[Plugin] How to delete a checkpoint?

[lomkiri]

Hi,

In a plugin, is there any way to delete a checkpoint by it's name, without action on the container?
I would like to do something like this:

for i, some_action in enumerate(actions):
	point_name = 'partial checkpoint n. {}'.format(i)
	self.boss.add_savepoint(point_name)
	some_action()	# user get a win-diff and may rewind_savepoint() or not

        # if still existing, just delete our CP with no rewind action,
        # as it's not needeed anymore:
	self.boss.delete_savepoint(point_name)

I ask this because the for loop may create a lot of actions (maybe more than 100, in some circumstances), and I don't want to have the risk to reach MAX_SAVEPOINTS (100, from what I've seen ?).

By the way, is the creation of checkpoints a memory consuming process? Does it have much impact on the performances ?

Thank you.

[kovidgoyal]

No, checkpoints dont have names. They just have some descriptive text which is not guaranteed to be unique. If you want to perform lots of operations its best to just create a checkpoint before the whole set.

And no checkpoints are stored on disk not in ram and creating them is very cheap as they use copy-on-write and hard links.

[lomkiri]

Thank you , Kovid !

It's annoying because I would need granularity: the user will have the possibility to interpose personal changes in the ebook between two "some_action" and I would like not to revert those ones.

It is not possible either to delete the last one, with no rewind action ?

The limit is effectively 100 ? What happens if we reach this limit ? CP is not created, or first ones are deleted, or an exception is raised ?

[kovidgoyal]

You can rewind the last checkpoint with rewind_savepoint(). And if you exceed the limit old checkpoints are removed.

[lomkiri]

Ok, thanks. I'll do as you said and generate more generalistic CPs. The confirm box will warn the user that rewinding will also undo his own changes.