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Re: Enhancement suggestions

From: Peter <bf3_at_telenet.be>
Date: 2007-03-15 20:22:27 CET

Miller, Eric wrote:
> Wow. All of my issues with svn summed up in a single post!
> Just a few of my favorites:
>> - Automatic detection of renames and moves.
> And copies- This one is a pain and is mostly related to...

You mean that a copy is actually a branched revision of the original?
Yeah that would be cool. But that would be very difficult to do using
the NTFS change journal I guess.

>> - No ".svn" folders.
> When these get deleted, copied, moved, or looked at funny bad things can
> happen. It'd be great to get them out of the working copy at the very
> least. I know there has been considerable discussion regarding this in
> the past but I don't know if there is any implementation plan.

Evolver stored all metadata using NTFS Alternate Data Streams. It stored
it in the root directory of the "unit/project", but if you want to get
rid of the unit concept, it could just as well be stored as an ADS in
the root drive (e.g. C:/)

>> - Proper handling of "file with same name exists in working copy".
> AKA obstructions- a major pain in some cases. Ever try to fix an
> obstructed directory that was scheduled for deletion but not yet
> committed?

Indeed, horrible. In the beginning I was almost tempted to develop a new
"Evolver2" (as I don't own the rights of Evolver) because I was cleaning
up and manually deleting files all the time to get SVN updates working,
grr... Luckily for me, I had no spare time to do this - it would be at
least 9 man-months of full-time development, and it's not my focus.

>> - The concept of a "unit".
> While I think your definition of a 'unit' is sufficient for most, I'd
> like to see a configurable option that can define multiple 'unit types'
> that can auto-select your path list for versioning operations.
> OTOH it's probably just easier to implement this in a wrapper on a
> per-case basis than try to come up with a general solution.

You are right. This is just some kind of "company commit policy".

>> - Inter-branch locking.
> Hallelujah!
> Also brought up before - working copy lock tracking.
> Tracking down locks based on uid alone is not sufficient - hostname and
> working copy path all should be logged when a lock is acquired.

Well, in Evolver that was handled by introducing an extra "proxy" object
on the server; no matter how many working copies of an "asset" (=file or
directory) existed, they all tracked back to this proxy object, and all
locking was done on it.

> Great stuff!

Thank you. It seems the quest for the ultimate version control system is
not over yet ;)

> Eric
>> -----Original Message-----
>> From: Peter [mailto:bf3@telenet.be]
>> Sent: Thursday, March 15, 2007 5:22 AM
>> To: dev@subversion.tigris.org
>> Subject: Enhancement suggestions
>> Hi,
>> A couple of years ago, I developed a source control system - called
>> Evolver - for a company that hired me. The company made video-games,
> and
>> wanted a source control system that was powerful enough for
> developers,
>> yet very easy to use for the other kinds of users (mainly "artists").
>> Evolver worked exclusive on Windows/NTFS, but I guess most NTFS
> features
>> are also found in Unix-like systems.
>> Although subversion goes way beyond the system I developed, I do miss
> a
>> couple of things. I must admit I'm new to subversion, so some of these
>> might already be implemented.
>> - Automatic detection of renames and moves. Evolver used NTFS
>> object-identifiers and the change-journal to track this.
>> - No "cleanup" needed. Because the above, "cleanup" did not exist. All
>> possible changes allowed by the file system got tracked automatically.
>> The only "cleanup" needed was when a new file with the same name as a
>> deleted file was created. Although most of the time this issue was
>> handled internally by NTFS file tunneling, it could happen when
> software
>> moved a file with the same name across different volumes.
>> - Properly handling of "file with same name exists in working copy".
>> - Concept of "generated" files. When a conflict occured on these
> files,
>> they got deleted by default, because they can be re-generated. Of
> course
>> a build-system like SCONS that uses caching is much more suitable to
>> handle this, but this is not always usable with content creation tools
>> that often do not support batch / command-line support.
>> - Semi atomic updates. Using a method of file locking and renaming,
> and
>> update of a working folder either completely succeeded or failed.
>> Rollback after a failure was possible because a special naming scheme.
>> - No ".svn" folders. Evolver stored all information in extra NTFS
>> streams, removing clutter.
>> - The concept of a "unit". Currently, it is possible to commit just
> one
>> file, but doing this is a bit like hacking. Usually one works on a
>> "project" which is an atomic unit. Committing only a subset of changes
>> is dangerous because they cannot be tested, and this quickly converges
>> into a "but it works on my machine" situation. In Subversion a "unit"
>> would be just some parent directory that is always used when
> committing,
>> unless explicitly overriden.
>> - Dependencies to other units. A unit usually makes use of other
> units.
>> Changes in the dependencies must usually be committed at the same
> time.
>> - NTFS junctions and hardlinks. I've seen this in discussions but have
>> no idea what the current status is. We used junctions to dependencies,
>> so that all required files were located under a single project
>> directory. The problem is that Windows itself does not support
>> junctions/hardlinks (e.g. Windows Explorer does not understand them).
>> - Concept of automatic locking of files. Although subversion supports
>> locking now, it must still be performed manually? Evolver performed an
>> automatic lock as soon as a file was overwritten. After all, binary
>> files cannot be merged, and parallel evolution of such a files should
> be
>> prohibited as soon as possible. Binary files are evil, but they are
> very
>> common in content development systems (Adobe Flash, Autodesk 3D
> Studio
>> MAX, Adobe Photoshop, etc).
>> - Multiple branches in the same working folder. One directory could
>> contain assets for multiple branches at the same time. One just
> selects
>> the current branch, and commits/updates automatically pick a parent
>> branch for finding the "common/base" revision. I have a feeling
>> subversion supports this, but I haven't figured out yet how.
>> - Inter-branch locking. A binary file that lives in multiple branches
>> could be locked in all branches at the same time.
>> - By default, reverting a directory deletes local files in it. After
>> all, reverting restores the previous revision, and since the file did
>> not exist in the previous revision, its previous state is void.
>> - An experimental feature was "refactor friendly structured storage".
> So
>> instead of storing dumb source code, a DOM was stored instead, using
>> unique-object-identifiers instead of names to refer to symbols. So
>> basically, source control did not stop on the file level, but at the
>> object level. Merging was done on this tree, which eased extreme
>> programming and refactoring. For example, renaming a class was just
> one
>> change to the DOM in which the class was declared, although it might
>> change dozens of source text files that used it. This was never used
>> because it would also require different source code editors that work
> on
>> the symbolic level.
>> I hope this information was useful, although I'm not expecting to see
>> any of this in subversion soon, as you guys probably have really good
>> reasons not to have implemented these "features".
>> Cheers,
>> Peter
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Received on Thu Mar 15 20:22:41 2007

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