gitweb: refactor If-Modified-Since handling

The current gitweb only generates Last-Modified and handles
If-Modified-Since headers for the git_feed action.  This patch breaks
the Last-Modified and If-Modified-Since handling code out from
git_feed into a new function exit_if_unmodified_since.  This makes the
code easy to reuse for other actions.

Only gitweb actions which can easily calculate a modification time
should use exit_if_unmodified_since, as the goal is to balance local
processing time vs. upload bandwidth.

Signed-off-by: W Trevor King <wking@drexel.edu>
Acked-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 041da17..6d3f9c0 100755 (executable)
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -7003,6 +7003,28 @@ sub snapshot_name {
        return wantarray ? ($name, $name) : $name;
 }
 
+sub exit_if_unmodified_since {
+       my ($latest_epoch) = @_;
+       our $cgi;
+
+       my $if_modified = $cgi->http('IF_MODIFIED_SINCE');
+       if (defined $if_modified) {
+               my $since;
+               if (eval { require HTTP::Date; 1; }) {
+                       $since = HTTP::Date::str2time($if_modified);
+               } elsif (eval { require Time::ParseDate; 1; }) {
+                       $since = Time::ParseDate::parsedate($if_modified, GMT => 1);
+               }
+               if (defined $since && $latest_epoch <= $since) {
+                       my %latest_date = parse_date($latest_epoch);
+                       print $cgi->header(
+                               -last_modified => $latest_date{'rfc2822'},
+                               -status => '304 Not Modified');
+                       goto DONE_GITWEB;
+               }
+       }
+}
+
 sub git_snapshot {
        my $format = $input_params{'snapshot_format'};
        if (!@snapshot_fmts) {
@@ -7820,35 +7842,14 @@ sub git_feed {
        if (defined($commitlist[0])) {
                %latest_commit = %{$commitlist[0]};
                my $latest_epoch = $latest_commit{'committer_epoch'};
-               %latest_date   = parse_date($latest_epoch, $latest_commit{'comitter_tz'});
-               my $if_modified = $cgi->http('IF_MODIFIED_SINCE');
-               if (defined $if_modified) {
-                       my $since;
-                       if (eval { require HTTP::Date; 1; }) {
-                               $since = HTTP::Date::str2time($if_modified);
-                       } elsif (eval { require Time::ParseDate; 1; }) {
-                               $since = Time::ParseDate::parsedate($if_modified, GMT => 1);
-                       }
-                       if (defined $since && $latest_epoch <= $since) {
-                               print $cgi->header(
-                                       -type => $content_type,
-                                       -charset => 'utf-8',
-                                       -last_modified => $latest_date{'rfc2822'},
-                                       -status => '304 Not Modified');
-                               return;
-                       }
-               }
-               print $cgi->header(
-                       -type => $content_type,
-                       -charset => 'utf-8',
-                       -last_modified => $latest_date{'rfc2822'},
-                       -status => '200 OK');
-       } else {
-               print $cgi->header(
-                       -type => $content_type,
-                       -charset => 'utf-8',
-                       -status => '200 OK');
+               exit_if_unmodified_since($latest_epoch);
+               %latest_date = parse_date($latest_epoch, $latest_commit{'comitter_tz'});
        }
+       print $cgi->header(
+               -type => $content_type,
+               -charset => 'utf-8',
+               %latest_date ? (-last_modified => $latest_date{'rfc2822'}) : (),
+               -status => '200 OK');
 
        # Optimization: skip generating the body if client asks only
        # for Last-Modified date.

diff --git a/t/t9501-gitweb-standalone-http-status.sh b/t/t9501-gitweb-standalone-http-status.sh
index 31076ed..3580103 100755 (executable)
--- a/t/t9501-gitweb-standalone-http-status.sh
+++ b/t/t9501-gitweb-standalone-http-status.sh
@@ -92,7 +92,7 @@ test_debug 'cat gitweb.output'
 test_expect_success 'snapshots: bad tree-ish id (tagged object)' '
        echo object > tag-object &&
        git add tag-object &&
-       git commit -m "Object to be tagged" &&
+       test_tick && git commit -m "Object to be tagged" &&
        git tag tagged-object `git hash-object tag-object` &&
        gitweb_run "p=.git;a=snapshot;h=tagged-object;sf=tgz" &&
        grep "400 - Object is not a tree-ish" gitweb.output
@@ -112,6 +112,31 @@ test_expect_success 'snapshots: bad object id' '
 '
 test_debug 'cat gitweb.output'
 
+# ----------------------------------------------------------------------
+# modification times (Last-Modified and If-Modified-Since)
+
+test_expect_success 'modification: feed last-modified' '
+       gitweb_run "p=.git;a=atom;h=master" &&
+       grep "Status: 200 OK" gitweb.headers &&
+       grep "Last-modified: Thu, 7 Apr 2005 22:14:13 +0000" gitweb.headers
+'
+test_debug 'cat gitweb.headers'
+
+test_expect_success 'modification: feed if-modified-since (modified)' '
+       export HTTP_IF_MODIFIED_SINCE="Wed, 6 Apr 2005 22:14:13 +0000" &&
+       test_when_finished "unset HTTP_IF_MODIFIED_SINCE" &&
+       gitweb_run "p=.git;a=atom;h=master" &&
+       grep "Status: 200 OK" gitweb.headers
+'
+test_debug 'cat gitweb.headers'
+
+test_expect_success 'modification: feed if-modified-since (unmodified)' '
+       export HTTP_IF_MODIFIED_SINCE="Thu, 7 Apr 2005 22:14:13 +0000" &&
+       test_when_finished "unset HTTP_IF_MODIFIED_SINCE" &&
+       gitweb_run "p=.git;a=atom;h=master" &&
+       grep "Status: 304 Not Modified" gitweb.headers
+'
+test_debug 'cat gitweb.headers'
 
 # ----------------------------------------------------------------------
 # load checking