Transaction Fee Multiplier

core/sr-primitives/src/weights.rs

@@ -28,6 +28,11 @@
 /// expression must evaluate to.
 pub type Weight = u32;
 
+/// Maximum block saturation: 4mb
+pub const MAX_TRANSACTIONS_WEIGHT: u32 = 4 * 1024 * 1024;
+/// Target block saturation: 25% of max block saturation = 1mb
+pub const IDEAL_TRANSACTIONS_WEIGHT: u32 = 1024 * 1024;
+
 /// A `Call` enum (aka transaction) that can be weighted using the custom weight attribute of
 /// its dispatchable functions. Is implemented by default in the `decl_module!`.
 ///

node-template/runtime/src/lib.rs

@@ -168,6 +168,8 @@ impl timestamp::Trait for Runtime {
 impl balances::Trait for Runtime {
 	/// The type for recording an account's balance.
 	type Balance = u128;
+	/// To convert transaction weight to fee
+	type WeightToFee = ();
 	/// What to do if an account's free balance gets zeroed.
 	type OnFreeBalanceZero = ();
 	/// What to do if a new account is created.

node-template/src/chain_spec.rs

@@ -104,8 +104,6 @@ fn testnet_genesis(initial_authorities: Vec<AuthorityId>, endowed_accounts: Vec<
 			ids: endowed_accounts.clone(),
 		}),
 		balances: Some(BalancesConfig {
-			transaction_base_fee: 1,
-			transaction_byte_fee: 0,
 			existential_deposit: 500,
 			transfer_fee: 0,
 			creation_fee: 0,

node/cli/src/chain_spec.rs

@@ -85,8 +85,6 @@ fn staging_testnet_config_genesis() -> GenesisConfig {
 		}),
 		system: None,
 		balances: Some(BalancesConfig {
-			transaction_base_fee: 1 * CENTS,
-			transaction_byte_fee: 10 * MILLICENTS,
 			balances: endowed_accounts.iter().cloned()
 				.map(|k| (k, ENDOWMENT))
 				.chain(initial_authorities.iter().map(|x| (x.0.clone(), STASH)))
@@ -269,8 +267,6 @@ pub fn testnet_genesis(
 			ids: endowed_accounts.clone(),
 		}),
 		balances: Some(BalancesConfig {
-			transaction_base_fee: 1,
-			transaction_byte_fee: 0,
 			existential_deposit: 500,
 			transfer_fee: 0,
 			creation_fee: 0,

node/executor/src/lib.rs

@@ -127,9 +127,7 @@ mod tests {
 			twox_128(<balances::CreationFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<balances::TransferFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<indices::NextEnumSet<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32],
-			twox_128(<balances::TransactionBaseFee<Runtime>>::key()).to_vec() => vec![70u8; 16],
-			twox_128(<balances::TransactionByteFee<Runtime>>::key()).to_vec() => vec![0u8; 16]
+			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32]
 		]);
 
 		let r = executor().call::<_, NeverNativeValue, fn() -> _>(
@@ -160,9 +158,7 @@ mod tests {
 			twox_128(<balances::CreationFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<balances::TransferFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<indices::NextEnumSet<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32],
-			twox_128(<balances::TransactionBaseFee<Runtime>>::key()).to_vec() => vec![70u8; 16],
-			twox_128(<balances::TransactionByteFee<Runtime>>::key()).to_vec() => vec![0u8; 16]
+			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32]
 		]);
 
 		let r = executor().call::<_, NeverNativeValue, fn() -> _>(
@@ -193,9 +189,7 @@ mod tests {
 			twox_128(<balances::CreationFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<balances::TransferFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<indices::NextEnumSet<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32],
-			twox_128(<balances::TransactionBaseFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			twox_128(<balances::TransactionByteFee<Runtime>>::key()).to_vec() => vec![0u8; 16]
+			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32]
 		]);
 
 		let r = executor().call::<_, NeverNativeValue, fn() -> _>(
@@ -230,9 +224,7 @@ mod tests {
 			twox_128(<balances::CreationFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<balances::TransferFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<indices::NextEnumSet<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32],
-			twox_128(<balances::TransactionBaseFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			twox_128(<balances::TransactionByteFee<Runtime>>::key()).to_vec() => vec![0u8; 16]
+			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32]
 		]);
 
 		let r = executor().call::<_, NeverNativeValue, fn() -> _>(
@@ -273,8 +265,6 @@ mod tests {
 				ids: vec![alice(), bob(), charlie(), dave(), eve(), ferdie()],
 			}),
 			balances: Some(BalancesConfig {
-				transaction_base_fee: 1,
-				transaction_byte_fee: 0,
 				balances: vec![
 					(alice(), 111),
 					(bob(), 100),
@@ -828,9 +818,7 @@ mod tests {
 			twox_128(<balances::CreationFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<balances::TransferFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<indices::NextEnumSet<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32],
-			twox_128(<balances::TransactionBaseFee<Runtime>>::key()).to_vec() => vec![70u8; 16],
-			twox_128(<balances::TransactionByteFee<Runtime>>::key()).to_vec() => vec![0u8; 16]
+			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32]
 		]);
 
 		let r = WasmExecutor::new().call(&mut t, 8, COMPACT_CODE, "Core_initialize_block", &vec![].and(&from_block_number(1u64)));
@@ -850,9 +838,7 @@ mod tests {
 			twox_128(<balances::CreationFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<balances::TransferFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
 			twox_128(<indices::NextEnumSet<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32],
-			twox_128(<balances::TransactionBaseFee<Runtime>>::key()).to_vec() => vec![0u8; 16],
-			twox_128(<balances::TransactionByteFee<Runtime>>::key()).to_vec() => vec![0u8; 16]
+			blake2_256(&<system::BlockHash<Runtime>>::key_for(0)).to_vec() => vec![0u8; 32]
 		]);
 
 		let r = WasmExecutor::new().call(&mut t, 8, COMPACT_CODE, "Core_initialize_block", &vec![].and(&from_block_number(1u64)));

node/runtime/src/lib.rs

@@ -33,6 +33,7 @@ use client::{
 };
 use runtime_primitives::{ApplyResult, generic, create_runtime_str};
 use runtime_primitives::transaction_validity::TransactionValidity;
+use runtime_primitives::weights::{Weight, IDEAL_TRANSACTIONS_WEIGHT};
 use runtime_primitives::traits::{
 	BlakeTwo256, Block as BlockT, DigestFor, NumberFor, StaticLookup, AuthorityIdFor, Convert,
 };
@@ -86,6 +87,28 @@ impl Convert<u128, u128> for CurrencyToVoteHandler {
 	fn convert(x: u128) -> u128 { x * Self::factor() }
 }
 
+pub struct WeightToFeeHandler;
+
+impl Convert<Weight, Balance> for WeightToFeeHandler {
+	fn convert(weight: Weight) -> Balance {
+		// 40/1000000 = 4/100000 = 4/10^5 = 0.00004
+		let variability_fee = Permill::from_parts(40);
+		// 0.00004^2 = 16/10^10 ~= 2/10^9
+		let variability_fee_squared = Perbill::from_parts(2);
+		let potential_weight = <system::Module<Runtime>>::all_extrinsics_weight() + weight;
+		let high_fee: bool =  IDEAL_TRANSACTIONS_WEIGHT <= potential_weight;
+		// workaround because unsigned cannot be negative
+		let diff = if high_fee { potential_weight - IDEAL_TRANSACTIONS_WEIGHT }
+					else { IDEAL_TRANSACTIONS_WEIGHT - potential_weight};
+		let first_term = variability_fee * diff;
+		let second_term = variability_fee_squared * diff * diff / 2;
+		let fee_multiplier = if high_fee { 1 + first_term + second_term }
+								else { 1 + second_term - first_term };
+		let transaction_fee = weight * fee_multiplier;
+		transaction_fee.into()
+	}
+}
+
 impl system::Trait for Runtime {
 	type Origin = Origin;
 	type Index = Index;
@@ -113,6 +136,7 @@ impl indices::Trait for Runtime {
 
 impl balances::Trait for Runtime {
 	type Balance = Balance;
+	type WeightToFee = WeightToFeeHandler;
 	type OnFreeBalanceZero = ((Staking, Contract), Session);
 	type OnNewAccount = Indices;
 	type Event = Event;

srml/balances/src/lib.rs

@@ -156,9 +156,10 @@ use srml_support::traits::{
 };
 use srml_support::dispatch::Result;
 use primitives::traits::{
-	Zero, SimpleArithmetic, StaticLookup, Member, CheckedAdd, CheckedSub,
+	Zero, Convert, SimpleArithmetic, StaticLookup, Member, CheckedAdd, CheckedSub,
 	MaybeSerializeDebug, Saturating
 };
+use primitives::weights::Weight;
 use system::{IsDeadAccount, OnNewAccount, ensure_signed};
 
 mod mock;
@@ -171,6 +172,9 @@ pub trait Subtrait<I: Instance = DefaultInstance>: system::Trait {
 	type Balance: Parameter + Member + SimpleArithmetic + Codec + Default + Copy +
 		MaybeSerializeDebug + From<Self::BlockNumber>;
 
+	/// Handler for converting transactions weights to fees
+	type WeightToFee: Convert<Weight, Self::Balance>;
+
 	/// A function that is invoked when the free-balance has fallen below the existential deposit and
 	/// has been reduced to zero.
 	///
@@ -186,6 +190,9 @@ pub trait Trait<I: Instance = DefaultInstance>: system::Trait {
 	type Balance: Parameter + Member + SimpleArithmetic + Codec + Default + Copy +
 		MaybeSerializeDebug + From<Self::BlockNumber>;
 
+	/// Handler for converting transaction weights to fees
+	type WeightToFee: Convert<Weight, Self::Balance>;
+
 	/// A function that is invoked when the free-balance has fallen below the existential deposit and
 	/// has been reduced to zero.
 	///
@@ -211,6 +218,7 @@ pub trait Trait<I: Instance = DefaultInstance>: system::Trait {
 
 impl<T: Trait<I>, I: Instance> Subtrait<I> for T {
 	type Balance = T::Balance;
+	type WeightToFee = T::WeightToFee;
 	type OnFreeBalanceZero = T::OnFreeBalanceZero;
 	type OnNewAccount = T::OnNewAccount;
 }
@@ -273,10 +281,6 @@ decl_storage! {
 		pub TransferFee get(transfer_fee) config(): T::Balance;
 		/// The fee required to create an account.
 		pub CreationFee get(creation_fee) config(): T::Balance;
-		/// The fee to be paid for making a transaction; the base.
-		pub TransactionBaseFee get(transaction_base_fee) config(): T::Balance;
-		/// The fee to be paid for making a transaction; the per-byte portion.
-		pub TransactionByteFee get(transaction_byte_fee) config(): T::Balance;
 
 		/// Information regarding the vesting of a given account.
 		pub Vesting get(vesting) build(|config: &GenesisConfig<T, I>| {
@@ -684,6 +688,7 @@ impl<T: Subtrait<I>, I: Instance> system::Trait for ElevatedTrait<T, I> {
 }
 impl<T: Subtrait<I>, I: Instance> Trait<I> for ElevatedTrait<T, I> {
 	type Balance = T::Balance;
+	type WeightToFee = T::WeightToFee;
 	type OnFreeBalanceZero = T::OnFreeBalanceZero;
 	type OnNewAccount = T::OnNewAccount;
 	type Event = ();
@@ -1040,9 +1045,8 @@ where
 }
 
 impl<T: Trait<I>, I: Instance> MakePayment<T::AccountId> for Module<T, I> {
-	fn make_payment(transactor: &T::AccountId, encoded_len: usize) -> Result {
-		let encoded_len = T::Balance::from(encoded_len as u32);
-		let transaction_fee = Self::transaction_base_fee() + Self::transaction_byte_fee() * encoded_len;
+	fn make_payment(transactor: &T::AccountId, weight: Weight) -> Result {
+		let transaction_fee = T::WeightToFee::convert(weight);
 		let imbalance = Self::withdraw(
 			transactor,
 			transaction_fee,

srml/balances/src/mock.rs

@@ -47,6 +47,7 @@ impl system::Trait for Runtime {
 }
 impl Trait for Runtime {
 	type Balance = u64;
+	type WeightToFee = ();
 	type OnFreeBalanceZero = ();
 	type OnNewAccount = ();
 	type Event = ();
@@ -56,8 +57,6 @@ impl Trait for Runtime {
 }
 
 pub struct ExtBuilder {
-	transaction_base_fee: u64,
-	transaction_byte_fee: u64,
 	existential_deposit: u64,
 	transfer_fee: u64,
 	creation_fee: u64,
@@ -67,8 +66,6 @@ pub struct ExtBuilder {
 impl Default for ExtBuilder {
 	fn default() -> Self {
 		Self {
-			transaction_base_fee: 0,
-			transaction_byte_fee: 0,
 			existential_deposit: 0,
 			transfer_fee: 0,
 			creation_fee: 0,
@@ -91,11 +88,6 @@ impl ExtBuilder {
 		self.creation_fee = creation_fee;
 		self
 	}
-	pub fn transaction_fees(mut self, base_fee: u64, byte_fee: u64) -> Self {
-		self.transaction_base_fee = base_fee;
-		self.transaction_byte_fee = byte_fee;
-		self
-	}
 	pub fn monied(mut self, monied: bool) -> Self {
 		self.monied = monied;
 		if self.existential_deposit == 0 {
@@ -110,8 +102,6 @@ impl ExtBuilder {
 	pub fn build(self) -> runtime_io::TestExternalities<Blake2Hasher> {
 		let mut t = system::GenesisConfig::<Runtime>::default().build_storage().unwrap().0;
 		t.extend(GenesisConfig::<Runtime> {
-			transaction_base_fee: self.transaction_base_fee,
-			transaction_byte_fee: self.transaction_byte_fee,
 			balances: if self.monied {
 				vec![(1, 10 * self.existential_deposit), (2, 20 * self.existential_deposit), (3, 30 * self.existential_deposit), (4, 40 * self.existential_deposit)]
 			} else {

srml/balances/src/tests.rs

@@ -99,7 +99,7 @@ fn lock_value_extension_should_work() {
 
 #[test]
 fn lock_reasons_should_work() {
-	with_externalities(&mut ExtBuilder::default().existential_deposit(1).monied(true).transaction_fees(0, 1).build(), || {
+	with_externalities(&mut ExtBuilder::default().existential_deposit(1).monied(true).build(), || {
 		Balances::set_lock(ID_1, &1, 10, u64::max_value(), WithdrawReason::Transfer.into());
 		assert_noop!(<Balances as Currency<_>>::transfer(&1, &2, 1), "account liquidity restrictions prevent withdrawal");
 		assert_ok!(<Balances as ReservableCurrency<_>>::reserve(&1, 1));

srml/contract/src/tests.rs

@@ -81,6 +81,7 @@ impl system::Trait for Test {
 }
 impl balances::Trait for Test {
 	type Balance = u64;
+	type WeightToFee = ();
 	type OnFreeBalanceZero = Contract;
 	type OnNewAccount = ();
 	type Event = MetaEvent;
@@ -197,8 +198,6 @@ impl ExtBuilder {
 			.0;
 		t.extend(
 			balances::GenesisConfig::<Test> {
-				transaction_base_fee: 0,
-				transaction_byte_fee: 0,
 				balances: vec![],
 				existential_deposit: self.existential_deposit,
 				transfer_fee: self.transfer_fee,

srml/council/src/lib.rs

@@ -82,6 +82,7 @@ mod tests {
 	}
 	impl balances::Trait for Test {
 		type Balance = u64;
+		type WeightToFee = ();
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
 		type Event = Event;
@@ -176,8 +177,6 @@ mod tests {
 		pub fn build(self) -> runtime_io::TestExternalities<Blake2Hasher> {
 			let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
 			t.extend(balances::GenesisConfig::<Test>{
-				transaction_base_fee: 0,
-				transaction_byte_fee: 0,
 				balances: vec![
 					(1, 10 * self.balance_factor),
 					(2, 20 * self.balance_factor),

srml/democracy/src/lib.rs

@@ -957,6 +957,7 @@ mod tests {
 	}
 	impl balances::Trait for Test {
 		type Balance = u64;
+		type WeightToFee = ();
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
 		type Event = ();
@@ -1003,8 +1004,6 @@ mod tests {
 	fn new_test_ext() -> runtime_io::TestExternalities<Blake2Hasher> {
 		let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
 		t.extend(balances::GenesisConfig::<Test>{
-			transaction_base_fee: 0,
-			transaction_byte_fee: 0,
 			balances: vec![(1, 10), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)],
 			existential_deposit: 0,
 			transfer_fee: 0,

srml/example/src/lib.rs

@@ -532,6 +532,7 @@ mod tests {
 	}
 	impl balances::Trait for Test {
 		type Balance = u64;
+		type WeightToFee = ();
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
 		type Event = ();