Bug 79001 – undo manager retains RefPtr to nodes in documents that would otherwise have been GC'ed

• Status: NEW
• Component: HTML Editing

[Ryosuke Niwa]

Because WebKit's undo manager manages undo stack at the page level, all documents that have ever been edited on the same page will be kept in memory even if there were no other references to it.

This is pretty silly because we can't even undo editing actions on an unloaded frame/document even if the user had loaded it back.

[Ryosuke Niwa]

Since none of our editing actions do cross-frame editing, we should be able to delete all UndoStep objects that belong to an unloaded frame.

[Alexey Proskuryakov]

When are the undo steps currently cleared?

[Ryosuke Niwa]

(In reply to comment #2)
> When are the undo steps currently cleared?

It's cleared when the page is unloaded in FrameLoader::closeURL.

[Ryosuke Niwa]

Created attachment 127761 [details]
proof of concept wip patch

[Ryosuke Niwa]

Comment on attachment 127761 [details]
proof of concept wip patch

Here's my attempt to mitigate this issue. I'm removing all undo step objects when the frame is destroyed. For Mac port, this can be done by creating targets for each "host" document and then removing all targets when the corresponding frame is destroyed.

I probably need to hash out the details but it compiles & loads pages as is.