Merge PR #1481: Transient Stores

PENDING.md

@@ -35,6 +35,7 @@ FEATURES
 * [cosmos-sdk-cli] Added support for cosmos-sdk-cli tool under cosmos-sdk/cmd	
    * This allows SDK users to initialize a new project repository.
 * [tests] Remotenet commands for AWS (awsnet)
+* [store] Add transient store
 
 IMPROVEMENTS
 * [baseapp] Allow any alphanumeric character in route

cmd/gaia/app/app.go

@@ -47,6 +47,7 @@ type GaiaApp struct {
 	keyGov           *sdk.KVStoreKey
 	keyFeeCollection *sdk.KVStoreKey
 	keyParams        *sdk.KVStoreKey
+	tkeyParams       *sdk.TransientStoreKey
 
 	// Manage getting and setting accounts
 	accountMapper       auth.AccountMapper
@@ -77,6 +78,7 @@ func NewGaiaApp(logger log.Logger, db dbm.DB, traceStore io.Writer, baseAppOptio
 		keyGov:           sdk.NewKVStoreKey("gov"),
 		keyFeeCollection: sdk.NewKVStoreKey("fee"),
 		keyParams:        sdk.NewKVStoreKey("params"),
+		tkeyParams:       sdk.NewTransientStoreKey("params"),
 	}
 
 	// define the accountMapper
@@ -109,6 +111,7 @@ func NewGaiaApp(logger log.Logger, db dbm.DB, traceStore io.Writer, baseAppOptio
 	app.SetEndBlocker(app.EndBlocker)
 	app.SetAnteHandler(auth.NewAnteHandler(app.accountMapper, app.feeCollectionKeeper))
 	app.MountStoresIAVL(app.keyMain, app.keyAccount, app.keyIBC, app.keyStake, app.keySlashing, app.keyGov, app.keyFeeCollection, app.keyParams)
+	app.MountStore(app.tkeyParams, sdk.StoreTypeTransient)
 	err := app.LoadLatestVersion(app.keyMain)
 	if err != nil {
 		cmn.Exit(err.Error())

examples/democoin/x/assoc/validator_set.go

@@ -11,7 +11,7 @@ import (
 type ValidatorSet struct {
 	sdk.ValidatorSet
 
-	key sdk.KVStoreGetter
+	store sdk.KVStore
 	cdc   *wire.Codec
 
 	maxAssoc int
@@ -21,14 +21,14 @@ type ValidatorSet struct {
 var _ sdk.ValidatorSet = ValidatorSet{}
 
 // NewValidatorSet returns new ValidatorSet with underlying ValidatorSet
-func NewValidatorSet(cdc *wire.Codec, key sdk.KVStoreGetter, valset sdk.ValidatorSet, maxAssoc int, addrLen int) ValidatorSet {
+func NewValidatorSet(cdc *wire.Codec, store sdk.KVStore, valset sdk.ValidatorSet, maxAssoc int, addrLen int) ValidatorSet {
 	if maxAssoc < 0 || addrLen < 0 {
 		panic("Cannot use negative integer for NewValidatorSet")
 	}
 	return ValidatorSet{
 		ValidatorSet: valset,
 
-		key: key,
+		store: store,
 		cdc:   cdc,
 
 		maxAssoc: maxAssoc,
@@ -38,8 +38,7 @@ func NewValidatorSet(cdc *wire.Codec, key sdk.KVStoreGetter, valset sdk.Validato
 
 // Implements sdk.ValidatorSet
 func (valset ValidatorSet) Validator(ctx sdk.Context, addr sdk.AccAddress) (res sdk.Validator) {
-	store := valset.key.KVStore(ctx)
+	base := valset.store.Get(GetBaseKey(addr))
-	base := store.Get(GetBaseKey(addr))
 	res = valset.ValidatorSet.Validator(ctx, base)
 	if res == nil {
 		res = valset.ValidatorSet.Validator(ctx, addr)
@@ -67,13 +66,12 @@ func (valset ValidatorSet) Associate(ctx sdk.Context, base sdk.AccAddress, assoc
 	if len(base) != valset.addrLen || len(assoc) != valset.addrLen {
 		return false
 	}
-	store := valset.key.KVStore(ctx)
 	// If someone already owns the associated address
-	if store.Get(GetBaseKey(assoc)) != nil {
+	if valset.store.Get(GetBaseKey(assoc)) != nil {
 		return false
 	}
-	store.Set(GetBaseKey(assoc), base)
+	valset.store.Set(GetBaseKey(assoc), base)
-	store.Set(GetAssocKey(base, assoc), []byte{0x00})
+	valset.store.Set(GetAssocKey(base, assoc), []byte{0x00})
 	return true
 }
 
@@ -82,21 +80,19 @@ func (valset ValidatorSet) Dissociate(ctx sdk.Context, base sdk.AccAddress, asso
 	if len(base) != valset.addrLen || len(assoc) != valset.addrLen {
 		return false
 	}
-	store := valset.key.KVStore(ctx)
 	// No associated address found for given validator
-	if !bytes.Equal(store.Get(GetBaseKey(assoc)), base) {
+	if !bytes.Equal(valset.store.Get(GetBaseKey(assoc)), base) {
 		return false
 	}
-	store.Delete(GetBaseKey(assoc))
+	valset.store.Delete(GetBaseKey(assoc))
-	store.Delete(GetAssocKey(base, assoc))
+	valset.store.Delete(GetAssocKey(base, assoc))
 	return true
 }
 
 // Associations returns all associated addresses with a validator
 func (valset ValidatorSet) Associations(ctx sdk.Context, base sdk.AccAddress) (res []sdk.AccAddress) {
-	store := valset.key.KVStore(ctx)
 	res = make([]sdk.AccAddress, valset.maxAssoc)
-	iter := sdk.KVStorePrefixIterator(store, GetAssocPrefix(base))
+	iter := sdk.KVStorePrefixIterator(valset.store, GetAssocPrefix(base))
 	i := 0
 	for ; iter.Valid(); iter.Next() {
 		key := iter.Key()

examples/democoin/x/assoc/validator_set_test.go

@@ -36,7 +36,7 @@ func TestValidatorSet(t *testing.T) {
 		{addr2, sdk.NewRat(2)},
 	}}
 
-	valset := NewValidatorSet(wire.NewCodec(), sdk.NewPrefixStoreGetter(key, []byte("assoc")), base, 1, 5)
+	valset := NewValidatorSet(wire.NewCodec(), ctx.KVStore(key).Prefix([]byte("assoc")), base, 1, 5)
 
 	require.Equal(t, base.Validator(ctx, addr1), valset.Validator(ctx, addr1))
 	require.Equal(t, base.Validator(ctx, addr2), valset.Validator(ctx, addr2))

examples/democoin/x/oracle/handler.go

@@ -26,7 +26,7 @@ func (keeper Keeper) update(ctx sdk.Context, val sdk.Validator, valset sdk.Valid
 		info.Power = sdk.ZeroRat()
 		info.Hash = hash
 		prefix := GetSignPrefix(p, keeper.cdc)
-		store := keeper.key.KVStore(ctx)
+		store := ctx.KVStore(keeper.key)
 		iter := sdk.KVStorePrefixIterator(store, prefix)
 		for ; iter.Valid(); iter.Next() {
 			if valset.Validator(ctx, iter.Value()) != nil {

examples/democoin/x/oracle/keeper.go

@@ -8,7 +8,7 @@ import (
 
 // Keeper of the oracle store
 type Keeper struct {
-	key sdk.KVStoreGetter
+	key sdk.StoreKey
 	cdc *wire.Codec
 
 	valset sdk.ValidatorSet
@@ -18,7 +18,7 @@ type Keeper struct {
 }
 
 // NewKeeper constructs a new keeper
-func NewKeeper(key sdk.KVStoreGetter, cdc *wire.Codec, valset sdk.ValidatorSet, supermaj sdk.Rat, timeout int64) Keeper {
+func NewKeeper(key sdk.StoreKey, cdc *wire.Codec, valset sdk.ValidatorSet, supermaj sdk.Rat, timeout int64) Keeper {
 	if timeout < 0 {
 		panic("Timeout should not be negative")
 	}
@@ -64,7 +64,7 @@ func EmptyInfo(ctx sdk.Context) Info {
 
 // Info returns the information about a payload
 func (keeper Keeper) Info(ctx sdk.Context, p Payload) (res Info) {
-	store := keeper.key.KVStore(ctx)
+	store := ctx.KVStore(keeper.key)
 
 	key := GetInfoKey(p, keeper.cdc)
 	bz := store.Get(key)
@@ -77,7 +77,7 @@ func (keeper Keeper) Info(ctx sdk.Context, p Payload) (res Info) {
 }
 
 func (keeper Keeper) setInfo(ctx sdk.Context, p Payload, info Info) {
-	store := keeper.key.KVStore(ctx)
+	store := ctx.KVStore(keeper.key)
 
 	key := GetInfoKey(p, keeper.cdc)
 	bz := keeper.cdc.MustMarshalBinary(info)
@@ -85,21 +85,21 @@ func (keeper Keeper) setInfo(ctx sdk.Context, p Payload, info Info) {
 }
 
 func (keeper Keeper) sign(ctx sdk.Context, p Payload, signer sdk.AccAddress) {
-	store := keeper.key.KVStore(ctx)
+	store := ctx.KVStore(keeper.key)
 
 	key := GetSignKey(p, signer, keeper.cdc)
 	store.Set(key, signer)
 }
 
 func (keeper Keeper) signed(ctx sdk.Context, p Payload, signer sdk.AccAddress) bool {
-	store := keeper.key.KVStore(ctx)
+	store := ctx.KVStore(keeper.key)
 
 	key := GetSignKey(p, signer, keeper.cdc)
 	return store.Has(key)
 }
 
 func (keeper Keeper) clearSigns(ctx sdk.Context, p Payload) {
-	store := keeper.key.KVStore(ctx)
+	store := ctx.KVStore(keeper.key)
 
 	prefix := GetSignPrefix(p, keeper.cdc)
 

examples/democoin/x/oracle/oracle_test.go

@@ -119,7 +119,7 @@ func TestOracle(t *testing.T) {
 	require.Nil(t, err)
 	ctx = ctx.WithBlockHeader(abci.Header{ValidatorsHash: bz})
 
-	ork := NewKeeper(sdk.NewPrefixStoreGetter(key, []byte("oracle")), cdc, valset, sdk.NewRat(2, 3), 100)
+	ork := NewKeeper(key, cdc, valset, sdk.NewRat(2, 3), 100)
 	h := seqHandler(ork, key, sdk.CodespaceRoot)
 
 	// Nonmock.Validator signed, transaction failed

server/mock/store.go

@@ -8,6 +8,8 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
+var _ sdk.MultiStore = multiStore{}
+
 type multiStore struct {
 	kv map[sdk.StoreKey]kvStore
 }
@@ -76,10 +78,6 @@ func (ms multiStore) GetKVStore(key sdk.StoreKey) sdk.KVStore {
 	return ms.kv[key]
 }
 
-func (ms multiStore) GetKVStoreWithGas(meter sdk.GasMeter, key sdk.StoreKey) sdk.KVStore {
-	panic("not implemented")
-}
-
 func (ms multiStore) GetStore(key sdk.StoreKey) sdk.Store {
 	panic("not implemented")
 }
@@ -88,6 +86,8 @@ func (ms multiStore) GetStoreType() sdk.StoreType {
 	panic("not implemented")
 }
 
+var _ sdk.KVStore = kvStore{}
+
 type kvStore struct {
 	store map[string][]byte
 }
@@ -129,6 +129,10 @@ func (kv kvStore) Prefix(prefix []byte) sdk.KVStore {
 	panic("not implemented")
 }
 
+func (kv kvStore) Gas(meter sdk.GasMeter, config sdk.GasConfig) sdk.KVStore {
+	panic("not implmeneted")
+}
+
 func (kv kvStore) Iterator(start, end []byte) sdk.Iterator {
 	panic("not implemented")
 }

store/cachekvstore.go

@@ -85,6 +85,11 @@ func (ci *cacheKVStore) Prefix(prefix []byte) KVStore {
 	return prefixStore{ci, prefix}
 }
 
+// Implements KVStore
+func (ci *cacheKVStore) Gas(meter GasMeter, config GasConfig) KVStore {
+	return NewGasKVStore(meter, config, ci)
+}
+
 // Implements CacheKVStore.
 func (ci *cacheKVStore) Write() {
 	ci.mtx.Lock()

store/cachemultistore.go

@@ -134,6 +134,6 @@ func (cms cacheMultiStore) GetKVStore(key StoreKey) KVStore {
 }
 
 // Implements MultiStore.
-func (cms cacheMultiStore) GetKVStoreWithGas(meter sdk.GasMeter, key StoreKey) KVStore {
+func (cms cacheMultiStore) GetKVStoreWithGas(meter sdk.GasMeter, config sdk.GasConfig, key StoreKey) KVStore {
-	return NewGasKVStore(meter, cms.GetKVStore(key))
+	return NewGasKVStore(meter, config, cms.GetKVStore(key))
 }

store/dbstoreadapter.go

@@ -7,6 +7,7 @@ import (
 	dbm "github.com/tendermint/tendermint/libs/db"
 )
 
+// Wrapper type for dbm.Db with implementation of KVStore
 type dbStoreAdapter struct {
 	dbm.DB
 }
@@ -31,5 +32,10 @@ func (dsa dbStoreAdapter) Prefix(prefix []byte) KVStore {
 	return prefixStore{dsa, prefix}
 }
 
+// Implements KVStore
+func (dsa dbStoreAdapter) Gas(meter GasMeter, config GasConfig) KVStore {
+	return NewGasKVStore(meter, config, dsa)
+}
+
 // dbm.DB implements KVStore so we can CacheKVStore it.
-var _ KVStore = dbStoreAdapter{dbm.DB(nil)}
+var _ KVStore = dbStoreAdapter{}

store/gaskvstore.go

@@ -6,28 +6,20 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
-// nolint
+var _ KVStore = &gasKVStore{}
-const (
-	HasCost          = 10
-	ReadCostFlat     = 10
-	ReadCostPerByte  = 1
-	WriteCostFlat    = 10
-	WriteCostPerByte = 10
-	KeyCostFlat      = 5
-	ValueCostFlat    = 10
-	ValueCostPerByte = 1
-)
 
 // gasKVStore applies gas tracking to an underlying kvstore
 type gasKVStore struct {
 	gasMeter  sdk.GasMeter
+	gasConfig sdk.GasConfig
 	parent    sdk.KVStore
 }
 
 // nolint
-func NewGasKVStore(gasMeter sdk.GasMeter, parent sdk.KVStore) *gasKVStore {
+func NewGasKVStore(gasMeter sdk.GasMeter, gasConfig sdk.GasConfig, parent sdk.KVStore) *gasKVStore {
 	kvs := &gasKVStore{
 		gasMeter:  gasMeter,
+		gasConfig: gasConfig,
 		parent:    parent,
 	}
 	return kvs
@@ -40,24 +32,25 @@ func (gi *gasKVStore) GetStoreType() sdk.StoreType {
 
 // Implements KVStore.
 func (gi *gasKVStore) Get(key []byte) (value []byte) {
-	gi.gasMeter.ConsumeGas(ReadCostFlat, "GetFlat")
+	gi.gasMeter.ConsumeGas(gi.gasConfig.ReadCostFlat, "ReadFlat")
 	value = gi.parent.Get(key)
 	// TODO overflow-safe math?
-	gi.gasMeter.ConsumeGas(ReadCostPerByte*sdk.Gas(len(value)), "ReadPerByte")
+	gi.gasMeter.ConsumeGas(gi.gasConfig.ReadCostPerByte*sdk.Gas(len(value)), "ReadPerByte")
+
 	return value
 }
 
 // Implements KVStore.
 func (gi *gasKVStore) Set(key []byte, value []byte) {
-	gi.gasMeter.ConsumeGas(WriteCostFlat, "SetFlat")
+	gi.gasMeter.ConsumeGas(gi.gasConfig.WriteCostFlat, "WriteFlat")
 	// TODO overflow-safe math?
-	gi.gasMeter.ConsumeGas(WriteCostPerByte*sdk.Gas(len(value)), "SetPerByte")
+	gi.gasMeter.ConsumeGas(gi.gasConfig.WriteCostPerByte*sdk.Gas(len(value)), "WritePerByte")
 	gi.parent.Set(key, value)
 }
 
 // Implements KVStore.
 func (gi *gasKVStore) Has(key []byte) bool {
-	gi.gasMeter.ConsumeGas(HasCost, "Has")
+	gi.gasMeter.ConsumeGas(gi.gasConfig.HasCost, "Has")
 	return gi.parent.Has(key)
 }
 
@@ -69,7 +62,17 @@ func (gi *gasKVStore) Delete(key []byte) {
 
 // Implements KVStore
 func (gi *gasKVStore) Prefix(prefix []byte) KVStore {
-	return prefixStore{gi, prefix}
+	// Keep gasstore layer at the top
+	return &gasKVStore{
+		gasMeter:  gi.gasMeter,
+		gasConfig: gi.gasConfig,
+		parent:    prefixStore{gi.parent, prefix},
+	}
+}
+
+// Implements KVStore
+func (gi *gasKVStore) Gas(meter GasMeter, config GasConfig) KVStore {
+	return NewGasKVStore(meter, config, gi)
 }
 
 // Implements KVStore.
@@ -99,17 +102,19 @@ func (gi *gasKVStore) iterator(start, end []byte, ascending bool) sdk.Iterator {
 	} else {
 		parent = gi.parent.ReverseIterator(start, end)
 	}
-	return newGasIterator(gi.gasMeter, parent)
+	return newGasIterator(gi.gasMeter, gi.gasConfig, parent)
 }
 
 type gasIterator struct {
 	gasMeter  sdk.GasMeter
+	gasConfig sdk.GasConfig
 	parent    sdk.Iterator
 }
 
-func newGasIterator(gasMeter sdk.GasMeter, parent sdk.Iterator) sdk.Iterator {
+func newGasIterator(gasMeter sdk.GasMeter, gasConfig sdk.GasConfig, parent sdk.Iterator) sdk.Iterator {
 	return &gasIterator{
 		gasMeter:  gasMeter,
+		gasConfig: gasConfig,
 		parent:    parent,
 	}
 }
@@ -131,7 +136,7 @@ func (g *gasIterator) Next() {
 
 // Implements Iterator.
 func (g *gasIterator) Key() (key []byte) {
-	g.gasMeter.ConsumeGas(KeyCostFlat, "KeyFlat")
+	g.gasMeter.ConsumeGas(g.gasConfig.KeyCostFlat, "KeyFlat")
 	key = g.parent.Key()
 	return key
 }
@@ -139,8 +144,8 @@ func (g *gasIterator) Key() (key []byte) {
 // Implements Iterator.
 func (g *gasIterator) Value() (value []byte) {
 	value = g.parent.Value()
-	g.gasMeter.ConsumeGas(ValueCostFlat, "ValueFlat")
+	g.gasMeter.ConsumeGas(g.gasConfig.ValueCostFlat, "ValueFlat")
-	g.gasMeter.ConsumeGas(ValueCostPerByte*sdk.Gas(len(value)), "ValuePerByte")
+	g.gasMeter.ConsumeGas(g.gasConfig.ValueCostPerByte*sdk.Gas(len(value)), "ValuePerByte")
 	return value
 }
 

store/gaskvstore_test.go

@@ -3,21 +3,23 @@ package store
 import (
 	"testing"
 
-	sdk "github.com/cosmos/cosmos-sdk/types"
-	"github.com/stretchr/testify/require"
 	dbm "github.com/tendermint/tendermint/libs/db"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+
+	"github.com/stretchr/testify/require"
 )
 
 func newGasKVStore() KVStore {
 	meter := sdk.NewGasMeter(1000)
 	mem := dbStoreAdapter{dbm.NewMemDB()}
-	return NewGasKVStore(meter, mem)
+	return NewGasKVStore(meter, sdk.DefaultGasConfig(), mem)
 }
 
 func TestGasKVStoreBasic(t *testing.T) {
 	mem := dbStoreAdapter{dbm.NewMemDB()}
 	meter := sdk.NewGasMeter(1000)
-	st := NewGasKVStore(meter, mem)
+	st := NewGasKVStore(meter, sdk.DefaultGasConfig(), mem)
 	require.Empty(t, st.Get(keyFmt(1)), "Expected `key1` to be empty")
 	st.Set(keyFmt(1), valFmt(1))
 	require.Equal(t, valFmt(1), st.Get(keyFmt(1)))
@@ -29,7 +31,7 @@ func TestGasKVStoreBasic(t *testing.T) {
 func TestGasKVStoreIterator(t *testing.T) {
 	mem := dbStoreAdapter{dbm.NewMemDB()}
 	meter := sdk.NewGasMeter(1000)
-	st := NewGasKVStore(meter, mem)
+	st := NewGasKVStore(meter, sdk.DefaultGasConfig(), mem)
 	require.Empty(t, st.Get(keyFmt(1)), "Expected `key1` to be empty")
 	require.Empty(t, st.Get(keyFmt(2)), "Expected `key2` to be empty")
 	st.Set(keyFmt(1), valFmt(1))
@@ -53,16 +55,51 @@ func TestGasKVStoreIterator(t *testing.T) {
 func TestGasKVStoreOutOfGasSet(t *testing.T) {
 	mem := dbStoreAdapter{dbm.NewMemDB()}
 	meter := sdk.NewGasMeter(0)
-	st := NewGasKVStore(meter, mem)
+	st := NewGasKVStore(meter, sdk.DefaultGasConfig(), mem)
 	require.Panics(t, func() { st.Set(keyFmt(1), valFmt(1)) }, "Expected out-of-gas")
 }
 
 func TestGasKVStoreOutOfGasIterator(t *testing.T) {
 	mem := dbStoreAdapter{dbm.NewMemDB()}
 	meter := sdk.NewGasMeter(200)
-	st := NewGasKVStore(meter, mem)
+	st := NewGasKVStore(meter, sdk.DefaultGasConfig(), mem)
 	st.Set(keyFmt(1), valFmt(1))
 	iterator := st.Iterator(nil, nil)
 	iterator.Next()
 	require.Panics(t, func() { iterator.Value() }, "Expected out-of-gas")
 }
+
+func testGasKVStoreWrap(t *testing.T, store KVStore) {
+	meter := sdk.NewGasMeter(10000)
+
+	store = store.Gas(meter, sdk.GasConfig{HasCost: 10})
+	require.Equal(t, int64(0), meter.GasConsumed())
+
+	store.Has([]byte("key"))
+	require.Equal(t, int64(10), meter.GasConsumed())
+
+	store = store.Gas(meter, sdk.GasConfig{HasCost: 20})
+
+	store.Has([]byte("key"))
+	require.Equal(t, int64(40), meter.GasConsumed())
+}
+
+func TestGasKVStoreWrap(t *testing.T) {
+	db := dbm.NewMemDB()
+	tree, _ := newTree(t, db)
+	iavl := newIAVLStore(tree, numRecent, storeEvery)
+	testGasKVStoreWrap(t, iavl)
+
+	st := NewCacheKVStore(iavl)
+	testGasKVStoreWrap(t, st)
+
+	pref := st.Prefix([]byte("prefix"))
+	testGasKVStoreWrap(t, pref)
+
+	dsa := dbStoreAdapter{dbm.NewMemDB()}
+	testGasKVStoreWrap(t, dsa)
+
+	ts := newTransientStore()
+	testGasKVStoreWrap(t, ts)
+
+}

store/iavlstore.go

@@ -67,7 +67,6 @@ func newIAVLStore(tree *iavl.VersionedTree, numRecent int64, storeEvery int64) *
 
 // Implements Committer.
 func (st *iavlStore) Commit() CommitID {
-
 	// Save a new version.
 	hash, version, err := st.tree.SaveVersion()
 	if err != nil {
@@ -161,6 +160,11 @@ func (st *iavlStore) Prefix(prefix []byte) KVStore {
 	return prefixStore{st, prefix}
 }
 
+// Implements KVStore
+func (st *iavlStore) Gas(meter GasMeter, config GasConfig) KVStore {
+	return NewGasKVStore(meter, config, st)
+}
+
 // Implements KVStore.
 func (st *iavlStore) Iterator(start, end []byte) Iterator {
 	return newIAVLIterator(st.tree.Tree(), start, end, true)

store/iavlstore_test.go

@@ -446,6 +446,7 @@ func TestIAVLStoreQuery(t *testing.T) {
 	require.Equal(t, uint32(sdk.CodeOK), qres.Code)
 	require.Equal(t, v3, qres.Value)
 	query2 := abci.RequestQuery{Path: "/key", Data: k2, Height: cid.Version}
+
 	qres = iavlStore.Query(query2)
 	require.Equal(t, uint32(sdk.CodeOK), qres.Code)
 	require.Equal(t, v2, qres.Value)

store/prefixstore.go

@@ -6,14 +6,16 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
+var _ KVStore = prefixStore{}
+
 type prefixStore struct {
-	store  KVStore
+	parent KVStore
 	prefix []byte
 }
 
 // Implements Store
 func (s prefixStore) GetStoreType() StoreType {
-	return sdk.StoreTypePrefix
+	return s.parent.GetStoreType()
 }
 
 // Implements CacheWrap
@@ -28,22 +30,22 @@ func (s prefixStore) CacheWrapWithTrace(w io.Writer, tc TraceContext) CacheWrap
 
 // Implements KVStore
 func (s prefixStore) Get(key []byte) []byte {
-	return s.store.Get(append(s.prefix, key...))
+	return s.parent.Get(append(s.prefix, key...))
 }
 
 // Implements KVStore
 func (s prefixStore) Has(key []byte) bool {
-	return s.store.Has(append(s.prefix, key...))
+	return s.parent.Has(append(s.prefix, key...))
 }
 
 // Implements KVStore
 func (s prefixStore) Set(key, value []byte) {
-	s.store.Set(append(s.prefix, key...), value)
+	s.parent.Set(append(s.prefix, key...), value)
 }
 
 // Implements KVStore
 func (s prefixStore) Delete(key []byte) {
-	s.store.Delete(append(s.prefix, key...))
+	s.parent.Delete(append(s.prefix, key...))
 }
 
 // Implements KVStore
@@ -51,6 +53,11 @@ func (s prefixStore) Prefix(prefix []byte) KVStore {
 	return prefixStore{s, prefix}
 }
 
+// Implements KVStore
+func (s prefixStore) Gas(meter GasMeter, config GasConfig) KVStore {
+	return NewGasKVStore(meter, config, s)
+}
+
 // Implements KVStore
 func (s prefixStore) Iterator(start, end []byte) Iterator {
 	if end == nil {
@@ -60,7 +67,7 @@ func (s prefixStore) Iterator(start, end []byte) Iterator {
 	}
 	return prefixIterator{
 		prefix: s.prefix,
-		iter:   s.store.Iterator(append(s.prefix, start...), end),
+		iter:   s.parent.Iterator(append(s.prefix, start...), end),
 	}
 }
 
@@ -73,7 +80,7 @@ func (s prefixStore) ReverseIterator(start, end []byte) Iterator {
 	}
 	return prefixIterator{
 		prefix: s.prefix,
-		iter:   s.store.ReverseIterator(start, end),
+		iter:   s.parent.ReverseIterator(start, end),
 	}
 }
 

store/prefixstore_test.go

@@ -4,7 +4,6 @@ import (
 	"math/rand"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/tendermint/iavl"
@@ -35,32 +34,34 @@ func setRandomKVPairs(t *testing.T, store KVStore) []kvpair {
 
 func testPrefixStore(t *testing.T, baseStore KVStore, prefix []byte) {
 	prefixStore := baseStore.Prefix(prefix)
+	prefixPrefixStore := prefixStore.Prefix([]byte("prefix"))
 
-	kvps := setRandomKVPairs(t, prefixStore)
+	kvps := setRandomKVPairs(t, prefixPrefixStore)
-
-	buf := make([]byte, 32)
-	for i := 0; i < 20; i++ {
-		rand.Read(buf)
-		assert.False(t, prefixStore.Has(buf))
-		assert.Nil(t, prefixStore.Get(buf))
-		assert.False(t, baseStore.Has(append(prefix, buf...)))
-		assert.Nil(t, baseStore.Get(append(prefix, buf...)))
-	}
 
 	for i := 0; i < 20; i++ {
 		key := kvps[i].key
-		assert.True(t, prefixStore.Has(key))
+		value := kvps[i].value
-		assert.Equal(t, kvps[i].value, prefixStore.Get(key))
+		require.True(t, prefixPrefixStore.Has(key))
-		assert.True(t, baseStore.Has(append(prefix, key...)))
+		require.Equal(t, value, prefixPrefixStore.Get(key))
-		assert.Equal(t, kvps[i].value, baseStore.Get(append(prefix, key...)))
 
-		prefixStore.Delete(key)
+		key = append([]byte("prefix"), key...)
-		assert.False(t, prefixStore.Has(key))
+		require.True(t, prefixStore.Has(key))
-		assert.Nil(t, prefixStore.Get(key))
+		require.Equal(t, value, prefixStore.Get(key))
-		assert.False(t, baseStore.Has(append(prefix, buf...)))
+		key = append(prefix, key...)
-		assert.Nil(t, baseStore.Get(append(prefix, buf...)))
+		require.True(t, baseStore.Has(key))
+		require.Equal(t, value, baseStore.Get(key))
+
+		key = kvps[i].key
+		prefixPrefixStore.Delete(key)
+		require.False(t, prefixPrefixStore.Has(key))
+		require.Nil(t, prefixPrefixStore.Get(key))
+		key = append([]byte("prefix"), key...)
+		require.False(t, prefixStore.Has(key))
+		require.Nil(t, prefixStore.Get(key))
+		key = append(prefix, key...)
+		require.False(t, baseStore.Has(key))
+		require.Nil(t, baseStore.Get(key))
 	}
-
 }
 
 func TestIAVLStorePrefix(t *testing.T) {
@@ -80,7 +81,7 @@ func TestCacheKVStorePrefix(t *testing.T) {
 func TestGasKVStorePrefix(t *testing.T) {
 	meter := sdk.NewGasMeter(100000000)
 	mem := dbStoreAdapter{dbm.NewMemDB()}
-	gasStore := NewGasKVStore(meter, mem)
+	gasStore := NewGasKVStore(meter, sdk.DefaultGasConfig(), mem)
 
 	testPrefixStore(t, gasStore, []byte("test"))
 }

store/rootmultistore.go

@@ -99,7 +99,7 @@ func (rs *rootMultiStore) LoadVersion(ver int64) error {
 	if ver == 0 {
 		for key, storeParams := range rs.storesParams {
 			id := CommitID{}
-			store, err := rs.loadCommitStoreFromParams(id, storeParams)
+			store, err := rs.loadCommitStoreFromParams(key, id, storeParams)
 			if err != nil {
 				return fmt.Errorf("failed to load rootMultiStore: %v", err)
 			}
@@ -122,19 +122,22 @@ func (rs *rootMultiStore) LoadVersion(ver int64) error {
 	for _, storeInfo := range cInfo.StoreInfos {
 		key, commitID := rs.nameToKey(storeInfo.Name), storeInfo.Core.CommitID
 		storeParams := rs.storesParams[key]
-		store, err := rs.loadCommitStoreFromParams(commitID, storeParams)
+		store, err := rs.loadCommitStoreFromParams(key, commitID, storeParams)
 		if err != nil {
 			return fmt.Errorf("failed to load rootMultiStore: %v", err)
 		}
 		newStores[key] = store
 	}
 
-	// If any CommitStoreLoaders were not used, return error.
+	// TODO: detecting transient is quite adhoc
-	for key := range rs.storesParams {
+	// If any nontransient CommitStoreLoaders were not used, return error.
+	for key, param := range rs.storesParams {
+		if param.typ != sdk.StoreTypeTransient {
 			if _, ok := newStores[key]; !ok {
 				return fmt.Errorf("unused CommitStoreLoader: %v", key)
 			}
 		}
+	}
 
 	// Success.
 	rs.lastCommitID = cInfo.CommitID()
@@ -242,10 +245,7 @@ func (rs *rootMultiStore) GetKVStore(key StoreKey) KVStore {
 	return store
 }
 
-// Implements MultiStore.
+// Implements MultiStore
-func (rs *rootMultiStore) GetKVStoreWithGas(meter sdk.GasMeter, key StoreKey) KVStore {
-	return NewGasKVStore(meter, rs.GetKVStore(key))
-}
 
 // getStoreByName will first convert the original name to
 // a special key, before looking up the CommitStore.
@@ -309,7 +309,7 @@ func parsePath(path string) (storeName string, subpath string, err sdk.Error) {
 
 //----------------------------------------
 
-func (rs *rootMultiStore) loadCommitStoreFromParams(id CommitID, params storeParams) (store CommitStore, err error) {
+func (rs *rootMultiStore) loadCommitStoreFromParams(key sdk.StoreKey, id CommitID, params storeParams) (store CommitStore, err error) {
 	var db dbm.DB
 	if params.db != nil {
 		db = dbm.NewPrefixDB(params.db, []byte("s/_/"))
@@ -326,6 +326,14 @@ func (rs *rootMultiStore) loadCommitStoreFromParams(id CommitID, params storePar
 		return
 	case sdk.StoreTypeDB:
 		panic("dbm.DB is not a CommitStore")
+	case sdk.StoreTypeTransient:
+		_, ok := key.(*sdk.TransientStoreKey)
+		if !ok {
+			err = fmt.Errorf("invalid StoreKey for StoreTypeTransient: %s", key.String())
+			return
+		}
+		store = newTransientStore()
+		return
 	default:
 		panic(fmt.Sprintf("unrecognized store type %v", params.typ))
 	}
@@ -440,6 +448,10 @@ func commitStores(version int64, storeMap map[StoreKey]CommitStore) commitInfo {
 		// Commit
 		commitID := store.Commit()
 
+		if store.GetStoreType() == sdk.StoreTypeTransient {
+			continue
+		}
+
 		// Record CommitID
 		si := storeInfo{}
 		si.Name = key.Name()

store/rootmultistore_test.go

@@ -13,6 +13,14 @@ import (
 
 const useDebugDB = false
 
+func TestStoreType(t *testing.T) {
+	db := dbm.NewMemDB()
+	store := NewCommitMultiStore(db)
+	store.MountStoreWithDB(
+		sdk.NewKVStoreKey("store1"), sdk.StoreTypeIAVL, db)
+
+}
+
 func TestMultistoreCommitLoad(t *testing.T) {
 	var db dbm.DB = dbm.NewMemDB()
 	if useDebugDB {

store/tracekvstore.go

@@ -82,6 +82,11 @@ func (tkv *TraceKVStore) Prefix(prefix []byte) KVStore {
 	return prefixStore{tkv, prefix}
 }
 
+// Gas implements the KVStore interface.
+func (tkv *TraceKVStore) Gas(meter GasMeter, config GasConfig) KVStore {
+	return NewGasKVStore(meter, config, tkv.parent)
+}
+
 // Iterator implements the KVStore interface. It delegates the Iterator call
 // the to the parent KVStore.
 func (tkv *TraceKVStore) Iterator(start, end []byte) sdk.Iterator {

store/transientstore.go

@@ -0,0 +1,43 @@
+package store
+
+import (
+	dbm "github.com/tendermint/tendermint/libs/db"
+)
+
+var _ KVStore = (*transientStore)(nil)
+
+// transientStore is a wrapper for a MemDB with Commiter implementation
+type transientStore struct {
+	dbStoreAdapter
+}
+
+// Constructs new MemDB adapter
+func newTransientStore() *transientStore {
+	return &transientStore{dbStoreAdapter{dbm.NewMemDB()}}
+}
+
+// Implements CommitStore
+// Commit cleans up transientStore.
+func (ts *transientStore) Commit() (id CommitID) {
+	ts.dbStoreAdapter = dbStoreAdapter{dbm.NewMemDB()}
+	return
+}
+
+// Implements CommitStore
+func (ts *transientStore) SetPruning(pruning PruningStrategy) {
+}
+
+// Implements CommitStore
+func (ts *transientStore) LastCommitID() (id CommitID) {
+	return
+}
+
+// Implements KVStore
+func (ts *transientStore) Prefix(prefix []byte) KVStore {
+	return prefixStore{ts, prefix}
+}
+
+// Implements KVStore
+func (ts *transientStore) Gas(meter GasMeter, config GasConfig) KVStore {
+	return NewGasKVStore(meter, config, ts)
+}

store/transientstore_test.go

@@ -0,0 +1,23 @@
+package store
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+var k, v = []byte("hello"), []byte("world")
+
+func TestTransientStore(t *testing.T) {
+	tstore := newTransientStore()
+
+	require.Nil(t, tstore.Get(k))
+
+	tstore.Set(k, v)
+
+	require.Equal(t, v, tstore.Get(k))
+
+	tstore.Commit()
+
+	require.Nil(t, tstore.Get(k))
+}

store/types.go

@@ -7,6 +7,7 @@ import (
 // Import cosmos-sdk/types/store.go for convenience.
 // nolint
 type (
+	PruningStrategy  = types.PruningStrategy
 	Store            = types.Store
 	Committer        = types.Committer
 	CommitStore      = types.CommitStore
@@ -25,4 +26,7 @@ type (
 	StoreType        = types.StoreType
 	Queryable        = types.Queryable
 	TraceContext     = types.TraceContext
+	Gas              = types.Gas
+	GasMeter         = types.GasMeter
+	GasConfig        = types.GasConfig
 )

types/context.go

@@ -31,7 +31,6 @@ type Context struct {
 
 // create a new context
 func NewContext(ms MultiStore, header abci.Header, isCheckTx bool, logger log.Logger) Context {
-
 	c := Context{
 		Context: context.Background(),
 		pst:     newThePast(),
@@ -70,7 +69,12 @@ func (c Context) Value(key interface{}) interface{} {
 
 // KVStore fetches a KVStore from the MultiStore.
 func (c Context) KVStore(key StoreKey) KVStore {
-	return c.multiStore().GetKVStoreWithGas(c.GasMeter(), key)
+	return c.multiStore().GetKVStore(key).Gas(c.GasMeter(), cachedDefaultGasConfig)
+}
+
+// TransientStore fetches a TransientStore from the MultiStore.
+func (c Context) TransientStore(key StoreKey) KVStore {
+	return c.multiStore().GetKVStore(key).Gas(c.GasMeter(), cachedTransientGasConfig)
 }
 
 //----------------------------------------
@@ -125,6 +129,7 @@ const (
 	contextKeyMultiStore contextKey = iota
 	contextKeyBlockHeader
 	contextKeyBlockHeight
+	contextKeyConsensusParams
 	contextKeyChainID
 	contextKeyTxBytes
 	contextKeyLogger
@@ -146,6 +151,9 @@ func (c Context) BlockHeader() abci.Header {
 func (c Context) BlockHeight() int64 {
 	return c.Value(contextKeyBlockHeight).(int64)
 }
+func (c Context) ConsensusParams() abci.ConsensusParams {
+	return c.Value(contextKeyConsensusParams).(abci.ConsensusParams)
+}
 func (c Context) ChainID() string {
 	return c.Value(contextKeyChainID).(string)
 }
@@ -171,6 +179,13 @@ func (c Context) WithBlockHeader(header abci.Header) Context {
 func (c Context) WithBlockHeight(height int64) Context {
 	return c.withValue(contextKeyBlockHeight, height)
 }
+func (c Context) WithConsensusParams(params *abci.ConsensusParams) Context {
+	if params == nil {
+		return c
+	}
+	return c.withValue(contextKeyConsensusParams, params).
+		WithGasMeter(NewGasMeter(params.TxSize.MaxGas))
+}
 func (c Context) WithChainID(chainID string) Context {
 	return c.withValue(contextKeyChainID, chainID)
 }

types/gas.go

@@ -54,3 +54,40 @@ func (g *infiniteGasMeter) GasConsumed() Gas {
 func (g *infiniteGasMeter) ConsumeGas(amount Gas, descriptor string) {
 	g.consumed += amount
 }
+
+// GasConfig defines gas cost for each operation on KVStores
+type GasConfig struct {
+	HasCost          Gas
+	ReadCostFlat     Gas
+	ReadCostPerByte  Gas
+	WriteCostFlat    Gas
+	WriteCostPerByte Gas
+	KeyCostFlat      Gas
+	ValueCostFlat    Gas
+	ValueCostPerByte Gas
+}
+
+var (
+	cachedDefaultGasConfig   = DefaultGasConfig()
+	cachedTransientGasConfig = TransientGasConfig()
+)
+
+// Default gas config for KVStores
+func DefaultGasConfig() GasConfig {
+	return GasConfig{
+		HasCost:          10,
+		ReadCostFlat:     10,
+		ReadCostPerByte:  1,
+		WriteCostFlat:    10,
+		WriteCostPerByte: 10,
+		KeyCostFlat:      5,
+		ValueCostFlat:    10,
+		ValueCostPerByte: 1,
+	}
+}
+
+// Default gas config for TransientStores
+func TransientGasConfig() GasConfig {
+	// TODO: define gasconfig for transient stores
+	return DefaultGasConfig()
+}

types/store.go

@@ -65,7 +65,6 @@ type MultiStore interface { //nolint
 	// Convenience for fetching substores.
 	GetStore(StoreKey) Store
 	GetKVStore(StoreKey) KVStore
-	GetKVStoreWithGas(GasMeter, StoreKey) KVStore
 
 	// TracingEnabled returns if tracing is enabled for the MultiStore.
 	TracingEnabled() bool
@@ -134,9 +133,6 @@ type KVStore interface {
 	// Delete deletes the key. Panics on nil key.
 	Delete(key []byte)
 
-	// Prefix applied keys with the argument
-	Prefix(prefix []byte) KVStore
-
 	// Iterator over a domain of keys in ascending order. End is exclusive.
 	// Start must be less than end, or the Iterator is invalid.
 	// Iterator must be closed by caller.
@@ -155,6 +151,16 @@ type KVStore interface {
 
 	// TODO Not yet implemented.
 	// GetSubKVStore(key *storeKey) KVStore
+
+	// Prefix applied keys with the argument
+	// CONTRACT: when Prefix is called on a KVStore more than once,
+	// the concatanation of the prefixes is applied
+	Prefix(prefix []byte) KVStore
+
+	// Gas consuming store
+	// CONTRACT: when Gas is called on a KVStore more than once,
+	// the concatanation of the meters/configs is applied
+	Gas(GasMeter, GasConfig) KVStore
 }
 
 // Alias iterator to db's Iterator for convenience.
@@ -186,11 +192,6 @@ type CommitKVStore interface {
 	KVStore
 }
 
-// Wrapper for StoreKeys to get KVStores
-type KVStoreGetter interface {
-	KVStore(Context) KVStore
-}
-
 //----------------------------------------
 // CacheWrap
 
@@ -245,7 +246,7 @@ const (
 	StoreTypeMulti StoreType = iota
 	StoreTypeDB
 	StoreTypeIAVL
-	StoreTypePrefix
+	StoreTypeTransient
 )
 
 //----------------------------------------
@@ -279,11 +280,6 @@ func (key *KVStoreKey) String() string {
 	return fmt.Sprintf("KVStoreKey{%p, %s}", key, key.name)
 }
 
-// Implements KVStoreGetter
-func (key *KVStoreKey) KVStore(ctx Context) KVStore {
-	return ctx.KVStore(key)
-}
-
 // PrefixEndBytes returns the []byte that would end a
 // range query for all []byte with a certain prefix
 // Deals with last byte of prefix being FF without overflowing
@@ -310,19 +306,27 @@ func PrefixEndBytes(prefix []byte) []byte {
 	return end
 }
 
-// Getter struct for prefixed stores
+// TransientStoreKey is used for indexing transient stores in a MultiStore
-type PrefixStoreGetter struct {
+type TransientStoreKey struct {
-	key    StoreKey
+	name string
-	prefix []byte
 }
 
-func NewPrefixStoreGetter(key StoreKey, prefix []byte) PrefixStoreGetter {
+// Constructs new TransientStoreKey
-	return PrefixStoreGetter{key, prefix}
+// Must return a pointer according to the ocap principle
+func NewTransientStoreKey(name string) *TransientStoreKey {
+	return &TransientStoreKey{
+		name: name,
+	}
 }
 
-// Implements sdk.KVStoreGetter
+// Implements StoreKey
-func (getter PrefixStoreGetter) KVStore(ctx Context) KVStore {
+func (key *TransientStoreKey) Name() string {
-	return ctx.KVStore(getter.key).Prefix(getter.prefix)
+	return key.name
+}
+
+// Implements StoreKey
+func (key *TransientStoreKey) String() string {
+	return fmt.Sprintf("TransientStoreKey{%p, %s}", key, key.name)
 }
 
 //----------------------------------------