statedb: Add checks to see if table is registered

If a user forgets to register a table with the DB instance and then
proceeds to use it, the tablePos defaults to 0. This causes writes to
the table to end up in the wrong table.

This commit defaults the table pos to -1 to cause deliberate panics if
the code ever attempts to use the index of a unregistered table. This
commit also adds checks on the read and write transactions to detect
when an unregistered table is being used and throw a clear error.

Signed-off-by: Dylan Reimerink <[email protected]>

db.go

@@ -249,6 +249,9 @@ func (h Handle) WriteTxn(table TableMeta, tables ...TableMeta) WriteTxn {
 	smus := internal.SortableMutexes{}
 	for _, table := range allTables {
 		smus = append(smus, table.sortableMutex())
+		if table.tablePos() < 0 {
+			panic(tableError(table.Name(), ErrTableNotRegistered))
+		}
 	}
 	lockAt := time.Now()
 	smus.Lock()

errors.go

@@ -13,6 +13,10 @@ var (
 	// that share the same table name.
 	ErrDuplicateTable = errors.New("table already exists")
 
+	// ErrTableNotRegistered indicates that a user tries to write to a table that has not been
+	// registered with this StateDB instance.
+	ErrTableNotRegistered = errors.New("table not registered")
+
 	// ErrPrimaryIndexNotUnique indicates that the primary index for the table is not marked unique.
 	ErrPrimaryIndexNotUnique = errors.New("primary index not unique")
 

table.go

@@ -48,6 +48,7 @@ func NewTable[Obj any](
 		primaryIndexer:       primaryIndexer,
 		secondaryAnyIndexers: make(map[string]anyIndexer, len(secondaryIndexers)),
 		indexPositions:       make(map[string]int),
+		pos:                  -1,
 	}
 
 	table.indexPositions[primaryIndexer.indexName()] = PrimaryIndexPos

txn.go

@@ -68,6 +68,9 @@ func (txn *txn) getRevision(meta TableMeta) Revision {
 // indexReadTxn returns a transaction to read from the specific index.
 // If the table or index is not found this returns nil & error.
 func (txn *txn) indexReadTxn(meta TableMeta, indexPos int) (indexReadTxn, error) {
+	if meta.tablePos() < 0 {
+		return indexReadTxn{}, tableError(meta.Name(), ErrTableNotRegistered)
+	}
 	if txn.modifiedTables != nil {
 		entry := txn.modifiedTables[meta.tablePos()]
 		if entry != nil {