store/rootmulti: non-determinism in (*Store).buildCommitInfo due to map iteration

[odeke-em]

Summary of Bug

If we examine the code in

cosmos-sdk/store/rootmulti/store.go

Lines 911 to 919 in 686c50d

	for key, store := range rs.stores {
	if store.GetStoreType() == types.StoreTypeTransient {
	continue
	}
	storeInfos = append(storeInfos, types.StoreInfo{
	Name: key.Name(),
	CommitId: store.LastCommitID(),
	})
	}

we can see that the result returned sends back an object whose .StoreInfos value was built from map iteration, which is non-deterministic unfortunately.

Version

77cf430

Fix

The fix for this is to firstly collect the values into a slice of types.StoreKey, invoking sort.Slice using key.Name() as the sorter, and then iterating using that sorted slice, like this

diff --git a/store/rootmulti/store.go b/store/rootmulti/store.go
index d31cb2e42..7a046959f 100644
--- a/store/rootmulti/store.go
+++ b/store/rootmulti/store.go
@@ -907,8 +907,17 @@ func (rs *Store) loadCommitStoreFromParams(key types.StoreKey, id types.CommitID
 }
 
 func (rs *Store) buildCommitInfo(version int64) *types.CommitInfo {
+	keys := make([]types.StoreKey, 0, len(rs.stores))
+	for key := range rs.stores {
+		keys = append(keys, key)
+	}
+	sort.Slice(keys, func(i, j int) bool {
+		return keys[i].Name() < keys[j].Name()
+	})
+
 	storeInfos := []types.StoreInfo{}
-	for key, store := range rs.stores {
+	for _, key := range keys {
+		store := rs.stores[key]
 		if store.GetStoreType() == types.StoreTypeTransient {
 			continue
 		}

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[kocubinski]

@odeke-em Would you be willing to a make PR of this patch?

[odeke-em]

@odeke-em Would you be willing to a make PR of this patch?

@kirbyquerby might be interested in this.