Merge pull request #894 from iotaledger/fix/increase_rew_precision

use Safe64MulDiv for increased precision

Author: muXxer

pkg/protocol/sybilprotection/sybilprotectionv1/performance/rewards.go

@@ -185,14 +185,9 @@ func (t *Tracker) DelegatorReward(validatorID iotago.AccountID, delegatedAmount
 			return 0, 0, 0, ierrors.Wrapf(err, "failed to multiply profitMarginComplement and poolReward for unDecayedEpochRewards due to overflow for epoch %d and validator accountID %s", epoch, validatorID)
 		}
 
-		result, err = safemath.SafeDiv(result>>profitMarginExponent, uint64(rewardsForAccountInEpoch.PoolStake))
+		undecayedEpochRewards, err := safemath.Safe64MulDiv(result>>profitMarginExponent, uint64(delegatedAmount), uint64(rewardsForAccountInEpoch.PoolStake))
 		if err != nil {
-			return 0, 0, 0, ierrors.Wrapf(err, "failed to divide by PoolStake for unDecayedEpochRewards due to overflow for epoch %d and validator accountID %s", epoch, validatorID)
-		}
-
-		undecayedEpochRewards, err := safemath.SafeMul(result, uint64(delegatedAmount))
-		if err != nil {
-			return 0, 0, 0, ierrors.Wrapf(err, "failed to multiply by delegatedAmmount for unDecayedEpochRewards due to overflow for epoch %d and validator accountID %s", epoch, validatorID)
+			return 0, 0, 0, ierrors.Wrapf(err, "failed to calculate unDecayedEpochRewards due to overflow for epoch %d and validator accountID %s", epoch, validatorID)
 		}
 
 		decayProvider := t.apiProvider.APIForEpoch(epoch).ManaDecayProvider()

pkg/protocol/sybilprotection/sybilprotectionv1/performance/testsuite_test.go

@@ -7,6 +7,8 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	"github.com/iotaledger/hive.go/core/safemath"
+
 	"github.com/iotaledger/hive.go/kvstore"
 	"github.com/iotaledger/hive.go/kvstore/mapdb"
 	"github.com/iotaledger/hive.go/lo"
@@ -272,7 +274,10 @@ func (t *TestSuite) delegatorReward(epoch iotago.EpochIndex, profitMargin, poolR
 	if poolRewardWithFixedCost >= fixedCost {
 		poolRewards = poolRewardWithFixedCost - fixedCost
 	}
-	unDecayedEpochRewards := (((profitMarginComplement * poolRewards) >> profitMarginExponent) / poolStake) * delegatedAmount
+
+	result := (profitMarginComplement * poolRewards) >> profitMarginExponent
+	unDecayedEpochRewards, err := safemath.Safe64MulDiv(result, delegatedAmount, poolStake)
+	require.NoError(t.T, err)
 
 	decayProvider := t.api.ManaDecayProvider()
 	decayedEpochRewards, err := decayProvider.DecayManaByEpochs(iotago.Mana(unDecayedEpochRewards), epoch, epoch)