git-svn: speed up blame command

'git svn blame' now uses the 'git cat-file --batch' command to
speed up resolving SVN revision number out of commit SHA by
removing fork+exec overhead.

[ew: enforced 80-column line wrap]

Signed-off-by: Boris Byk <boris.byk@gmail.com>
Acked-by: Eric Wong <normalperson@yhbt.net>

diff --git a/git-svn.perl b/git-svn.perl
index cb718b8519f1f1d6704154b839c6a14b63776274..50a398b3e75d75c0f917290bb56c699ca866a9e5 100755 (executable)
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -47,7 +47,8 @@ BEGIN {
        # import functions from Git into our packages, en masse
        no strict 'refs';
        foreach (qw/command command_oneline command_noisy command_output_pipe
-                   command_input_pipe command_close_pipe/) {
+                   command_input_pipe command_close_pipe
+                   command_bidi_pipe command_close_bidi_pipe/) {
                for my $package ( qw(SVN::Git::Editor SVN::Git::Fetcher
                        Git::SVN::Migration Git::SVN::Log Git::SVN),
                        __PACKAGE__) {
@@ -1264,6 +1265,40 @@ sub cmt_metadata {
                command(qw/cat-file commit/, shift)))[-1]);
 }
 
+sub cmt_sha2rev_batch {
+       my %s2r;
+       my ($pid, $in, $out, $ctx) = command_bidi_pipe(qw/cat-file --batch/);
+       my $list = shift;
+
+       foreach my $sha (@{$list}) {
+               my $first = 1;
+               my $size = 0;
+               print $out $sha, "\n";
+
+               while (my $line = <$in>) {
+                       if ($first && $line =~ /^[[:xdigit:]]{40}\smissing$/) {
+                               last;
+                       } elsif ($first &&
+                              $line =~ /^[[:xdigit:]]{40}\scommit\s(\d+)$/) {
+                               $first = 0;
+                               $size = $1;
+                               next;
+                       } elsif ($line =~ /^(git-svn-id: )/) {
+                               my (undef, $rev, undef) =
+                                                     extract_metadata($line);
+                               $s2r{$sha} = $rev;
+                       }
+
+                       $size -= length($line);
+                       last if ($size == 0);
+               }
+       }
+
+       command_close_bidi_pipe($pid, $in, $out, $ctx);
+
+       return \%s2r;
+}
+
 sub working_head_info {
        my ($head, $refs) = @_;
        my @args = ('log', '--no-color', '--first-parent', '--pretty=medium');
@@ -5001,11 +5036,22 @@ sub cmd_blame {
                                                  '--', $path);
                my ($sha1);
                my %authors;
+               my @buffer;
+               my %dsha; #distinct sha keys
+
                while (my $line = <$fh>) {
+                       push @buffer, $line;
+                       if ($line =~ /^([[:xdigit:]]{40})\s\d+\s\d+/) {
+                               $dsha{$1} = 1;
+                       }
+               }
+
+               my $s2r = ::cmt_sha2rev_batch([keys %dsha]);
+
+               foreach my $line (@buffer) {
                        if ($line =~ /^([[:xdigit:]]{40})\s\d+\s\d+/) {
-                               $sha1 = $1;
-                               (undef, $rev, undef) = ::cmt_metadata($1);
-                               $rev = '0' if (!$rev);
+                               $rev = $s2r->{$1};
+                               $rev = '0' if (!$rev)
                        }
                        elsif ($line =~ /^author (.*)/) {
                                $authors{$rev} = $1;