x/slashing/keeper: SlashRedelegation should hoist non-changing ValidatorAddress and DelegatorAddress parsing out of hot loop

[odeke-em]

Is there an existing issue for this?

• I have searched the existing issues

What happened?

I was auditing and testing out code in x/slashing/keeper over the weekend and I noticed this code in a loop

cosmos-sdk/x/staking/keeper/slash.go

Lines 310 to 321 in 599b58d

	continue
	}
	valDstAddr, err := k.validatorAddressCodec.StringToBytes(redelegation.ValidatorDstAddress)
	if err != nil {
	panic(err)
	}
	delegatorAddress, err := k.authKeeper.AddressCodec().StringToBytes(redelegation.DelegatorAddress)
	if err != nil {
	panic(err)
	}

and it doesn't change much so no need to keep it in that loop while redelegating

This fixes it by hoisting that code out

diff --git a/x/staking/keeper/slash.go b/x/staking/keeper/slash.go
index 5a0886141f..e61cbb5181 100644
--- a/x/staking/keeper/slash.go
+++ b/x/staking/keeper/slash.go
math.LegacyNewDecFromInt(tokensToBurn).QuoRoundUp(math.LegacyNewDecFromInt(validator.Tokens))
@@ -287,6 +299,16 @@ func (k Keeper) SlashRedelegation(ctx context.Context, srcValidator types.Valida
 	totalSlashAmount = math.ZeroInt()
 	bondedBurnedAmount, notBondedBurnedAmount := math.ZeroInt(), math.ZeroInt()
 
+	valDstAddr, err := k.validatorAddressCodec.StringToBytes(redelegation.ValidatorDstAddress)
+	if err != nil {
+		return math.ZeroInt(), fmt.Errorf("SlashRedelegation: could not parse validator destination address: %w", err)
+	}
+
+	delegatorAddress, err := k.authKeeper.AddressCodec().StringToBytes(redelegation.DelegatorAddress)
+	if err != nil {
+		return math.ZeroInt(), fmt.Errorf("SlashRedelegation: could not parse delegator address: %w", err)
+	}
+
 	// perform slashing on all entries within the redelegation
 	for _, entry := range redelegation.Entries {
 		// If redelegation started before this height, stake didn't contribute to infraction
@@ -310,16 +332,7 @@ func (k Keeper) SlashRedelegation(ctx context.Context, srcValidator types.Valida
 			continue
 		}
 
-		valDstAddr, err := k.validatorAddressCodec.StringToBytes(redelegation.ValidatorDstAddress)
-		if err != nil {
-			panic(err)
-		}
-
-		delegatorAddress, err := k.authKeeper.AddressCodec().StringToBytes(redelegation.DelegatorAddress)
-		if err != nil {
-			panic(err)
-		}
-
+		// Delegations can be dynamic hence need to be looked up on every redelegation entry loop.
 		delegation, err := k.Delegations.Get(ctx, collections.Join(sdk.AccAddress(delegatorAddress), sdk.ValAddress(valDstAddr)))
 		if err != nil {
 			// If deleted, delegation has zero shares, and we can't unbond any more

/cc @elias-orijtech

Cosmos SDK Version

main

How to reproduce?

Auditing the code