Refactor routers directory (#15800)

* refactor routers directory

* move func used for web and api to common

* make corsHandler a function to prohibit side efects

* rm unused func

Co-authored-by: 6543 <6543@obermui.de>

routers/common/db.go

@@ -0,0 +1,39 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package common
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/models/migrations"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+// InitDBEngine In case of problems connecting to DB, retry connection. Eg, PGSQL in Docker Container on Synology
+func InitDBEngine(ctx context.Context) (err error) {
+	log.Info("Beginning ORM engine initialization.")
+	for i := 0; i < setting.Database.DBConnectRetries; i++ {
+		select {
+		case <-ctx.Done():
+			return fmt.Errorf("Aborted due to shutdown:\nin retry ORM engine initialization")
+		default:
+		}
+		log.Info("ORM engine initialization attempt #%d/%d...", i+1, setting.Database.DBConnectRetries)
+		if err = models.NewEngine(ctx, migrations.Migrate); err == nil {
+			break
+		} else if i == setting.Database.DBConnectRetries-1 {
+			return err
+		}
+		log.Error("ORM engine initialization attempt #%d/%d failed. Error: %v", i+1, setting.Database.DBConnectRetries, err)
+		log.Info("Backing off for %d seconds", int64(setting.Database.DBConnectBackoff/time.Second))
+		time.Sleep(setting.Database.DBConnectBackoff)
+	}
+	models.HasEngine = true
+	return nil
+}