1731565 - Cleanup global "browsing context event map" when a browsing context gets closed

Status: NEW

(Remote Protocol :: WebDriver BiDi, task, P3)

Description

[Henrik Skupin [:whimboo][⌚️UTC+2]]

When browsing contexts are getting closed with events registered, we might have to clean-up some internal state and distribute that across content processes.

Comment 1

[Julian Descottes [:jdescottes]]

Note that when a BrowsingContext closes, the corresponding JS Window Actor pair is destroyed, which destroys all MessageHandler, which destroys all modules. Normally we already remove log.entryAdded listeners via https://searchfox.org/mozilla-central/rev/13378066961f195595822d4f543c8ac5b7f46490/remote/webdriver-bidi/modules/windowglobal/log.jsm#26-31

Or maybe you have something else/more specific in mind?

(otherwise there is an issue when a session end and we destroy a Root MessageHandler, but that's Bug 1730913)

Comment 2

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Nothing specific here. It's just a place-holder for whatever could come up.

Comment 3

[Henrik Skupin [:whimboo][⌚️UTC+2]]

This bug is actually about cleaning up the global subscription state for a closed top-level browsing context. Right now it's not clear from the spec if this should be done or not when a browsingContext.contextDestroyed event is handled. If we won't do it then outdated event subscriptions will remain in the global subscription map.

James, is that an issue with the spec and we should define it there?

Comment 4

[James Graham [:jgraham]]

It's a leak in the spec, but I don't think it's observable (you can't end up reusing the same state for another context), so you can either regard it as a bug in the spec, or as unnecessary to specify because it doesn't affect any requirements on implementations.

Comment 5

[Henrik Skupin [:whimboo][⌚️UTC+2]]

I filed https://github.com/w3c/webdriver-bidi/issues/166 for this particular question.

As long as we do not support event subscriptions for individual browsing contexts (bug 1723102) we won't have to do anything here.