Add Status Updates whilst Gitea migrations are occurring (#15076)

* Add migrating message

Signed-off-by: Andrew Thornton <art27@cantab.net>

* simplify messenger

Signed-off-by: Andrew Thornton <art27@cantab.net>

* make messenger an interface

Signed-off-by: Andrew Thornton <art27@cantab.net>

* rename

Signed-off-by: Andrew Thornton <art27@cantab.net>

* prepare for merge

Signed-off-by: Andrew Thornton <art27@cantab.net>

* as per tech

Signed-off-by: Andrew Thornton <art27@cantab.net>

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

models/migrations/migrations.go

@@ -317,6 +317,8 @@ var migrations = []Migration{
 	NewMigration("Add issue resource index table", addIssueResourceIndexTable),
 	// v183 -> v184
 	NewMigration("Create PushMirror table", createPushMirrorTable),
+	// v184 -> v185
+	NewMigration("Rename Task errors to message", renameTaskErrorsToMessage),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v184.go

@@ -0,0 +1,47 @@
+// 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 migrations
+
+import (
+	"fmt"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"xorm.io/xorm"
+)
+
+func renameTaskErrorsToMessage(x *xorm.Engine) error {
+	type Task struct {
+		Errors string `xorm:"TEXT"` // if task failed, saved the error reason
+		Type   int
+		Status int `xorm:"index"`
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	if err := sess.Sync2(new(Task)); err != nil {
+		return fmt.Errorf("error on Sync2: %v", err)
+	}
+
+	switch {
+	case setting.Database.UseMySQL:
+		if _, err := sess.Exec("ALTER TABLE `task` CHANGE errors message text"); err != nil {
+			return err
+		}
+	case setting.Database.UseMSSQL:
+		if _, err := sess.Exec("sp_rename 'task.errors', 'message', 'COLUMN'"); err != nil {
+			return err
+		}
+	default:
+		if _, err := sess.Exec("ALTER TABLE `task` RENAME COLUMN errors TO message"); err != nil {
+			return err
+		}
+	}
+	return sess.Commit()
+}