From: Jakub Narebski <jnareb@gmail.com>
Date: Sun, 5 Dec 2010 23:01:09 +0000 (+0100)
Subject: gitweb: Add startup delay to activity indicator for cache
X-Git-Url: https://repo.or.cz/w/git/jnareb-git.git/commitdiff_plain/fc07456a656eb7d685d78d8e8f7b5e50007d1970

gitweb: Add startup delay to activity indicator for cache

This adds support for [optional] startup delay to git_generating_data_html()
subroutine, which is used to provide "Generating..." page as activity
indicator when waiting for page to be generated if caching.  If the data
(page contents) gets generated within $generating_options{'staryp_delay'}
seconds, the "Generating..." page won't get displayed.

This feature was created in response to complaint by Petr 'Pasky' Baudis'
about "Generating..." feature.


NOTE: This startup delay allows to use git_generating_data_html() also
for process generating data, assuming that die_error(), which turns of
capturing and which output (error page) is not cache, finishes within
startup delay.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index efaa69b5e1..d181ba3648 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -357,11 +357,22 @@ our %cache_options = (
 	# is passed the following parameters: $cache instance, human-readable
 	# $key to current page, and filehandle $lock_fh to lockfile.
 	'generating_info' => \&git_generating_data_html,
+
+	# This enables/disables using 'generating_info' subroutine by process
+	# generating data, when not too stale data is not available (data is then
+	# generated in background).  Because git_generating_data_html() includes
+	# initial delay (of 1 second by default), and we can assume that die_error
+	# finishes within this time, then generating error pages should be safe
+	# from infinite "Generating page..." loop.
+	'generating_info_is_safe' => 1,
 );
 # You define site-wide options for "Generating..." page (if enabled) here
 # (which means that $cache_options{'generating_info'} is set to coderef);
 # override them with $GITWEB_CONFIG as necessary.
 our %generating_options = (
+	# The delay before displaying "Generating..." page, in seconds.  It is
+	# intended for "Generating..." page to be shown only when really needed.
+	'startup_delay' => 1,
 	# The time between generating new piece of output to prevent from
 	# redirection before data is ready, i.e. time between printing each
 	# dot in activity indicator / progress info, in seconds.
@@ -3607,6 +3618,23 @@ sub git_generating_data_html {
 		return;
 	}
 
+	# Initial delay
+	if ($generating_options{'startup_delay'} > 0) {
+		eval {
+			local $SIG{ALRM} = sub { die "alarm clock restart\n" }; # NB: \n required
+			alarm $generating_options{'startup_delay'};
+			flock($lock_fh, LOCK_SH); # blocking readers lock
+			alarm 0;
+		};
+		if ($@) {
+			# propagate unexpected errors
+			die $@ if $@ !~ /alarm clock restart/;
+		} else {
+			# we got response within 'startup_delay' timeout
+			return;
+		}
+	}
+
 	my $title = "[Generating...] " . get_page_title();
 	# TODO: the following line of code duplicates the one
 	# in git_header_html, and it should probably be refactored.