Store supply as Int bytes rather than string bytes

CHANGELOG.md

@@ -89,6 +89,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (x/bank) [\#8656](https://github.com/cosmos/cosmos-sdk/pull/8656) balance and supply are now correctly tracked via `coin_spent`, `coin_received`, `coinbase` and `burn` events.
 * (x/bank) [\#8517](https://github.com/cosmos/cosmos-sdk/pull/8517) Supply is now stored and tracked as `sdk.Coins`
 * (store) [\#8790](https://github.com/cosmos/cosmos-sdk/pull/8790) Reduce gas costs by 10x for transient store operations.
+* (x/bank) [\#9051](https://github.com/cosmos/cosmos-sdk/pull/9051) Supply value is stored as `sdk.Int` rather than `string`.
 
 ### Improvements
 

x/bank/keeper/keeper.go

@@ -1,6 +1,8 @@
 package keeper
 
 import (
+	"fmt"
+
 	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/store/prefix"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -184,9 +186,10 @@ func (k BaseKeeper) GetSupply(ctx sdk.Context, denom string) sdk.Coin {
 		}
 	}
 
-	amount, ok := sdk.NewIntFromString(string(bz))
-	if !ok {
-		panic("unexpected supply")
+	var amount sdk.Int
+	err := amount.Unmarshal(bz)
+	if err != nil {
+		panic(fmt.Errorf("unable to unmarshal supply value %v", err))
 	}
 
 	return sdk.Coin{
@@ -413,7 +416,11 @@ func (k BaseKeeper) setSupply(ctx sdk.Context, coin sdk.Coin) {
 	store := ctx.KVStore(k.storeKey)
 	supplyStore := prefix.NewStore(store, types.SupplyKey)
 
-	supplyStore.Set([]byte(coin.GetDenom()), []byte(coin.Amount.String()))
+	intBytes, err := coin.Amount.Marshal()
+	if err != nil {
+		panic(fmt.Errorf("unable to marshal amount value %v", err))
+	}
+	supplyStore.Set([]byte(coin.GetDenom()), intBytes)
 }
 
 func (k BaseKeeper) trackDelegation(ctx sdk.Context, addr sdk.AccAddress, balance, amt sdk.Coins) error {
@@ -454,9 +461,10 @@ func (k BaseViewKeeper) IterateTotalSupply(ctx sdk.Context, cb func(sdk.Coin) bo
 	defer iterator.Close()
 
 	for ; iterator.Valid(); iterator.Next() {
-		amount, ok := sdk.NewIntFromString(string(iterator.Value()))
-		if !ok {
-			panic("unexpected supply")
+		var amount sdk.Int
+		err := amount.Unmarshal(iterator.Value())
+		if err != nil {
+			panic(fmt.Errorf("unable to unmarshal supply value %v", err))
 		}
 
 		balance := sdk.Coin{

x/bank/legacy/v043/store.go

@@ -35,7 +35,7 @@ func migrateSupply(store sdk.KVStore, cdc codec.BinaryMarshaler) error {
 	oldSupply := oldSupplyI.(*types.Supply)
 	for i := range oldSupply.Total {
 		coin := oldSupply.Total[i]
-		coinBz, err := cdc.MarshalBinaryBare(&coin)
+		coinBz, err := coin.Amount.Marshal()
 		if err != nil {
 			return err
 		}

x/bank/legacy/v043/store_test.go

@@ -36,12 +36,26 @@ func TestSupplyMigration(t *testing.T) {
 	require.NoError(t, err)
 
 	// New supply is indexed by denom.
-	var newFooCoin, newBarCoin sdk.Coin
 	supplyStore := prefix.NewStore(store, types.SupplyKey)
-	encCfg.Marshaler.MustUnmarshalBinaryBare(supplyStore.Get([]byte("foo")), &newFooCoin)
-	encCfg.Marshaler.MustUnmarshalBinaryBare(supplyStore.Get([]byte("bar")), &newBarCoin)
+	bz := supplyStore.Get([]byte("foo"))
+	var amount sdk.Int
+	err = amount.Unmarshal(bz)
+	require.NoError(t, err)
 
+	newFooCoin := sdk.Coin{
+		Denom:  "foo",
+		Amount: amount,
+	}
 	require.Equal(t, oldFooCoin, newFooCoin)
+
+	bz = supplyStore.Get([]byte("bar"))
+	err = amount.Unmarshal(bz)
+	require.NoError(t, err)
+
+	newBarCoin := sdk.Coin{
+		Denom:  "bar",
+		Amount: amount,
+	}
 	require.Equal(t, oldBarCoin, newBarCoin)
 }
 

x/bank/spec/01_state.md

@@ -7,6 +7,6 @@ order: 1
 The `x/bank` module keeps state of three primary objects, account balances, denom metadata and the
 total supply of all balances.
 
-- Supply: `0x0 | byte(denom) -> ProtocolBuffer(coin)`
+- Supply: `0x0 | byte(denom) -> byte(amount)`
 - Denom Metadata: `0x1 | byte(denom) -> ProtocolBuffer(Metadata)`
 - Balances: `0x2 | byte(address length) | []byte(address) | []byte(balance.Denom) -> ProtocolBuffer(balance)`