gitweb: add If-Modified-Since handling to git_snapshot().

Because snapshots can be large, you can save some bandwidth by
supporting caching via If-Modified-Since.  This patch adds support for
the i-m-s request to git_snapshot() if the request is a commit.
Requests for snapshots of trees, which lack well defined timestamps,
are still handled as they were before.

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

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 6d3f9c0..ede804a 100755 (executable)
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -7051,6 +7051,10 @@ sub git_snapshot {
 
        my ($name, $prefix) = snapshot_name($project, $hash);
        my $filename = "$name$known_snapshot_formats{$format}{'suffix'}";
+
+       my %co = parse_commit($hash);
+       exit_if_unmodified_since($co{'committer_epoch'}) if %co;
+
        my $cmd = quote_command(
                git_cmd(), 'archive',
                "--format=$known_snapshot_formats{$format}{'format'}",
@@ -7060,9 +7064,15 @@ sub git_snapshot {
        }
 
        $filename =~ s/(["\\])/\\$1/g;
+       my %latest_date;
+       if (%co) {
+               %latest_date = parse_date($co{'committer_epoch'}, $co{'committer_tz'});
+       }
+
        print $cgi->header(
                -type => $known_snapshot_formats{$format}{'type'},
                -content_disposition => 'inline; filename="' . $filename . '"',
+               %co ? (-last_modified => $latest_date{'rfc2822'}) : (),
                -status => '200 OK');
 
        open my $fd, "-|", $cmd

diff --git a/t/t9501-gitweb-standalone-http-status.sh b/t/t9501-gitweb-standalone-http-status.sh
index 3580103..fa2f65f 100755 (executable)
--- a/t/t9501-gitweb-standalone-http-status.sh
+++ b/t/t9501-gitweb-standalone-http-status.sh
@@ -138,6 +138,39 @@ test_expect_success 'modification: feed if-modified-since (unmodified)' '
 '
 test_debug 'cat gitweb.headers'
 
+test_expect_success 'modification: snapshot last-modified' '
+       gitweb_run "p=.git;a=snapshot;h=master;sf=tgz" &&
+       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: snapshot 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=snapshot;h=master;sf=tgz" &&
+       grep "Status: 200 OK" gitweb.headers
+'
+test_debug 'cat gitweb.headers'
+
+test_expect_success 'modification: snapshot 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=snapshot;h=master;sf=tgz" &&
+       grep "Status: 304 Not Modified" gitweb.headers
+'
+test_debug 'cat gitweb.headers'
+
+test_expect_success 'modification: tree snapshot' '
+       ID=`git rev-parse --verify HEAD^{tree}` &&
+       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=snapshot;h=$ID;sf=tgz" &&
+       grep "Status: 200 OK" gitweb.headers &&
+       ! grep -i "last-modified" gitweb.headers
+'
+test_debug 'cat gitweb.headers'
+
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