+=head1 cache
+
+=head2 calculate_etags
+
+ calculate_etags(files => [qw(list of files)],additional_data => [qw(any additional data)]);
+
+=cut
+
+sub calculate_etags {
+ my %param =
+ validate_with(params => \@_,
+ spec => {files => {type => ARRAYREF,
+ default => [],
+ },
+ additional_data => {type => ARRAYREF,
+ default => [],
+ },
+ },
+ );
+ my @additional_data = @{$param{additional_data}};
+ for my $file (@{$param{files}}) {
+ my $st = stat($file) or warn "Unable to stat $file: $!";
+ push @additional_data,$st->mtime;
+ push @additional_data,$st->size;
+ }
+ return(md5_hex(join('',sort @additional_data)));
+}
+
+=head2 etag_does_not_match
+
+ etag_does_not_match(cgi=>$q,files=>[qw(list of files)],
+ additional_data=>[qw(any additional data)])
+
+
+Checks to see if the CGI request contains an etag which matches the calculated
+etag.
+
+If there wasn't an etag given, or the etag given doesn't match, return the etag.
+
+If the etag does match, return 0.
+
+=cut
+
+sub etag_does_not_match {
+ my %param =
+ validate_with(params => \@_,
+ spec => {files => {type => ARRAYREF,
+ default => [],
+ },
+ additional_data => {type => ARRAYREF,
+ default => [],
+ },
+ cgi => {type => OBJECT},
+ },
+ );
+ my $submitted_etag =
+ $param{cgi}->http('if-none-match');
+ my $etag =
+ calculate_etags(files=>$param{files},
+ additional_data=>$param{additional_data});
+ if (not defined $submitted_etag or
+ length($submitted_etag) != 32
+ or $etag ne $submitted_etag
+ ) {
+ return $etag;
+ }
+ if ($etag eq $submitted_etag) {
+ return 0;
+ }
+}
+