From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sun, 24 Jan 2016 21:53:17 +0000 (+0100)
Subject: Use standalone tablebase probes to convert +123.xx scores to mates. It causes some... 
X-Git-Url: https://git.sesse.net/?p=remoteglot;a=commitdiff_plain;h=92c3ae694d679a17fe546179c06b54ac8578eb9a;hp=233222cc738d382d962f69bdcfe9eedd01ad7e43

Use standalone tablebase probes to convert +123.xx scores to mates. It causes some funny effects, but is better than nothing.
---

diff --git a/Position.pm b/Position.pm
index 6840e7f..c3dbcca 100644
--- a/Position.pm
+++ b/Position.pm
@@ -38,6 +38,7 @@ sub new {
 	}
 	$pos->{'last_move'} = $x[29];
 	$pos->{'prettyprint_cache'} = {};
+	$pos->{'tbprobe_cache'} = {};
 
 	bless $pos, $class;
 	return $pos;
@@ -78,6 +79,7 @@ sub from_fen {
 	$pos->{'last_move_uci'} = undef;
 	$pos->{'last_move'} = undef;
 	$pos->{'prettyprint_cache'} = {};
+	$pos->{'tbprobe_cache'} = {};
 	
 	bless $pos, $class;
 	return $pos;
@@ -164,6 +166,7 @@ sub to_json_hash {
 	my $json = { %$pos, fen => $pos->fen() };
 	delete $json->{'board'};
 	delete $json->{'prettyprint_cache'};
+	delete $json->{'tbprobe_cache'};
 	delete $json->{'black_castle_k'};
 	delete $json->{'black_castle_q'};
 	delete $json->{'white_castle_k'};
diff --git a/config.pm b/config.pm
index 77fa74e..55f6d35 100644
--- a/config.pm
+++ b/config.pm
@@ -61,6 +61,10 @@ our @masters = (
 	'Sesse',
 );
 
+# Command line to run the Fathom tablebase lookup program, if installed,
+# including the --path= argument.
+our $fathom_cmdline = undef;
+
 # ChessOK serial key (of the form NNNNN-NNNNN-NNNNN-NNNNN-NNNNN-NNNNN)
 # for looking up 7-man tablebases; undef means no lookup. Note that
 # you probably need specific prior permission to use this.
diff --git a/remoteglot.pl b/remoteglot.pl
index 9f0ac3f..ca5263c 100755
--- a/remoteglot.pl
+++ b/remoteglot.pl
@@ -530,6 +530,61 @@ sub prettyprint_pv {
 	}
 }
 
+sub complete_using_tbprobe {
+	my ($pos, $info, $mpv) = @_;
+
+	# We need Fathom installed to do standalone TB probes.
+	return if (!defined($remoteglotconf::fathom_cmdline));
+
+	# If we already have a mate, don't bother; in some cases, it would even be
+	# better than a tablebase score.
+	return if defined($info->{'score_mate' . $mpv});
+
+	# If we have a draw or near-draw score, there's also not much interesting
+	# we could add from a tablebase. We only really want mates.
+	return if ($info->{'score_cp' . $mpv} >= -12250 && $info->{'score_cp' . $mpv} <= 12250);
+
+	# Run through the PV until we are at a 6-man position.
+	# TODO: We could in theory only have 5-man data.
+	my @pv = @{$info->{'pv' . $mpv}};
+	my $key = join('', @pv);
+	my @moves = ();
+	if (exists($pos->{'tbprobe_cache'}{$key})) {
+		@moves = $pos->{'tbprobe_cache'}{$key};
+	} else {
+		while ($pos->num_pieces() > 6 && $#pv > -1) {
+			my $move = shift @pv;
+			push @moves, $move;
+			$pos = $pos->make_move(parse_uci_move($move));
+		}
+
+		return if ($pos->num_pieces() > 6);
+
+		my $fen = $pos->fen();
+		my $pgn_text = `fathom --path=/srv/syzygy "$fen"`;
+		my $pgn = Chess::PGN::Parse->new(undef, $pgn_text);
+		return if (!defined($pgn) || !$pgn->read_game() || ($pgn->result ne '0-1' && $pgn->result ne '1-0'));
+		$pgn->quick_parse_game;
+		$info->{'pv' . $mpv} = \@moves;
+
+		# Splice the PV from the tablebase onto what we have so far.
+		for my $move (@{$pgn->moves}) {
+			my $uci_move;
+			($pos, $uci_move) = $pos->make_pretty_move($move);
+			push @moves, $uci_move;
+		}
+	}
+
+	$info->{'pv' . $mpv} = \@moves;
+
+	my $matelen = int((1 + scalar @moves) / 2);
+	if ((scalar @moves) % 2 == 0) {
+		$info->{'score_mate' . $mpv} = -$matelen;
+	} else {
+		$info->{'score_mate' . $mpv} = $matelen;
+	}
+}
+
 sub output {
 	#return;
 
@@ -622,6 +677,17 @@ sub output {
 		return;
 	}
 
+	# Now do our own Syzygy tablebase probes to convert scores like +123.45 to mate.
+	if (exists($info->{'pv'})) {
+		complete_using_tbprobe($pos_calculating, $info, '');
+	}
+
+	my $mpv = 1;
+	while (exists($info->{'pv' . $mpv})) {
+		complete_using_tbprobe($pos_calculating, $info, $mpv);
+		++$mpv;
+	}
+
 	output_screen();
 	output_json(0);
 	$latest_update = [Time::HiRes::gettimeofday];
@@ -710,8 +776,8 @@ sub output_screen {
 			my $info = $engine2->{'info'};
 			last if (!exists($info->{'pv' . $mpv}));
 			eval {
+				complete_using_tbprobe($pos_calculating_second_engine, $info, $mpv);
 				my $pv = $info->{'pv' . $mpv};
-
 				my $pretty_move = join('', prettyprint_pv($pos_calculating_second_engine, $pv->[0]));
 				my @pretty_pv = prettyprint_pv($pos_calculating_second_engine, @$pv);
 				if (scalar @pretty_pv > 5) {
@@ -788,6 +854,7 @@ sub output_json {
 			last if (!exists($info->{'pv' . $mpv}));
 
 			eval {
+				complete_using_tbprobe($pos_calculating, $info, $mpv);
 				my $pv = $info->{'pv' . $mpv};
 				my $pretty_move = join('', prettyprint_pv($pos_calculating, $pv->[0]));
 				my @pretty_pv = prettyprint_pv($pos_calculating, @$pv);