[PATCH 0/3 v2] gitweb: Support caching projects list

[Jakub Narebski <jnareb@gmail.com>]

This series of patches is resend of patch by Petr 'Pasky' Baudis with
the same subject, which can be found in,
  Message-ID: <20080313231413.27966.3383.stgit@rover>
  http://permalink.gmane.org/gmane.comp.version-control.git/77151
split into two patches (so the exact details of serializing and
caching can be separated from independent code improvement), and with
added lazy filling of details for a project.

At the bottom there is interdiff between Pasky's result and result
after first two patches here.  Besides a bit of style changes the main
difference is that in this version dump of @projects array is done in
'terse' form, so it can be eval'ed directly into @projects.

Table of contents:
==================
 [PATCH 1/3] gitweb: Separate filling projects info
             into git_get_projects_details()
 [PATCH 2/3] gitweb: Support caching projects list
 [PATCH 3/3] gitweb: Fill project details only if project path
              mtime changed

Shortlog:
=========
Jakub Narebski (1):
  gitweb: Fill project details only if project path mtime changed

Petr Baudis (2):
  gitweb: Separate filling projects info into git_get_projects_details()
  gitweb: Support caching projects list

Diffstat:
=========
 gitweb/gitweb.css  |    6 ++++
 gitweb/gitweb.perl |   73 ++++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 74 insertions(+), 5 deletions(-)

Interdiff:
==========
 gitweb/gitweb.perl |   35 ++++++++++++++++++++---------------
 1 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index bee5ec8..5527378 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -123,7 +123,7 @@ our @diff_opts = ('-M'); # taken from git_commit
 # index lifetime in minutes
 # the cached list version is stored in /tmp and can be tweaked
 # by other scripts running with the same uid as gitweb - use this
-# only at secure installations; only single gitweb project root per
+# ONLY at secure installations; only single gitweb project root per
 # system is supported!
 our $projlist_cache_lifetime = 0;
 
@@ -3482,6 +3482,8 @@ sub git_patchset_body {
 
 # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
 
+# fill age, description, owner, forks (last one only if $check_forks)
+# for all projects in $projlist reference; fill projects info
 sub git_get_projects_details {
 	my ($projlist, $check_forks) = @_;
 
@@ -3521,34 +3523,37 @@ sub git_project_list_body {
 
 	my ($check_forks) = gitweb_check_feature('forks');
 
-	my $cache_file = '/tmp/gitweb.index.cache';
 	use File::stat;
+	use POSIX qw(:fcntl_h);
+
+	my $cache_file =  '/tmp/gitweb.index.cache';
 
 	my @projects;
 	my $stale = 0;
-	if ($cache_lifetime and -f $cache_file
-	    and stat($cache_file)->mtime + $cache_lifetime * 60 > time()
-	    and open (my $fd, $cache_file)) {
-		$stale = time() - stat($cache_file)->mtime;
-		my @dump = <$fd>;
+	my $now = time();
+	if ($cache_lifetime && -f $cache_file &&
+	    stat($cache_file)->mtime + $cache_lifetime * 60 > $now &&
+	    open(my $fd, '<', $cache_file)) {
+		$stale = $now - stat($cache_file)->mtime;
+		local $/ = undef;
+		my $dump = <$fd>;
 		close $fd;
-		# Hack zone start
-		my $VAR1;
-		eval join("\n", @dump);
-		@projects = @$VAR1;
-		# Hack zone end
+		@projects = @{ eval $dump };
 	} else {
-		if ($cache_lifetime and -f $cache_file) {
+		if ($cache_lifetime && -f $cache_file) {
 			# Postpone timeout by two minutes so that we get
 			# enough time to do our job.
 			my $time = time() - $cache_lifetime + 120;
 			utime $time, $time, $cache_file;
 		}
 		@projects = git_get_projects_details($projlist, $check_forks);
-		if ($cache_lifetime and open (my $fd, '>'.$cache_file)) {
+		if ($cache_lifetime &&
+		    sysopen(my $fd, "$cache_file.lock", O_WRONLY|O_CREAT|O_EXCL, 0600)) {
 			use Data::Dumper;
+			$Data::Dumper::Terse = 1;
 			print $fd Dumper(\@projects);
 			close $fd;
+			rename "$cache_file.lock", $cache_file;
 		}
 	}
 
@@ -3556,7 +3561,7 @@ sub git_project_list_body {
 	$from = 0 unless defined $from;
 	$to = $#projects if (!defined $to || $#projects < $to);
 
-	if ($cache_lifetime and $stale) {
+	if ($cache_lifetime && $stale) {
 		print "<div class=\"stale_info\">Cached version (${stale}s old)</div>\n";
 	}