// GenID adds step to the value for key and returns the sum.
func GenID(txn kv.Transaction, key []byte, step int) (int64, error) {
if len(key) == 0 {
return 0, errors.New("Invalid key")
}
err := txn.LockKeys(key)
if err != nil {
return 0, err
}
id, err := txn.Inc(key, int64(step))
if err != nil {
return 0, errors.Trace(err)
}
return id, errors.Trace(err)
}
func (d *ddl) verifySchemaMetaVersion(txn kv.Transaction, schemaMetaVersion int64) error {
curVer, err := txn.GetInt64(meta.SchemaMetaVersionKey)
if err != nil {
return errors.Trace(err)
}
if curVer != schemaMetaVersion {
return errors.Errorf("Schema changed, our version %d, but got %d", schemaMetaVersion, curVer)
}
// Increment version.
_, err = txn.Inc(meta.SchemaMetaVersionKey, 1)
if err != nil {
return errors.Trace(err)
}
if err := txn.LockKeys(meta.SchemaMetaVersionKey); err != nil {
return errors.Trace(err)
}
return errors.Trace(err)
}