From 55776234257e165e887a1695d92cd569a63a13e7 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ian@liberator.relativity.greenend.org.uk>
Date: Sun, 27 Dec 2009 18:13:21 +0000
Subject: [PATCH] Try LP-only if MIP fails, and round everything down

---
 yarrg/web/routetrade | 40 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/yarrg/web/routetrade b/yarrg/web/routetrade
index 59b0267..b2bbf2e 100644
--- a/yarrg/web/routetrade
+++ b/yarrg/web/routetrade
@@ -580,16 +580,23 @@ if ($qa->{'debug'}) {
 <%perl>
 }
 
-{
+my $try_solve= sub {
+	my (@opts) = @_;
 	my $input= pipethrough_prep();
 	print $input $cplex or die $!;
 	my $output= pipethrough_run_along($input, undef, 'glpsol',
-		qw(glpsol --tmlim 5 --memlim 5 --intopt --cuts --bfs
-		          --cpxlp /dev/stdin -o /dev/stdout));
-	print "<pre>\n" if $qa->{'debug'};
+		qw(glpsol --tmlim 1 --memlim 5), @opts,
+		qw( --cpxlp /dev/stdin -o /dev/stdout));
+	if ($qa->{'debug'}) {
+		print "<h3>@opts</h3>\n<pre>\n";
+	}
+	$expected_total_profit= undef;
+	$_->{OptQty}= undef foreach @subflows;
 	my $found_section= 0;
 	my $glpsol_out= '';
 	my $continuation='';
+	my $timelimit= 0;
+	my $somemip= 0;
 	while (<$output>) {
 		$glpsol_out.= $_;
 		print encode_entities($_) if $qa->{'debug'};
@@ -598,6 +605,14 @@ if ($qa->{'debug'}) {
 			$found_section= 1;
 			next;
 		}
+		if ((m/^Integer optimization begins/ .. 0) &&
+		    m/^\+ \s* \d+\: \s* mip \s* = \s* \d/) {
+			$somemip= 1;
+			next;
+		}
+		if (m/^TIME LIMIT EXCEEDED/) {
+			$timelimit= 1;
+		}
 		if (m/^Objective:\s+totalprofit = (\d+(?:\.\d*)?) /) {
 			$expected_total_profit= $1;
 		}
@@ -618,7 +633,7 @@ if ($qa->{'debug'}) {
 		my ($varname, $qty) = m/^
 			\s* \d+ \s+
 			(\w+) \s+ (?: [A-Z*]+ \s+ )?
-			([+-e0-9.]+) \s
+			([-+0-9]+)(?: [.e][-+e0-9.]* )? \s
 			/x or die "$cplex \n==\n $glpsol_out $_ ?";
 		if ($varname =~ m/^f(\d+)s(\d+)_/) {
 			my ($ix,$orgix) = ($1,$2);
@@ -640,8 +655,23 @@ if ($qa->{'debug'}) {
 	pipethrough_run_finish($output,$prerr);
 	map { defined $_->{OptQty} or die "$prerr $_->{Flow}{Ix}" } @subflows;
 	defined $expected_total_profit or die "$prerr ?";
+	return $somemip || !$timelimit;
 };
 
+unless ($try_solve->(qw( --intopt --cuts --bfs )) or
+	$try_solve->(qw( --nomip ))) {
+</%perl>
+<h2>Optimisation failed</h2>
+The linear/mixed-integer optimisation failed.
+Please report this problem.
+
+<pre>
+<% $cplex |h %>
+</pre>
+<%perl>
+	return;
+}
+
 $addcols->({ DoReverse => 1, TotalSubflows => 1, Special => sub {
 	my ($flow,$col,$v,$spec) = @_;
 	if ($flow->{ExpectedUnitProfit} < 0) {
-- 
2.30.2