Add a new table issue_index to store the max issue index so that issu…

…e could be deleted with no duplicated index (#15599)

* Add a new table issue_index to store the max issue index so that issue could be deleted with no duplicated index

* Fix pull index

* Add tests for concurrent creating issues

* Fix lint

* Fix tests

* Fix postgres test

* Add test for migration v180

* Rename wrong test file name

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lauris BH <lauris@nix.lv>

models/fixtures/issue.yml

@@ -152,7 +152,7 @@
 -
   id: 13
   repo_id: 50
-  index: 0
+  index: 1
   poster_id: 2
   name: issue in active repo
   content: we'll be testing github issue 13171 with this.
@@ -164,7 +164,7 @@
 -
   id: 14
   repo_id: 51
-  index: 0
+  index: 1
   poster_id: 2
   name: issue in archived repo
   content: we'll be testing github issue 13171 with this.

models/fixtures/issue_index.yml

@@ -0,0 +1,24 @@
+-
+  group_id: 1
+  max_index: 5
+-
+  group_id: 2
+  max_index: 2
+-
+  group_id: 3
+  max_index: 2
+-
+  group_id: 10
+  max_index: 1
+-
+  group_id: 48
+  max_index: 1
+-
+  group_id: 42
+  max_index: 1
+-
+  group_id: 50
+  max_index: 1
+-
+  group_id: 51
+  max_index: 1

models/index.go

@@ -0,0 +1,113 @@
+// Copyright 2021 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 models
+
+import (
+	"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.
+type ResourceIndex struct {
+	GroupID  int64 `xorm:"unique"`
+	MaxIndex int64 `xorm:"index"`
+}
+
+// IssueIndex represents the issue index table
+type IssueIndex ResourceIndex
+
+// upsertResourceIndex the function will not return until it acquires the lock or receives an error.
+func upsertResourceIndex(e Engine, 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 = e.Exec(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 = e.Exec(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 = e.Exec(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
+}
+
+var (
+	// ErrResouceOutdated represents an error when request resource outdated
+	ErrResouceOutdated = errors.New("resource outdated")
+	// ErrGetResourceIndexFailed represents an error when resource index retries 3 times
+	ErrGetResourceIndexFailed = errors.New("get resource index failed")
+)
+
+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
+	}
+	return 0, ErrGetResourceIndexFailed
+}
+
+// deleteResouceIndex delete resource index
+func deleteResouceIndex(e Engine, tableName string, groupID int64) error {
+	_, err := e.Exec(fmt.Sprintf("DELETE FROM %s WHERE group_id=?", tableName), groupID)
+	return err
+}
+
+// getNextResourceIndex return the next index
+func getNextResourceIndex(tableName string, groupID int64) (int64, error) {
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return 0, err
+	}
+	var preIdx int64
+	_, err := sess.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id = ?", tableName), groupID).Get(&preIdx)
+	if err != nil {
+		return 0, err
+	}
+
+	if err := upsertResourceIndex(sess, tableName, groupID); err != nil {
+		return 0, err
+	}
+
+	var curIdx int64
+	has, err := sess.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id = ? AND max_index=?", tableName), groupID, preIdx+1).Get(&curIdx)
+	if err != nil {
+		return 0, err
+	}
+	if !has {
+		return 0, ErrResouceOutdated
+	}
+	if err := sess.Commit(); err != nil {
+		return 0, err
+	}
+	return curIdx, nil
+}

models/index_test.go

@@ -0,0 +1,27 @@
+// Copyright 2021 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 models
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestResourceIndex(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	var wg sync.WaitGroup
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		go func(i int) {
+			testInsertIssue(t, fmt.Sprintf("issue %d", i+1), "my issue", 0)
+			wg.Done()
+		}(i)
+	}
+	wg.Wait()
+}

models/issue.go

@@ -78,9 +78,8 @@ var (
 )
 
 const (
-	issueTasksRegexpStr      = `(^\s*[-*]\s\[[\sxX]\]\s.)|(\n\s*[-*]\s\[[\sxX]\]\s.)`
-	issueTasksDoneRegexpStr  = `(^\s*[-*]\s\[[xX]\]\s.)|(\n\s*[-*]\s\[[xX]\]\s.)`
-	issueMaxDupIndexAttempts = 3
+	issueTasksRegexpStr     = `(^\s*[-*]\s\[[\sxX]\]\s.)|(\n\s*[-*]\s\[[\sxX]\]\s.)`
+	issueTasksDoneRegexpStr = `(^\s*[-*]\s\[[xX]\]\s.)|(\n\s*[-*]\s\[[xX]\]\s.)`
 )
 
 func init() {
@@ -896,21 +895,17 @@ func newIssue(e *xorm.Session, doer *User, opts NewIssueOptions) (err error) {
 		}
 	}
 
-	// Milestone validation should happen before insert actual object.
-	if _, err := e.SetExpr("`index`", "coalesce(MAX(`index`),0)+1").
-		Where("repo_id=?", opts.Issue.RepoID).
-		Insert(opts.Issue); err != nil {
-		return ErrNewIssueInsert{err}
+	if opts.Issue.Index <= 0 {
+		return fmt.Errorf("no issue index provided")
+	}
+	if opts.Issue.ID > 0 {
+		return fmt.Errorf("issue exist")
 	}
 
-	inserted, err := getIssueByID(e, opts.Issue.ID)
-	if err != nil {
+	if _, err := e.Insert(opts.Issue); err != nil {
 		return err
 	}
 
-	// Patch Index with the value calculated by the database
-	opts.Issue.Index = inserted.Index
-
 	if opts.Issue.MilestoneID > 0 {
 		if _, err = e.Exec("UPDATE `milestone` SET num_issues=num_issues+1 WHERE id=?", opts.Issue.MilestoneID); err != nil {
 			return err
@@ -987,24 +982,13 @@ func newIssue(e *xorm.Session, doer *User, opts NewIssueOptions) (err error) {
 
 // NewIssue creates new issue with labels for repository.
 func NewIssue(repo *Repository, issue *Issue, labelIDs []int64, uuids []string) (err error) {
-	// Retry several times in case INSERT fails due to duplicate key for (repo_id, index); see #7887
-	i := 0
-	for {
-		if err = newIssueAttempt(repo, issue, labelIDs, uuids); err == nil {
-			return nil
-		}
-		if !IsErrNewIssueInsert(err) {
-			return err
-		}
-		if i++; i == issueMaxDupIndexAttempts {
-			break
-		}
-		log.Error("NewIssue: error attempting to insert the new issue; will retry. Original error: %v", err)
+	idx, err := GetNextResourceIndex("issue_index", repo.ID)
+	if err != nil {
+		return fmt.Errorf("generate issue index failed: %v", err)
 	}
-	return fmt.Errorf("NewIssue: too many errors attempting to insert the new issue. Last error was: %v", err)
-}
 
-func newIssueAttempt(repo *Repository, issue *Issue, labelIDs []int64, uuids []string) (err error) {
+	issue.Index = idx
+
 	sess := x.NewSession()
 	defer sess.Close()
 	if err = sess.Begin(); err != nil {

models/issue_test.go

@@ -345,37 +345,45 @@ func TestGetRepoIDsForIssuesOptions(t *testing.T) {
 	}
 }
 
-func testInsertIssue(t *testing.T, title, content string) {
-	repo := AssertExistsAndLoadBean(t, &Repository{ID: 1}).(*Repository)
-	user := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
-
-	issue := Issue{
-		RepoID:   repo.ID,
-		PosterID: user.ID,
-		Title:    title,
-		Content:  content,
-	}
-	err := NewIssue(repo, &issue, nil, nil)
-	assert.NoError(t, err)
-
+func testInsertIssue(t *testing.T, title, content string, expectIndex int64) *Issue {
 	var newIssue Issue
-	has, err := x.ID(issue.ID).Get(&newIssue)
-	assert.NoError(t, err)
-	assert.True(t, has)
-	assert.EqualValues(t, issue.Title, newIssue.Title)
-	assert.EqualValues(t, issue.Content, newIssue.Content)
-	// there are 5 issues and max index is 5 on repository 1, so this one should 6
-	assert.EqualValues(t, 6, newIssue.Index)
+	t.Run(title, func(t *testing.T) {
+		repo := AssertExistsAndLoadBean(t, &Repository{ID: 1}).(*Repository)
+		user := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
+
+		issue := Issue{
+			RepoID:   repo.ID,
+			PosterID: user.ID,
+			Title:    title,
+			Content:  content,
+		}
+		err := NewIssue(repo, &issue, nil, nil)
+		assert.NoError(t, err)
 
-	_, err = x.ID(issue.ID).Delete(new(Issue))
-	assert.NoError(t, err)
+		has, err := x.ID(issue.ID).Get(&newIssue)
+		assert.NoError(t, err)
+		assert.True(t, has)
+		assert.EqualValues(t, issue.Title, newIssue.Title)
+		assert.EqualValues(t, issue.Content, newIssue.Content)
+		if expectIndex > 0 {
+			assert.EqualValues(t, expectIndex, newIssue.Index)
+		}
+	})
+	return &newIssue
 }
 
 func TestIssue_InsertIssue(t *testing.T) {
 	assert.NoError(t, PrepareTestDatabase())
 
-	testInsertIssue(t, "my issue1", "special issue's comments?")
-	testInsertIssue(t, `my issue2, this is my son's love \n \r \ `, "special issue's '' comments?")
+	// there are 5 issues and max index is 5 on repository 1, so this one should 6
+	issue := testInsertIssue(t, "my issue1", "special issue's comments?", 6)
+	_, err := x.ID(issue.ID).Delete(new(Issue))
+	assert.NoError(t, err)
+
+	issue = testInsertIssue(t, `my issue2, this is my son's love \n \r \ `, "special issue's '' comments?", 7)
+	_, err = x.ID(issue.ID).Delete(new(Issue))
+	assert.NoError(t, err)
+
 }
 
 func TestIssue_ResolveMentions(t *testing.T) {

models/issue_xref_test.go

@@ -125,12 +125,27 @@ func TestXRef_ResolveCrossReferences(t *testing.T) {
 func testCreateIssue(t *testing.T, repo, doer int64, title, content string, ispull bool) *Issue {
 	r := AssertExistsAndLoadBean(t, &Repository{ID: repo}).(*Repository)
 	d := AssertExistsAndLoadBean(t, &User{ID: doer}).(*User)
-	i := &Issue{RepoID: r.ID, PosterID: d.ID, Poster: d, Title: title, Content: content, IsPull: ispull}
+
+	idx, err := GetNextResourceIndex("issue_index", r.ID)
+	assert.NoError(t, err)
+	i := &Issue{
+		RepoID:   r.ID,
+		PosterID: d.ID,
+		Poster:   d,
+		Title:    title,
+		Content:  content,
+		IsPull:   ispull,
+		Index:    idx,
+	}
 
 	sess := x.NewSession()
 	defer sess.Close()
+
 	assert.NoError(t, sess.Begin())
-	_, err := sess.SetExpr("`index`", "coalesce(MAX(`index`),0)+1").Where("repo_id=?", repo).Insert(i)
+	err = newIssue(sess, d, NewIssueOptions{
+		Repo:  r,
+		Issue: i,
+	})
 	assert.NoError(t, err)
 	i, err = getIssueByID(sess, i.ID)
 	assert.NoError(t, err)

models/migrations/migrations.go

@@ -313,6 +313,8 @@ var migrations = []Migration{
 	NewMigration("Delete credentials from past migrations", deleteMigrationCredentials),
 	// v181 -> v182
 	NewMigration("Always save primary email on email address table", addPrimaryEmail2EmailAddress),
+	// v182 -> v183
+	NewMigration("Add issue resource index table", addIssueResourceIndexTable),
 }
 
 // GetCurrentDBVersion returns the current db version