Race condition in embedded requests for stacked data

[igorsantos07]

It seems there's a race condition when you try to use stacked data to debug embedded requests (i.e. iframes).

I can confirm what the doc says about "using the debug bar storage mechanism to store the data and re-open it later can be cumbersome". It doesn't seem easy to debug embedded docs simply using header data because the ID generated is different. Thus, I moved to a less-optimal but still doable solution with stacked data. However, that brings up another issue: the race condition between the main request persisting the session, and the embedded one writing to it.

I guess this could be solved if session was not used whatsoever for stacked information - i.e. Redis storage is able to append information without having to write the entire list (and creating the said race). Or else, if it was possible to easily pass-down the DebugBar request ID - no idea about this without munging embedded URLs, though, but I guess it happens with AJAX requests AjaxHandler.handle()?

Entirely replacing the session layer could probably work if there were some adjustments on the stack data code - i.e. deleting each used key instead of clearing up the entire object. I think DebugBar should come with a basic session replacer for itself, as it would otherwise be dependent on external implementation in order to solve this race condition.

• ~not sure but it seems stackData() is not really storing the stack in the storage?~ couldn't really double-check this but I guess it's working fine
• [ ] is there a reasonable way to solve the race condition with embedded requests?
• [ ] setStackAlwaysUseSessionStorage() doesn't seem to be documented
• [ ] unclear from the docs that, even with storage, session is still used to identify which information will be shown next

[igorsantos07]

Ok, while still trying to find a way to solve my need (which seems to be a race condition between writing to and deleting the whole debugbar session array), I noticed getStackedData() does use the storage. I would suggest looping over array_keys($stackedData) to make it clear you're only using its keys :))

[igorsantos07]

I'll edit the original post to reflect my updated findings.