Uncouple emptying gas_meter from updating the gas spent for the block

frame/contracts/src/gas.rs

@@ -209,6 +209,18 @@ pub trait GasHandler<T: Trait> {
 		buy_gas::<T>(transactor, gas_limit)
 	}
 
+	/// This function should be called when the contract has stopped consuming gas and the gas_meter
+	/// is ready to be read. This will update the gas spent for the block and then empties the
+	/// unused gas.
+	fn update(transactor: &T::AccountId, gas_meter: GasMeter<T>) {
+		// Increase total spent gas.
+		// This cannot overflow, since `gas_spent` is never greater than `block_gas_limit`, which
+		// also has Gas type.
+		GasSpent::mutate(|block_gas_spent| *block_gas_spent += gas_meter.spent());
+
+		Self::empty_unused_gas(transactor, gas_meter);
+	}
+
 	/// This function empties the remaining gas in the gas meter
 	/// Default behaviour will deposit currency into the user's balance to refund un-used gas
 	fn empty_unused_gas(
@@ -257,14 +269,8 @@ pub fn refund_unused_gas<T: Trait>(
 	transactor: &T::AccountId,
 	gas_meter: GasMeter<T>,
 ) {
-	let gas_spent = gas_meter.spent();
 	let gas_left = gas_meter.gas_left();
 
-	// Increase total spent gas.
-	// This cannot overflow, since `gas_spent` is never greater than `block_gas_limit`, which
-	// also has Gas type.
-	GasSpent::mutate(|block_gas_spent| *block_gas_spent += gas_spent);
-
 	// Refund gas left by the price it was bought at.
 	let refund = gas_meter.gas_price * gas_left.unique_saturated_into();
 	let _imbalance = T::Currency::deposit_creating(transactor, refund);

frame/contracts/src/gas_tests.rs

@@ -302,7 +302,7 @@ fn user_is_charged_on_empty_unused_gas() {
 
             // Spend half the gas, then empty the gas meter, the user should be charged here
             gas_meter.charge(&(), SimpleToken(gas_used));
-            TestGasHandler::empty_unused_gas(&ALICE, gas_meter);
+            TestGasHandler::update(&ALICE, gas_meter);
 
             assert_eq!(Balances::free_balance(&ALICE), expected_remaining_balance);
         });
@@ -327,7 +327,7 @@ fn user_is_charged_if_out_of_gas() {
 
             // Spend more gas than the `gas_limit`, then empty the gas meter, the user should be charged here
             gas_meter.charge(&(), SimpleToken(gas_limit + 1));
-            TestGasHandler::empty_unused_gas(&ALICE, gas_meter);
+            TestGasHandler::update(&ALICE, gas_meter);
 
             assert_eq!(Balances::free_balance(&ALICE), expected_remaining_balance);
         });

frame/contracts/src/lib.rs

@@ -588,7 +588,7 @@ decl_module! {
 			if let Ok(code_hash) = result {
 				Self::deposit_event(RawEvent::CodeStored(code_hash));
 			}
-			T::GasHandler::empty_unused_gas(&origin, gas_meter);
+			T::GasHandler::update(&origin, gas_meter);
 
 			result.map(|_| ()).map_err(Into::into)
 		}
@@ -756,7 +756,7 @@ impl<T: Trait> Module<T> {
 		//
 		// NOTE: This should go after the commit to the storage, since the storage changes
 		// can alter the balance of the caller.
-		T::GasHandler::empty_unused_gas(&origin, gas_meter);
+		T::GasHandler::update(&origin, gas_meter);
 
 		// Execute deferred actions.
 		ctx.deferred.into_iter().for_each(|deferred| {