Re: [pve-devel] [PATCH widget-toolkit 3/3] window: edit: avoid shared object for extra request params

["Stefan Sterz" <s.sterz@proxmox.com>]

On Thu Apr 4, 2024 at 12:54 PM CEST, Stefan Sterz wrote:
> On Thu Apr 4, 2024 at 12:10 PM CEST, Friedrich Weber wrote:
> > On 04/04/2024 11:23, Stefan Sterz wrote:
> > > -- >8 snip 8< --
> > >>>
> > >>> i did a quick an dirty test and using a constructor like this seems to
> > >>> rule out this class of bug completelly:
> > >>>
> > >>> ```js
> > >>>     constructor: function(conf) {
> > >>>         let me = this;
> > >>>         me.extraRequestParams = {};
> > >>>         me.initConfig(conf);
> > >>>         me.callParent();
> > >>>     },
> > >>> ```
> > >>>
> > >>> basically it configures the edit window as usual, but overwrites the
> > >>> `extraRequestParams` object for each instance with a new empty object.
> > >>> so there are no more shared objects :) could you check whether that also
> > >>> fixes the other instances?
> > >>>
> > >>> [1]: https://docs-devel.sencha.com/extjs/7.0.0/classic/Ext.window.Window.html#method-constructor
> > >>
> > >> Nifty, didn't think about a constructor solution. Such a general
> > >> solution would be way more elegant, thanks for suggesting it!
> > >>
> > >> However, this particular constructor seems to break the pattern of
> > >> defining `extraRequestParams` in the subclass properties, as done by
> > >> `PVE.Pool.AddVM` [1]. With the constructor above, the API request done
> > >> by `AddVM` seems to be missing the `allow-move` parameter.
> > >>
> > >> Looks like once `PVE.Pool.AddVM` is instantiated and the constructor is
> > >> called, `extraRequestParams` with `allow-move` is only defined in
> > >> `me.__proto__`, so `me.extraRequestParams = {}` essentially shadows it
> > >> with an empty object, losing the `allow-move`.
> > >>
> > >
> > > not sure what you mean by that, if an `PVE.Pool.AddVM` is instantiated,
> > > the `extraRequestParams` is already set, so it isn't just in `__proto__`
> > > for me. but yeah, the problem is correct as `me.extraRequestParams = {}`
> > > overwrites the field.
> >
> > I agree it doesn't matter here, but just for completeness, I meant that
> > if I set a breakpoint before line 2, so before the overwrite:
> >
> > ```js
> >     constructor: function(conf) {
> >         let me = this;
> > =>        me.extraRequestParams = {};
> >         me.initConfig(conf);
> >         me.callParent();
> >     },
> > ```
> >
> > ... `extraRequestParams` is not a property of `me`, but inherited from
> > its prototype:
> >
> > ```
> > >> me.extraRequestParams
> > Object { "allow-move": 1 }
> > >> "extraRequestParams" in me
> > true
> > >> Object.hasOwn(me, "extraRequestParams")
> > false
> > ```
> >
> > Doesn't make a difference for the overwrite, though.
> >
>
> ah yeah, that makes sense, but yeah, it doesn't really matter here i
> suppose.
>
> > >> Do you have an idea how to fix this? Maybe making a copy of
> > >> `extraRequestParams` would work (I suppose the overhead of creating a
> > >> new object for all edit window (subclass) instances is negligible).
> > >>
> > >> [1]
> > >> https://git.proxmox.com/?p=pve-manager.git;a=blob;f=www/manager6/grid/PoolMembers.js;h=75f20cab;hb=4b06efb5#l9
> > >
> > > this worked for me, can you confirm that this also does what it should
> > > for you?
> > >
> > > ```js
> > >     extraRequestParams: undefined,
> > >
> > >     constructor: function(conf) {
> > >         let me = this;
> > >         if (!me.extraRequestParams) {
> > >                 me.extraRequestParams = {};
> > >         }
> > >         me.initConfig(conf);
> > >         me.callParent();
> > >     },
> > > ```
> >
> > It works in the sense that it fixes the bug mentioned in my patch 1/3,
> > and fixes the lost `allow-move` issue from the previous constructor. But
> > with this constructor, all instances of `AddVM` share the same
> > `extraRequestParams` (the body of the `if` never gets executed for
> > `AddVM` instances), which is the condition that my patch 2/3 tries to
> > avoid (even though it is currently not buggy).
> >
> > Maybe we could do:
> >
> > ```js
> >     extraRequestParams: {},
> >
> >     constructor: function(conf) {
> >         let me = this;
> > 	me.extraRequestParams = Ext.clone(me.extraRequestParams);
> >         me.initConfig(conf);
> >         me.callParent();
> >     },
> > ```
> >
> > ... which, if I'm not missing anything, *should* cover everything (with
> > the cost of allocating unnecessary empty objects)?
>
> yeah looks good to me. cloning shouldn't cost too much here. if we are
> really worried we could check whether the object is empty, clone
> it in that case and assign an empty object otherwise.
>

i just looked through the code for `Ext.clone` [1], if i'm not mistaken
in modern browsers (which we restrict ourselves to anyway, mostly), this
basically returns an empty object anyway, we would skip a few
assignments and checks, but i doubt performance would improve to the
point where adding such a check makes sense.

[1]: https://docs.sencha.com/extjs/7.0.0/modern/src/Ext.js.html#Ext-method-clone

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