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