Re: [gentoo-portage-dev] [PATCH] egencache --update-changelogs: fix timestamp assumptions (bug 579292)

[Brian Dolbec]

On Thu,  7 Apr 2016 22:46:25 -0700
Zac Medico <zmedico@g.o> wrote:

> Since commit times are not necessarily ordered, synchronize the
> ChangeLog mtime with the last commit time, and use exact comparison
> to detect changes.
>
> X-Gentoo-bug: 579292
> X-Gentoo-bug-url: https://bugs.gentoo.org/show_bug.cgi?id=579292
> ---
>  bin/egencache | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/bin/egencache b/bin/egencache
> index 0123d57..41612e5 100755
> --- a/bin/egencache
> +++ b/bin/egencache
> @@ -775,12 +775,16 @@ class GenChangeLogs(object):
>  			# This cp has not been added to the repo.
>  			return
>
> +		lmod = long(lmod)
> +
>  		try:
> -			cmod = os.stat('ChangeLog').st_mtime
> +			cmod = os.stat('ChangeLog')[stat.ST_MTIME]
>  		except OSError:
>  			cmod = 0
>
> -		if float(cmod) >= float(lmod):
> +		# Use exact comparison, since commit times are
> +		# not necessarily ordered.
> +		if cmod == lmod:
>  			return
>
>  		try:
> @@ -903,6 +907,7 @@ class GenChangeLogs(object):
>  				'\n%s\n\n' %
> '\n'.join(self._wrapper.fill(x) for x in body))
>  		output.close()
> +		os.utime(self._changelog_output, (lmod, lmod))
>
>  	def _task_iter(self):
>  		if not os.path.isdir(os.environ.get('GIT_DIR',
> os.path.join(self._repo_path, '.git'))):

the above looks good, but what about:


[19:01] <dwfreed|phone> just use --first-parent
[19:01] <dwfreed|phone> also take into account merge commits
[19:03] <dwfreed|phone> git really complicates ChangeLog generation in general
[19:03] <dwfreed|phone> because your ChangeLog should reflect when these commits became part of master, but you still need to perserve their messages
[19:04] * zmedico is skeptical about the linearizability of the timestamps
[19:04] <dwfreed|phone> if you don't look at merge commits for your timestamps of changes, correct, it is not linear
[19:05] <dwfreed|phone> but if you take a set of commits and determine when they became part of master, it is linear
[19:05] <dol-sen> so: git log --first-parent --format=%ct -1 .
[19:05] <dol-sen> to get the last timestamp of changes to htat pkg
[19:06] <dol-sen> then use that timestamp
[19:06] <dol-sen> lmod = self.grab(['git', self._work_tree, 'log', '--format=%ct', '-1', '.'])
[19:06] <dol-sen> that is the current code
[19:06] <dwfreed|phone> git log -m --first-parent --format=%ct -1 .
[19:06] <dol-sen> so just add the --first-parent option?
[19:07] <dwfreed|phone> you want -m toolmod = self.grab(['git',
self._work_tree, 'log', '--format=%ct', '-1', '.'])

[19:06] <dwfreed|phone> git log -m --first-parent --format=%ct -1 .
[19:06] <dol-sen> so just add the --first-parent option?
[19:07] <dwfreed|phone> you want -m too


Don't we need to add the -m --first-parent  ???
-- 
Brian Dolbec <dolsen>