[Vm-dev] VMMaker in Pharo [Was: Squeak and Tonel]

Tudor Girba tudor at tudorgirba.com
Mon Feb 18 06:33:20 UTC 2019

Hi Eliot,

You raise a few technical concerns related to VMMaker that seem addressable:

1. Rendering technology: Both in Pharo and in GT, there exist in-image canvases, Athens and Sparta respectively, that are backend independent. This allows us to have image-based drawing logic, like BitBlt or even better, the drawing capabilities that Juan Vuletich built in Morphic 3, transparently. In fact, we even started to look at the code from Morphic 3 and we think it’s not much effort to make it work behind Sparta. This would provide a complete solution that would not rely on any external libraries.

2. Git history. We used to have the author and timestamp in the metadata of Tonel but because it generated unwanted conflicts it was decided to remove it. I think this is a good decision and one based on the experience of using it. But, why do you think the algorithm of retrieving Git could not be made to work in Squeak? Is there a specific technical reason, or is it more that you do not see the effort being spent in this direction? I am asking to understand what could a possible solution be.

But, let’s take a step back. George and Andrei did move the VMMaker code, including all its history, into Git using (and enhancing) https://github.com/peteruhnak/git-migration.

The code is here:

Our goal was to make the code loadable and runnable in Pharo through Git. We have a reproducible process to produce this history, and this means that we can also synchronize all changes from the Monticello VMMaker repository and produce a history-preserving Git repository. 

The current code comes with a BaselineOfVMMaker that loads in Pharo, and the code generation seems to work to a good extent without much effort. There is still work that needs to be done especially on the simulation part, but we think most of it can be addressed through a Pharo-specific package that provides compatibility logic.

I see two benefits for doing this:
1. It allows people in Pharo to play with the VM within the Pharo context and consequently contribute.
2. It allows us to build an environment dedicated for VM development without affecting the current contribution process. We can judge later whether this is useful.


> On Feb 17, 2019, at 9:27 PM, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> Hi All, Hi Torsten, Hi Jakob,
> On Thu, Feb 14, 2019 at 6:17 AM Torsten Bergmann <astares at gmx.de> wrote:
> Hi,
> as some of you might already know "Tonel" is a file-per-class format for monticello repositories [1].
> In Pharo land many projects are already converted to it - as regular "file tree" solution faces issues 
> with git handling due to very long file names / deep file hierarchy (often leading to trouble on Windows).
> Dales's Rowan (a new project/package manager for Smalltalk) supports FileTree and also Tonel 
> repositories [2]. There is also a tool to convert from STORE (VisualWorks Source-Code Versioning System) 
> to Tonel format [3].
> So I wonder about adoption of Tonel in Squeak land. 
> Any status/comments?
> Last year I was given contract employment by Tudor Girba's feenk which in part was to involve me porting VMMaker.oscog to Pharo in order to reap the productivity benefits of the Glamorous Toolkit when applied to VMMaker.  The major direction was to unify the opensmalltalk-vm repository with a Toned-Format repository holding the Smalltalk code.
> This project, though no fault of feenk's did not go well.  A big part of it was my own emotional attachment to Squeak, my "muscle memory" with Squeak and my long experience with Smalltalk-80 derived meta programming which I make extensive use of in VMMaker.oscog.  But a key issue was that I was not prepared to *move* VMMaker.oscog to Pharo; for me it is key that it can live in both places.  In particular I will not risk VMMaker.oscog being stranded on Pharo as it moves away from the "image-based rendering model".  This is not because I don't believe in pixel-independent rendering models, but because productivity in VMMaker depends much more than on GToolkit inspection on the key architectural feature of being completely, safely simulateable (not a real English word; but meaning capable of being simulated).  As Pharo moves towards external libraries to implement its UI so the degree to which VMMaker is simulated is reduced.  Thus crashes in external code cannot be handled with the same power as with errors presented within the Smalltalk environment itself, and this (as harsh experience over thirty five years has taught me) is far more important for overall productivity than having powerful tailorable inspectors.
> I therefore wanted a Tonel that could both function for Squeak's Monticello and for Pharo's Iceberg.  I had modified the Tonel serialization a little to provide well-formatted support for method timestamps, which are still a key and extremely useful part of Squeak Monticello's "blame" equivalent.  Until git author attribution can be imported into Squeak's Monticello (something I don't see happening) I wanted merely to be able to have a variant of Tonel, enabled for example by a class variable, and hence /not/ present in Pharo, that would allow VMMaker.oscog to use Tonel but still be functional inside Squeak.  I asked Esteban and was met by a flat no.  Not "OK, but this is an option only you will use", but a flat "not under any circumstance".
> So here I am joining in this thread reluctantly.  I'm extremely frustrated by the state of Tonel in Squeak and between the two dialects.  Clément had moved his Scorch optimizer to Tonel/git and I tried to use Metacello and Jakob's Tonel code to at least allow me to load that code and try and push forward on Sista/Scorch.  The port *does not work*.  Metacello fails to load Scorch.  Neither Jakob nor Fabio, after putting in some effort, were able to fix the problem, and it is well beyond me.  So I have accepted the fact that I will have to use the Monticello repository for Scorch/Sista.
> I had deep concerns that the pursuit of git integration would end up splitting the Pharo and Squeak communities and indeed this is now in progress.  I am utterly unmotivated by the lack of cooperation, the sheer arrogance and bullying of those that say "you will move to git/tonel or else", and considering leaving VMMaker altogether.  The only things that are keeping me interested are Ron Teitelbaum's Terf and me pursuing a PhD on register allocation in the context of Sista/Scorch with Robert Hirshfeld's group at HPI.
> Here's the kind of crap people like Ducasse throw at me:
> "Eliot 
> At the end of the day I will probably ask the two phds that should work on language design to use truffle or pypy
> because let us face it we cannot work with the Pharo VM. Else we will simply have to fork it (because we do not want to have 
> to jump over cuis, newspeak, squeak code constraints and I do not what) and it will be another drama is in the pico world 
> of the “open” smalltalk VM. "
> I am so over this crap.
> _,,,^..^,,,_
> best, Eliot


“Software has no shape. Actually, it has no one shape. It has many."

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