func (db *DB) GetConfig(inst flux.InstanceID) (instance.Config, error) {
var c string
err := db.conn.QueryRow(`SELECT config FROM config WHERE instance = $1`, string(inst)).Scan(&c)
switch err {
case nil:
break
case sql.ErrNoRows:
return instance.MakeConfig(), nil
default:
return instance.Config{}, err
}
var conf instance.Config
return conf, json.Unmarshal([]byte(c), &conf)
}
func (db *DB) UpdateConfig(inst flux.InstanceID, update instance.UpdateFunc) error {
tx, err := db.conn.Begin()
if err != nil {
return err
}
var (
currentConfig instance.Config
confString string
)
switch tx.QueryRow(`SELECT config FROM config WHERE instance = $1`, string(inst)).Scan(&confString) {
case sql.ErrNoRows:
currentConfig = instance.MakeConfig()
case nil:
if err = json.Unmarshal([]byte(confString), ¤tConfig); err != nil {
return err
}
default:
return err
}
newConfig, err := update(currentConfig)
if err != nil {
err2 := tx.Rollback()
if err2 != nil {
return errors.Wrapf(err, "transaction rollback failed: %s", err2)
}
return err
}
newConfigBytes, err := json.Marshal(newConfig)
if err != nil {
return err
}
_, err = tx.Exec(`DELETE FROM config WHERE instance = $1`, string(inst))
if err == nil {
_, err = tx.Exec(`INSERT INTO config (instance, config, stamp) VALUES
($1, $2, now())`, string(inst), string(newConfigBytes))
}
if err == nil {
err = tx.Commit()
}
return err
}