simplify 'gasUsed' and 'refundGas'

nimbus/p2p/executor.nim

@@ -13,21 +13,22 @@ proc processTransaction*(tx: Transaction, sender: EthAddress, vmState: BaseVMSta
   trace "Sender", sender
   trace "txHash", rlpHash = tx.rlpHash
 
-  var gasUsed = 0.GasInt
   if validateTransaction(vmState, tx, sender, fork):
-    gasUsed = tx.gasLimit
     var c = setupComputation(vmState, tx, sender, fork)
     vmState.mutateStateDB:
       db.subBalance(sender, tx.gasLimit.u256 * tx.gasPrice.u256)
     execComputation(c)
-    if not c.shouldBurnGas:
-      gasUsed = c.refundGas(tx, sender)
 
-  vmState.cumulativeGasUsed += gasUsed
+    result = tx.gasLimit
+    if not c.shouldBurnGas:
+      c.refundGas(tx, sender)
+      result -= c.gasMeter.gasRemaining
+
+  vmState.cumulativeGasUsed += result
 
   vmState.mutateStateDB:
     # miner fee
-    let txFee = gasUsed.u256 * tx.gasPrice.u256
+    let txFee = result.u256 * tx.gasPrice.u256
     db.addBalance(vmState.blockHeader.coinbase, txFee)
 
     for deletedAccount in vmState.suicides:
@@ -42,7 +43,6 @@ proc processTransaction*(tx: Transaction, sender: EthAddress, vmState: BaseVMSta
           db.deleteAccount(account)
 
   vmState.accountDb.updateOriginalRoot()
-  result = gasUsed
 
 type
   # TODO: these types need to be removed

nimbus/vm_state_transactions.nim

@@ -84,17 +84,11 @@ proc execComputation*(c: Computation) =
 
   c.vmstate.status = c.isSuccess
 
-proc refundGas*(c: Computation, tx: Transaction, sender: EthAddress): GasInt =
-  let
-    gasRemaining = c.gasMeter.gasRemaining
-    gasRefunded = c.getGasRefund()
-    gasUsed = tx.gasLimit - gasRemaining
-    gasRefund = min(gasRefunded, gasUsed div 2)
-
+proc refundGas*(c: Computation, tx: Transaction, sender: EthAddress) =
+  let maxRefund = (tx.gasLimit - c.gasMeter.gasRemaining) div 2
+  c.gasMeter.returnGas min(c.getGasRefund(), maxRefund)
   c.vmState.mutateStateDB:
-    db.addBalance(sender, (gasRemaining + gasRefund).u256 * tx.gasPrice.u256)
-
-  result = gasUsed - gasRefund
+    db.addBalance(sender, c.gasMeter.gasRemaining.u256 * tx.gasPrice.u256)
 
 #[
 method executeTransaction(vmState: BaseVMState, transaction: Transaction): (Computation, BlockHeader) {.base.}=