[RFC PATCH 11/9] [PoC] gitweb/lib - HTTP-aware output caching

@@ -360,6 +360,9 @@ our %cache_options = (
 		# pages will be cached if were generated in detached process).
 		# Default is undef.
 		'-cache_errors' => undef,
+		# Mark that we are caching HTTP response, and that we want extra treatment,
+		# i.e. automatic adding of Expires/Cache-Control and Content-Length headers
+		'-http_output' => 1,
 	},
 );
 # You define site-wide options for "Generating..." page (if enabled) here

@@ -19,6 +19,7 @@ use warnings;
 
 use File::Copy qw();
 use Symbol qw(qualify_to_ref);
+use CGI::Util qw(expires);
 
 use Exporter qw(import);
 our @EXPORT      = qw(cache_output);

@@ -69,6 +70,37 @@ sub cache_output {
 		$filename ||= $capture_filename;
 	}
 
+	if ($opts{'-http_output'}) {
+		# we need filehandle; filename is not enough
+		open $fh, '<', $filename unless defined $fh;
+
+		# get HTTP headers first
+		my (@headers, %norm_headers);
+		while (my $line = <$fh>) {
+			last if $line eq "\r\n";
+			push @headers, $line;
+			if ($line =~ /^([^:]+:)\s+(.*)$/) {
+				(my $header = lc($1)) =~ s/_/-/;
+				$norm_headers{$header} = $2;
+			}
+		}
+		print join('', @headers);
+
+		# extra headers
+		if (!exists $norm_headers{lc('Expires')} &&
+		    !exists $norm_headers{lc('Cache-Control')}) {
+			my $expires_in = $cache->expires_in($key);
+			print "Expires: " . expires($expires_in, 'http')."\r\n".
+			      "Cache-Control: max-age=$expires_in\r\n";
+		}
+		if (!exists $norm_headers{lc('Content-Length')}) {
+			my $length = (-s $fh) - (tell $fh);
+			print "Content-Length: $length\r\n" if $length;
+		}
+
+		print "\r\n"; # separates headers from body
+	}
+
 	if (defined $fh || defined $filename) {
 		# set binmode only if $fh is defined (is a filehandle)
 		# File::Copy::copy opens files given by filename in binary mode

@@ -457,6 +457,30 @@ sub is_valid {
 	return (($now - $mtime) < $expires_in);
 }
 
+# $cache->expires_in($key)
+#
+# Returns number of seconds an entry would be valid, or undef
+# if cache entry for given $key does not exists.
+sub expires_in {
+	my ($self, $key) = @_;
+
+	my $path = $self->path_to_key($key);
+
+	# does file exists in cache?
+	return undef unless -f $path;
+	# get its modification time
+	my $mtime = (stat(_))[9] # _ to reuse stat structure used in -f test
+		or $self->_handle_error("Couldn't stat file '$path' for key '$key': $!");
+
+	my $expires_in = $self->get_expires_in();
+
+	my $now = time();
+	print STDERR __PACKAGE__."now=$now; mtime=$mtime; ".
+		"expires_in=$expires_in; diff=".($now - $mtime)."\n";
+
+	return $expires_in == 0 ? 0 : ($self->get_expires_in() - ($now - $mtime));
+}
+
 # Getting and setting
 
 # ($fh, $filename) = $cache->compute_fh($key, $code);

@@ -6,6 +6,8 @@ use strict;
 
 use Test::More;
 
+use CGI qw(:standard);
+
 # test source version
 use lib $ENV{GITWEBLIBDIR} || "$ENV{GIT_BUILD_DIR}/gitweb/lib";
 

@@ -158,5 +160,28 @@ subtest 'errors are cached with -cache_errors => 1' => sub {
 };
 
 
+# caching HTTP output
+subtest 'HTTP output' => sub {
+	$cache->remove($key);
+	$cache->set_expires_in(60);
+
+	my $header =
+		header(-status=>'200 OK', -type=>'text/plain', -charset => 'utf-8');
+	my $data = "1234567890";
+	$action_output = $header.$data;
+	$test_data = capture_output_of_cache_output(\&action, '-http_output' => 1);
+
+	$header =~ s/\r\n$//;
+	my $length = do { use bytes; length($data); };
+	like($test_data, qr/^\Q$header\E/, 'http: starts with provided http header');
+	like($test_data, qr/\Q$data\E$/,   'http: ends with body (payload)');
+	like($test_data, qr/^Expires: /m,  'http: some "Expires:" header added');
+	like($test_data, qr/^Cache-Control: max-age=\d+\r\n/m,
+	                                   'http: "Cache-Control:" with max-age added');
+	like($test_data, qr/^Content-Length: $length\r\n/m,
+	                                   'http: "Content-Length:" header with correct value'); 
+};
+
+
 done_testing();
 __END__