Before this change, if a file was created on a remote but deleted
externally from that remote then there was potential for the delete to
never be noticed.
The sequence of events was:
- Create file on VFS - creates virtual directory entry
- File deleted externally to remote before the directory refreshed
- Now the file has a virtual add but is not in the listings so will never disappear
This patch fixes it by removing all virtual directory entries except
the following when the directory is re-read.
- On remotes which can't have empty directories: virtual directory
adds are not flushed. These will remain virtual as long as the
directory is empty.
- For virtual file add: files that are in the process of being
uploaded are not flushed
This patch also adds the distinction between virtually added files and
directories.
It also refactors the virtual directory logic to make it easier to follow.
Fixes#4446
Rclone adds virtual directory entries to the directory cache when it
creates a file or directory.
Before this change these dropped out of the directory cache when the
directory cache was reloaded. This meant that when the directory cache
expired:
- On bucket based backends, empty directories would disappear
- When using VFS writeback, files in the process of uploading would disappear
This is fixed by keeping track of the virtual entries in each
directory. The virtual entries are removed when they become real - ie
the object is read back from the listing.
This also keeps tracks of deletes in the same way so if a file is
deleted, it will not re-appear when the directory cache is reloaded if
the deletion hasn't finished yet.
