On 2013-08-16, at 17:00, Chris Muller <asqueaker at gmail.com> wrote:

>>> Did you notice that I uploaded ALL interim versions of
>>> Monticello-cmm.[552-557]?  Why would I do that when technically I only
>>> needed to upload 557?
>> 
>> We try to have a continuous "trunk" of versions in the trunk repository. We named it that way, even. But we do not store copies of all branches, because MC doesn't need them, and we don't need them. So versions that got merged into trunk do not need to be in trunk themselves, and for sure not their ancestors.
> 
> Bottom line -- if you want to find the diffs between two old versions
> in the ancestry, you'll need them both.  For you to assert "for sure
> not their ancestors" is wrong -- you CAN'T be sure.  No one knows what
> might be needed in the future.

We only store trunk versions in trunk, not the non-trunk ancestors of merged versions. Seems reasonable to me.

>>> Because MC functions depend on the ancestry model matching what's in
>>> the repositories.  Keeping all versions supports incremental
>>> development and rollback.  Besides that we should just maintain an MC
>>> model that is "whole" and operational rather than broken.  Are you
>>> concerned about disk space?
>> 
>> No, I am concerned about putting even more restrictions onto Monticello. We have gradually moved from a system with very few assumptions, over a period of non-enforced conventions, to a rigidly enforced one. Version names are an example of that. And now your adding a requirement to have an internet connection all the time because MC can unpredictably request an ancient version. I do not see that as a good idea.
> 
> You know what was restrictive about the version names before?  It was
> that they were dumb Strings being treated as a multi-field object,
> from 10 different places in the code, all similar but slightly
> different, and none commented.  It caused paralysis because changes
> could not be made safely.  It's why it took weeks for me to dissect
> and do the surgery necessary to reify that crap.

Actually the MC code base is very careful to not assign any meaning to a version name. Only the UI would try to parse it to present multiple versions in a useful way to the user. A version name *is* just a string, nothing more. Everything meaningful in MC had its own class, but version names were just that, dumb labels, intentionally.  Now that you have "reified that crap" people tend to misuse it for all sorts of things.

> Did you know, Bert, that before I did that work, we were "restricted"
> to use only FileBasedRepository's.  Now we we have a unified API
> between all repository types.

I did not know that. But I also don't think MCVersionName would have been necessary to achieve that goal, because, again, it's supposed to be strictly a UI thing.

> Or, we DID, until recently when you and Eliot slapped that branch-name
> in it.  At least it's no longer hidden like it was before
> MCVersionName, but MC has no notion of branches anywhere in its
> domain.  Guess what?  Projects using your feature are now stuck back
> on only FileBasedRepositories once again.

Branches have been supported by file naming conventions since the inception of Monticello. Ask Colin.

>>>> But as soon as you use MC it needs the ancestry anyway.
>>> 
>>> Not all of it.  We're up to version 600+ of Morphic, when was the last
>>> time version 1 of Morphic was needed?  But we continue to carry that
>>> around, in and out of the system, forever.
>> 
>> It does not need to load these old versions, but it often needs to their version names, and sometimes the UUID, and having the commit message is useful too at times.
> 
> Dodge.  Please explain the use-case where Morphic.1 would need to be
> consumed by a human or the system.

Select Morphic in the MC browser. Open the trunk repo. Done.

Actually, I couldn't try it because even in a fully updated image I get a proxy error doing just that. To make sure it's not just my image I did the same using a trunk image from the build server. Same error.

(using MC-cmm.560 in both cases)

>> You're not doing anything about that need. You're just hiding it out of sight. That's not a solution.
> 
> What need?  Hiding what?  Huh?

I thought the actual issue was that accessing the trunk repo feels slow. Okay, you're not hiding that, I take it back. (I had a mental image of hiding problems behind a proxy, but it's not that easy to verbalize).

>>> It's a gradual decline, unsustainable.
>>> Levente and I are interested in addressing this.
>> 
>> A noble goal, and I agree we need to work on it, but you're not addressing it.
> 
> You obviously didn't read my note to Levente in this thread which
> explained the next-step I want to take with this.

I only saw you proposing to reduce the need for materializing your proxies by ignoring older meta data. Which has nothing to do with the actual issues, cf above.

>>> We haven't lost clarity or simplicity.  That's the nice thing about
>>> this solution, it changes _nothing_ about the MC model.  It's very
>>> transient, all-in-memory.  There's no disaster scenario.
>> 
>> Wrong. Now just about anything you do can cause a file read or network access because MC is trying to materialize a proxy that shouldn't have been stubbed out in the first place.  Before, each working copy could access its full ancestry data. That is a very serious change of behavior, in my book.
> 
> Look, I'm glad you at least agree it's a noble _goal_.  So please give
> us a solution, won't you?  Please share your wildest imagination about
> how it would be possible to achieve this goal without needing to be
> connected to a repository?

I don't have a solution for that, but then I also don't see the ancestry data in the image as a big problem. We could talk about inefficiencies with the squeaksource server, but that would be a different topic.

> Levente has an alternate solution that does not employ proxies.  I
> personally like the Proxy solution because it's just a simple "one
> off" solution that makes no changes to the MC model.  But realizing
> the goal is more important to me than using Proxies.  Perhaps, Bert,
> you would approve of Levente's solution or propose one yourself.

Levente's idea was very different. He did not imply to purge anything from memory which would have to be separately loaded on demand. He is looking for a more efficient way to store the ancestry data.

> Until then, I'll make the purging of ancestry a separate menu item, so
> you don't have to select it and you can stay happy.


That's a good idea, to avoid running into the problem by accident. Or perhaps a preference, then you wouldn't even need a menu entry. Also useful would be a menu item (or do-it) that would restore the full meta data without going through the proxy machinery (which also could get triggered when you turn off the preference).

- Bert -