On 21/05/07, Karl Hasselström <kha@xxxxxxxxxxx> wrote:
On 2007-05-21 12:15:40 +0200, Karl Hasselström wrote: > We might consider having plumbing written in C or something, and > make sure that the plumbing can be called directly if there's need, > but it's going to complicate things greatly compared to pure Python.
Yes, it will complicate things. I think StGIT would have progressed at a much slower pace if written in C :-).
What I'm (foggily) envisioning here is to rewrite parts of StGIT (as little as possible) as a C library (libstgit.so?), and call the library both from the Python code, and from a "plumbing" C program (stgit-helper?). We should not try to make the library API stable, just like the current git library.
Apart from the start-up time, I don't see other major slowdowns caused by Python. It would be useful to use a git library directly without invoking external applications (I'm not sure what's the state of a "libgit.a" or what improvement we would get). As for the start-up time, unless you write most of the commands in C, we would still have to load Python modules. If you run stg-prof instead of stg for a simple command like 'top', you can see that the main function takes about 60-70ms, the rest to 150ms reported by the external 'time' is Python start-up and module loading. I had a quick try at using "freeze.py" to generate a binary (well, it includes python bytecodes but it might save time on module look-up) but it got confused by my optimisation to only load module commands based on the stg arguments. Maybe we should try this first.
There are two kinds of things we'd want to have in the library: (1) things that are too slow to do in Python, and (2) things that need to be available from stgit-helper in order to avoid Python's startup cost, such as top/applied/unapplied for the bash completion and bash prompt.
As you probably guessed, I'm not really in favour of re-writing parts of StGIT in C, at least not in the near future, though anyone can fork and re-implement it :-). -- Catalin - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
