From: Dominik Csapak <d.csapak@proxmox.com>
To: Thomas Lamprecht <t.lamprecht@proxmox.com>,
Proxmox VE development discussion <pve-devel@lists.proxmox.com>,
Friedrich Weber <f.weber@proxmox.com>
Subject: Re: [pve-devel] [PATCH widget-toolkit] fix #4421: ui: guard setProxy against races of slow vs fast requests
Date: Wed, 8 Mar 2023 07:34:08 +0100 [thread overview]
Message-ID: <8c8e6645-50a2-4d1a-87aa-32da027ab16a@proxmox.com> (raw)
In-Reply-To: <9e245a3d-98ea-8ea0-e953-d1dbc0496393@proxmox.com>
On 3/7/23 19:49, Thomas Lamprecht wrote:
> Am 06/03/2023 um 15:03 schrieb Friedrich Weber:
>> Some UI components use `Ext.data.Store.setProxy` to change their
>> associated API endpoint URL in reaction to user input. One example is
>> `BackupView`, which calls `setProxy` when the user switches from
>> listing backups on storage A to listing backups on storage B. However,
>> if A is slow, the UI may receive the response for A *after* the
>> response for B. It will then display the contents of A as if they were
>> the contents of B, resulting in a UI inconsistency.
>>
>> The reason is that `Ext.data.Store` still processes the slow response
>> for A, even though it is obsolete. This patch overrides the
>> responsible callback of `Ext.data.Store` to only process responses
>> belonging to the currently active proxy object. This should rule out
>> similar race conditions in all components that use the `setProxy` API.
>> In the above example, the patch results in the response for A being
>> ignored.
>>
>> Ignored responses are logged to the browser console.
>>
>> Note that this patch only concerns components that use `setProxy` for
>> changing API endpoints. Other components (e.g. those using
>> `proxy.setURL` for the same purpose) may be open to similar race
>> conditions.
>>
>> Signed-off-by: Friedrich Weber <f.weber@proxmox.com>
>> ---
>> The original report only concerns the backup view [1], where the race
>> condition is easy to trigger. While ruling out this particular race is
>> simple, I thought it would be worthwhile to rule out race condition of
>> this category for all components. Hence this patch. However, most of the
>> other races are much harder to trigger, so it may be questionable
>> whether a general fix is needed. So if wanted, I can alternatively
>> submit a patch that only fixes the backup view.
>
> IMO a general fix/future proofing can be OK, so besides a small nit inline:
> LGTM, but did not checked/tested this too closely - @Dominik, what do you
> think on this?
>
This change is non-intrusive enough that it's OK, since it
fixes the reported issue and potentially some more.
When we're only fixing the one reported place, i guess
sooner or later someone else reports another instance of this,
and by then we probably forgot that we fixed it already once ;)
Really fixing all points where something like that can happen is
not easy since most of them are using Proxmox.Utils.API2Request
instead of a store, or as Friedrich already wrote, setting
the URL of the proxy manually, so this seems to be good
middle ground for now.
next prev parent reply other threads:[~2023-03-08 6:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 14:03 Friedrich Weber
2023-03-07 18:49 ` Thomas Lamprecht
2023-03-08 6:34 ` Dominik Csapak [this message]
2023-03-08 6:42 ` [pve-devel] applied: " Thomas Lamprecht
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