cgi-bin/LJ/LocalCache.pm

   1 package LJ::LocalCache;
   2
   3 use strict;
   4 use warnings;
   5
   6 use LJ::ModuleLoader;
   7
   8 # Usage example:
   9 #
  10 #   LJ::LocalCache::get_cache()->set("ml.${lncode}.${dmid}.${itcode}", $text, 30*60);
  11 #
  12
  13
  14 my @SUBCLASSES = LJ::ModuleLoader->module_subclasses(__PACKAGE__);
  15 my %modules_info;
  16 my $loaded = 0;
  17
  18 use constant {
  19     LOAD_SUCCESSFUL => 1,
  20     LOAD_FAILED     => -1,
  21     NOT_LOADED      => 0,
  22     CRITICAL_ERROR  => 2,
  23 };
  24
  25 sub __load_packages {
  26     return if $loaded;
  27
  28     if (LJ::is_enabled("local_cache")) {
  29         %modules_info = map { $_ => NOT_LOADED } @SUBCLASSES;
  30         $loaded = 1;
  31     }
  32 }
  33
  34 # this function will disable a module from using
  35 # even it is already loaded
  36 sub __critical_error {
  37     my $module = shift;
  38     $modules_info{$module} = CRITICAL_ERROR;
  39 }
  40
  41 sub __get_package {
  42     my $module = shift;
  43     my $status = $modules_info{$module};
  44
  45     return "LJ::LocalCache::$module" if $status == LOAD_SUCCESSFUL;
  46     return 'LJ::LocalCache' if $status == LOAD_FAILED ||
  47                                $status == CRITICAL_ERROR;
  48
  49     # try to load
  50     eval  "use $module" ;
  51
  52     if ($@) {
  53         $modules_info{$module} = LOAD_FAILED;
  54         return 'LJ::LocalCache';
  55     }
  56
  57     return $module;
  58 }
  59
  60 sub get_cache {
  61     my ($handler) = @_;
  62     $handler ||= $LJ::LOCAL_CACHE_DEFAULT_HANDLER;
  63
  64     return 'LJ::LocalCache' if !LJ::is_enabled("local_cache");
  65     __load_packages();
  66     return __get_package("LJ::LocalCache::$handler");
  67 }
  68
  69 sub expire {
  70     my ($class, $key, $expire) = @_;
  71     return 0;
  72 }
  73
  74 sub get {
  75     my ($class, $key) = @_;
  76     return undef;
  77 }
  78
  79 sub get_multi {
  80     my ($class, $keys, $not_fetched_keys) = @_;
  81     @$not_fetched_keys = @$keys;
  82     return undef;
  83 }
  84
  85 sub set {
  86     my ($class, $key, $value, $expire) = @_;
  87     return undef;
  88 }
  89
  90 sub replace {
  91     my ($class, $key, $value, $expire) = @_;
  92     return 0;
  93 }
  94
  95 sub delete {
  96     my ($class, $key) = @_;
  97     return 0;
  98 }
  99
 100 sub incr {
 101     my ($class, $key, $value) = @_;
 102     return 0;
 103 }
 104
 105 sub decr {
 106     my ($class, $key, $value) = @_;
 107     return 0;
 108 }
 109
 110 sub exists {
 111     my ($class, $key) = @_;
 112     return 0;
 113 }
 114
 115 sub rpush {
 116     my ($class, $key, $value) = @_;
 117     return 0;
 118 }
 119
 120 sub lpush {
 121     my ($class, $key, $value) = @_;
 122     return 0;
 123 }
 124
 125 sub lpop {
 126     my ($class, $key) = @_;
 127     return undef;
 128 }
 129
 130 sub rpop {
 131     my ($class, $key) = @_;
 132     return undef;
 133 }
 134
 135 1;
 136