gitweb/lib/GitwebCache/CacheOutput.pm

   1 # gitweb - simple web interface to track changes in git repositories
   2 #
   3 # (C) 2010, Jakub Narebski <jnareb@gmail.com>
   4 # (C) 2006, John 'Warthog9' Hawley <warthog19@eaglescrag.net>
   5 #
   6 # This program is licensed under the GPLv2
   7
   8 #
   9 # Capturing and caching (gitweb) output
  10 #
  11
  12 # Capture output, save it in cache and print it, or retrieve it from
  13 # cache and print it.
  14
  15 package GitwebCache::CacheOutput;
  16
  17 use strict;
  18 use warnings;
  19
  20 use Exporter qw(import);
  21 our @EXPORT      = qw(cache_output capture_stop);
  22 our %EXPORT_TAGS = (all => [ @EXPORT ]);
  23
  24 # cache_output($cache, $capture, $key, $action_code);
  25 #
  26 # Attempts to get $key from $cache; if successful, prints the value.
  27 # Otherwise, calls $action_code, capture its output using $capture,
  28 # and use the captured output as the new value for $key in $cache,
  29 # then print captured output.
  30 #
  31 # It is assumed that captured data is already converted and it is
  32 # in ':raw' format (and thus restored in ':raw' from cache)
  33
  34 # default capture class (engine), if none provided
  35 our $DEFAULT_CAPTURE_CLASS = 'GitwebCache::Capture::Simple';
  36 sub cache_output {
  37         my ($cache, $capture, $key, $code) = @_;
  38
  39         $capture = setup_capture($capture);
  40
  41         # check if data is in the cache
  42         my $data = $cache->get($key);
  43
  44         # capture and cache output, if there was nothing in the cache
  45         if (!defined $data) {
  46                 $data = $capture->capture($code);
  47                 $cache->set($key, $data) if defined $data;
  48         }
  49
  50         # print cached data
  51         if (defined $data) {
  52                 binmode STDOUT, ':raw';
  53                 print $data;
  54         }
  55
  56         return $data;
  57 }
  58
  59 # capture_stop($cache, $capture);
  60 #
  61 # Stops capturing output; to be used in die_error, so that error pages
  62 # are not cached (not captured and cached).
  63 sub capture_stop {
  64         my ($cache, $capture) = @_;
  65
  66         if (defined $capture) {
  67                 return $capture->capture_stop();
  68         }
  69         return;
  70 }
  71
  72 # ......................................................................
  73 # helper subroutines
  74
  75 # setup capture engine
  76 sub setup_capture {
  77         my $capture = shift;
  78
  79         $capture ||= $DEFAULT_CAPTURE_CLASS;
  80         if (!ref($capture)) {
  81                 eval "require $capture;" or die $@;
  82                 $capture = $capture->new();
  83         }
  84
  85         return $capture;
  86 }
  87
  88 1;
  89 __END__
  90 # end of package GitwebCache::CacheOutput