baseapp: save header on commit. fixes #507

baseapp/baseapp.go

@@ -16,7 +16,11 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
-var mainHeaderKey = []byte("header")
+// Key to store the header in the DB itself.
+// Use the db directly instead of a store to avoid
+// conflicts with handlers writing to the store
+// and to avoid affecting the Merkle root.
+var dbHeaderKey = []byte("header")
 
 // The ABCI application
 type BaseApp struct {
@@ -126,19 +130,20 @@ func (app *BaseApp) LastBlockHeight() int64 {
 // initializes the remaining logic from app.cms
 func (app *BaseApp) initFromStore(mainKey sdk.StoreKey) error {
 	var lastCommitID = app.cms.LastCommitID()
-	var main = app.cms.GetKVStore(mainKey)
 	var header abci.Header
 
 	// main store should exist.
+	// TODO: we don't actually need the main store here
+	main := app.cms.GetKVStore(mainKey)
 	if main == nil {
 		return errors.New("BaseApp expects MultiStore with 'main' KVStore")
 	}
 
-	// if we've committed before, we expect main://<mainHeaderKey>
+	// if we've committed before, we expect <dbHeaderKey> to exist in the db
 	if !lastCommitID.IsZero() {
-		headerBytes := main.Get(mainHeaderKey)
+		headerBytes := app.db.Get(dbHeaderKey)
 		if len(headerBytes) == 0 {
-			errStr := fmt.Sprintf("Version > 0 but missing key %s", mainHeaderKey)
+			errStr := fmt.Sprintf("Version > 0 but missing key %s", dbHeaderKey)
 			return errors.New(errStr)
 		}
 		err := proto.Unmarshal(headerBytes, &header)
@@ -147,7 +152,7 @@ func (app *BaseApp) initFromStore(mainKey sdk.StoreKey) error {
 		}
 		lastVersion := lastCommitID.Version
 		if header.Height != lastVersion {
-			errStr := fmt.Sprintf("Expected main://%s.Height %v but got %v", mainHeaderKey, lastVersion, header.Height)
+			errStr := fmt.Sprintf("Expected main://%s.Height %v but got %v", dbHeaderKey, lastVersion, header.Height)
 			return errors.New(errStr)
 		}
 	}
@@ -369,6 +374,14 @@ func (app *BaseApp) EndBlock(req abci.RequestEndBlock) (res abci.ResponseEndBloc
 
 // Implements ABCI
 func (app *BaseApp) Commit() (res abci.ResponseCommit) {
+	// Write the latest Header to the store
+	header := app.ctxDeliver.BlockHeader()
+	headerBytes, err := proto.Marshal(&header)
+	if err != nil {
+		panic(err)
+	}
+	app.db.Set(dbHeaderKey, headerBytes)
+
 	// Write the Deliver state and commit the MultiStore
 	app.msDeliver.Write()
 	commitID := app.cms.Commit()
@@ -379,7 +392,6 @@ func (app *BaseApp) Commit() (res abci.ResponseCommit) {
 	// Reset the Check state
 	// NOTE: safe because Tendermint holds a lock on the mempool for Commit.
 	// Use the header from this latest block.
-	header := app.ctxDeliver.BlockHeader()
 	app.msCheck = app.cms.CacheMultiStore()
 	app.ctxCheck = app.NewContext(true, header)
 

baseapp/baseapp_test.go

@@ -42,19 +42,82 @@ func TestMountStores(t *testing.T) {
 
 	app.MountStoresIAVL(capKey1, capKey2)
 
-	// both stores are mounted
+	// stores are mounted
 	err := app.LoadLatestVersion(capKey1)
 	assert.Nil(t, err)
-	err = app.LoadLatestVersion(capKey2)
-	assert.Nil(t, err)
+
+	// check both stores
+	store1 := app.cms.GetCommitKVStore(capKey1)
+	assert.NotNil(t, store1)
+	store2 := app.cms.GetCommitKVStore(capKey2)
+	assert.NotNil(t, store2)
 }
 
 // Test that we can make commits and then reload old versions.
 // Test that LoadLatestVersion actually does.
 func TestLoadVersion(t *testing.T) {
-	// TODO
+	logger := defaultLogger()
+	db := dbm.NewMemDB()
+	name := t.Name()
+	app := NewBaseApp(name, logger, db)
+
+	// make a cap key and mount the store
+	capKey := sdk.NewKVStoreKey("main")
+	app.MountStoresIAVL(capKey)
+	err := app.LoadLatestVersion(capKey) // needed to make stores non-nil
+	assert.Nil(t, err)
+
+	emptyCommitID := sdk.CommitID{}
+
+	lastHeight := app.LastBlockHeight()
+	lastID := app.LastCommitID()
+	assert.Equal(t, int64(0), lastHeight)
+	assert.Equal(t, emptyCommitID, lastID)
+
+	// execute some blocks
+	header := abci.Header{Height: 1}
+	app.BeginBlock(abci.RequestBeginBlock{Header: header})
+	res := app.Commit()
+	commitID := sdk.CommitID{1, res.Data}
+
+	// reload
+	app = NewBaseApp(name, logger, db)
+	app.MountStoresIAVL(capKey)
+	err = app.LoadLatestVersion(capKey) // needed to make stores non-nil
+	assert.Nil(t, err)
+
+	lastHeight = app.LastBlockHeight()
+	lastID = app.LastCommitID()
+	assert.Equal(t, int64(1), lastHeight)
+	assert.Equal(t, commitID, lastID)
 }
 
+// Test that the app hash is static
+// TODO: https://github.com/cosmos/cosmos-sdk/issues/520
+/*func TestStaticAppHash(t *testing.T) {
+	app := newBaseApp(t.Name())
+
+	// make a cap key and mount the store
+	capKey := sdk.NewKVStoreKey("main")
+	app.MountStoresIAVL(capKey)
+	err := app.LoadLatestVersion(capKey) // needed to make stores non-nil
+	assert.Nil(t, err)
+
+	// execute some blocks
+	header := abci.Header{Height: 1}
+	app.BeginBlock(abci.RequestBeginBlock{Header: header})
+	res := app.Commit()
+	commitID1 := sdk.CommitID{1, res.Data}
+
+	header = abci.Header{Height: 2}
+	app.BeginBlock(abci.RequestBeginBlock{Header: header})
+	res = app.Commit()
+	commitID2 := sdk.CommitID{2, res.Data}
+
+	assert.Equal(t, commitID1.Hash, commitID2.Hash)
+}
+*/
+
 // Test that txs can be unmarshalled and read and that
 // correct error codes are returned when not
 func TestTxDecoder(t *testing.T) {
@@ -246,7 +309,8 @@ func TestValidatorChange(t *testing.T) {
 
 	// Create app.
 	app := newBaseApp(t.Name())
-	storeKeys := createMounts(app.cms)
+	capKey := sdk.NewKVStoreKey("key")
+	app.MountStoresIAVL(capKey)
 	app.SetTxDecoder(func(txBytes []byte) (sdk.Tx, sdk.Error) {
 		var ttx testUpdatePowerTx
 		fromJSON(txBytes, &ttx)
@@ -260,7 +324,7 @@ func TestValidatorChange(t *testing.T) {
 	})
 
 	// Load latest state, which should be empty.
-	err := app.LoadLatestVersion(storeKeys["main"])
+	err := app.LoadLatestVersion(capKey)
 	assert.Nil(t, err)
 	assert.Equal(t, app.LastBlockHeight(), int64(0))
 
@@ -369,17 +433,3 @@ func fromJSON(bz []byte, ptr interface{}) {
 		panic(err)
 	}
 }
-
-// Mounts stores to CommitMultiStore and returns a map of keys.
-func createMounts(ms sdk.CommitMultiStore) map[string]sdk.StoreKey {
-	dbMain := dbm.NewMemDB()
-	dbXtra := dbm.NewMemDB()
-	keyMain := sdk.NewKVStoreKey("main")
-	keyXtra := sdk.NewKVStoreKey("xtra")
-	ms.MountStoreWithDB(keyMain, sdk.StoreTypeIAVL, dbMain)
-	ms.MountStoreWithDB(keyXtra, sdk.StoreTypeIAVL, dbXtra)
-	return map[string]sdk.StoreKey{
-		"main": keyMain,
-		"xtra": keyXtra,
-	}
-}