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                 $fname = "MessageCache::loadFromDB";
  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, $wgLang;
  98                 if ( !$this->mKeys ) {
  99                         $this->mKeys = array();
 100                         foreach ( $wgAllMessagesEn as $key => $value ) {
 101                                 array_push( $this->mKeys, $wgLang->ucfirst( $key ) );
 102                         }
 103                 }
 104                 return $this->mKeys;
 105         }
 106
 107         function isCacheable( $key ) {
 108                 global $wgAllMessagesEn, $wgLang;
 109                 return array_key_exists( $wgLang->lcfirst( $key ), $wgAllMessagesEn ) ||
 110                         array_key_exists( $key, $wgAllMessagesEn );
 111         }
 112
 113         function replace( $title, $text ) {
 114                 global $wgMemc;
 115                 if ( $this->isCacheable( $title ) ) {
 116                         $this->lock();
 117                         $this->load();
 118                         if ( is_array( $this->mCache ) ) {
 119                                 $this->mCache[$title] = $text;
 120                                 $wgMemc->set( $this->mMemcKey, $this->mCache, $this->mExpiry );
 121                         }
 122                         $this->unlock();
 123                 }
 124         }
 125
 126         # Returns success
 127         # Represents a write lock on the messages key
 128         function lock() {
 129                 global $wgMemc;
 130
 131                 if ( !$this->mUseCache ) {
 132                         return true;
 133                 }
 134
 135                 $lockKey = $this->mMemcKey . "lock";
 136                 for ($i=0; $i < MSG_WAIT_TIMEOUT && !$wgMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 137                         sleep(1);
 138                 }
 139
 140                 return $i >= MSG_WAIT_TIMEOUT;
 141         }
 142
 143         function unlock() {
 144                 global $wgMemc;
 145
 146                 if ( !$this->mUseCache ) {
 147                         return;
 148                 }
 149
 150                 $lockKey = $this->mMemcKey . "lock";
 151                 $wgMemc->delete( $lockKey );
 152         }
 153
 154         function get( $key, $useDB ) {
 155                 global $wgLang, $wgLanguageCode;
 156
 157                 # If uninitialised, someone is trying to call this halfway through Setup.php
 158                 if ( !$this->mInitialised ) {
 159                         return "&lt;$key&gt;";
 160                 }
 161
 162                 if ( $this->mDisable ) {
 163                         return $wgLang->getMessage( $key );
 164                 }
 165                 $title = $wgLang->ucfirst( $key );
 166
 167                 $message = false;
 168
 169                 # Try the cache
 170                 if ( $this->mUseCache && $this->mCache ) {
 171                         $message = $this->mCache[$title];
 172                 }
 173
 174                 # If it wasn't in the cache, load each message from the DB individually
 175                 if ( !$message && $useDB) {
 176                         $sql = "SELECT cur_text FROM cur WHERE cur_namespace=" . NS_MEDIAWIKI .
 177                                 " AND cur_title='$title'";
 178                         $res = wfQuery( $sql, DB_READ, $fname );
 179
 180                         if ( wfNumRows( $res ) ) {
 181                                 $obj = wfFetchObject( $res );
 182                                 $message = $obj->cur_text;
 183                                 wfFreeResult( $res );
 184                         }
 185                 }
 186
 187                 # Try the array in $wgLang
 188                 if ( !$message ) {
 189                         $message = $wgLang->getMessage( $key );
 190                 }
 191
 192                 # Try the English array
 193                 if ( !$message && $wgLanguageCode != "en" ) {
 194                         $message = Language::getMessage( $key );
 195                 }
 196
 197                 # Final fallback
 198                 if ( !$message ) {
 199                         $message = "&lt;$key&gt;";
 200                 }
 201                 return $message;
 202         }
 203 }
 204 ?>