includes/MessageCache.php

   1 <?
   2
   3 # Message cache
   4 # Performs various useful MediaWiki namespace-related functions
   5
   6 define( "MSG_LOAD_TIMEOUT", 60);
   7 define( "MSG_LOCK_TIMEOUT", 10);
   8 define( "MSG_WAIT_TIMEOUT", 10);
   9
  10 class MessageCache
  11 {
  12         var $mCache, $mUseCache, $mDisable, $mExpiry;
  13         var $mMemcKey, $mKeys;
  14
  15         function MessageCache( $useMemCached, $useDB, $expiry, $memcPrefix ) {
  16                 $this->initialise( $useMemCached, $useDB, $expiry, $memcPrefix );
  17         }
  18
  19         function initialise( $useMemCached, $useDB, $expiry, $memcPrefix ) {
  20                 $this->mUseCache = $useMemCached;
  21                 $this->mDisable = !$useDB;
  22                 $this->mExpiry = $expiry;
  23                 $this->mMemcKey = "$memcPrefix:messages";
  24                 $this->mKeys = false; # initialised on demand
  25
  26                 $this->load();
  27         }
  28
  29         # Loads messages either from memcached or the database, if not disabled
  30         # On error, quietly switches to a fallback mode
  31         # Returns false for a reportable error, true otherwise
  32         function load() {
  33                 global $wgAllMessagesEn, $wgMemc;
  34
  35                 if ( $this->mDisable ) {
  36                         return true;
  37                 }
  38
  39                 $success = true;
  40
  41                 if ( $this->mUseCache ) {
  42                         $this->mCache = $wgMemc->get( $this->mMemcKey );
  43
  44                         # If there's nothing in memcached, load all the messages from the database
  45                         if ( !$this->mCache ) {
  46                                 $this->lock();
  47                                 # Other threads don't need to load the messages if another thread is doing it.
  48                                 $wgMemc->set( $this->mMemcKey, "loading", MSG_LOAD_TIMEOUT );
  49                                 $this->loadFromDB();
  50                                 # Save in memcached
  51                                 if ( !$wgMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry ) ) {
  52                                         # Hack for slabs reassignment problem
  53                                         $wgMemc->set( $this->mMemcKey, "error" );
  54                                         wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
  55                                 }
  56                                 $this->unlock();
  57                         }
  58
  59                         if ( !is_array( $this->mCache ) ) {
  60                                 # If it is 'loading' or 'error', switch to individual message mode, otherwise disable
  61                                 if ( $this->mCache == "loading" ) {
  62                                         $this->mUseCache = false;
  63                                 } elseif ( $this->mCache == "error" ) {
  64                                         $this->mUseCache = false;
  65                                         $success = false;
  66                                 } else {
  67                                         $this->mDisable = true;
  68                                         $success = false;
  69                                 }
  70                                 $this->mCache = false;
  71                         }
  72                 }
  73                 return $success;
  74         }
  75
  76         # Loads all cacheable messages from the database
  77         function loadFromDB()
  78         {
  79                 $sql = "SELECT cur_title,cur_text FROM cur WHERE cur_namespace=" . NS_MEDIAWIKI;
  80                 $sql .= " AND cur_title IN ('";
  81                 $sql .= implode( "','", $this->getKeys() ) . "')";
  82                 wfDebug( "$sql\n" );
  83
  84                 $res = wfQuery( $sql, DB_READ, $fname );
  85
  86                 $this->mCache = array();
  87                 for ( $row = wfFetchObject( $res ); $row; $row = wfFetchObject( $res ) ) {
  88                         $this->mCache[$row->cur_title] = $row->cur_text;
  89                 }
  90
  91                 wfDebug( var_export( $this->mCache, true ) );
  92
  93                 wfFreeResult( $res );
  94         }
  95
  96         function getKeys() {
  97                 global $wgAllMessagesEn;
  98                 if ( !$this->mKeys ) {
  99                         $this->mKeys = array_map( 'ucfirst', array_keys( $wgAllMessagesEn ) );
 100                 }
 101                 return $this->mKeys;
 102         }
 103
 104         function isCacheable( $key ) {
 105                 global $wgAllMessagesEn;
 106                 return array_key_exists( lcfirst( $key ), $wgAllMessagesEn ) ||
 107                         array_key_exists( $key, $wgAllMessagesEn );
 108         }
 109
 110         function replace( $title, $text ) {
 111                 global $wgMemc;
 112                 if ( $this->isCacheable( $title ) ) {
 113                         $this->lock();
 114                         $this->load();
 115                         if ( is_array( $this->mCache ) ) {
 116                                 $this->mCache[$title] = $text;
 117                                 $wgMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry );
 118                         }
 119                         $this->unlock();
 120                 }
 121         }
 122
 123         # Returns success
 124         # Represents a write lock on the messages key
 125         function lock() {
 126                 global $wgMemc;
 127
 128                 if ( !$this->mUseCache ) {
 129                         return true;
 130                 }
 131
 132                 $lockKey = $this->mMemcKey . "lock";
 133                 for ($i=0; $i < MSG_WAIT_TIMEOUT && !$wgMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 134                         sleep(1);
 135                 }
 136
 137                 return $i >= MSG_WAIT_TIMEOUT;
 138         }
 139
 140         function unlock() {
 141                 global $wgMemc;
 142
 143                 if ( !$this->mUseCache ) {
 144                         return;
 145                 }
 146
 147                 $lockKey = $this->mMemcKey . "lock";
 148                 $wgMemc->delete( $lockKey );
 149         }
 150
 151         function get( $key, $useDB ) {
 152                 global $wgLang, $wgLanguageCode;
 153
 154                 if ( $this->mDisable ) {
 155                         return $wgLang->getMessage( $key );
 156                 }
 157                 $title = ucfirst( $key );
 158
 159                 $message = false;
 160
 161                 # Try the cache
 162                 if ( $this->mUseCache && $this->mCache ) {
 163                         $message = $this->mCache[$title];
 164                 }
 165
 166                 # If it wasn't in the cache, load each message from the DB individually
 167                 if ( !$message && $useDB) {
 168                         $sql = "SELECT cur_text FROM cur WHERE cur_namespace=" . NS_MEDIAWIKI .
 169                                 " AND cur_title='$title'";
 170                         $res = wfQuery( $sql, DB_READ, $fname );
 171
 172                         if ( wfNumRows( $res ) ) {
 173                                 $obj = wfFetchObject( $res );
 174                                 $message = $obj->cur_text;
 175                                 wfFreeResult( $res );
 176                         }
 177                 }
 178
 179                 # Try the array in $wgLang
 180                 if ( !$message ) {
 181                         $message = $wgLang->getMessage( $key );
 182                 }
 183
 184                 # Try the English array
 185                 if ( !$message && $wgLanguageCode != "en" ) {
 186                         $message = Language::getMessage( $key );
 187                 }
 188
 189                 # Final fallback
 190                 if ( !$message ) {
 191                         $message = "&lt;$key&gt;";
 192                 }
 193                 return $message;
 194         }
 195 }
 196
 197 function lcfirst( $s ) {
 198         return strtolower( $s{0}  ). substr( $s, 1 );
 199 }
 200 ?>