Problem: MultiStore interface is bloated

baseapp/abci.go

@@ -1213,7 +1213,7 @@ func (app *BaseApp) CreateQueryContext(height int64, prove bool) (sdk.Context, e
 	// use custom query multi-store if provided
 	qms := app.qms
 	if qms == nil {
-		qms = app.cms.(storetypes.MultiStore)
+		qms = storetypes.RootMultiStore(app.cms)
 	}
 
 	lastBlockHeight := qms.LatestVersion()

baseapp/baseapp.go

@@ -65,7 +65,7 @@ type BaseApp struct {
 	name              string                      // application name from abci.BlockInfo
 	db                dbm.DB                      // common DB backend
 	cms               storetypes.CommitMultiStore // Main (uncached) state
-	qms               storetypes.MultiStore       // Optional alternative multistore for querying only.
+	qms               storetypes.RootMultiStore   // Optional alternative multistore for querying only.
 	storeLoader       StoreLoader                 // function to handle store loading, may be overridden with SetStoreLoader()
 	grpcQueryRouter   *GRPCQueryRouter            // router for redirecting gRPC query calls
 	msgServiceRouter  *MsgServiceRouter           // router for redirecting Msg service messages

baseapp/options.go

@@ -314,7 +314,7 @@ func (app *BaseApp) SetTxEncoder(txEncoder sdk.TxEncoder) {
 // SetQueryMultiStore set a alternative MultiStore implementation to support grpc query service.
 //
 // Ref: https://github.com/cosmos/cosmos-sdk/issues/13317
-func (app *BaseApp) SetQueryMultiStore(ms storetypes.MultiStore) {
+func (app *BaseApp) SetQueryMultiStore(ms storetypes.RootMultiStore) {
 	app.qms = ms
 }
 

server/mock/store.go

@@ -12,7 +12,7 @@ import (
 	storetypes "cosmossdk.io/store/types"
 )
 
-var _ storetypes.MultiStore = multiStore{}
+var _ storetypes.CommitMultiStore = multiStore{}
 
 type multiStore struct {
 	kv map[storetypes.StoreKey]kvStore

store/CHANGELOG.md

@@ -29,6 +29,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * [#207](https://github.com/crypto-org-chain/cosmos-sdk/pull/207) Remove api CacheWrapWithTrace.
 * [#205](https://github.com/crypto-org-chain/cosmos-sdk/pull/205) Support object store.
+* [#240](https://github.com/crypto-org-chain/cosmos-sdk/pull/240) Split methods from `MultiStore` into specialized `RootMultiStore`, keep `MultiStore` generic.
 
 ## v1.1.0 (March 20, 2024)
 

store/cachemulti/store.go

@@ -111,11 +111,6 @@ func (cms Store) TracingEnabled() bool {
 	return cms.traceWriter != nil
 }
 
-// LatestVersion returns the branch version of the store
-func (cms Store) LatestVersion() int64 {
-	panic("cannot get latest version from branch cached multi-store")
-}
-
 // GetStoreType returns the type of the store.
 func (cms Store) GetStoreType() types.StoreType {
 	return types.StoreTypeMulti
@@ -139,15 +134,6 @@ func (cms Store) CacheMultiStore() types.CacheMultiStore {
 	return newCacheMultiStoreFromCMS(cms)
 }
 
-// CacheMultiStoreWithVersion implements the MultiStore interface. It will panic
-// as an already cached multi-store cannot load previous versions.
-//
-// TODO: The store implementation can possibly be modified to support this as it
-// seems safe to load previous versions (heights).
-func (cms Store) CacheMultiStoreWithVersion(_ int64) (types.CacheMultiStore, error) {
-	panic("cannot branch cached multi-store with a version")
-}
-
 // GetStore returns an underlying Store by key.
 func (cms Store) GetStore(key types.StoreKey) types.Store {
 	s := cms.stores[key]

store/types/store.go

@@ -128,10 +128,6 @@ type MultiStore interface {
 	// call CacheMultiStore.Write().
 	CacheMultiStore() CacheMultiStore
 
-	// CacheMultiStoreWithVersion branches the underlying MultiStore where
-	// each stored is loaded at a specific version (height).
-	CacheMultiStoreWithVersion(version int64) (CacheMultiStore, error)
-
 	// Convenience for fetching substores.
 	// If the store does not exist, panics.
 	GetStore(StoreKey) Store
@@ -150,6 +146,14 @@ type MultiStore interface {
 	// implied that the caller should update the context when necessary between
 	// tracing operations. The modified MultiStore is returned.
 	SetTracingContext(TraceContext) MultiStore
+}
+
+type RootMultiStore interface {
+	MultiStore
+
+	// CacheMultiStoreWithVersion branches the underlying MultiStore where
+	// each stored is loaded at a specific version (height).
+	CacheMultiStoreWithVersion(version int64) (CacheMultiStore, error)
 
 	// LatestVersion returns the latest version in the store
 	LatestVersion() int64
@@ -164,7 +168,7 @@ type CacheMultiStore interface {
 // CommitMultiStore is an interface for a MultiStore without cache capabilities.
 type CommitMultiStore interface {
 	Committer
-	MultiStore
+	RootMultiStore
 	snapshottypes.Snapshotter
 
 	// Mount a store of type using the given db.