gitea/models/db/engine_init.go

// Copyright 2024 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package db

import (
	"context"
	"database/sql"
	"fmt"
	"time"

	"gitea.dev/modules/log"
	"gitea.dev/modules/setting"

	"xorm.io/xorm"
	"xorm.io/xorm/names"
)

func init() {
	gonicNames := []string{"SSL", "UID"}
	for _, name := range gonicNames {
		names.LintGonicMapper[name] = true
	}
}

// newXORMEngine returns a new XORM engine from the configuration
func newXORMEngine() (*xorm.Engine, error) {
	connOpts := GlobalConnOptions()
	driver, connStr, err := ConnStr(connOpts)
	if err != nil {
		return nil, err
	}

	engine, err := xorm.NewEngine(driver, connStr)
	if err != nil {
		return nil, err
	}
	switch {
	case connOpts.Type.IsMySQL():
		engine.Dialect().SetParams(map[string]string{"rowFormat": "DYNAMIC"})
	case connOpts.Type.IsMSSQL():
		engine.Dialect().SetParams(map[string]string{"DEFAULT_VARCHAR": "nvarchar"})
	}
	engine.SetSchema(connOpts.Schema)
	return engine, nil
}

// InitEngine initializes the xorm.Engine and sets it as XORM's default context
func InitEngine(ctx context.Context) error {
	xe, err := newXORMEngine()
	if err != nil {
		return fmt.Errorf("failed to init database engine: %w", err)
	}

	xe.SetMapper(names.GonicMapper{})
	// WARNING: for serv command, MUST remove the output to os.stdout,
	// so use log file to instead print to stdout.
	xe.SetLogger(NewXORMLogger(setting.Database.LogSQL))
	xe.ShowSQL(setting.Database.LogSQL)
	xe.SetMaxOpenConns(setting.Database.MaxOpenConns)
	xe.SetMaxIdleConns(setting.Database.MaxIdleConns)
	xe.SetConnMaxLifetime(setting.Database.ConnMaxLifetime)

	if setting.Database.Type.IsMySQL() {
		// like PostgreSQL and MSSQL, avoids MariaDB snapshot isolation errors
		xe.SetDefaultTxOptions(&sql.TxOptions{Isolation: sql.LevelReadCommitted})
	}

	if setting.Database.SlowQueryThreshold > 0 {
		xe.AddHook(&EngineHook{
			Threshold: setting.Database.SlowQueryThreshold,
			Logger:    log.GetLogger("xorm"),
		})
	}

	SetDefaultEngine(ctx, xe)
	return nil
}

// SetDefaultEngine sets the default engine for db
func SetDefaultEngine(ctx context.Context, eng *xorm.Engine) {
	xormEngine = eng
	xormEngine.SetDefaultContext(ctx)
}

// UnsetDefaultEngine closes and unsets the default engine
// We hope the SetDefaultEngine and UnsetDefaultEngine can be paired, but it's impossible now,
// there are many calls to InitEngine -> SetDefaultEngine directly to overwrite the `xormEngine` and `xormContext` without close
// Global database engine related functions are all racy and there is no graceful close right now.
func UnsetDefaultEngine() {
	if xormEngine != nil {
		_ = xormEngine.Close()
		xormEngine = nil
	}
}

// InitEngineWithMigration initializes a new xorm.Engine and sets it as the XORM's default context
// This function must never call .Sync() if the provided migration function fails.
// When called from the "doctor" command, the migration function is a version check
// that prevents the doctor from fixing anything in the database if the migration level
// is different from the expected value.
func InitEngineWithMigration(ctx context.Context, migrateFunc func(context.Context, EngineMigration) error) (err error) {
	if err = InitEngine(ctx); err != nil {
		return err
	}

	if err = xormEngine.Ping(); err != nil {
		return err
	}

	preprocessDatabaseCollation(xormEngine)

	if setting.Database.Type.IsMSSQL() {
		enableMSSQLReadCommittedSnapshot(ctx, xormEngine)
	}

	// We have to run migrateFunc here in case the user is re-running installation on a previously created DB.
	// If we do not then table schemas will be changed and there will be conflicts when the migrations run properly.
	//
	// Installation should only be being re-run if users want to recover an old database.
	// However, we should think carefully about should we support re-install on an installed instance,
	// as there may be other problems due to secret reinitialization.
	if err = migrateFunc(ctx, xormEngine); err != nil {
		return fmt.Errorf("migrate: %w", err)
	}

	if err = SyncAllTables(); err != nil {
		return fmt.Errorf("sync database struct error: %w", err)
	}

	for _, initFunc := range registeredInitFuncs {
		if err := initFunc(); err != nil {
			return fmt.Errorf("initFunc failed: %w", err)
		}
	}

	return nil
}

// enableMSSQLReadCommittedSnapshot stops MSSQL reads waiting on writers, like PostgreSQL and MySQL
func enableMSSQLReadCommittedSnapshot(ctx context.Context, engine EngineMigration) {
	ctx, cancel := context.WithTimeout(ctx, 5*time.Second) // ALTER waits for all other connections to close
	defer cancel()
	if _, err := engine.Context(ctx).Exec("IF (SELECT is_read_committed_snapshot_on FROM sys.databases WHERE database_id = DB_ID()) = 0 ALTER DATABASE CURRENT SET READ_COMMITTED_SNAPSHOT ON"); err != nil {
		log.Error("Unable to set READ_COMMITTED_SNAPSHOT=ON: %v", err)
	}
}