Abstract: In 2016, Iceberg was born so people could host their Pharo projects on git repositories. Since 2017, Pharo is hosted in git and bootstrapped from sources on each new commit. Iceberg is then not only important for private projects but also crucial in Pharo's contribution process. Today, more than two years since the project started, we have learnt some lessons: not everybody understands git, and Pharo projects are not simple git projects. This talk gives an overview of the challenges we had to overcome, such as dual working copies, in-memory merge strategies, external resources and performance issues arising from big Pharo projects (e.g., Pharo itself). Bio: Guille Polito is research engineer at the CRIStAL laboratory in the university of Lille, working in tight relation with the RMoD team. Guille's main research interests are techniques to develop modular systems and new development tools. Guille participates in the Pharo community since 2010. His most noticeable contributions in the past months are in the Pharo bootstrap process, Pharo stream management, Iceberg and OSSubprocess.

1. Iceberg 2018
Ge-ng more solid
by Guille Polito
@GuillePolito

2. What is Iceberg?
+ =
h@ps://github.com/pharo-vcs/iceberg

3. Eat our own food
Iceberg OSSubprocess
Ring2 Spec
Launcher
UFFI
Smalltalk
CI
Pillar

4. Why ?
• Visibility
• Manage more than only code
• Lower entry barrier into the community
• Lots of exisVng tools
• Good branch support, good diff
• …

5. 2年 aZer the 1st Iceberg
• Git is a misunderstood monster:
“With great power comes great responsibility“
• Iceberg grew up, it’s not
a prototype anymore
(v1.2.2)

6. Much things going on...

7. Easier & More Robust
New UI
Lots of CI
64bit support
53% coverage
Dual Working Copy
- =
- =
=+
Three-Way Merge

8. IceTip: New UI
Spec based
+ new widgets (toolbars, status bars...)

9. 3 Guidelines
• Be explicit: preview destrucVve operaVons
• Be explicit: warn problemaVc states
• Be explicit: let the user decide

10. Explicit Commit

11. Explicit Pull

12. Explicit Checkout

13. Explicit Repository Status

14. Explicit Repository Status
Problem
DescripVon
Proposed
SoluVons
Consequences
+
Tradeoffs

15. Easier & More Robust
New UI
Lots of CI
64bit support
53% coverage
Dual Working Copy
- =
- =
=+
Three-Way Merge

16. Robustness through
AutomaVon

17. Iceberg is ge-ng big
• packages size
=> 17
• packages sum: [ :e | e definedClasses size ]
=> 589
• packages sum: [ :e | e linesOfCode ]
=> 21769

18. Code coverage in last
~6 months
~6% => ~53%

19. Parameterized tests
To define complex test cases and fixtures
h@ps://github.com/tesonep/ParametrizedTests

20. Lots of tests,
Lots of
running Vme

21. Speed-up with Ring2
Esug ’17
Meta-Modeling of
Custom Pharo Images
Pavel Krivanek
Because slow-downs come most from impacVng the
system, e.g., compilaVon, system coherence

22. Huge Investment In CI
• 18 jobs, mulVple plarorms x Pharo versions
• Pharo integraVon pre-test, metacello integraVon, wiki
synchronizaVon
• SmalltalkCI!!

23. Make sure it runs in x64
• Make OSSubprocess stable in 64bits
• Latest release v1.0.1, stable since mid-may

24. Key points for robustness
• Not fear the change
• Lots, fast, both integraVon and unitary tests
• In mulVple plarorms
• Automated
• Enhance our infrastructure
• OSSubprocess, Ring, ParameterizedTests, Spec...

25. Easier & More Robust
New UI
Lots of CI
64bit support
53% coverage
Dual Working Copy
- =
- =
=+
Three-Way Merge

26. The Working Copy

27. Iceberg’s Working Copy
• A repository has an
in-image working copy
• A working copy remembers its
current commit
• Required for pulling, pushing,
diffing...
Pharo Image
Iceberg
Working Copy
commit=dc4a3e7

28. Dual Working Copy
Working Copy Repository
…
To be able to work, the working copy
should be in-sync with the working
copy in disk
Pharo Image
Iceberg
Working Copy
commit=dc4a3e7
commit=dc4a3e7

29. Detached Working Copy
Working Copy Repository
…
The working copy in the image can get
desync from the working copy in disk
Pharo Image
Iceberg
Working Copy
commit=dc4a3e7
commit=0c0c5ff

30. Why do I get
Detached Working Copy?
Although quite rare:
• Possibility 1) You touched your git repository from
outside the image
• Possibility 2) Your image crashed in between commits
• Possibility 3) You forgot to save your image aZer a
commit

31. How do I get out of
Detached Working Copy?
• OpVon 1) Move your image to your repository state
(load what is in the disk)
• OpVon 2) Move your repository state to what is in the
image (checkout image’s commit)
• OpVon 3) Try merging both

32. A simpler design
• SimplificaVon over the model on
Iceberg < 0.7
• Less error prone
• SVll, we are looking on workflow
simplificaVons (virtual branches?)
Working Copy
Pharo
Iceberg
Working Copy
commit=dc4a3e7
commit=dc4a3e7

33. Easier & More Robust
New UI
Lots of CI
64bit support
53% coverage
Dual Working Copy
- =
- =
=+
Three-Way Merge

34. New merge algorithm
• Repository-project based instead of package based
• Allow file merges
• Honors git merge (ff, non-ff…)
• Three-way!

35. Three-way merge
37adf4e
master
0c0e5ff
development
b894b84 dc4a3e71. Diff merged
commits against
common parent
2. Merge both diff
trees (and check
conflicts)

36. 37adf4e
master
0c0e5ff
pment
b894b84 dc4a3e7
HEAD
t1 t2
t3
t1 t3- = d1
t2 t3
- = d2
d1 d2 m
=+
Three-way Merge Explained

37. And all these are objects...
Diff tree
in Checkout
Merge tree
in Merge

38. Reliable merge
• Do not lose code
• Correctly calculate conflicts
• SVll need some UI enhancements

39. Easier & More Robust
New UI
Lots of CI
64bit support
53% coverage
Dual Working Copy
- =
- =
=+
Three-Way Merge

40. The next evoluVon
• Manage more than code?
• Sub-projects?

41. Conclusion
- =
- =
=+
Iceberg OSSubprocess
Ring Spec
Launcher
:)
UFFI
h@ps://github.com/pharo-vcs/iceberg

42. Extra Slides!

43. Inspect, inspect, inspect

44. iceCommit fileSystem

45. CredenVal Manager

46. Prototyping about Files