From a42a7b25408acf92a72a4c04f4b577e5c8b38195 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Tue, 19 Nov 2013 23:05:39 +0100
Subject: [PATCH 1/1] Implement If-Modified-Since manually, since browser
 support is so strange.

---
 www/analysis.pl      | 30 ++++++++++++++----------------
 www/js/remoteglot.js |  6 ++++--
 2 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/www/analysis.pl b/www/analysis.pl
index 6169764..46795a9 100755
--- a/www/analysis.pl
+++ b/www/analysis.pl
@@ -1,7 +1,6 @@
 #! /usr/bin/perl
 use CGI;
 use POSIX;
-use Date::Manip;
 use Linux::Inotify2;
 use AnyEvent;
 use strict;
@@ -26,11 +25,11 @@ my $wait = AnyEvent->timer (
 	cb    => sub { $cv->send; },
 );
 
+# Yes, this is reinventing If-Modified-Since, but browsers are so incredibly
+# unpredictable on this, so blargh.
 my $ims = 0;
-if (exists($ENV{'HTTP_IF_MODIFIED_SINCE'})) {
-	my $date = Date::Manip::Date->new;
-	$date->parse($ENV{'HTTP_IF_MODIFIED_SINCE'});
-	$ims = $date->printf("%s");
+if (defined($cgi->param('ims')) && $cgi->param('ims') ne '') {
+	$ims = $cgi->param('ims');
 }
 my $time = (stat($json_filename))[9];
 
@@ -40,20 +39,11 @@ if ($time > $ims) {
 	exit;
 }
 
-# If not, wait, then send. Apache will deal with the 304-ing.
-if (defined($cgi->param('first')) && $cgi->param('first') != 1) {
-	$cv->recv;
-}
+# If not, wait, then send.
+$cv->recv;
 output();
 
 sub output {
-	my $time = (stat($json_filename))[9];
-	my $lm_str = POSIX::strftime("%a, %d %b %Y %H:%M:%S %z", localtime($time));
-
-	print CGI->header(-type=>'text/json',
-			  -last_modified=>$lm_str,
-	                  -access_control_allow_origin=>'http://analysis.sesse.net',
-	                  -expires=>'now');
 	open my $fh, "<", $json_filename
 		or die "$json_filename: $!";
 	my $data;
@@ -61,5 +51,13 @@ sub output {
 		local $/ = undef;
 		$data = <$fh>;
 	}
+	my $time = (stat($fh))[9];
+	close $fh;
+
+	print CGI->header(-type=>'text/json',
+			  -x_remoteglot_last_modified=>$time,
+	                  -access_control_allow_origin=>'http://analysis.sesse.net',
+	                  -access_control_expose_headers=>'X-Remoteglot-Last-Modified',
+	                  -expires=>'now');
 	print $data;
 }
diff --git a/www/js/remoteglot.js b/www/js/remoteglot.js
index 34fa7f7..e220f4a 100644
--- a/www/js/remoteglot.js
+++ b/www/js/remoteglot.js
@@ -2,14 +2,16 @@ var board = [];
 var arrows = [];
 var arrow_targets = [];
 var occupied_by_arrows = [];
+var ims = 0;
 var highlight_from = undefined;
 var highlight_to = undefined;
 
 var request_update = function(board, first) {
 	$.ajax({
 		//url: "http://analysis.sesse.net/analysis.pl?first=" + first
-		url: "http://analysis.sesse.net:5000/analysis.pl?first=" + first
-	}).done(function(data) {
+		url: "http://analysis.sesse.net:5000/analysis.pl?ims=" + ims
+	}).done(function(data, textstatus, xhr) {
+		ims = xhr.getResponseHeader('X-Remoteglot-Last-Modified');
 		update_board(board, data);
 	});
 }
-- 
2.39.2