git-svn: use do_switch for --follow-parent if the SVN library supports it

do_switch works with the SVN Perl bindings after r22312 in the
Subversion trunk.  Since no released version of SVN currently
supports it; we'll just autodetect it and enable its usage
when a user has a recent-enough version of SVN.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/git-svn.perl b/git-svn.perl
index ff61b9201fefd7563d4937ad5db00ecd25ffe986..1f8a3b0e0736cc9175a18c12d57b8e25a8025ba0 100755 (executable)
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -72,7 +72,7 @@ my ($_revision,$_stdin,$_no_ignore_ext,$_no_stop_copy,$_help,$_rmdir,$_edit,
        $_username, $_config_dir, $_no_auth_cache, $_xfer_delta,
        $_pager, $_color);
 my (@_branch_from, %tree_map, %users, %rusers, %equiv);
-my ($_svn_co_url_revs, $_svn_pg_peg_revs);
+my ($_svn_co_url_revs, $_svn_pg_peg_revs, $_svn_can_do_switch);
 my @repo_path_split_cache;
 
 my %fc_opts = ( 'no-ignore-externals' => \$_no_ignore_ext,
@@ -2877,6 +2877,24 @@ sub libsvn_connect {
        return $ra;
 }
 
+sub libsvn_can_do_switch {
+       unless (defined $_svn_can_do_switch) {
+               my $pool = SVN::Pool->new;
+               my $rep = eval {
+                       $SVN->do_switch(1, '', 0, $SVN->{url},
+                                       SVN::Delta::Editor->new, $pool);
+               };
+               if ($@) {
+                       $_svn_can_do_switch = 0;
+               } else {
+                       $rep->abort_report($pool);
+                       $_svn_can_do_switch = 1;
+               }
+               $pool->clear;
+       }
+       $_svn_can_do_switch;
+}
+
 sub libsvn_dup_ra {
        my ($ra) = @_;
        SVN::Ra->new(map { $_ => $ra->{$_} } qw/config url
@@ -3198,12 +3216,26 @@ sub libsvn_find_parent_branch {
                unlink $GIT_SVN_INDEX;
                print STDERR "Found branch parent: ($GIT_SVN) $parent\n";
                sys(qw/git-read-tree/, $parent);
-               # I can't seem to get do_switch() to work correctly with
-               # the SWIG interface (TypeError when passing switch_url...),
-               # so we'll unconditionally bypass the delta interface here
-               # for now
-               return libsvn_fetch_full($parent, $paths, $rev,
-                                       $author, $date, $msg);
+               unless (libsvn_can_do_switch()) {
+                       return libsvn_fetch_full($parent, $paths, $rev,
+                                               $author, $date, $msg);
+               }
+               # do_switch works with svn/trunk >= r22312, but that is not
+               # included with SVN 1.4.2 (the latest version at the moment),
+               # so we can't rely on it.
+               my $ra = libsvn_connect("$url/$branch_from");
+               my $ed = SVN::Git::Fetcher->new({c => $parent, q => $_q});
+               my $pool = SVN::Pool->new;
+               my $reporter = $ra->do_switch($rev, '', 1, $SVN->{url},
+                                             $ed, $pool);
+               my @lock = $SVN::Core::VERSION ge '1.2.0' ? (undef) : ();
+               $reporter->set_path('', $r0, 0, @lock, $pool);
+               $reporter->finish_report($pool);
+               $pool->clear;
+               unless ($ed->{git_commit_ok}) {
+                       die "SVN connection failed somewhere...\n";
+               }
+               return libsvn_log_entry($rev, $author, $date, $msg, [$parent]);
        }
        print STDERR "Nope, branch point not imported or unknown\n";
        return undef;