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contrib/git-svn: add -b/--branch switch for branch detection

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I've said I don't like branches in Subversion, and I still don't.
This is a bit more flexible, though, as the argument for -b is any
arbitrary git head/tag reference.

This makes some things easier:
 * Importing git history into a brand new SVN branch.
 * Tracking multiple SVN branches via GIT_SVN_ID, even from multiple
   repositories.
 * Adding tags from SVN (still need to use GIT_SVN_ID, though).
 * Even merge tracking is supported, if and only the heads end up with
   100% equivalent tree objects.  This is more stricter but more robust
   and foolproof than parsing commit messages, imho.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Eric Wong 2006-03-03 01:20:07 -08:00 committed by Junio C Hamano
parent a41c175d6f
commit 69f0d91e49
2 changed files with 54 additions and 1 deletions
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38
contrib/git-svn/git-svn.perl
View file

@ -35,6 +35,7 @@
my $sha1_short = qr/[a-f\d]{6,40}/;
my ($_revision,$_stdin,$_no_ignore_ext,$_no_stop_copy,$_help,$_rmdir,$_edit,
$_find_copies_harder, $_l, $_version, $_upgrade);
my (@_branch_from, %tree_map);
GetOptions( 'revision|r=s' => \$_revision,
'no-ignore-externals' => \$_no_ignore_ext,
@ -43,6 +44,7 @@
'rmdir' => \$_rmdir,
'upgrade' => \$_upgrade,
'help|H|h' => \$_help,
'branch|b=s' => \@_branch_from,
'find-copies-harder' => \$_find_copies_harder,
'l=i' => \$_l,
'version|V' => \$_version,
@ -831,6 +833,8 @@ sub git_commit {
my $uuid = $info->{'Repository UUID'};
defined $uuid or croak "Unable to get Repository UUID\n";
map_tree_joins() if (@_branch_from && !%tree_map);
# commit parents can be conditionally bound to a particular
# svn revision via: "svn_revno=commit_sha1", filter them out here:
my @exec_parents;
@ -852,6 +856,17 @@ sub git_commit {
git_addremove();
chomp(my $tree = `git-write-tree`);
croak if $?;
if (exists $tree_map{$tree}) {
my %seen_parent = map { $_ => 1 } @exec_parents;
foreach (@{$tree_map{$tree}}) {
# MAXPARENT is defined to 16 in commit-tree.c:
if ($seen_parent{$_} || @exec_parents > 16) {
next;
}
push @exec_parents, $_;
$seen_parent{$_} = 1;
}
}
my $msg_fh = IO::File->new_tmpfile or croak $!;
print $msg_fh $log_msg->{msg}, "\ngit-svn-id: ",
"$SVN_URL\@$log_msg->{revision}",
@ -975,6 +990,29 @@ sub check_upgrade_needed {
}
}
# fills %tree_map with a reverse mapping of trees to commits. Useful
# for finding parents to commit on.
sub map_tree_joins {
foreach my $br (@_branch_from) {
my $pid = open my $pipe, '-|';
defined $pid or croak $!;
if ($pid == 0) {
exec(qw(git-rev-list --pretty=raw), $br) or croak $?;
}
while (<$pipe>) {
if (/^commit ($sha1)$/o) {
my $commit = $1;
my ($tree) = (<$pipe> =~ /^tree ($sha1)$/o);
unless (defined $tree) {
die "Failed to parse commit $commit\n";
}
push @{$tree_map{$tree}}, $commit;
}
}
close $pipe or croak $?;
}
}
__END__
Data structures:

17
contrib/git-svn/git-svn.txt
View file

@ -27,7 +27,7 @@ For importing svn, git-svnimport is potentially more powerful when
operating on repositories organized under the recommended
trunk/branch/tags structure, and should be faster, too.
git-svn completely ignores the very limited view of branching that
git-svn mostly ignores the very limited view of branching that
Subversion has. This allows git-svn to be much easier to use,
especially on repositories that are not organized in a manner that
git-svnimport is designed for.
@ -116,6 +116,21 @@ OPTIONS
They are both passed directly to git-diff-tree see
git-diff-tree(1) for more information.
-b<refname>::
--branch <refname>::
Used with 'fetch' or 'commit'.
This can be used to join arbitrary git branches to remotes/git-svn
on new commits where the tree object is equivalent.
When used with different GIT_SVN_ID values, tags and branches in
SVN can be tracked this way, as can some merges where the heads
end up having completely equivalent content. This can even be
used to track branches across multiple SVN _repositories_.
This option may be specified multiple times, once for each
branch.
COMPATIBILITY OPTIONS
---------------------
--no-ignore-externals::