Mercurial > gemma
view pkg/imports/misc.go @ 4955:5c43427fc2bf fairway-marks-import
Do not rollback savepoint if statement returned no rows
Statements that might or might not return rows can modify the database
in both cases e.g. through DML in functions, CTEs or triggers.
Not returning any rows but modifying the database is not an error
in such a case. Thus, prevent ROLLBACK.
author | Tom Gottfried <tom@intevation.de> |
---|---|
date | Wed, 26 Feb 2020 11:25:28 +0100 |
parents | 1d50ac8dd688 |
children |
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// This is Free Software under GNU Affero General Public License v >= 3.0 // without warranty, see README.md and license for details. // // SPDX-License-Identifier: AGPL-3.0-or-later // License-Filename: LICENSES/AGPL-3.0.txt // // Copyright (C) 2018 by via donau // – Österreichische Wasserstraßen-Gesellschaft mbH // Software engineering by Intevation GmbH // // Author(s): // * Sascha L. Teichmann <sascha.teichmann@intevation.de> package imports import ( "context" "database/sql" "fmt" "strings" ) type stringCounter map[string]int func (sc stringCounter) String() string { var b strings.Builder for t, c := range sc { if b.Len() > 0 { b.WriteString(", ") } b.WriteString(fmt.Sprintf("%s: %d", t, c)) } return b.String() } // Savepoint is a function wrapper to hide the details // of managing database SAVEPOINTs. // If the returned function is called with a callback // the callback is run in a SAVEPOINT. // If the callback returns w/o an error or with sql.ErrNoRows the SAVEPOINT // is released. Otherwise the SAVEPOINT is rolled back. func Savepoint( ctx context.Context, tx *sql.Tx, name string, ) func(func() error) error { var ( savepoint = "SAVEPOINT " + name rollback = "ROLLBACK TO SAVEPOINT " + name release = "RELEASE SAVEPOINT " + name ) return func(fn func() error) (err error) { if _, err = tx.ExecContext(ctx, savepoint); err != nil { return } var done bool defer func() { if !done { _, err2 := tx.ExecContext(ctx, rollback) if err == nil { err = err2 } } }() // Release SAVEPOINT if statements run in fn returned no database error if err = fn(); err == nil || err == sql.ErrNoRows { done = true if _, err2 := tx.ExecContext(ctx, release); err2 != nil { err = err2 } } return } }