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         var $mInitialised = false;
  16
  17         function initialise( $useMemCached, $useDB, $expiry, $memcPrefix ) {
  18                 $this->mUseCache = $useMemCached;
  19                 $this->mDisable = !$useDB;
  20                 $this->mExpiry = $expiry;
  21                 $this->mMemcKey = "$memcPrefix:messages";
  22                 $this->mKeys = false; # initialised on demand
  23                 $this->mInitialised = true;
  24
  25                 $this->load();
  26         }
  27
  28         # Loads messages either from memcached or the database, if not disabled
  29         # On error, quietly switches to a fallback mode
  30         # Returns false for a reportable error, true otherwise
  31         function load() {
  32                 global $wgAllMessagesEn, $wgMemc;
  33
  34                 if ( $this->mDisable ) {
  35                         return true;
  36                 }
  37
  38                 $success = true;
  39
  40                 if ( $this->mUseCache ) {
  41                         $this->mCache = $wgMemc->get( $this->mMemcKey );
  42
  43                         # If there's nothing in memcached, load all the messages from the database
  44                         if ( !$this->mCache ) {
  45                                 $this->lock();
  46                                 # Other threads don't need to load the messages if another thread is doing it.
  47                                 $wgMemc->set( $this->mMemcKey, "loading", MSG_LOAD_TIMEOUT );
  48                                 $this->loadFromDB();
  49                                 # Save in memcached
  50                                 if ( !$wgMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry ) ) {
  51                                         # Hack for slabs reassignment problem
  52                                         $wgMemc->set( $this->mMemcKey, "error" );
  53                                         wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
  54                                 }
  55                                 $this->unlock();
  56                         }
  57
  58                         if ( !is_array( $this->mCache ) ) {
  59                                 # If it is 'loading' or 'error', switch to individual message mode, otherwise disable
  60                                 if ( $this->mCache == "loading" ) {
  61                                         $this->mUseCache = false;
  62                                 } elseif ( $this->mCache == "error" ) {
  63                                         $this->mUseCache = false;
  64                                         $success = false;
  65                                 } else {
  66                                         $this->mDisable = true;
  67                                         $success = false;
  68                                 }
  69                                 $this->mCache = false;
  70                         }
  71                 }
  72                 return $success;
  73         }
  74
  75         # Loads all cacheable messages from the database
  76         function loadFromDB()
  77         {
  78                 $sql = "SELECT cur_title,cur_text FROM cur WHERE cur_namespace=" . NS_MEDIAWIKI;
  79                 $sql .= " AND cur_title IN ('";
  80                 $sql .= implode( "','", $this->getKeys() ) . "')";
  81                 wfDebug( "$sql\n" );
  82
  83                 $res = wfQuery( $sql, DB_READ, $fname );
  84
  85                 $this->mCache = array();
  86                 for ( $row = wfFetchObject( $res ); $row; $row = wfFetchObject( $res ) ) {
  87                         $this->mCache[$row->cur_title] = $row->cur_text;
  88                 }
  89
  90                 wfDebug( var_export( $this->mCache, true ) );
  91
  92                 wfFreeResult( $res );
  93         }
  94
  95         function getKeys() {
  96                 global $wgAllMessagesEn, $wgLang;
  97                 $ucfirst = get_class($wgLang) . "::ucfirst";
  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, $wgLang;
 106                 return array_key_exists( $wgLang->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, $wgLanguageCode;
 153
 154                 # If uninitialised, someone is trying to call this halfway through Setup.php
 155                 if ( !$this->mInitialised ) {
 156                         return "&lt;$key&gt;";
 157                 }
 158
 159                 if ( $this->mDisable ) {
 160                         return $wgLang->getMessage( $key );
 161                 }
 162                 $title = $wgLang->ucfirst( $key );
 163
 164                 $message = false;
 165
 166                 # Try the cache
 167                 if ( $this->mUseCache && $this->mCache ) {
 168                         $message = $this->mCache[$title];
 169                 }
 170
 171                 # If it wasn't in the cache, load each message from the DB individually
 172                 if ( !$message && $useDB) {
 173                         $sql = "SELECT cur_text FROM cur WHERE cur_namespace=" . NS_MEDIAWIKI .
 174                                 " AND cur_title='$title'";
 175                         $res = wfQuery( $sql, DB_READ, $fname );
 176
 177                         if ( wfNumRows( $res ) ) {
 178                                 $obj = wfFetchObject( $res );
 179                                 $message = $obj->cur_text;
 180                                 wfFreeResult( $res );
 181                         }
 182                 }
 183
 184                 # Try the array in $wgLang
 185                 if ( !$message ) {
 186                         $message = $wgLang->getMessage( $key );
 187                 }
 188
 189                 # Try the English array
 190                 if ( !$message && $wgLanguageCode != "en" ) {
 191                         $message = Language::getMessage( $key );
 192                 }
 193
 194                 # Final fallback
 195                 if ( !$message ) {
 196                         $message = "&lt;$key&gt;";
 197                 }
 198                 return $message;
 199         }
 200 }
 201 ?>