events: notify listeners before commit state tx

vochain/indexer/indexer.go

@@ -363,7 +363,13 @@ func (idx *Indexer) Commit(height uint32) error {
 			// TODO: can we get previousVote from sqlite via blockTx?
 			var previousVote *models.StateDBVote
 			if v.Overwrites > 0 {
-				previousVote, _ = idx.App.State.Vote(v.ProcessID, v.Nullifier, true)
+				previousVote, err = idx.App.State.Vote(v.ProcessID, v.Nullifier, true)
+				if err != nil {
+					log.Warnw("cannot get previous vote",
+						"nullifier", hex.EncodeToString(v.Nullifier),
+						"processID", hex.EncodeToString(v.ProcessID),
+						"error", err.Error())
+				}
 			}
 			if previousVote != nil {
 				log.Debugw("vote overwrite, previous vote",

vochain/state/state.go

@@ -386,6 +386,23 @@ func (v *State) RevealProcessKeys(tx *models.AdminTx) error {
 func (v *State) Save() ([]byte, error) {
 	height := v.CurrentHeight()
 	var pidsStartNextBlock [][]byte
+
+	// Notify listeners about processes that start in the next block.
+	if len(pidsStartNextBlock) > 0 {
+		for _, l := range v.eventListeners {
+			l.OnProcessesStart(pidsStartNextBlock)
+		}
+	}
+	// Notify listeners about the commit state
+	for _, l := range v.eventListeners {
+		if err := l.Commit(height); err != nil {
+			log.Warnf("event callback error on commit: %v", err)
+		}
+	}
+
+	// Commit the statedb tx
+	// Note that we need to commit the tx after calling listeners, because
+	// the listeners may need to get the previous (not committed) state.
 	v.tx.Lock()
 	err := func() error {
 		var err error
@@ -401,18 +418,6 @@ func (v *State) Save() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	// Notify listeners about processes that start in the next block.
-	if len(pidsStartNextBlock) > 0 {
-		for _, l := range v.eventListeners {
-			l.OnProcessesStart(pidsStartNextBlock)
-		}
-	}
-	// Notify listeners about the commit state
-	for _, l := range v.eventListeners {
-		if err := l.Commit(height); err != nil {
-			log.Warnf("event callback error on commit: %v", err)
-		}
-	}
 
 	// Update the main state tree
 	mainTreeView, err := v.store.TreeView(nil)

vochain/state/votes.go

@@ -235,6 +235,7 @@ func (s *State) Vote(processID, nullifier []byte, committed bool) (*models.State
 	} else if err != nil {
 		return nil, err
 	}
+
 	sdbVoteBytes, err := votesTree.Get(vid)
 	if errors.Is(err, arbo.ErrKeyNotFound) {
 		return nil, ErrVoteNotFound