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0 pointstheamk6y ago0 comments

Thanks for the answers, I am glad to hear from the author!

- What do you mean "app code have to do migration by hand"? I'd say that most of the existing file formats need no migration -- images, videos, music basically don't change; and even very complex file formats like Microsoft doc only change with major versions, not with the minor ones -- MS word had tens of thousands code updates (service packs, localization, etc..) but only a dozen or so file formats.

- What do you mean by "restart" in "Persistence does not _forbid_ to restart things."?

if by "restart", you mean "kill all the threads related to object", then I don't think it will help in most cases. If you have a bug in "Draw()" function, this bug will still be there after thread restart.

If by "restart", you mean "wipe all the state, and start from the clean slate", then won't this destroy all the documents user made?

---

We live in persistent world, and we do suffer a lot from it, we are just very used to it. I have to wash my dishes every day, buy new clothes, and repair my car. I would love to be able to "save" the make, model, and license plate # of my car, then "restart" it to get a brand-new car with the same properties.

Default persistence of everything is annoying, and moving it to software is just unnatural :)

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4 comments · 1 top-level

dzavalishin6y ago· 3 in thread

Well, you just can't imagine non-persistent world. :) I'll try to illustrate.

In non-persistent world you have to disassemble and store to special boxes all the objects in a room before getting out of that room. Or else it all will just vanish. :)

On migration: if you change code in Phantom in a way that does not change object representation, you can just use new code with old data. New paintDocumentPart() can be called for same document object as long as interface is the same.

The problem is with objects with running threads in them. You can't change implementation which is currently running.

Hopefully, it would not be a usual case. As far as I see, Phantom applications won't need forever running threads at all.

os ->(repaint)->window->(get state of)->document

doc->(update state trigger)->window->(repaint)->canvas

In either case it's just an event. Update and finish.

Actually, Phantom was a huge mind game of mine for years (first ideas started to form some 25 years ago) and one of the reasons to start actual implementation was that I can't imagine all of the potential problems and solutions for such an environment.

But - I don't want Phantom to be just a test bed for new ideas. I hope it will find its place as practical tool.

theamkOP6y ago

I can certainly imagine a non-persistent world -- why do you keep saying that I cannot? It is called "restaurant". You come in and get a clean, fresh table. You sit on it and eat, and if you have leftovers, you put them in special boxes. When you leave, everything on the table that you did not put in a box disappears. Very nice and handy!

=====

So what happens in case of errors?

os ->(repaint)->window->(get state of)->document->(EXCEPTION: LIST INDEX OUT OF RANGE)

Does this result in losing the document forever?

dzavalishin6y ago

Word->Open file->Error reading file: LIST INDEX OUT OF RANGE

Does this?

Your point is obvious, but not specific to persistent environment. Things are getting broken sometimes.

Actually, back in 2009 when first message about Phantom appeared, I've got a message from team in Stanford. THey did an experiment about things we discuss.

Relatively big Java program was stopped in the middle of work, serialized to (I believe) XML and some objects were removed from that XML. After that program state was de-serialized and program continued to run.

Experiments shown that modern code degrades quite gracefully in such cases. Most of time problems were not global and affected just parts of program's abilities.

But again, it is not a persistent world specific problem.

If your code is wrong, no matter where index lies - in persistent memory object or in file. Index will be wrong.

The question is how system must be built, what kinds of services it must provide to limit app ability to shoot itself in a foot. That is one of the goals of this project.

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dzavalishin6y ago

Returning to restaurant: you just went off a problem. In your case restaurant is persistent. And a road to your home exists. Suppose, home exists too and you do not rebuild it returning from the dinner.

And at the moment when Linux boots, all the world is absent and is built again from files.

(There's not just no spoon - there's no restaurant. :) And no white rabbit. :)

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4 comments · 1 top-level

dzavalishin6y ago· 3 in thread

Well, you just can't imagine non-persistent world. :) I'll try to illustrate.

In non-persistent world you have to disassemble and store to special boxes all the objects in a room before getting out of that room. Or else it all will just vanish. :)

The problem is with objects with running threads in them. You can't change implementation which is currently running.

Hopefully, it would not be a usual case. As far as I see, Phantom applications won't need forever running threads at all.

os ->(repaint)->window->(get state of)->document

doc->(update state trigger)->window->(repaint)->canvas

In either case it's just an event. Update and finish.

But - I don't want Phantom to be just a test bed for new ideas. I hope it will find its place as practical tool.

theamkOP6y ago

=====

So what happens in case of errors?

os ->(repaint)->window->(get state of)->document->(EXCEPTION: LIST INDEX OUT OF RANGE)

Does this result in losing the document forever?

dzavalishin6y ago

Word->Open file->Error reading file: LIST INDEX OUT OF RANGE

Does this?

Your point is obvious, but not specific to persistent environment. Things are getting broken sometimes.

Actually, back in 2009 when first message about Phantom appeared, I've got a message from team in Stanford. THey did an experiment about things we discuss.

Experiments shown that modern code degrades quite gracefully in such cases. Most of time problems were not global and affected just parts of program's abilities.

But again, it is not a persistent world specific problem.

If your code is wrong, no matter where index lies - in persistent memory object or in file. Index will be wrong.

The question is how system must be built, what kinds of services it must provide to limit app ability to shoot itself in a foot. That is one of the goals of this project.

1 more reply

dzavalishin6y ago

And at the moment when Linux boots, all the world is absent and is built again from files.

(There's not just no spoon - there's no restaurant. :) And no white rabbit. :)

1 more reply

j / k navigate · click thread line to collapse