refactor: make db iterate context aware (#27710)

the iteration will run until finished atm.

this changes it by checking if if the context got canceled before each
run of a loop sequence is executed

[View this pull with now
whitespace](https://github.com/go-gitea/gitea/pull/27710/files?diff=unified&w=1)

models/db/iterate.go

@@ -17,22 +17,27 @@ func Iterate[Bean any](ctx context.Context, cond builder.Cond, f func(ctx contex
 	batchSize := setting.Database.IterateBufferSize
 	sess := GetEngine(ctx)
 	for {
-		beans := make([]*Bean, 0, batchSize)
-		if cond != nil {
-			sess = sess.Where(cond)
-		}
-		if err := sess.Limit(batchSize, start).Find(&beans); err != nil {
-			return err
-		}
-		if len(beans) == 0 {
-			return nil
-		}
-		start += len(beans)
-
-		for _, bean := range beans {
-			if err := f(ctx, bean); err != nil {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+			beans := make([]*Bean, 0, batchSize)
+			if cond != nil {
+				sess = sess.Where(cond)
+			}
+			if err := sess.Limit(batchSize, start).Find(&beans); err != nil {
 				return err
 			}
+			if len(beans) == 0 {
+				return nil
+			}
+			start += len(beans)
+
+			for _, bean := range beans {
+				if err := f(ctx, bean); err != nil {
+					return err
+				}
+			}
 		}
 	}
 }

modules/doctor/repository.go

@@ -37,24 +37,29 @@ func deleteOrphanedRepos(ctx context.Context) (int64, error) {
 	adminUser := &user_model.User{IsAdmin: true}
 
 	for {
-		var ids []int64
-		if err := e.Table("`repository`").
-			Join("LEFT", "`user`", "repository.owner_id=user.id").
-			Where(builder.IsNull{"`user`.id"}).
-			Select("`repository`.id").Limit(batchSize).Find(&ids); err != nil {
-			return deleted, err
-		}
+		select {
+		case <-ctx.Done():
+			return deleted, ctx.Err()
+		default:
+			var ids []int64
+			if err := e.Table("`repository`").
+				Join("LEFT", "`user`", "repository.owner_id=user.id").
+				Where(builder.IsNull{"`user`.id"}).
+				Select("`repository`.id").Limit(batchSize).Find(&ids); err != nil {
+				return deleted, err
+			}
 
-		// if we don't get ids we have deleted them all
-		if len(ids) == 0 {
-			return deleted, nil
-		}
+			// if we don't get ids we have deleted them all
+			if len(ids) == 0 {
+				return deleted, nil
+			}
 
-		for _, id := range ids {
-			if err := repo_service.DeleteRepositoryDirectly(ctx, adminUser, id, true); err != nil {
-				return deleted, err
+			for _, id := range ids {
+				if err := repo_service.DeleteRepositoryDirectly(ctx, adminUser, id, true); err != nil {
+					return deleted, err
+				}
+				deleted++
 			}
-			deleted++
 		}
 	}
 }