可靠性: 完善 R2 备份恢复与对象生命周期

internal/db/upload_images.go

@@ -10,6 +10,8 @@ import (
 	"github.com/pkg/errors"
 	"github.com/samber/lo"
 	"gorm.io/gorm"
+
+	"github.com/tamakyi/TamaBox/internal/conf"
 )
 
 var UploadImages UploadImagesStore
@@ -23,12 +25,8 @@ type UploadImagesStore interface {
 	// 用于账号导出等场景，将 N 次单题查询合并为少量 IN 查询，避免 N+1。
 	GetByQuestionIDs(ctx context.Context, questionIDs []uint) (map[uint][]*UploadImage, error)
 	GetByTypeQuestionID(ctx context.Context, typ UploadImageQuestionType, questionID uint) ([]*UploadImage, error)
-	// DeleteByQuestionID 删除某条提问时级联清理其全部上传图片记录与关联行。
-	//
-	// 用 Unscoped 真删：图片元数据（name/md5/key）随提问一并真删，与 questions.DeleteByID
-	// 对主表的真删口径一致。软删会留下带 deleted_at 的图片行，且关联行的 question_id
-	// 指向已不存在的提问。注意这里只清数据库记录，对象存储里的实际文件不在本函数删除
-	// （图片可能被多条记录复用，避免误删共享资源）。
+	// DeleteByQuestionID 先删除当前题目的关联，再物理删除不再被任何题目引用的主体。
+	// 实际删除的主体的对象 key 与元数据删除在同一事务中登记 R2 outbox。
 	DeleteByQuestionID(ctx context.Context, questionID uint) error
 }
 
@@ -87,9 +85,24 @@ func (db *uploadImages) Create(ctx context.Context, opts CreateUploadImageOption
 		}
 
 		if opts.IsDeletingPrevious {
-			if err := tx.WithContext(ctx).Where("type = ? AND question_id = ?", opts.Type, opts.QuestionID).Delete(&UploadImageQuestion{}).Error; err != nil {
+			var previousLinks []*UploadImageQuestion
+			if err := tx.WithContext(ctx).
+				Where("type = ? AND question_id = ?", opts.Type, opts.QuestionID).
+				Find(&previousLinks).Error; err != nil {
+				return errors.Wrap(err, "get previous image question links")
+			}
+			previousImageIDs := lo.Map(previousLinks, func(item *UploadImageQuestion, _ int) uint {
+				return item.UploadImageID
+			})
+			if err := tx.WithContext(ctx).
+				Where("type = ? AND question_id = ?", opts.Type, opts.QuestionID).
+				Delete(&UploadImageQuestion{}).Error; err != nil {
 				return errors.Wrap(err, "delete previous image question link")
 			}
+			// 新图已经创建但尚未关联；即使它与旧图使用相同 key，也绝不加入删除队列。
+			if err := deleteUnreferencedUploadImages(ctx, tx, previousImageIDs, opts.Key); err != nil {
+				return err
+			}
 		}
 		if err := tx.WithContext(ctx).Create(&UploadImageQuestion{
 			Type:          opts.Type,
@@ -167,10 +180,44 @@ func (db *uploadImages) GetByTypeQuestionID(ctx context.Context, typ UploadImage
 	return db.getBy(ctx, "type = ? AND question_id = ?", typ, questionID)
 }
 
-// DeleteByQuestionID 删除某条提问时级联清理其全部上传图片记录（软删除，与提问保持一致）。
-// 注意：question_id 列在关联表 upload_image_questions 上，不在 upload_images 表上，
-// 需先查关联行拿到 imageID 列表，再软删图片主体并删除关联行（同一事务内完成）。
-// 注：仅清理数据库记录，对象存储中的实际文件不在此处删除（避免误删复用资源）。
+// unreferencedUploadImagePredicate 是所有 UploadImage 删除入口共用的共享保护谓词。
+// 调用方必须先解除当前作用域的关联，再使用该谓词收集并删除真正的孤儿主体。
+const unreferencedUploadImagePredicate = `NOT EXISTS (
+	SELECT 1 FROM upload_image_questions AS shared_links
+	WHERE shared_links.upload_image_id = upload_images.id
+)`
+
+func deleteUnreferencedUploadImages(ctx context.Context, tx *gorm.DB, imageIDs []uint, excludedKeys ...string) error {
+	if len(imageIDs) == 0 {
+		return nil
+	}
+
+	var images []*UploadImage
+	if err := tx.WithContext(ctx).Unscoped().
+		Where("id IN ?", imageIDs).
+		Where(unreferencedUploadImagePredicate).
+		Find(&images).Error; err != nil {
+		return errors.Wrap(err, "get unreferenced upload images")
+	}
+	if len(images) == 0 {
+		return nil
+	}
+
+	ids := lo.Map(images, func(image *UploadImage, _ int) uint { return image.ID })
+	if err := tx.WithContext(ctx).Unscoped().
+		Where("id IN ?", ids).
+		Where(unreferencedUploadImagePredicate).
+		Delete(&UploadImage{}).Error; err != nil {
+		return errors.Wrap(err, "delete unreferenced upload images")
+	}
+
+	values := lo.Map(images, func(image *UploadImage, _ int) string { return image.Key })
+	if err := enqueueR2DeleteTasksForValues(tx.WithContext(ctx), conf.Upload.ImageBucket, values, excludedKeys...); err != nil {
+		return errors.Wrap(err, "enqueue deleted upload images")
+	}
+	return nil
+}
+
 func (db *uploadImages) DeleteByQuestionID(ctx context.Context, questionID uint) error {
 	return db.Transaction(func(tx *gorm.DB) error {
 		var links []*UploadImageQuestion
@@ -184,13 +231,10 @@ func (db *uploadImages) DeleteByQuestionID(ctx context.Context, questionID uint)
 		imageIDs := lo.Map(links, func(item *UploadImageQuestion, _ int) uint {
 			return item.UploadImageID
 		})
-		if err := tx.WithContext(ctx).Where("id IN ?", imageIDs).Unscoped().Delete(&UploadImage{}).Error; err != nil {
-			return errors.Wrap(err, "delete upload images by question id")
-		}
-		// 关联表 UploadImageQuestion 无 DeletedAt，Delete 本就是真删，无需 Unscoped。
+		// 关联表无 DeletedAt，Delete 本就是真删；先解除当前题目关联。
 		if err := tx.WithContext(ctx).Where("question_id = ?", questionID).Delete(&UploadImageQuestion{}).Error; err != nil {
 			return errors.Wrap(err, "delete image question links")
 		}
-		return nil
+		return deleteUnreferencedUploadImages(ctx, tx, imageIDs)
 	})
 }