Disable multithreaded scanners for sqlite

as it's not reliable

api/database/database.go

@@ -5,9 +5,9 @@ import (
 	"log"
 	"net/url"
 	"os"
-	"strings"
 	"time"
 
+	"github.com/photoview/photoview/api/database/drivers"
 	"github.com/photoview/photoview/api/graphql/models"
 	"github.com/pkg/errors"
 
@@ -66,9 +66,8 @@ func SetupDatabase() (*gorm.DB, error) {
 	config.Logger = logger.Default.LogMode(logger.Info)
 
 	var databaseDialect gorm.Dialector
-	databaseDriver := strings.ToLower(os.Getenv("PHOTOVIEW_DATABASE_DRIVER"))
-	switch databaseDriver {
-	case "mysql":
+	switch drivers.DatabaseDriver() {
+	case drivers.DatabaseDriverMysql:
 		mysqlAddress, err := getMysqlAddress()
 		if err != nil {
 			return nil, err
@@ -76,7 +75,7 @@ func SetupDatabase() (*gorm.DB, error) {
 		log.Printf("Connecting to database: %s", mysqlAddress)
 		databaseDialect = mysql.Open(mysqlAddress.String())
 
-	case "sqlite":
+	case drivers.DatabaseDriverSqlite:
 		sqliteAddress, err := getSqliteAddress()
 		if err != nil {
 			return nil, err

api/database/drivers/database_drivers.go

@@ -0,0 +1,28 @@
+package drivers
+
+import (
+	"os"
+	"strings"
+)
+
+type DatabaseDriverType string
+
+const (
+	DatabaseDriverMysql  DatabaseDriverType = "mysql"
+	DatabaseDriverSqlite DatabaseDriverType = "sqlite"
+)
+
+func DatabaseDriver() DatabaseDriverType {
+
+	var driver DatabaseDriverType
+	driverString := strings.ToLower(os.Getenv("PHOTOVIEW_DATABASE_DRIVER"))
+
+	switch driverString {
+	case "mysql":
+		driver = DatabaseDriverMysql
+	case "sqlite":
+		driver = DatabaseDriverSqlite
+	}
+
+	return driver
+}

api/graphql/models/site_info.go

@@ -1,6 +1,7 @@
 package models
 
 import (
+	db_drivers "github.com/photoview/photoview/api/database/drivers"
 	"github.com/pkg/errors"
 	"gorm.io/gorm"
 )
@@ -22,10 +23,16 @@ func GetSiteInfo(db *gorm.DB) (*SiteInfo, error) {
 
 	if err := db.First(&siteInfo).Error; err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
+
+			defaultConcurrentWorkers := 3
+			if db_drivers.DatabaseDriver() == db_drivers.DatabaseDriverSqlite {
+				defaultConcurrentWorkers = 1
+			}
+
 			siteInfo = SiteInfo{
 				InitialSetup:         true,
 				PeriodicScanInterval: 0,
-				ConcurrentWorkers:    3,
+				ConcurrentWorkers:    defaultConcurrentWorkers,
 			}
 
 			if err := db.Create(&siteInfo).Error; err != nil {

api/graphql/resolvers/scanner.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"time"
 
+	"github.com/photoview/photoview/api/database/drivers"
 	"github.com/photoview/photoview/api/graphql/models"
 	"github.com/photoview/photoview/api/scanner"
 	"github.com/pkg/errors"
@@ -66,6 +67,10 @@ func (r *mutationResolver) SetScannerConcurrentWorkers(ctx context.Context, work
 		return 0, errors.New("concurrent workers must at least be 1")
 	}
 
+	if workers > 1 && drivers.DatabaseDriver() == drivers.DatabaseDriverSqlite {
+		return 0, errors.New("multiple workers not supported for SQLite databases")
+	}
+
 	if err := r.Database.Session(&gorm.Session{AllowGlobalUpdate: true}).Model(&models.SiteInfo{}).Update("concurrent_workers", workers).Error; err != nil {
 		return 0, err
 	}