Inject DB into DataStore, instead of hardcode the dependency

db/db.go

@@ -4,12 +4,12 @@ import (
 	"database/sql"
 	"fmt"
 	"os"
-	"sync"
 
 	_ "github.com/mattn/go-sqlite3"
 	"github.com/navidrome/navidrome/conf"
 	_ "github.com/navidrome/navidrome/db/migration"
 	"github.com/navidrome/navidrome/log"
+	"github.com/navidrome/navidrome/utils/singleton"
 	"github.com/pressly/goose"
 )
 
@@ -18,26 +18,21 @@ var (
 	Path   string
 )
 
-var (
-	once sync.Once
-	db   *sql.DB
-)
-
 func Db() *sql.DB {
-	once.Do(func() {
-		var err error
+	instance := singleton.Get(&sql.DB{}, func() interface{} {
 		Path = conf.Server.DbPath
 		if Path == ":memory:" {
 			Path = "file::memory:?cache=shared&_foreign_keys=on"
 			conf.Server.DbPath = Path
 		}
 		log.Debug("Opening DataBase", "dbPath", Path, "driver", Driver)
-		db, err = sql.Open(Driver, Path)
+		instance, err := sql.Open(Driver, Path)
 		if err != nil {
 			panic(err)
 		}
+		return instance
 	})
-	return db
+	return instance.(*sql.DB)
 }
 
 func EnsureLatestVersion() {