.part file remains when encountered insufficient disk space

[iowk]

Overview

If downloading fails because of insufficient disk space, .part file remains and is not removed.

Steps to Reproduce

1. Sync iCloud Photos on a device with insufficient disk space.
2. Downloading should fail on some files, logging IOError while writing...

Expected Behavior

The .part file should be deleted after downloading fails.

Actual Behavior

The .part file remains.

Context

I think we can add a try-finally block in download_response_to_path to remove the .part file on error.

[AndreyNikiforov]

Thanks for reporting. Yes, .part files will be left on the drive if app crashes. A number of thoughts on the subject:

• there may be recoverable errors during downloading, e.g. re-auth - hypothetical, and it would be beneficial to resume downloading rather then deleting and restarting
• there may be app crashes that cannot be caught in code (e.g. os-level terminations)
• .part files can be stored in tmp location of the OS and in case of crashes, OS will take care of cleaning space
• using tmp storage may add extra complexities (where tmp storage is managed separately from main one) and performance degradation (for final move of the file)
• .part files in final destination may impact backups (.part files will be backed up) - undesirable

Seems that simple try-catch wrapping and silent file deletion may cover most probable case (space issues). It will not hurt re-auth hypothetical case.