git-svn: use sys* IO functions for reading rev_db

Using buffered IO for reading 40-41 bytes at a time isn't very
efficient.  Buffering writes for a short duration is alright
since we close() right away and buffers will be flushed.

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

diff --git a/git-svn.perl b/git-svn.perl
index b1d91fa471b11ef6ab2f9c005bb1efac6ea53119..1e3a3c08f11372857c5152d7c20b50df8784a673 100755 (executable)
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -891,23 +891,20 @@ sub last_rev_commit {
        my $rl;
        open my $fh, '<', $self->{db_path} or
                                 croak "$self->{db_path} not readable: $!\n";
-       seek $fh, $offset, 2;
-       $rl = readline $fh;
-       defined $rl or return (undef, undef);
+       sysseek($fh, $offset, 2); # don't care for errors
+       sysread($fh, $rl, 41) == 41 or return (undef, undef);
        chomp $rl;
-       while (('0' x40) eq $rl && tell $fh != 0) {
+       while (('0' x40) eq $rl && sysseek($fh, 0, 1) != 0) {
                $offset -= 41;
-               seek $fh, $offset, 2;
-               $rl = readline $fh;
-               defined $rl or return (undef, undef);
+               sysseek($fh, $offset, 2); # don't care for errors
+               sysread($fh, $rl, 41) == 41 or return (undef, undef);
                chomp $rl;
        }
        if ($c) {
                die "$self->{db_path} and ", $self->refname,
                    " inconsistent!:\n$c != $rl\n";
        }
-       my $rev = tell $fh;
-       croak $! if ($rev < 0);
+       my $rev = sysseek($fh, 0, 1) or croak $!;
        $rev =  ($rev - 41) / 41;
        close $fh or croak $!;
        ($self->{last_rev}, $self->{last_commit}) = ($rev, $c);
@@ -1419,12 +1416,9 @@ sub rev_db_get {
        my $ret;
        my $offset = $rev * 41;
        open my $fh, '<', $self->{db_path} or croak $!;
-       if (seek $fh, $offset, 0) {
-               $ret = readline $fh;
-               if (defined $ret) {
-                       chomp $ret;
-                       $ret = undef if ($ret =~ /^0{40}$/);
-               }
+       if (sysseek($fh, $offset, 0) == $offset) {
+               my $read = sysread($fh, $ret, 40);
+               $ret = undef if ($read != 40 || $ret eq ('0'x40));
        }
        close $fh or croak $!;
        $ret;