perf: x/bank create reverse prefix for denom<->address

x/bank/keeper/grpc_query.go

@@ -179,24 +179,13 @@ func (k BaseKeeper) DenomOwners(
 	}
 
 	ctx := sdk.UnwrapSDKContext(goCtx)
-
-	store := ctx.KVStore(k.storeKey)
-	balancesStore := prefix.NewStore(store, types.BalancesPrefix)
+	denomPrefixStore := k.getDenomPrefixStore(ctx, req.Denom)
 
 	var denomOwners []*types.DenomOwner
 	pageRes, err := query.FilteredPaginate(
-		balancesStore,
+		denomPrefixStore,
 		req.Pagination,
 		func(key []byte, value []byte, accumulate bool) (bool, error) {
-			var balance sdk.Coin
-			if err := k.cdc.Unmarshal(value, &balance); err != nil {
-				return false, err
-			}
-
-			if req.Denom != balance.Denom {
-				return false, nil
-			}
-
 			if accumulate {
 				address, err := types.AddressFromBalancesStore(key)
 				if err != nil {
@@ -207,7 +196,7 @@ func (k BaseKeeper) DenomOwners(
 					denomOwners,
 					&types.DenomOwner{
 						Address: address.String(),
-						Balance: balance,
+						Balance: k.GetBalance(ctx, address, req.Denom),
 					},
 				)
 			}

x/bank/keeper/send.go

@@ -4,6 +4,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/telemetry"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/types/address"
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 	"github.com/cosmos/cosmos-sdk/x/bank/types"
 	paramtypes "github.com/cosmos/cosmos-sdk/x/params/types"
@@ -254,13 +255,19 @@ func (k BaseSendKeeper) setBalance(ctx sdk.Context, addr sdk.AccAddress, balance
 	}
 
 	accountStore := k.getAccountStore(ctx, addr)
+	denomPrefixStore := k.getDenomPrefixStore(ctx, balance.Denom)
 
-	// Bank invariants require to not store zero balances.
+	// x/bank invariants prohibit persistence of zero balances
 	if balance.IsZero() {
 		accountStore.Delete([]byte(balance.Denom))
+		denomPrefixStore.Delete(address.MustLengthPrefix(addr))
 	} else {
 		bz := k.cdc.MustMarshal(&balance)
 		accountStore.Set([]byte(balance.Denom), bz)
+
+		// Store a reverse index from denomination to account address with a
+		// sentinel value.
+		denomPrefixStore.Set(address.MustLengthPrefix(addr), []byte{0})
 	}
 
 	return nil

x/bank/keeper/view.go

@@ -228,6 +228,11 @@ func (k BaseViewKeeper) ValidateBalance(ctx sdk.Context, addr sdk.AccAddress) er
 // getAccountStore gets the account store of the given address.
 func (k BaseViewKeeper) getAccountStore(ctx sdk.Context, addr sdk.AccAddress) prefix.Store {
 	store := ctx.KVStore(k.storeKey)
-
 	return prefix.NewStore(store, types.CreateAccountBalancesPrefix(addr))
 }
+
+// getDenomPrefixStore returns a prefix store that acts as a reverse index
+// between a denomination and account balance for that denomination.
+func (k BaseViewKeeper) getDenomPrefixStore(ctx sdk.Context, denom string) prefix.Store {
+	return prefix.NewStore(ctx.KVStore(k.storeKey), types.CreateDenomPrefix(denom))
+}

x/bank/types/key.go

@@ -23,6 +23,7 @@ const (
 var (
 	// BalancesPrefix is the prefix for the account balances store. We use a byte
 	// (instead of `[]byte("balances")` to save some disk space).
+	DenomPrefix         = []byte{0x03}
 	BalancesPrefix      = []byte{0x02}
 	SupplyKey           = []byte{0x00}
 	DenomMetadataPrefix = []byte{0x1}
@@ -43,15 +44,24 @@ func AddressFromBalancesStore(key []byte) (sdk.AccAddress, error) {
 	if len(key) == 0 {
 		return nil, ErrInvalidKey
 	}
+
 	addrLen := key[0]
 	bound := int(addrLen)
+
 	if len(key)-1 < bound {
 		return nil, ErrInvalidKey
 	}
+
 	return key[1 : bound+1], nil
 }
 
 // CreateAccountBalancesPrefix creates the prefix for an account's balances.
 func CreateAccountBalancesPrefix(addr []byte) []byte {
 	return append(BalancesPrefix, address.MustLengthPrefix(addr)...)
 }
+
+// CreateDenomPrefix creates a prefix for a reverse index of denomination to
+// account balance for that denomination.
+func CreateDenomPrefix(denom string) []byte {
+	return append(DenomPrefix, []byte(denom)...)
+}