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Refactor GetNextResourceIndex to make it work properly with transaction (#21469)

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Related:
* #21362

This PR uses a general and stable method to generate resource index (eg:
Issue Index, PR Index)

If the code looks good, I can add more tests

ps: please skip the diff, only have a look at the new code. It's
entirely re-written.

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
This commit is contained in:
wxiaoguang 2022-10-16 18:44:16 +08:00 • committed by GitHub
parent 0647df3e83
commit 6f48a36227
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GPG key ID: 4AEE18F83AFDEB23
7 changed files with 215 additions and 89 deletions
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130
models/db/index.go
View file

@ -8,45 +8,15 @@ import (
"context"
"errors"
"fmt"
"code.gitea.io/gitea/modules/setting"
)
// ResourceIndex represents a resource index which could be used as issue/release and others
// We can create different tables i.e. issue_index, release_index and etc.
// We can create different tables i.e. issue_index, release_index, etc.
type ResourceIndex struct {
GroupID int64 `xorm:"pk"`
MaxIndex int64 `xorm:"index"`
}
// UpsertResourceIndex the function will not return until it acquires the lock or receives an error.
func UpsertResourceIndex(ctx context.Context, tableName string, groupID int64) (err error) {
// An atomic UPSERT operation (INSERT/UPDATE) is the only operation
// that ensures that the key is actually locked.
switch {
case setting.Database.UseSQLite3 || setting.Database.UsePostgreSQL:
_, err = Exec(ctx, fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
"VALUES (?,1) ON CONFLICT (group_id) DO UPDATE SET max_index = %s.max_index+1",
tableName, tableName), groupID)
case setting.Database.UseMySQL:
_, err = Exec(ctx, fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
"VALUES (?,1) ON DUPLICATE KEY UPDATE max_index = max_index+1", tableName),
groupID)
case setting.Database.UseMSSQL:
// https://weblogs.sqlteam.com/dang/2009/01/31/upsert-race-condition-with-merge/
_, err = Exec(ctx, fmt.Sprintf("MERGE %s WITH (HOLDLOCK) as target "+
"USING (SELECT ? AS group_id) AS src "+
"ON src.group_id = target.group_id "+
"WHEN MATCHED THEN UPDATE SET target.max_index = target.max_index+1 "+
"WHEN NOT MATCHED THEN INSERT (group_id, max_index) "+
"VALUES (src.group_id, 1);", tableName),
groupID)
default:
return fmt.Errorf("database type not supported")
}
return err
}
var (
// ErrResouceOutdated represents an error when request resource outdated
ErrResouceOutdated = errors.New("resource outdated")
@ -59,53 +29,85 @@ const (
MaxDupIndexAttempts = 3
)
// GetNextResourceIndex retried 3 times to generate a resource index
func GetNextResourceIndex(tableName string, groupID int64) (int64, error) {
for i := 0; i < MaxDupIndexAttempts; i++ {
idx, err := getNextResourceIndex(tableName, groupID)
if err == ErrResouceOutdated {
continue
}
if err != nil {
return 0, err
}
return idx, nil
// SyncMaxResourceIndex sync the max index with the resource
func SyncMaxResourceIndex(ctx context.Context, tableName string, groupID, maxIndex int64) (err error) {
e := GetEngine(ctx)
// try to update the max_index and acquire the write-lock for the record
res, err := e.Exec(fmt.Sprintf("UPDATE %s SET max_index=? WHERE group_id=? AND max_index<?", tableName), maxIndex, groupID, maxIndex)
if err != nil {
return err
}
return 0, ErrGetResourceIndexFailed
affected, err := res.RowsAffected()
if err != nil {
return err
}
if affected == 0 {
// if nothing is updated, the record might not exist or might be larger, it's safe to try to insert it again and then check whether the record exists
_, errIns := e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) VALUES (?, ?)", tableName), groupID, maxIndex)
var savedIdx int64
has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&savedIdx)
if err != nil {
return err
}
// if the record still doesn't exist, there must be some errors (insert error)
if !has {
if errIns == nil {
return errors.New("impossible error when SyncMaxResourceIndex, insert succeeded but no record is saved")
}
return errIns
}
}
return nil
}
// DeleteResouceIndex delete resource index
func DeleteResouceIndex(ctx context.Context, tableName string, groupID int64) error {
_, err := Exec(ctx, fmt.Sprintf("DELETE FROM %s WHERE group_id=?", tableName), groupID)
return err
}
// GetNextResourceIndex generates a resource index, it must run in the same transaction where the resource is created
func GetNextResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
e := GetEngine(ctx)
// getNextResourceIndex return the next index
func getNextResourceIndex(tableName string, groupID int64) (int64, error) {
ctx, commiter, err := TxContext()
// try to update the max_index to next value, and acquire the write-lock for the record
res, err := e.Exec(fmt.Sprintf("UPDATE %s SET max_index=max_index+1 WHERE group_id=?", tableName), groupID)
if err != nil {
return 0, err
}
defer commiter.Close()
var preIdx int64
if _, err := GetEngine(ctx).SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id = ?", tableName), groupID).Get(&preIdx); err != nil {
affected, err := res.RowsAffected()
if err != nil {
return 0, err
}
if err := UpsertResourceIndex(ctx, tableName, groupID); err != nil {
return 0, err
if affected == 0 {
// this slow path is only for the first time of creating a resource index
_, errIns := e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) VALUES (?, 0)", tableName), groupID)
res, err = e.Exec(fmt.Sprintf("UPDATE %s SET max_index=max_index+1 WHERE group_id=?", tableName), groupID)
if err != nil {
return 0, err
}
affected, err = res.RowsAffected()
if err != nil {
return 0, err
}
// if the update still can not update any records, the record must not exist and there must be some errors (insert error)
if affected == 0 {
if errIns == nil {
return 0, errors.New("impossible error when GetNextResourceIndex, insert and update both succeeded but no record is updated")
}
return 0, errIns
}
}
var curIdx int64
has, err := GetEngine(ctx).SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id = ? AND max_index=?", tableName), groupID, preIdx+1).Get(&curIdx)
// now, the new index is in database (protected by the transaction and write-lock)
var newIdx int64
has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&newIdx)
if err != nil {
return 0, err
}
if !has {
return 0, ErrResouceOutdated
return 0, errors.New("impossible error when GetNextResourceIndex, upsert succeeded but no record can be selected")
}
if err := commiter.Commit(); err != nil {
return 0, err
}
return curIdx, nil
return newIdx, nil
}
// DeleteResourceIndex delete resource index
func DeleteResourceIndex(ctx context.Context, tableName string, groupID int64) error {
_, err := Exec(ctx, fmt.Sprintf("DELETE FROM %s WHERE group_id=?", tableName), groupID)
return err
}

127
models/db/index_test.go Normal file
View file

@ -0,0 +1,127 @@
// Copyright 2022 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package db_test
import (
"context"
"errors"
"fmt"
"testing"
"code.gitea.io/gitea/models/db"
"code.gitea.io/gitea/models/unittest"
"github.com/stretchr/testify/assert"
)
type TestIndex db.ResourceIndex
func getCurrentResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
e := db.GetEngine(ctx)
var idx int64
has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&idx)
if err != nil {
return 0, err
}
if !has {
return 0, errors.New("no record")
}
return idx, nil
}
func TestSyncMaxResourceIndex(t *testing.T) {
assert.NoError(t, unittest.PrepareTestDatabase())
xe := unittest.GetXORMEngine()
assert.NoError(t, xe.Sync(&TestIndex{}))
err := db.SyncMaxResourceIndex(db.DefaultContext, "test_index", 10, 51)
assert.NoError(t, err)
// sync new max index
maxIndex, err := getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
assert.NoError(t, err)
assert.EqualValues(t, 51, maxIndex)
// smaller index doesn't change
err = db.SyncMaxResourceIndex(db.DefaultContext, "test_index", 10, 30)
assert.NoError(t, err)
maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
assert.NoError(t, err)
assert.EqualValues(t, 51, maxIndex)
// larger index changes
err = db.SyncMaxResourceIndex(db.DefaultContext, "test_index", 10, 62)
assert.NoError(t, err)
maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
assert.NoError(t, err)
assert.EqualValues(t, 62, maxIndex)
// commit transaction
err = db.WithTx(func(ctx context.Context) error {
err = db.SyncMaxResourceIndex(ctx, "test_index", 10, 73)
assert.NoError(t, err)
maxIndex, err = getCurrentResourceIndex(ctx, "test_index", 10)
assert.NoError(t, err)
assert.EqualValues(t, 73, maxIndex)
return nil
})
assert.NoError(t, err)
maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
assert.NoError(t, err)
assert.EqualValues(t, 73, maxIndex)
// rollback transaction
err = db.WithTx(func(ctx context.Context) error {
err = db.SyncMaxResourceIndex(ctx, "test_index", 10, 84)
maxIndex, err = getCurrentResourceIndex(ctx, "test_index", 10)
assert.NoError(t, err)
assert.EqualValues(t, 84, maxIndex)
return errors.New("test rollback")
})
assert.Error(t, err)
maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 10)
assert.NoError(t, err)
assert.EqualValues(t, 73, maxIndex) // the max index doesn't change because the transaction was rolled back
}
func TestGetNextResourceIndex(t *testing.T) {
assert.NoError(t, unittest.PrepareTestDatabase())
xe := unittest.GetXORMEngine()
assert.NoError(t, xe.Sync(&TestIndex{}))
// create a new record
maxIndex, err := db.GetNextResourceIndex(db.DefaultContext, "test_index", 20)
assert.NoError(t, err)
assert.EqualValues(t, 1, maxIndex)
// increase the existing record
maxIndex, err = db.GetNextResourceIndex(db.DefaultContext, "test_index", 20)
assert.NoError(t, err)
assert.EqualValues(t, 2, maxIndex)
// commit transaction
err = db.WithTx(func(ctx context.Context) error {
maxIndex, err = db.GetNextResourceIndex(ctx, "test_index", 20)
assert.NoError(t, err)
assert.EqualValues(t, 3, maxIndex)
return nil
})
assert.NoError(t, err)
maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 20)
assert.NoError(t, err)
assert.EqualValues(t, 3, maxIndex)
// rollback transaction
err = db.WithTx(func(ctx context.Context) error {
maxIndex, err = db.GetNextResourceIndex(ctx, "test_index", 20)
assert.NoError(t, err)
assert.EqualValues(t, 4, maxIndex)
return errors.New("test rollback")
})
assert.Error(t, err)
maxIndex, err = getCurrentResourceIndex(db.DefaultContext, "test_index", 20)
assert.NoError(t, err)
assert.EqualValues(t, 3, maxIndex) // the max index doesn't change because the transaction was rolled back
}

14
models/issues/issue.go
View file

@ -1064,19 +1064,19 @@ func NewIssueWithIndex(ctx context.Context, doer *user_model.User, opts NewIssue
// NewIssue creates new issue with labels for repository.
func NewIssue(repo *repo_model.Repository, issue *Issue, labelIDs []int64, uuids []string) (err error) {
idx, err := db.GetNextResourceIndex("issue_index", repo.ID)
if err != nil {
return fmt.Errorf("generate issue index failed: %v", err)
}
issue.Index = idx
ctx, committer, err := db.TxContext()
if err != nil {
return err
}
defer committer.Close()
idx, err := db.GetNextResourceIndex(ctx, "issue_index", repo.ID)
if err != nil {
return fmt.Errorf("generate issue index failed: %w", err)
}
issue.Index = idx
if err = NewIssueWithIndex(ctx, issue.Poster, NewIssueOptions{
Repo: repo,
Issue: issue,

8
models/issues/issue_index.go
View file

@ -15,16 +15,12 @@ func RecalculateIssueIndexForRepo(repoID int64) error {
}
defer committer.Close()
if err := db.UpsertResourceIndex(ctx, "issue_index", repoID); err != nil {
return err
}
var max int64
if _, err := db.GetEngine(ctx).Select(" MAX(`index`)").Table("issue").Where("repo_id=?", repoID).Get(&max); err != nil {
if _, err = db.GetEngine(ctx).Select(" MAX(`index`)").Table("issue").Where("repo_id=?", repoID).Get(&max); err != nil {
return err
}
if _, err := db.GetEngine(ctx).Exec("UPDATE `issue_index` SET max_index=? WHERE group_id=?", max, repoID); err != nil {
if err = db.SyncMaxResourceIndex(ctx, "issue_index", repoID, max); err != nil {
return err
}

9
models/issues/issue_xref_test.go
View file

@ -131,7 +131,11 @@ func testCreateIssue(t *testing.T, repo, doer int64, title, content string, ispu
r := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: repo})
d := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: doer})
idx, err := db.GetNextResourceIndex("issue_index", r.ID)
ctx, committer, err := db.TxContext()
assert.NoError(t, err)
defer committer.Close()
idx, err := db.GetNextResourceIndex(ctx, "issue_index", r.ID)
assert.NoError(t, err)
i := &issues_model.Issue{
RepoID: r.ID,
@ -143,9 +147,6 @@ func testCreateIssue(t *testing.T, repo, doer int64, title, content string, ispu
Index: idx,
}
ctx, committer, err := db.TxContext()
assert.NoError(t, err)
defer committer.Close()
err = issues_model.NewIssueWithIndex(ctx, d, issues_model.NewIssueOptions{
Repo: r,
Issue: i,

14
models/issues/pull.go
View file

@ -490,13 +490,6 @@ func (pr *PullRequest) SetMerged(ctx context.Context) (bool, error) {
// NewPullRequest creates new pull request with labels for repository.
func NewPullRequest(outerCtx context.Context, repo *repo_model.Repository, issue *Issue, labelIDs []int64, uuids []string, pr *PullRequest) (err error) {
idx, err := db.GetNextResourceIndex("issue_index", repo.ID)
if err != nil {
return fmt.Errorf("generate pull request index failed: %v", err)
}
issue.Index = idx
ctx, committer, err := db.TxContext()
if err != nil {
return err
@ -504,6 +497,13 @@ func NewPullRequest(outerCtx context.Context, repo *repo_model.Repository, issue
defer committer.Close()
ctx.WithContext(outerCtx)
idx, err := db.GetNextResourceIndex(ctx, "issue_index", repo.ID)
if err != nil {
return fmt.Errorf("generate pull request index failed: %v", err)
}
issue.Index = idx
if err = NewIssueWithIndex(ctx, issue.Poster, NewIssueOptions{
Repo: repo,
Issue: issue,

2
models/repo.go
View file

@ -163,7 +163,7 @@ func DeleteRepository(doer *user_model.User, uid, repoID int64) error {
}
// Delete issue index
if err := db.DeleteResouceIndex(ctx, "issue_index", repoID); err != nil {
if err := db.DeleteResourceIndex(ctx, "issue_index", repoID); err != nil {
return err
}