[Cuis-dev] Morphic's design

[Szabolcs Komáromi]

Hi Juan, Ken,

Thanks for the explanation. I'm constantly confused, at least for the time being, by the dichotomy of Smalltalk's "operating systemness" and its implementation as an application. 

If Smalltalk would be an operating system it would be normal to have multiple GUI-threads. But Smalltalk is an application thus it is perfectly normal to have only one GUI-thread. If i understand correctly.

I'm currently reading John Maloney's papers about Morphic to better understand what Morphic is. If I'm correct Morphic at its core is an abstract idea about a GUI framework that emphasizes concreteness, liveness, and uniformity. 

When I asked my question what was in my mind is Apple's struggle with QuickDraw and the classic Mac OS's basic design what prohibited preemptive multitasking during the 1990s. I thought maybe there is something similar about Morphic. A somewhat better question would have been whether Cuis' Morphic implementation is inherently not tread safe or every possible implementation of Morphic wouldn't be be thread safe. But this is also a silly question if Morphic is an abstract idea. 

Regards,
Szabolcs

On Mon, Aug 14, 2023, at 00:53, Juan Vuletich wrote:
> Hi Szabolcs,
> 
> On 8/13/2023 12:54 PM, Szabolcs Komáromi via Cuis-dev wrote:
>> Hi,
>> 
>> I'm reading back through the mailing list to gain some knowledge. I found this comment from Phil:
>> https://lists.cuis.st/mailman/archives/cuis-dev/2021-August/003850.html
>>> If that is the issue, I think there's a larger problem to be solved.
>>> Morphic is inherently not thread safe so you're dealing with an intractable
>>> problem (short of re-architecting Morphic.)    Other than marking a morph
>>> for redraw, anything else touching Morphic from a background process needs
>>> to be wrapped in UISupervisor whenUIinSafeState: [].
>>> 
>> 
>> What makes Morphic inherently not thread safe? Why the community didn't addressed this shortcoming when the Morphic framework was reachitected anyway?
>> 
>> Regards,
>> Szabolcs
> 
> The usual wording would be "single threaded". Morphic is single threaded, like most (all?) GUI frameworks. You can google "UI thread" or "GUI thread" and see.
> 
> Synchronization and data protection between threads (we call them Processes for historical reasons) as required is the responsibility of the application programmer, like in any environment, except maybe functional languages and some other special kinds.
> 
> In the mail thread you mention, this was conflated with a similar issue if stepping messages modified Morphic data structures. There was only a single Process involved, so it was about a bug, and not about thread safety. I believe the bug was fixed.
> 
> So, I don't think we need to redesign Morphic to make it "thread safe", although anybody is welcome to experiment if so inclined. What we do need to keep doing is fixing bugs, defects and limitations as we face them.
> 
> Hope this helps.
> -- 
> Juan Vuletich
> cuis.st
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> independent.academia.edu/JuanVuletich
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