* Collection needs to be closed prior to backup even when not downgrading
* Backups -> BackupLimits
* Some improvements to backup_task
- backup_inner now returns the error instead of logging it, so that
the frontend can discover the issue when they await a backup (or create
another one)
- start_backup() was acquiring backup_task twice, and if another thread
started a backup between the two locks, the task could have been accidentally
overwritten without awaiting it
* Backups no longer require a collection close
- Instead of closing the collection, we ensure there is no active
transaction, and flush the WAL to disk. This means the undo history
is no longer lost on backup, which will be particularly useful if we
add a periodic backup in the future.
- Because a close is no longer required, backups are now achieved with
a separate command, instead of being included in CloseCollection().
- Full sync no longer requires an extra close+reopen step, and we now
wait for the backup to complete before proceeding.
- Create a backup before 'check db'
* Add File>Create Backup
https://forums.ankiweb.net/t/anki-mac-os-no-backup-on-sync/6157
* Defer checkpoint until we know we need it
When running periodic backups on a timer, we don't want to be fsync()ing
unnecessarily.
* Skip backup if modification time has not changed
We don't want the user leaving Anki open overnight, and coming back
to lots of identical backups.
* Periodic backups
Creates an automatic backup every 30 minutes if the collection has been
modified.
If there's a legacy checkpoint active, tries again 5 minutes later.
* Switch to a user-configurable backup duration
CreateBackup() now uses a simple force argument to determine whether
the user's limits should be respected or not, and only potentially
destructive ops (full download, check DB) override the user's configured
limit.
I considered having a separate limit for collection close and automatic
backups (eg keeping the previous 5 minute limit for collection close),
but that had two downsides:
- When the user closes their collection at the end of the day, they'd
get a recent backup. When they open the collection the next day, it
would get backed up again within 5 minutes, even though not much had
changed.
- Multiple limits are harder to communicate to users in the UI
Some remaining decisions I wasn't 100% sure about:
- If force is true but the collection has not been modified, the backup
will be skipped. If the user manually deleted their backups without
closing Anki, they wouldn't get a new one if the mtime hadn't changed.
- Force takes preference over the configured backup interval - should
we be ignored the user here, or take no backups at all?
Did a sneaky edit of the existing ftl string, as it hasn't been live
long.
* Move maybe_backup() into Collection
* Use a single method for manual and periodic backups
When manually creating a backup via the File menu, we no longer make
the user wait until the backup completes. As we continue waiting for
the backup in the background, if any errors occur, the user will get
notified about it fairly quickly.
* Show message to user if backup was skipped due to no changes
+ Don't incorrectly assert a backup will be created on force
* Add "automatic" to description
* Ensure we backup prior to importing colpkg if collection open
The backup doesn't happen when invoked from 'open backup' in the profile
screen, which matches Anki's previous behaviour. The user could
potentially clobber up to 30 minutes of their work if they exited to
the profile screen and restored a backup, but the alternative is we
create backups every time a backup is restored, which may happen a number
of times if the user is trying various ones. Or we could go back to a
separate throttle amount for this case, at the cost of more complexity.
* Remove the 0 special case on backup interval; minimum of 5 minutes
https://github.com/ankitects/anki/pull/1728#discussion_r830876833
4515c41d2c