impl Mul + saturating_mul by converting in u64 (#1610)

substrate/core/sr-primitives/src/lib.rs

@@ -123,14 +123,7 @@ impl BuildStorage for StorageMap {
 #[derive(Encode, Decode, Default, Copy, Clone, PartialEq, Eq)]
 pub struct Permill(u32);
 
-// TODO: impl Mul<Permill> for N where N: As<usize>
 impl Permill {
-	/// Multiplication.
-	pub fn times<N: traits::As<u64> + ::rstd::ops::Mul<N, Output=N> + ::rstd::ops::Div<N, Output=N>>(self, b: N) -> N {
-		// TODO: handle overflows
-		b * <N as traits::As<u64>>::sa(self.0 as u64) / <N as traits::As<u64>>::sa(1000000)
-	}
-
 	/// Wraps the argument into `Permill` type.
 	pub fn from_millionths(x: u32) -> Permill { Permill(x) }
 
@@ -142,6 +135,16 @@ impl Permill {
 	pub fn from_fraction(x: f64) -> Permill { Permill((x * 1_000_000.0) as u32) }
 }
 
+impl<N> ::rstd::ops::Mul<N> for Permill
+where
+	N: traits::As<u64>
+{
+	type Output = N;
+	fn mul(self, b: N) -> Self::Output {
+		<N as traits::As<u64>>::sa(b.as_().saturating_mul(self.0 as u64) / 1_000_000)
+	}
+}
+
 #[cfg(feature = "std")]
 impl From<f64> for Permill {
 	fn from(x: f64) -> Permill {
@@ -178,14 +181,7 @@ impl From<codec::Compact<Permill>> for Permill {
 #[derive(Encode, Decode, Default, Copy, Clone, PartialEq, Eq)]
 pub struct Perbill(u32);
 
-// TODO: impl Mul<Perbill> for N where N: As<usize>
 impl Perbill {
-	/// Attenuate `b` by self.
-	pub fn times<N: traits::As<u64> + ::rstd::ops::Mul<N, Output=N> + ::rstd::ops::Div<N, Output=N>>(self, b: N) -> N {
-		// TODO: handle overflows
-		b * <N as traits::As<u64>>::sa(self.0 as u64) / <N as traits::As<u64>>::sa(1_000_000_000)
-	}
-
 	/// Nothing.
 	pub fn zero() -> Perbill { Perbill(0) }
 
@@ -213,6 +209,16 @@ impl Perbill {
 	pub fn from_rational(n: f64, d: f64) -> Perbill { Perbill(((n / d).max(0.0).min(1.0) * 1_000_000_000.0) as u32) }
 }
 
+impl<N> ::rstd::ops::Mul<N> for Perbill
+where
+	N: traits::As<u64>
+{
+	type Output = N;
+	fn mul(self, b: N) -> Self::Output {
+		<N as traits::As<u64>>::sa(b.as_().saturating_mul(self.0 as u64) / 1_000_000_000)
+	}
+}
+
 #[cfg(feature = "std")]
 impl From<f64> for Perbill {
 	fn from(x: f64) -> Perbill {
@@ -659,4 +665,10 @@ mod tests {
 		let encoded = data.encode();
 		assert_eq!(data, WithCompact::<super::Perbill>::decode(&mut &encoded[..]).unwrap());
 	}
+
+	#[test]
+	fn saturating_mul() {
+		assert_eq!(super::Perbill::one() * std::u64::MAX, std::u64::MAX/1_000_000_000);
+		assert_eq!(super::Permill::from_percent(100) * std::u64::MAX, std::u64::MAX/1_000_000);
+	}
 }

substrate/srml/staking/src/lib.rs

@@ -494,8 +494,8 @@ impl<T: Trait> Module<T> {
 		<session::Module<T>>::set_validators(vals);
 
 		// Update the balances for slashing/rewarding according to the stakes.
-		<CurrentOfflineSlash<T>>::put(Self::offline_slash().times(stake_range.1));
-		<CurrentSessionReward<T>>::put(Self::session_reward().times(stake_range.1));
+		<CurrentOfflineSlash<T>>::put(Self::offline_slash() * stake_range.1);
+		<CurrentSessionReward<T>>::put(Self::session_reward() * stake_range.1);
 	}
 
 	/// Call when a validator is determined to be offline. `count` is the

substrate/srml/treasury/src/lib.rs

@@ -201,7 +201,7 @@ impl<T: Trait> Module<T> {
 
 	/// The needed bond for a proposal whose spend is `value`.
 	fn calculate_bond(value: T::Balance) -> T::Balance {
-		Self::proposal_bond_minimum().max(Self::proposal_bond().times(value))
+		Self::proposal_bond_minimum().max(Self::proposal_bond() * value)
 	}
 
 	// Spend some money!
@@ -238,7 +238,7 @@ impl<T: Trait> Module<T> {
 
 		if !missed_any {
 			// burn some proportion of the remaining budget if we run a surplus.
-			let burn = Self::burn().times(budget_remaining).min(budget_remaining);
+			let burn = (Self::burn() * budget_remaining).min(budget_remaining);
 			budget_remaining -= burn;
 			Self::deposit_event(RawEvent::Burnt(burn))
 		}