On Sat, Mar 23, 2013 at 07:15:42AM +0100, Thomas Rast wrote:
> > It involves a shell invocation, but it's not like we parse config in a
> > tight loop. Bonus points if git provides the name of the current config
> > file, so exec can use relative paths like:
>
> We do, however, parse config more than once:
>
> $ strace git log -1 2>&1 | grep 'open.*config'
> open("/home/thomas/.gitconfig", O_RDONLY) = 3
> open(".git/config", O_RDONLY) = 3
> open("/home/thomas/.gitconfig", O_RDONLY) = 3
> open(".git/config", O_RDONLY) = 3
> open("/home/thomas/.gitconfig", O_RDONLY) = 3
> open(".git/config", O_RDONLY) = 3
> open("/home/thomas/.gitconfig", O_RDONLY) = 3
> open(".git/config", O_RDONLY) = 3
>
> git-log might be somewhat of an extreme example, but I suspect it's at
> least twice for all commands (once for repo detection and once for
> actual parsing). So I further suspect that the slowdown in git's own
> shellscripts (rebase) would be quite large if you actually spawned two
> extra shells every time someone says 'git rev-parse ...'.
Yeah, I knew we parsed multiple times in some cases, but I don't think
it's that big a deal for a single command. But yeah, it might be
noticeable for a shell script which runs lots of git commands. Still, it
would only affect people who used the feature. And there is no reason
the config system could not learn to cache the results across a single
invocation, which would at least drop it to one shell per git command.
-Peff
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