mirror of https://codeberg.org/forgejo/forgejo
113 lines
3.9 KiB
Go
113 lines
3.9 KiB
Go
// Copyright 2021 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package db
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import (
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"context"
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"errors"
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"fmt"
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)
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// ResourceIndex represents a resource index which could be used as issue/release and others
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// We can create different tables i.e. issue_index, release_index, etc.
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type ResourceIndex struct {
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GroupID int64 `xorm:"pk"`
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MaxIndex int64 `xorm:"index"`
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}
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var (
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// ErrResouceOutdated represents an error when request resource outdated
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ErrResouceOutdated = errors.New("resource outdated")
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// ErrGetResourceIndexFailed represents an error when resource index retries 3 times
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ErrGetResourceIndexFailed = errors.New("get resource index failed")
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)
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const (
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// MaxDupIndexAttempts max retry times to create index
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MaxDupIndexAttempts = 3
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)
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// SyncMaxResourceIndex sync the max index with the resource
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func SyncMaxResourceIndex(ctx context.Context, tableName string, groupID, maxIndex int64) (err error) {
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e := GetEngine(ctx)
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// try to update the max_index and acquire the write-lock for the record
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res, err := e.Exec(fmt.Sprintf("UPDATE %s SET max_index=? WHERE group_id=? AND max_index<?", tableName), maxIndex, groupID, maxIndex)
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if err != nil {
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return err
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}
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affected, err := res.RowsAffected()
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if err != nil {
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return err
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}
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if affected == 0 {
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// 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
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_, errIns := e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) VALUES (?, ?)", tableName), groupID, maxIndex)
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var savedIdx int64
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has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&savedIdx)
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if err != nil {
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return err
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}
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// if the record still doesn't exist, there must be some errors (insert error)
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if !has {
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if errIns == nil {
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return errors.New("impossible error when SyncMaxResourceIndex, insert succeeded but no record is saved")
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}
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return errIns
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}
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}
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return nil
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}
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// GetNextResourceIndex generates a resource index, it must run in the same transaction where the resource is created
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func GetNextResourceIndex(ctx context.Context, tableName string, groupID int64) (int64, error) {
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e := GetEngine(ctx)
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// try to update the max_index to next value, and acquire the write-lock for the record
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res, err := e.Exec(fmt.Sprintf("UPDATE %s SET max_index=max_index+1 WHERE group_id=?", tableName), groupID)
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if err != nil {
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return 0, err
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}
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affected, err := res.RowsAffected()
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if err != nil {
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return 0, err
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}
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if affected == 0 {
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// this slow path is only for the first time of creating a resource index
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_, errIns := e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) VALUES (?, 0)", tableName), groupID)
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res, err = e.Exec(fmt.Sprintf("UPDATE %s SET max_index=max_index+1 WHERE group_id=?", tableName), groupID)
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if err != nil {
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return 0, err
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}
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affected, err = res.RowsAffected()
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if err != nil {
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return 0, err
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}
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// if the update still can not update any records, the record must not exist and there must be some errors (insert error)
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if affected == 0 {
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if errIns == nil {
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return 0, errors.New("impossible error when GetNextResourceIndex, insert and update both succeeded but no record is updated")
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}
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return 0, errIns
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}
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}
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// now, the new index is in database (protected by the transaction and write-lock)
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var newIdx int64
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has, err := e.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id=?", tableName), groupID).Get(&newIdx)
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if err != nil {
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return 0, err
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}
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if !has {
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return 0, errors.New("impossible error when GetNextResourceIndex, upsert succeeded but no record can be selected")
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}
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return newIdx, nil
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}
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// DeleteResourceIndex delete resource index
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func DeleteResourceIndex(ctx context.Context, tableName string, groupID int64) error {
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_, err := Exec(ctx, fmt.Sprintf("DELETE FROM %s WHERE group_id=?", tableName), groupID)
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return err
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}
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