[pve-devel] [RFC PATCH widget-toolkit] utils: API2Request: defer masking after layout

[Dominik Csapak]

On 3/18/24 16:50, Thomas Lamprecht wrote:
> On 18/03/2024 14:44, Dominik Csapak wrote:
>> since some time (not sure when exactly), the 'load()' method of the edit
>> window did not correctly mask the window anymore
>>
>> the reason seems to be that the API2Request tries to mask the component
>> before it's rendered, and that did never work correctly judging from the
>> existing comment.
>>
>> Instead of simply calling `setLoading`, test if the component is
>> rendered, and if not, mask it after it has finished it's layout.
>>
>> Since we cannot guarantee that the 'afterlayout' event is triggered
>> before the api call response handler, add a unique id marker to the
>> waitMsgTarget that is delted when the loading is done, and only trigger
> 
> s/delted/deleted/
> 
> And why do we need setting a unique ID here and not just a flag?
> Can a second load be triggered before the first one finished?

yes, my thought here (that i forgot to mention) was that when
we have multiple API2Requests their start/finish and the 'afterlayout'
may overlap so i only wanted to activate the mask when this load
was not finished

thinking about it a bit more though, i think what would be better here
is a ref counting of running api2 requests on that waitMsgTarget
and only unmask when the count reaches zero... I'll send a v2 for that

> 
>> the masking if this marker is still there. (thankfully javascript is
>> single threaded so this should not end up being a data race)
> 
> Note that async could cause data races also in single-threaded
> code, but as we do not use that here and no yield point exist
> that doesn't matter here – just mentioning it because the statement
> would suggest that one could not have code that is susceptible to
> such a race at all in JavaScript, which is not true.

true, but those can only happen (as you mentioned) at yield points (await)
and since most of our code is non-async i did not mention it here, but
yeah one additional sentence about it being non async is probably warranted

> 
>>
>> Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
>> ---
>> sending as RFC because i'm unsure if we accidentally broke the masking
>> somewhere along the way. AFAICS from the current code, this never could have
>> worked properly? anyway, i'll be looking into that sometimes soon, and
>> this patch should be correct anyway...
> 
> it surely did sometimes in the past, maybe ExtJS 7?


yeah maybe, I'll see if i can find out when it still worked and why..
could also be general browser behavior change though