Re: [PATCH/RFC] git-svn: Add --convert-timezone option
From: Eric Wong <hidden>
Date: 2016-06-15 22:45:58
Pete Harlan [off-list ref] wrote:
By default git svn stores timestamps of fetched commits in Subversion's UTC format, to facilitate interoperating with a Subversion repository. If you're using git svn to convert a repository to Git and aren't interested in pushing Git commits back to Subversion, you can use this option to store timestamps of fetched commits as though they were made in the local timezone of the host on which git svn is run. This makes the times and timezones of a resulting "git log" agree with what "svn log" shows for the same repository. Signed-off-by: Pete Harlan <redacted> --- This is a patch I've had floating around for a while. I haven't submitted it before because I find the solution ungainly. There has to be a better way to convert from one timezone to the other, but I didn't run across it and now that I've converted away from Subversion I'm sort of done thinking about it. I'm submitting it now because even in its current state it would have saved me some headache. Also, I'm not sure I'm correct when asserting that converting timezones like this will break Subversion interoperability. Eric, if that isn't true then I can remove that claim and resubmit. If converting timezones breaks nothing, then maybe it could even be the default.
Hi, It'll break interoperability between multiple users of git-svn tracking the same repo. But several options already allow for this (authors file, noMetdata, ...), so I'm fine with it as long as it's optional.
One improvement that I didn't bother to make would be to convert to different local timezones based on author. This change uses the timezone of the machine running git-svn, which in my case was fine. Using per-author timezones would be nice, but since parse_svn_date() doesn't already know which author the date is associated with it would be a more intrusive change.
Could be an interesting idea, but on the other hand I doubt many people would bother configuring the authors-file for it. On a side note, for the total conversions I've done, I've found it easier/faster/more bandwidth efficient to just forgo authors-file entirely and use git-filter-branch after-the-fact.
My primary motivation in this was to reduce transition shock among our development team. The fewer ways "git log" looks unhelpfully different than the old "svn log" the better; converting all commit times into GMT wasn't going to look friendly. Comments welcome.
My usual coding style nits apply (pretty much git (and Linux kernel) standard coding style things, too). No space between "function(arguments)". lower_snake_case, especially for local variables. mixedCase requires more effort to read IMO. More comments inline...
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--Pete Documentation/git-svn.txt | 8 ++++ contrib/completion/git-completion.bash | 2 +- git-svn.perl | 56 ++++++++++++++++++++++++++++++- 3 files changed, 63 insertions(+), 3 deletions(-)diff --git a/Documentation/git-svn.txt b/Documentation/git-svn.txt index 8d0c421..8811bf0 100644 --- a/Documentation/git-svn.txt +++ b/Documentation/git-svn.txt@@ -92,6 +92,14 @@ COMMANDS .git/config file may be specified as an optional command-line argument. +--convert-timezones;;
Is it "timezone" or "timezones" here? I think "convert-timezone" is more correct since we only use the local timezone, not different ones for each author. On the other hand, maybe "--localtime" is an even better name for this option... Any other opinions out there?
+ Store Git commit times in the local timezone instead of UTC. This + makes 'git-log' (even without --date=local) show the same times + that `svn log` would in the local timezone. + +This breaks interoperability with SVN, but may be cosmetically +desirable when converting a repository from SVN to Git.
Again, this only breaks interoperability with other users of git-svn using the default configuration on the same repo.
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'clone':: Runs 'init' and 'fetch'. It will automatically create a directory based on the basename of the URL passed to it;diff --git a/git-svn.perl b/git-svn.perl index ad01e18..c2f600d 100755 --- a/git-svn.perl +++ b/git-svn.perl@@ -66,7 +66,7 @@ my ($_stdin, $_help, $_edit, $_version, $_fetch_all, $_no_rebase, $_merge, $_strategy, $_dry_run, $_local, $_prefix, $_no_checkout, $_url, $_verbose, - $_git_format, $_commit_url, $_tag); + $_git_format, $_commit_url, $_tag, $_convert_timezones);
Not easy to tell (and apologies for that) but this new variable probably belongs in the Git::SVN namespace. I really need to find some time to reorganize and split out the source to git-svn.
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$Git::SVN::_follow_parent = 1; my %remote_opts = ( 'username=s' => \$Git::SVN::Prompt::_username, 'config-dir=s' => \$Git::SVN::Ra::config_dir,@@ -84,6 +84,7 @@ my %fc_opts = ( 'follow-parent|follow!' => \$Git::SVN::_follow_parent, \$Git::SVN::_repack_flags, 'use-log-author' => \$Git::SVN::_use_log_author, 'add-author-from' => \$Git::SVN::_add_author_from, + 'convert-timezones' => \$_convert_timezones, %remote_opts ); my ($_trunk, $_tags, $_branches, $_stdlayout);@@ -2526,12 +2527,63 @@ sub get_untracked { \@out; } +# parse_svn_date(DATE) +# -------------------- +# Given a date (in UTC) from Subversion, return a string in the format +# "<TZ Offset> <local date/time>" that Git will use. +# +# By default the parsed date will be in UTC for interoperating with +# Subversion, but if $_convert_timezones is true we'll convert it to +# the local timezone instead. sub parse_svn_date { my $date = shift || return '+0000 1970-01-01 00:00:00'; my ($Y,$m,$d,$H,$M,$S) = ($date =~ /^(\d{4})\-(\d\d)\-(\d\d)T (\d\d)\:(\d\d)\:(\d\d).\d+Z$/x) or croak "Unable to parse date: $date\n"; - "+0000 $Y-$m-$d $H:$M:$S"; + my $parsed_date; # Set next. + + if ($_convert_timezones) { + # Translate the Subversion datetime to an epoch time. + # We need to switch ourselves to $date's timezone, + # UTC, for this. + my $oldEnvTZ = $ENV{TZ}; + $ENV{TZ} = 'UTC'; + + my $epochUTC = + POSIX::strftime ('%s', $S, $M, $H, $d, $m - 1, $Y - 1900); + + # Determine our local timezone (including DST) at the + # time of $epochUTC. $Git::SVN::Log::TZ stored the + # value of TZ, if any, at the time we were run. + if (defined $Git::SVN::Log::TZ) { + $ENV{TZ} = $Git::SVN::Log::TZ; + } else { + delete $ENV{TZ}; + } + + my $ourTZ = + POSIX::strftime ('%Z', $S, $M, $H, $d, $m - 1, $Y - 1900); + + # This converts $epochUTC into our local timezone. + my ($sec, $min, $hour, $mday, $mon, $year, + $wday, $yday, $isdst) = localtime ($epochUTC); + + $parsed_date = sprintf ('%s %04d-%02d-%02d %02d:%02d:%02d', + $ourTZ, $year + 1900, $mon + 1, + $mday, $hour, $min, $sec);
There's probably a reason you didn't use strftime here, or is there? The stock Perl time/date handling functions have always frightened me, so I'll just trust the (+|-) (1|1900) things are correct :) -- Eric Wong