Re: mtimes of working files

[Eric Wong <normalperson@yhbt.net>]

Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
> Hi list,
> 
> > > > How difficult is it to have script (or maybe existing git option) 
> > > > that would make mtimes of all working files equal to time of last 
> > > > commit ?
> 
> Now I slowly get really curious.  Does _anybody_ know a scenario where 
> this makes sense?
> 
> (No, Eric, there are enough corner cases where your example of a clustered 
> webserver breaks down, so I am not fully convinced that this is a useful 
> case.)

I'll have to admit that most of my git usage is via git-svn, so I
mostly deal with linear history and some branching, but no real merges
in a git sense.

This is what I whipped up the other night:

http://yhbt.net/git-set-file-times

-----------------------------------8<-----------------------------------------
#!/usr/bin/perl -w
use strict;

# sets mtime and atime of files to the latest commit time in git
#
# This is useful for serving static content (managed by git)
# from a cluster of identically configured HTTP servers.  HTTP
# clients and content delivery networks can get consistent
# Last-Modified headers no matter which HTTP server in the
# cluster they hit.  This should improve caching behavior.
#
# This does not take into account merges, but if you're updating
# every machine in the cluster from the same commit (A) to the
# same commit (B), the mtimes will be _consistent_ across all
# machines if not necesarily accurate.
#
# THIS IS NOT INTENDED TO OPTIMIZE BUILD SYSTEMS SUCH AS 'make'
# YOU HAVE BEEN WARNED!

my %ls = ();
my $commit_time;

$/ = "\0";
open FH, 'git ls-files -z|' or die $!;
while (<FH>) {
	chomp;
	$ls{$_} = $_;
}
close FH;


$/ = "\n";
open FH, "git log -r --name-only --no-color --pretty=raw -z @ARGV |" or die $!;
while (<FH>) {
	chomp;
	if (/^committer .*? (\d+) (?:[\-\+]\d+)$/) {
		$commit_time = $1;
	} elsif (s/\0\0commit [a-f0-9]{40}$//) {
		my @files = delete @ls{split(/\0/, $_)};
		@files = grep { defined $_ } @files;
		next unless @files;
		utime $commit_time, $commit_time, @files;
	}
	last unless %ls;

}
close FH;
-----------------------------------8<-----------------------------------------

-- 
Eric Wong