Fix halfCommitter and WithTx (#22366)

Related to #22362.

I overlooked that there's always `committer.Close()`, like:

```go
		ctx, committer, err := db.TxContext(db.DefaultContext)
		if err != nil {
			return nil
		}
		defer committer.Close()

		// ...

		if err != nil {
			return nil
		}

		// ...

		return committer.Commit()
```

So the `Close` of `halfCommitter` should ignore `commit and close`, it's
not a rollback.

See: [Why `halfCommitter` and `WithTx` should rollback IMMEDIATELY or
commit
LATER](https://github.com/go-gitea/gitea/pull/22366#issuecomment-1374778612).

Co-authored-by: techknowlogick <techknowlogick@gitea.io>
This commit is contained in:
Jason Song 2023-01-10 01:19:19 +08:00 committed by GitHub
parent 99a675f4a1
commit a35714372d
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
2 changed files with 124 additions and 5 deletions

View file

@ -98,19 +98,31 @@ type Committer interface {
// halfCommitter is a wrapper of Committer.
// It can be closed early, but can't be committed early, it is useful for reusing a transaction.
type halfCommitter struct {
Committer
committer Committer
committed bool
}
func (*halfCommitter) Commit() error {
// do nothing
func (c *halfCommitter) Commit() error {
c.committed = true
// should do nothing, and the parent committer will commit later
return nil
}
func (c *halfCommitter) Close() error {
if c.committed {
// it's "commit and close", should do nothing, and the parent committer will commit later
return nil
}
// it's "rollback and close", let the parent committer rollback right now
return c.committer.Close()
}
// TxContext represents a transaction Context,
// it will reuse the existing transaction in the parent context or create a new one.
func TxContext(parentCtx context.Context) (*Context, Committer, error) {
if sess, ok := inTransaction(parentCtx); ok {
return newContext(parentCtx, sess, true), &halfCommitter{Committer: sess}, nil
return newContext(parentCtx, sess, true), &halfCommitter{committer: sess}, nil
}
sess := x.NewSession()
@ -126,7 +138,12 @@ func TxContext(parentCtx context.Context) (*Context, Committer, error) {
// this function will reuse it otherwise will create a new one and close it when finished.
func WithTx(parentCtx context.Context, f func(ctx context.Context) error) error {
if sess, ok := inTransaction(parentCtx); ok {
return f(newContext(parentCtx, sess, true))
err := f(newContext(parentCtx, sess, true))
if err != nil {
// rollback immediately, in case the caller ignores returned error and tries to commit the transaction.
_ = sess.Close()
}
return err
}
return txWithNoCheck(parentCtx, f)
}

View file

@ -0,0 +1,102 @@
// Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package db // it's not db_test, because this file is for testing the private type halfCommitter
import (
"fmt"
"testing"
"github.com/stretchr/testify/assert"
)
type MockCommitter struct {
wants []string
gots []string
}
func NewMockCommitter(wants ...string) *MockCommitter {
return &MockCommitter{
wants: wants,
}
}
func (c *MockCommitter) Commit() error {
c.gots = append(c.gots, "commit")
return nil
}
func (c *MockCommitter) Close() error {
c.gots = append(c.gots, "close")
return nil
}
func (c *MockCommitter) Assert(t *testing.T) {
assert.Equal(t, c.wants, c.gots, "want operations %v, but got %v", c.wants, c.gots)
}
func Test_halfCommitter(t *testing.T) {
/*
Do something like:
ctx, committer, err := db.TxContext(db.DefaultContext)
if err != nil {
return nil
}
defer committer.Close()
// ...
if err != nil {
return nil
}
// ...
return committer.Commit()
*/
testWithCommitter := func(committer Committer, f func(committer Committer) error) {
if err := f(&halfCommitter{committer: committer}); err == nil {
committer.Commit()
}
committer.Close()
}
t.Run("commit and close", func(t *testing.T) {
mockCommitter := NewMockCommitter("commit", "close")
testWithCommitter(mockCommitter, func(committer Committer) error {
defer committer.Close()
return committer.Commit()
})
mockCommitter.Assert(t)
})
t.Run("rollback and close", func(t *testing.T) {
mockCommitter := NewMockCommitter("close", "close")
testWithCommitter(mockCommitter, func(committer Committer) error {
defer committer.Close()
if true {
return fmt.Errorf("error")
}
return committer.Commit()
})
mockCommitter.Assert(t)
})
t.Run("close and commit", func(t *testing.T) {
mockCommitter := NewMockCommitter("close", "close")
testWithCommitter(mockCommitter, func(committer Committer) error {
committer.Close()
committer.Commit()
return fmt.Errorf("error")
})
mockCommitter.Assert(t)
})
}