Would love to see Darcs support, espe...

Hi kowey,

I really think it's great that there is interest in adding Darcs to ohloh_scm. Honestly, everyone here at Ohloh is excited about the prospect.

However, I want to be very careful to set expectations appropriately. This is a real crunch time for us, and we have no scheduled time available to work on this.

I suspect that a functioning Darcs adapter can be knocked out in a single evening. That's the easy part. The real price comes later, in debugging the endless variety of strange crashes and server performance sinks that arise in production deployment.

There's no "bare minimum" implementation that is useful, and if undertaken with that attitude it simply will not happen. We need some confidence that we aren't going to to be stuck solving a lot of problems after the rollout, and that we'll get good help from the community when we encounter them.

Regardless of our own scope intentions, the public is going to feed every Darcs repository in existence to this adapter, and will expect it to work -- even when given extremely large and/or invalid repositories. You'll be amazed at the variety of abuses people have committed with source control systems.

Also, this adapter code has to be well-behaved (low memory, low CPU), even when given extreme repositories, so that it will not interfere with our existing services.

This means that the adapter has to be very robust and efficient right from the starting gate, or it's not likely to be deployed.

So I'm not saying "no", I'm saying "yes if you really, really mean it and are willing to do some work to help us".

If after my stern warnings you're still up for it, I'm happy to slice out some time over the next few weeks and give it a shot. Here are some development pointers:

1. A similar OS will probably help a lot. While ohloh_scm should run on most any POSIX OS, we run Ubuntu 8.04 on our servers and OS X 10.5 on our development machines. Windows is a non-starter.

2. It will take some effort to get the ohloh_scm test suites passing on your development machine -- you have to install 4 different source control systems on your box, and few outside of Ohloh have ever run this code. Passing the unit tests are the first milestone. I am happy to help with this step over IRC.

3. Once you have the test suites passing, I would take a look at the Bazaar or Mercurial adapter (whichever is most similar to Darcs) and use it as a model. I would literally just copy and paste the entire lib/scm/adapters/hg directory and all of the test/unit/hg_* files, start renaming them to darcs, and go from there.

4. For the test suites, you'll need to prepare a couple of small sample repositories that exercise all of the key features, including whatever branching and merging possibilities may arise. Good coverage is essential -- I'll be a real stickler about this.

5. Finally, I know you all are Darcs users, but somehow you'll have to learn to like Git long enough to submit your patches to me, preferably via GitHub :-).

I'm happy to answer any questions, explain the big picture of how Ohloh uses this library, and help the process along. I hope there are some Darcs lovers who are willing to commit some time to this!

Thanks,

Robin

Hi kowey,

Although I'm stern, I'm actually pretty optimistic -- this should be pretty straightforward, unless there are a lot of surprises. It really is simply a time issue, which is the only reason it's still on our to-do list. To answer your questions:

First, yes, I'm happy to periodically accept and distribute preliminary code. Even if the code's not ready for production, there's value in having it for testing, review, and getting lots of eyes on it.

Second, yes, we can run the code on selected Ohloh projects long before opening it up to the public. We did this for Bazaar and Mercurial. Once private local testing has run out of bugs, we can throw the code into the lair and see what interesting ways Ohloh will find to explode :-).

Robin

Hi Ashley,

The easiest way to do this is probably for you to fork robin's github repo commit your patch and send us a pull request.

I'll try out your changes and give feedback.

Thanks for working on this.

Don't sweat it, I understand.