fix!: remove denom from DenomMetadata key (#9890)

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## Description

Closes: #9643 

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---

### Author Checklist

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please add links to any relevant follow up issues.*

I have...

- [x] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [x] added `!` to the type prefix if API or client breaking change
- [x] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [x] provided a link to the relevant issue or specification
- [x] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [x] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [x] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [x] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

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your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

CHANGELOG.md

@@ -96,6 +96,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (x/bank) [\#9611](https://github.com/cosmos/cosmos-sdk/pull/9611) Introduce a new index to act as a reverse index between a denomination and address allowing to query for
   token holders of a specific denomination. `DenomOwners` is updated to use the new reverse index.
 * (x/bank) [\#9832] (https://github.com/cosmos/cosmos-sdk/pull/9832) Account balance is stored as `sdk.Int` rather than `sdk.Coin`.
+* (x/bank) [\#9890] (https://github.com/cosmos/cosmos-sdk/pull/9890) Remove duplicate denom from denom metadata key.
 
 ## [v0.43.0](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.43.0) - 2021-08-10
 

x/bank/keeper/keeper.go

@@ -218,7 +218,7 @@ func (k BaseKeeper) GetSupply(ctx sdk.Context, denom string) sdk.Coin {
 // false otherwise.
 func (k BaseKeeper) GetDenomMetaData(ctx sdk.Context, denom string) (types.Metadata, bool) {
 	store := ctx.KVStore(k.storeKey)
-	store = prefix.NewStore(store, types.DenomMetadataKey(denom))
+	store = prefix.NewStore(store, types.DenomMetadataPrefix)
 
 	bz := store.Get([]byte(denom))
 	if bz == nil {
@@ -265,7 +265,7 @@ func (k BaseKeeper) IterateAllDenomMetaData(ctx sdk.Context, cb func(types.Metad
 // SetDenomMetaData sets the denominations metadata
 func (k BaseKeeper) SetDenomMetaData(ctx sdk.Context, denomMetaData types.Metadata) {
 	store := ctx.KVStore(k.storeKey)
-	denomMetaDataStore := prefix.NewStore(store, types.DenomMetadataKey(denomMetaData.Base))
+	denomMetaDataStore := prefix.NewStore(store, types.DenomMetadataPrefix)
 
 	m := k.cdc.MustMarshal(&denomMetaData)
 	denomMetaDataStore.Set([]byte(denomMetaData.Base), m)

x/bank/migrations/v043/keys.go

@@ -12,8 +12,9 @@ const (
 )
 
 var (
-	SupplyKey      = []byte{0x00}
-	BalancesPrefix = []byte{0x02}
+	SupplyKey           = []byte{0x00}
+	BalancesPrefix      = []byte{0x02}
+	DenomMetadataPrefix = []byte{0x1}
 
 	ErrInvalidKey = errors.New("invalid key")
 )
@@ -36,3 +37,9 @@ func AddressFromBalancesStore(key []byte) (sdk.AccAddress, error) {
 
 	return key[1 : bound+1], nil
 }
+
+// DenomMetadataKey returns the denomination metadata key.
+func DenomMetadataKey(denom string) []byte {
+	d := []byte(denom)
+	return append(DenomMetadataPrefix, d...)
+}

x/bank/migrations/v044/store.go

@@ -14,9 +14,15 @@ import (
 //
 // - Migrate coin storage to save only amount.
 // - Add an additional reverse index from denomination to address.
+// - Remove duplicate denom from denom metadata store key.
 func MigrateStore(ctx sdk.Context, storeKey sdk.StoreKey, cdc codec.BinaryCodec) error {
 	store := ctx.KVStore(storeKey)
-	return addDenomReverseIndex(store, cdc)
+	err := addDenomReverseIndex(store, cdc)
+	if err != nil {
+		return err
+	}
+
+	return migrateDenomMetadata(store)
 }
 
 func addDenomReverseIndex(store sdk.KVStore, cdc codec.BinaryCodec) error {
@@ -64,3 +70,21 @@ func addDenomReverseIndex(store sdk.KVStore, cdc codec.BinaryCodec) error {
 
 	return nil
 }
+
+func migrateDenomMetadata(store sdk.KVStore) error {
+	oldDenomMetaDataStore := prefix.NewStore(store, v043.DenomMetadataPrefix)
+
+	oldDenomMetaDataIter := oldDenomMetaDataStore.Iterator(nil, nil)
+	defer oldDenomMetaDataIter.Close()
+
+	for ; oldDenomMetaDataIter.Valid(); oldDenomMetaDataIter.Next() {
+		oldKey := oldDenomMetaDataIter.Key()
+		// old key: prefix_bytes | denom_bytes | denom_bytes
+		newKey := append(types.DenomMetadataPrefix, oldKey[:len(oldKey)/2+1]...)
+
+		store.Set(newKey, oldDenomMetaDataIter.Value())
+		oldDenomMetaDataStore.Delete(oldDenomMetaDataIter.Key())
+	}
+
+	return nil
+}

x/bank/migrations/v044/store_test.go

@@ -52,3 +52,77 @@ func TestMigrateStore(t *testing.T) {
 		require.NotNil(t, bz)
 	}
 }
+
+func TestMigrateDenomMetaData(t *testing.T) {
+	encCfg := simapp.MakeTestEncodingConfig()
+	bankKey := sdk.NewKVStoreKey("bank")
+	ctx := testutil.DefaultContext(bankKey, sdk.NewTransientStoreKey("transient_test"))
+	store := ctx.KVStore(bankKey)
+	metaData := []types.Metadata{
+		{
+			Name:        "Cosmos Hub Atom",
+			Symbol:      "ATOM",
+			Description: "The native staking token of the Cosmos Hub.",
+			DenomUnits: []*types.DenomUnit{
+				{"uatom", uint32(0), []string{"microatom"}},
+				{"matom", uint32(3), []string{"milliatom"}},
+				{"atom", uint32(6), nil},
+			},
+			Base:    "uatom",
+			Display: "atom",
+		},
+		{
+			Name:        "Token",
+			Symbol:      "TOKEN",
+			Description: "The native staking token of the Token Hub.",
+			DenomUnits: []*types.DenomUnit{
+				{"1token", uint32(5), []string{"decitoken"}},
+				{"2token", uint32(4), []string{"centitoken"}},
+				{"3token", uint32(7), []string{"dekatoken"}},
+			},
+			Base:    "utoken",
+			Display: "token",
+		},
+	}
+	denomMetadataStore := prefix.NewStore(store, v043.DenomMetadataPrefix)
+
+	for i := range []int{0, 1} {
+		key := append(v043.DenomMetadataPrefix, []byte(metaData[i].Base)...)
+		key = append(key, []byte(metaData[i].Base)...)
+		bz, err := encCfg.Codec.Marshal(&metaData[i])
+		require.NoError(t, err)
+		denomMetadataStore.Set(key, bz)
+	}
+
+	require.NoError(t, v044.MigrateStore(ctx, bankKey, encCfg.Codec))
+
+	denomMetadataStore = prefix.NewStore(store, v043.DenomMetadataPrefix)
+	denomMetadataIter := denomMetadataStore.Iterator(nil, nil)
+	defer denomMetadataIter.Close()
+	for i := 0; denomMetadataIter.Valid(); denomMetadataIter.Next() {
+		var result types.Metadata
+		newKey := denomMetadataIter.Key()
+
+		// make sure old entry is deleted
+		oldKey := append(newKey, newKey[1:]...)
+		bz := denomMetadataStore.Get(oldKey)
+		require.Nil(t, bz)
+
+		require.Equal(t, string(newKey)[1:], metaData[i].Base)
+		bz = denomMetadataStore.Get(denomMetadataIter.Key())
+		require.NotNil(t, bz)
+		err := encCfg.Codec.Unmarshal(bz, &result)
+		require.NoError(t, err)
+		assertMetaDataEqual(t, metaData[i], result)
+		i++
+	}
+}
+
+func assertMetaDataEqual(t *testing.T, expected, actual types.Metadata) {
+	require.Equal(t, expected.GetBase(), actual.GetBase())
+	require.Equal(t, expected.GetDisplay(), actual.GetDisplay())
+	require.Equal(t, expected.GetDescription(), actual.GetDescription())
+	require.Equal(t, expected.GetDenomUnits()[1].GetDenom(), actual.GetDenomUnits()[1].GetDenom())
+	require.Equal(t, expected.GetDenomUnits()[1].GetExponent(), actual.GetDenomUnits()[1].GetExponent())
+	require.Equal(t, expected.GetDenomUnits()[1].GetAliases(), actual.GetDenomUnits()[1].GetAliases())
+}

x/bank/types/key.go

@@ -31,12 +31,6 @@ var (
 	BalancesPrefix = []byte{0x02}
 )
 
-// DenomMetadataKey returns the denomination metadata key.
-func DenomMetadataKey(denom string) []byte {
-	d := []byte(denom)
-	return append(DenomMetadataPrefix, d...)
-}
-
 // AddressAndDenomFromBalancesStore returns an account address and denom from a balances prefix
 // store. The key must not contain the prefix BalancesPrefix as the prefix store
 // iterator discards the actual prefix.