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gitea/models/index.go
zeripath 6f261fdf47
Add unique constraint back into issue_index (#16938)
There is a flaw in #16820 where it was missed that although xorm will
not add a primary key to a table during syncing, it will remove an
unique constraint.

Users upgrading from 1.15.0 to 1.15.1 will therefore lose the unique
constraint that makes this table work unless they run `gitea doctor
recreate-table issue_index`.  Postgres helpfully warns about this
situation but MySQL does not.

Main/1.16-dev is not affected by this issue as there is a migration that
does the above recreation by default. Users moving directly to 1.15.1
from 1.14.x or lower are also not affected.

Whilst we could force all users who ran 1.15.0 to do the above
recreate-table call, this PR proposes an alternative: Just add the
unique constraint back in for 1.15.x. This won't have any long term
effects - just some wasted space for the unnecessary index.

Fix #16936

Signed-off-by: Andrew Thornton <art27@cantab.net>
2021-09-03 17:35:18 +08:00

113 lines
3.5 KiB
Go

// 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:"pk 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
}