postgres: Move lock out of ensureVersionTable, for consistency with other SQL operations.

Author: Lukas Joergensen

database/postgres/postgres.go

@@ -98,10 +98,23 @@ func WithInstance(instance *sql.DB, config *Config) (database.Driver, error) {
 		config: config,
 	}
 
+	if err = px.Lock(); err != nil {
+		return nil, err
+	}
+
 	if err := px.ensureVersionTable(); err != nil {
 		return nil, err
 	}
 
+	if e := px.Unlock(); e != nil {
+		if err == nil {
+			err = e
+		} else {
+			err = multierror.Append(err, e)
+		}
+		return nil, err
+	}
+
 	return px, nil
 }
 
@@ -334,20 +347,6 @@ func (p *Postgres) Drop() error {
 }
 
 func (p *Postgres) ensureVersionTable() (err error) {
-	if err = p.Lock(); err != nil {
-		return err
-	}
-
-	defer func() {
-		if e := p.Unlock(); e != nil {
-			if err == nil {
-				err = e
-			} else {
-				err = multierror.Append(err, e)
-			}
-		}
-	}()
-
 	query := `CREATE TABLE IF NOT EXISTS "` + p.config.MigrationsTable + `" (version bigint not null primary key, dirty boolean not null)`
 	if _, err = p.conn.ExecContext(context.Background(), query); err != nil {
 		return &database.Error{OrigErr: err, Query: []byte(query)}