[LU-19239] TCU: Repeated deletion of same filename

• Type: Technical task
• Resolution: Unresolved
• Priority: Medium
• Severity: 3
• Assignee: Qian Yingjin
• Reporter: Qian Yingjin

Description

If the same filename is repeatedly created and deleted within the same parent directory, then the deleted files will have conflicts when moved into the pFID directory in the Trash Can. To disambiguate the files in Trash, the conflicting filenames should be disambiguated by appending a timestamp to the filename, like filename.2025-04-03-00:11:24, possibly adding .microseconds if there is still a conflict. It isn't totally clear whether it would be better to use the timestamp from when the file was deleted, or when the file was created. Both have some value to help users distinguish between the different versions.
In order to avoid overwhelming the Trash Can with files that are rapidly created and deleted (e.g. short-lived temporary files), it would be desirable to impose an upper limit on the number of versions that will be saved in the trash can. Some complexity exists in implementing this, because the MDS shouldn't need to do a full directory listing to determine if there are multiple versions of a file in the trash.