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	* Fix commit status index problem * remove unused functions * Add fixture and test for migration * Fix lint * Fix fixture * Fix lint * Fix test * Fix bug * Fix bug
		
			
				
	
	
		
			112 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			112 lines
		
	
	
		
			3.5 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// Copyright 2021 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package db
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import (
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	"errors"
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	"fmt"
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	"code.gitea.io/gitea/modules/setting"
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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 and 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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// UpsertResourceIndex the function will not return until it acquires the lock or receives an error.
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func UpsertResourceIndex(e Engine, tableName string, groupID int64) (err error) {
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	// An atomic UPSERT operation (INSERT/UPDATE) is the only operation
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	// that ensures that the key is actually locked.
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	switch {
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	case setting.Database.UseSQLite3 || setting.Database.UsePostgreSQL:
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		_, err = e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
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			"VALUES (?,1) ON CONFLICT (group_id) DO UPDATE SET max_index = %s.max_index+1",
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			tableName, tableName), groupID)
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	case setting.Database.UseMySQL:
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		_, err = e.Exec(fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
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			"VALUES (?,1) ON DUPLICATE KEY UPDATE max_index = max_index+1", tableName),
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			groupID)
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	case setting.Database.UseMSSQL:
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		// https://weblogs.sqlteam.com/dang/2009/01/31/upsert-race-condition-with-merge/
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		_, err = e.Exec(fmt.Sprintf("MERGE %s WITH (HOLDLOCK) as target "+
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			"USING (SELECT ? AS group_id) AS src "+
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			"ON src.group_id = target.group_id "+
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			"WHEN MATCHED THEN UPDATE SET target.max_index = target.max_index+1 "+
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			"WHEN NOT MATCHED THEN INSERT (group_id, max_index) "+
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			"VALUES (src.group_id, 1);", tableName),
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			groupID)
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	default:
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		return fmt.Errorf("database type not supported")
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	}
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	return
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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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// GetNextResourceIndex retried 3 times to generate a resource index
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func GetNextResourceIndex(tableName string, groupID int64) (int64, error) {
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	for i := 0; i < MaxDupIndexAttempts; i++ {
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		idx, err := getNextResourceIndex(tableName, groupID)
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		if err == ErrResouceOutdated {
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			continue
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		}
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		if err != nil {
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			return 0, err
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		}
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		return idx, nil
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	}
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	return 0, ErrGetResourceIndexFailed
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}
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// DeleteResouceIndex delete resource index
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func DeleteResouceIndex(e Engine, tableName string, groupID int64) error {
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	_, err := e.Exec(fmt.Sprintf("DELETE FROM %s WHERE group_id=?", tableName), groupID)
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	return err
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}
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// getNextResourceIndex return the next index
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func getNextResourceIndex(tableName string, groupID int64) (int64, error) {
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	sess := x.NewSession()
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	defer sess.Close()
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	if err := sess.Begin(); err != nil {
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		return 0, err
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	}
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	var preIdx int64
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	_, err := sess.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id = ?", tableName), groupID).Get(&preIdx)
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	if err != nil {
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		return 0, err
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	}
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	if err := UpsertResourceIndex(sess, tableName, groupID); err != nil {
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		return 0, err
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	}
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	var curIdx int64
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	has, err := sess.SQL(fmt.Sprintf("SELECT max_index FROM %s WHERE group_id = ? AND max_index=?", tableName), groupID, preIdx+1).Get(&curIdx)
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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, ErrResouceOutdated
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	}
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	if err := sess.Commit(); err != nil {
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		return 0, err
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	}
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	return curIdx, nil
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}
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