let len = 10;
+
+			assert!(
+				ChargeTransactionPayment::<Runtime>::from(10) // tipped
+					.pre_dispatch(&1, CALL, info_from_weight(3), len)
+					.is_ok()
+			);
+			assert_eq!(Balances::free_balance(&1), 100 - 10 - (5 + 10 + 3) * 3 / 2);
+		})
+	}
+}
+
+

substrate/srml/treasury/src/lib.rs

@@ -383,7 +383,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;
@@ -395,23 +394,17 @@ mod tests {
 		pub const ExistentialDeposit: u64 = 0;
 		pub const TransferFee: u64 = 0;
 		pub const CreationFee: u64 = 0;
-		pub const TransactionBaseFee: u64 = 0;
-		pub const TransactionByteFee: u64 = 0;
 	}
 	impl balances::Trait for Test {
 		type Balance = u64;
 		type OnNewAccount = ();
 		type OnFreeBalanceZero = ();
 		type Event = ();
-		type TransactionPayment = ();
 		type TransferPayment = ();
 		type DustRemoval = ();
 		type ExistentialDeposit = ExistentialDeposit;
 		type TransferFee = TransferFee;
 		type CreationFee = CreationFee;
-		type TransactionBaseFee = TransactionBaseFee;
-		type TransactionByteFee = TransactionByteFee;
-		type WeightToFee = ();
 	}
 	parameter_types! {
 		pub const ProposalBond: Permill = Permill::from_percent(5);

substrate/srml/utility/src/lib.rs

@@ -99,7 +99,6 @@ mod tests {
 		type AccountId = u64;
 		type Lookup = IdentityLookup<Self::AccountId>;
 		type Header = Header;
-		type WeightMultiplierUpdate = ();
 		type Event = ();
 		type BlockHashCount = BlockHashCount;
 		type MaximumBlockWeight = MaximumBlockWeight;
@@ -111,23 +110,17 @@ mod tests {
 		pub const ExistentialDeposit: u64 = 0;
 		pub const TransferFee: u64 = 0;
 		pub const CreationFee: u64 = 0;
-		pub const TransactionBaseFee: u64 = 0;
-		pub const TransactionByteFee: u64 = 0;
 	}
 	impl balances::Trait for Test {
 		type Balance = u64;
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
 		type Event = ();
-		type TransactionPayment = ();
 		type TransferPayment = ();
 		type DustRemoval = ();
 		type ExistentialDeposit = ExistentialDeposit;
 		type TransferFee = TransferFee;
 		type CreationFee = CreationFee;
-		type TransactionBaseFee = TransactionBaseFee;
-		type TransactionByteFee = TransactionByteFee;
-		type WeightToFee = ();
 	}
 	impl Trait for Test {
 		type Event = ();