New Post overwriting a previously published post

[jackreichert]

This was seen on wordpress.com, a user had multiple draft windows open. At one point when saving one draft, it wrote over another previously published post.

I believe that it was caused by a race condition that has to do with the environment being hosted on multiple servers.

To reproduce:

1. Open in quick succession multiple draft windows.
2. Check in developer tools for post_id duplicate.

I believe that a possible solution would be to enhance post-locking to include if a post is open in duplicate windows by the same user.

[jackreichert]

Removes user check so that filelock will happen if the same post is opened in two separate windows.

[SergeyBiryukov]

Introduced in [7103], modified in [16901].

[SergeyBiryukov]

Related: #28378

[adamsilverstein]

rebase patch from trunk

[adamsilverstein]

I think this fix makes sense!

Since we are doing post locking you shouldn't be able to edit the same post from two locations, even you are the same user. The whole point of post locking is to prevent the strange things that happen when two sessions edit the same post (autosaves esp. - see #28378) - being the same user doesn't help the situation.

Am I missing a use case where one user should be able to edit a post from two windows or locations?

[adamsilverstein]

doc bloc update to match functional change; add missing brackets

[SergeyBiryukov]

Moving for investigation.

[adamsilverstein]

The patch still applies cleanly and I think is good to go for 4.0.

Maybe @azaozz can review to verify sanity of change?

[adamsilverstein]

After some discussion with azaozz and some further testing, its clear this will not work - the post lock is never cleared and when saving, auto-saving or even reloading you are locked out.

Here is a ​screencast showing the issue (with the patch applied).

[helen]

Probably still an issue worth investigating, but a punt for 4.0, given that we don't have a viable approach.