git-svn: optimize --branch and --branch-all-ref

By breaking the pipe read once we've seen a commit twice.

This should make -B/--branch-all-ref faster and usable on a
frequent basis.

We use topological order now for calling git-rev-list, and any
commit we've seen before should imply that all parents have been
seen (at least I hope that's the case for --topo-order).

Signed-off-by: Eric Wong <normalperson@yhbt.net>

diff --git a/contrib/git-svn/git-svn.perl b/contrib/git-svn/git-svn.perl
index c91160d..d4b9323 100755 (executable)
--- a/contrib/git-svn/git-svn.perl
+++ b/contrib/git-svn/git-svn.perl
@@ -1220,23 +1220,30 @@ 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 {
+       my %seen;
        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 $?;
+                       exec(qw(git-rev-list --topo-order --pretty=raw), $br)
+                                                               or croak $?;
                }
                while (<$pipe>) {
                        if (/^commit ($sha1)$/o) {
                                my $commit = $1;
+
+                               # if we've seen a commit,
+                               # we've seen its parents
+                               last if $seen{$commit};
                                my ($tree) = (<$pipe> =~ /^tree ($sha1)$/o);
                                unless (defined $tree) {
                                        die "Failed to parse commit $commit\n";
                                }
                                push @{$tree_map{$tree}}, $commit;
+                               $seen{$commit} = 1;
                        }
                }
-               close $pipe or croak $?;
+               close $pipe; # we could be breaking the pipe early
        }
 }