includes/cache/MessageCache.php

   1 <?php
   2 /**
   3  * @file
   4  * @ingroup Cache
   5  */
   6
   7 /**
   8  *
   9  */
  10 define( 'MSG_LOAD_TIMEOUT', 60 );
  11 define( 'MSG_LOCK_TIMEOUT', 10 );
  12 define( 'MSG_WAIT_TIMEOUT', 10 );
  13 define( 'MSG_CACHE_VERSION', 1 );
  14
  15 /**
  16  * Message cache
  17  * Performs various MediaWiki namespace-related functions
  18  * @ingroup Cache
  19  */
  20 class MessageCache {
  21         /**
  22          * Process local cache of loaded messages that are defined in
  23          * MediaWiki namespace. First array level is a language code,
  24          * second level is message key and the values are either message
  25          * content prefixed with space, or !NONEXISTENT for negative
  26          * caching.
  27          */
  28         protected $mCache;
  29
  30         // Should  mean that database cannot be used, but check
  31         protected $mDisable;
  32
  33         /// Lifetime for cache, used by object caching
  34         protected $mExpiry;
  35
  36         /**
  37          * Message cache has it's own parser which it uses to transform
  38          * messages.
  39          */
  40         protected $mParserOptions, $mParser;
  41
  42         /// Variable for tracking which variables are already loaded
  43         protected $mLoadedLanguages = array();
  44
  45         /**
  46          * Used for automatic detection of most used messages.
  47          */
  48         protected $mRequestedMessages = array();
  49
  50         /**
  51          * How long the message request counts are stored. Longer period gives
  52          * better sample, but also takes longer to adapt changes. The counts
  53          * are aggregrated per day, regardless of the value of this variable.
  54          */
  55         protected static $mAdaptiveDataAge = 604800; // Is 7*24*3600
  56
  57         /**
  58          * Filter the tail of less used messages that are requested more seldom
  59          * than this factor times the number of request of most requested message.
  60          * These messages are not loaded in the default set, but are still cached
  61          * individually on demand with the normal cache expiry time.
  62          */
  63         protected static $mAdaptiveInclusionThreshold = 0.05;
  64
  65         /**
  66          * Singleton instance
  67          *
  68          * @var MessageCache
  69          */
  70         private static $instance;
  71
  72         /**
  73          * @var bool
  74          */
  75         protected $mInParser = false;
  76
  77         /**
  78          * Get the signleton instance of this class
  79          *
  80          * @since 1.18
  81          * @return MessageCache object
  82          */
  83         public static function singleton() {
  84                 if ( is_null( self::$instance ) ) {
  85                         global $wgUseDatabaseMessages, $wgMsgCacheExpiry;
  86                         self::$instance = new self( wfGetMessageCacheStorage(), $wgUseDatabaseMessages, $wgMsgCacheExpiry );
  87                 }
  88                 return self::$instance;
  89         }
  90
  91         /**
  92          * Destroy the singleton instance
  93          *
  94          * @since 1.18
  95          */
  96         public static function destroyInstance() {
  97                 self::$instance = null;
  98         }
  99
 100         function __construct( $memCached, $useDB, $expiry ) {
 101                 if ( !$memCached ) {
 102                         $memCached = wfGetCache( CACHE_NONE );
 103                 }
 104
 105                 $this->mMemc = $memCached;
 106                 $this->mDisable = !$useDB;
 107                 $this->mExpiry = $expiry;
 108         }
 109
 110         /**
 111          * ParserOptions is lazy initialised.
 112          *
 113          * @return ParserOptions
 114          */
 115         function getParserOptions() {
 116                 if ( !$this->mParserOptions ) {
 117                         $this->mParserOptions = new ParserOptions;
 118                 }
 119                 return $this->mParserOptions;
 120         }
 121
 122         /**
 123          * Try to load the cache from a local file.
 124          * Actual format of the file depends on the $wgLocalMessageCacheSerialized
 125          * setting.
 126          *
 127          * @param $hash String: the hash of contents, to check validity.
 128          * @param $code Mixed: Optional language code, see documenation of load().
 129          * @return bool on failure.
 130          */
 131         function loadFromLocal( $hash, $code ) {
 132                 global $wgCacheDirectory, $wgLocalMessageCacheSerialized;
 133
 134                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 135
 136                 # Check file existence
 137                 wfSuppressWarnings();
 138                 $file = fopen( $filename, 'r' );
 139                 wfRestoreWarnings();
 140                 if ( !$file ) {
 141                         return false; // No cache file
 142                 }
 143
 144                 if ( $wgLocalMessageCacheSerialized ) {
 145                         // Check to see if the file has the hash specified
 146                         $localHash = fread( $file, 32 );
 147                         if ( $hash === $localHash ) {
 148                                 // All good, get the rest of it
 149                                 $serialized = '';
 150                                 while ( !feof( $file ) ) {
 151                                         $serialized .= fread( $file, 100000 );
 152                                 }
 153                                 fclose( $file );
 154                                 return $this->setCache( unserialize( $serialized ), $code );
 155                         } else {
 156                                 fclose( $file );
 157                                 return false; // Wrong hash
 158                         }
 159                 } else {
 160                         $localHash = substr( fread( $file, 40 ), 8 );
 161                         fclose( $file );
 162                         if ( $hash != $localHash ) {
 163                                 return false; // Wrong hash
 164                         }
 165
 166                         # Require overwrites the member variable or just shadows it?
 167                         require( $filename );
 168                         return $this->setCache( $this->mCache, $code );
 169                 }
 170         }
 171
 172         /**
 173          * Save the cache to a local file.
 174          */
 175         function saveToLocal( $serialized, $hash, $code ) {
 176                 global $wgCacheDirectory;
 177
 178                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 179                 wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail
 180
 181                 wfSuppressWarnings();
 182                 $file = fopen( $filename, 'w' );
 183                 wfRestoreWarnings();
 184
 185                 if ( !$file ) {
 186                         wfDebug( "Unable to open local cache file for writing\n" );
 187                         return;
 188                 }
 189
 190                 fwrite( $file, $hash . $serialized );
 191                 fclose( $file );
 192                 wfSuppressWarnings();
 193                 chmod( $filename, 0666 );
 194                 wfRestoreWarnings();
 195         }
 196
 197         function saveToScript( $array, $hash, $code ) {
 198                 global $wgCacheDirectory;
 199
 200                 $filename = "$wgCacheDirectory/messages-" . wfWikiID() . "-$code";
 201                 $tempFilename = $filename . '.tmp';
 202                 wfMkdirParents( $wgCacheDirectory, null, __METHOD__ ); // might fail
 203
 204                 wfSuppressWarnings();
 205                 $file = fopen( $tempFilename, 'w' );
 206                 wfRestoreWarnings();
 207
 208                 if ( !$file ) {
 209                         wfDebug( "Unable to open local cache file for writing\n" );
 210                         return;
 211                 }
 212
 213                 fwrite( $file, "<?php\n//$hash\n\n \$this->mCache = array(" );
 214
 215                 foreach ( $array as $key => $message ) {
 216                         $key = $this->escapeForScript( $key );
 217                         $message = $this->escapeForScript( $message );
 218                         fwrite( $file, "'$key' => '$message',\n" );
 219                 }
 220
 221                 fwrite( $file, ");\n?>" );
 222                 fclose( $file);
 223                 rename( $tempFilename, $filename );
 224         }
 225
 226         function escapeForScript( $string ) {
 227                 $string = str_replace( '\\', '\\\\', $string );
 228                 $string = str_replace( '\'', '\\\'', $string );
 229                 return $string;
 230         }
 231
 232         /**
 233          * Set the cache to $cache, if it is valid. Otherwise set the cache to false.
 234          *
 235          * @return bool
 236          */
 237         function setCache( $cache, $code ) {
 238                 if ( isset( $cache['VERSION'] ) && $cache['VERSION'] == MSG_CACHE_VERSION ) {
 239                         $this->mCache[$code] = $cache;
 240                         return true;
 241                 } else {
 242                         return false;
 243                 }
 244         }
 245
 246         /**
 247          * Loads messages from caches or from database in this order:
 248          * (1) local message cache (if $wgUseLocalMessageCache is enabled)
 249          * (2) memcached
 250          * (3) from the database.
 251          *
 252          * When succesfully loading from (2) or (3), all higher level caches are
 253          * updated for the newest version.
 254          *
 255          * Nothing is loaded if member variable mDisable is true, either manually
 256          * set by calling code or if message loading fails (is this possible?).
 257          *
 258          * Returns true if cache is already populated or it was succesfully populated,
 259          * or false if populating empty cache fails. Also returns true if MessageCache
 260          * is disabled.
 261          *
 262          * @param $code String: language to which load messages
 263          * @return bool
 264          */
 265         function load( $code = false ) {
 266                 global $wgUseLocalMessageCache;
 267
 268                 if( !is_string( $code ) ) {
 269                         # This isn't really nice, so at least make a note about it and try to
 270                         # fall back
 271                         wfDebug( __METHOD__ . " called without providing a language code\n" );
 272                         $code = 'en';
 273                 }
 274
 275                 # Don't do double loading...
 276                 if ( isset( $this->mLoadedLanguages[$code] ) ) {
 277                         return true;
 278                 }
 279
 280                 # 8 lines of code just to say (once) that message cache is disabled
 281                 if ( $this->mDisable ) {
 282                         static $shownDisabled = false;
 283                         if ( !$shownDisabled ) {
 284                                 wfDebug( __METHOD__ . ": disabled\n" );
 285                                 $shownDisabled = true;
 286                         }
 287                         return true;
 288                 }
 289
 290                 # Loading code starts
 291                 wfProfileIn( __METHOD__ );
 292                 $success = false; # Keep track of success
 293                 $where = array(); # Debug info, delayed to avoid spamming debug log too much
 294                 $cacheKey = wfMemcKey( 'messages', $code ); # Key in memc for messages
 295
 296                 # (1) local cache
 297                 # Hash of the contents is stored in memcache, to detect if local cache goes
 298                 # out of date (due to update in other thread?)
 299                 if ( $wgUseLocalMessageCache ) {
 300                         wfProfileIn( __METHOD__ . '-fromlocal' );
 301
 302                         $hash = $this->mMemc->get( wfMemcKey( 'messages', $code, 'hash' ) );
 303                         if ( $hash ) {
 304                                 $success = $this->loadFromLocal( $hash, $code );
 305                                 if ( $success ) $where[] = 'got from local cache';
 306                         }
 307                         wfProfileOut( __METHOD__ . '-fromlocal' );
 308                 }
 309
 310                 # (2) memcache
 311                 # Fails if nothing in cache, or in the wrong version.
 312                 if ( !$success ) {
 313                         wfProfileIn( __METHOD__ . '-fromcache' );
 314                         $cache = $this->mMemc->get( $cacheKey );
 315                         $success = $this->setCache( $cache, $code );
 316                         if ( $success ) {
 317                                 $where[] = 'got from global cache';
 318                                 $this->saveToCaches( $cache, false, $code );
 319                         }
 320                         wfProfileOut( __METHOD__ . '-fromcache' );
 321                 }
 322
 323                 # (3)
 324                 # Nothing in caches... so we need create one and store it in caches
 325                 if ( !$success ) {
 326                         $where[] = 'cache is empty';
 327                         $where[] = 'loading from database';
 328
 329                         $this->lock( $cacheKey );
 330
 331                         # Limit the concurrency of loadFromDB to a single process
 332                         # This prevents the site from going down when the cache expires
 333                         $statusKey = wfMemcKey( 'messages', $code, 'status' );
 334                         $success = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );
 335                         if ( $success ) {
 336                                 $cache = $this->loadFromDB( $code );
 337                                 $success = $this->setCache( $cache, $code );
 338                         }
 339                         if ( $success ) {
 340                                 $success = $this->saveToCaches( $cache, true, $code );
 341                                 if ( $success ) {
 342                                         $this->mMemc->delete( $statusKey );
 343                                 } else {
 344                                         $this->mMemc->set( $statusKey, 'error', 60 * 5 );
 345                                         wfDebug( "MemCached set error in MessageCache: restart memcached server!\n" );
 346                                 }
 347                         }
 348                         $this->unlock($cacheKey);
 349                 }
 350
 351                 if ( !$success ) {
 352                         # Bad luck... this should not happen
 353                         $where[] = 'loading FAILED - cache is disabled';
 354                         $info = implode( ', ', $where );
 355                         wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 356                         $this->mDisable = true;
 357                         $this->mCache = false;
 358                 } else {
 359                         # All good, just record the success
 360                         $info = implode( ', ', $where );
 361                         wfDebug( __METHOD__ . ": Loading $code... $info\n" );
 362                         $this->mLoadedLanguages[$code] = true;
 363                 }
 364                 wfProfileOut( __METHOD__ );
 365                 return $success;
 366         }
 367
 368         /**
 369          * Loads cacheable messages from the database. Messages bigger than
 370          * $wgMaxMsgCacheEntrySize are assigned a special value, and are loaded
 371          * on-demand from the database later.
 372          *
 373          * @param $code String: language code.
 374          * @return Array: loaded messages for storing in caches.
 375          */
 376         function loadFromDB( $code ) {
 377                 wfProfileIn( __METHOD__ );
 378                 global $wgMaxMsgCacheEntrySize, $wgLanguageCode, $wgAdaptiveMessageCache;
 379                 $dbr = wfGetDB( DB_SLAVE );
 380                 $cache = array();
 381
 382                 # Common conditions
 383                 $conds = array(
 384                         'page_is_redirect' => 0,
 385                         'page_namespace' => NS_MEDIAWIKI,
 386                 );
 387
 388                 $mostused = array();
 389                 if ( $wgAdaptiveMessageCache ) {
 390                         $mostused = $this->getMostUsedMessages();
 391                         if ( $code !== $wgLanguageCode ) {
 392                                 foreach ( $mostused as $key => $value ) {
 393                                         $mostused[$key] = "$value/$code";
 394                                 }
 395                         }
 396                 }
 397
 398                 if ( count( $mostused ) ) {
 399                         $conds['page_title'] = $mostused;
 400                 } elseif ( $code !== $wgLanguageCode ) {
 401                         $conds[] = 'page_title' . $dbr->buildLike( $dbr->anyString(), "/$code" );
 402                 } else {
 403                         # Effectively disallows use of '/' character in NS_MEDIAWIKI for uses
 404                         # other than language code.
 405                         $conds[] = 'page_title NOT' . $dbr->buildLike( $dbr->anyString(), '/', $dbr->anyString() );
 406                 }
 407
 408                 # Conditions to fetch oversized pages to ignore them
 409                 $bigConds = $conds;
 410                 $bigConds[] = 'page_len > ' . intval( $wgMaxMsgCacheEntrySize );
 411
 412                 # Load titles for all oversized pages in the MediaWiki namespace
 413                 $res = $dbr->select( 'page', 'page_title', $bigConds, __METHOD__ . "($code)-big" );
 414                 foreach ( $res as $row ) {
 415                         $cache[$row->page_title] = '!TOO BIG';
 416                 }
 417
 418                 # Conditions to load the remaining pages with their contents
 419                 $smallConds = $conds;
 420                 $smallConds[] = 'page_latest=rev_id';
 421                 $smallConds[] = 'rev_text_id=old_id';
 422                 $smallConds[] = 'page_len <= ' . intval( $wgMaxMsgCacheEntrySize );
 423
 424                 $res = $dbr->select(
 425                         array( 'page', 'revision', 'text' ),
 426                         array( 'page_title', 'old_text', 'old_flags' ),
 427                         $smallConds,
 428                         __METHOD__ . "($code)-small"
 429                 );
 430
 431                 foreach ( $res as $row ) {
 432                         $text = Revision::getRevisionText( $row );
 433                         if( $text === false ) {
 434                                 // Failed to fetch data; possible ES errors?
 435                                 // Store a marker to fetch on-demand as a workaround...
 436                                 $entry = '!TOO BIG';
 437                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$row->page_title} ($code)" );
 438                         } else {
 439                                 $entry = ' ' . $text;
 440                         }
 441                         $cache[$row->page_title] = $entry;
 442                 }
 443
 444                 foreach ( $mostused as $key ) {
 445                         if ( !isset( $cache[$key] ) ) {
 446                                 $cache[$key] = '!NONEXISTENT';
 447                         }
 448                 }
 449
 450                 $cache['VERSION'] = MSG_CACHE_VERSION;
 451                 wfProfileOut( __METHOD__ );
 452                 return $cache;
 453         }
 454
 455         /**
 456          * Updates cache as necessary when message page is changed
 457          *
 458          * @param $title String: name of the page changed.
 459          * @param $text Mixed: new contents of the page.
 460          */
 461         public function replace( $title, $text ) {
 462                 global $wgMaxMsgCacheEntrySize;
 463                 wfProfileIn( __METHOD__ );
 464
 465                 if ( $this->mDisable ) {
 466                         wfProfileOut( __METHOD__ );
 467                         return;
 468                 }
 469
 470                 list( $msg, $code ) = $this->figureMessage( $title );
 471
 472                 $cacheKey = wfMemcKey( 'messages', $code );
 473                 $this->load( $code );
 474                 $this->lock( $cacheKey );
 475
 476                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 477
 478                 if ( $text === false ) {
 479                         # Article was deleted
 480                         $this->mCache[$code][$title] = '!NONEXISTENT';
 481                         $this->mMemc->delete( $titleKey );
 482                 } elseif ( strlen( $text ) > $wgMaxMsgCacheEntrySize ) {
 483                         # Check for size
 484                         $this->mCache[$code][$title] = '!TOO BIG';
 485                         $this->mMemc->set( $titleKey, ' ' . $text, $this->mExpiry );
 486                 } else {
 487                         $this->mCache[$code][$title] = ' ' . $text;
 488                         $this->mMemc->delete( $titleKey );
 489                 }
 490
 491                 # Update caches
 492                 $this->saveToCaches( $this->mCache[$code], true, $code );
 493                 $this->unlock( $cacheKey );
 494
 495                 // Also delete cached sidebar... just in case it is affected
 496                 $codes = array( $code );
 497                 if ( $code === 'en'  ) {
 498                         // Delete all sidebars, like for example on action=purge on the
 499                         // sidebar messages
 500                         $codes = array_keys( Language::getLanguageNames() );
 501                 }
 502
 503                 global $wgMemc;
 504                 foreach ( $codes as $code ) {
 505                         $sidebarKey = wfMemcKey( 'sidebar', $code );
 506                         $wgMemc->delete( $sidebarKey );
 507                 }
 508
 509                 // Update the message in the message blob store
 510                 global $wgContLang;
 511                 MessageBlobStore::updateMessage( $wgContLang->lcfirst( $msg ) );
 512
 513                 wfRunHooks( 'MessageCacheReplace', array( $title, $text ) );
 514
 515                 wfProfileOut( __METHOD__ );
 516         }
 517
 518         /**
 519          * Shortcut to update caches.
 520          *
 521          * @param $cache Array: cached messages with a version.
 522          * @param $memc Bool: Wether to update or not memcache.
 523          * @param $code String: Language code.
 524          * @return bool on somekind of error.
 525          */
 526         protected function saveToCaches( $cache, $memc = true, $code = false ) {
 527                 wfProfileIn( __METHOD__ );
 528                 global $wgUseLocalMessageCache, $wgLocalMessageCacheSerialized;
 529
 530                 $cacheKey = wfMemcKey( 'messages', $code );
 531
 532                 if ( $memc ) {
 533                         $success = $this->mMemc->set( $cacheKey, $cache, $this->mExpiry );
 534                 } else {
 535                         $success = true;
 536                 }
 537
 538                 # Save to local cache
 539                 if ( $wgUseLocalMessageCache ) {
 540                         $serialized = serialize( $cache );
 541                         $hash = md5( $serialized );
 542                         $this->mMemc->set( wfMemcKey( 'messages', $code, 'hash' ), $hash, $this->mExpiry );
 543                         if ($wgLocalMessageCacheSerialized) {
 544                                 $this->saveToLocal( $serialized, $hash, $code );
 545                         } else {
 546                                 $this->saveToScript( $cache, $hash, $code );
 547                         }
 548                 }
 549
 550                 wfProfileOut( __METHOD__ );
 551                 return $success;
 552         }
 553
 554         /**
 555          * Represents a write lock on the messages key
 556          *
 557          * @param $key string
 558          *
 559          * @return Boolean: success
 560          */
 561         function lock( $key ) {
 562                 $lockKey = $key . ':lock';
 563                 for ( $i = 0; $i < MSG_WAIT_TIMEOUT && !$this->mMemc->add( $lockKey, 1, MSG_LOCK_TIMEOUT ); $i++ ) {
 564                         sleep( 1 );
 565                 }
 566
 567                 return $i >= MSG_WAIT_TIMEOUT;
 568         }
 569
 570         function unlock( $key ) {
 571                 $lockKey = $key . ':lock';
 572                 $this->mMemc->delete( $lockKey );
 573         }
 574
 575         /**
 576          * Get a message from either the content language or the user language.
 577          *
 578          * @param $key String: the message cache key
 579          * @param $useDB Boolean: get the message from the DB, false to use only
 580          *               the localisation
 581          * @param $langcode String: code of the language to get the message for, if
 582          *                  it is a valid code create a language for that language,
 583          *                  if it is a string but not a valid code then make a basic
 584          *                  language object, if it is a false boolean then use the
 585          *                  current users language (as a fallback for the old
 586          *                  parameter functionality), or if it is a true boolean
 587          *                  then use the wikis content language (also as a
 588          *                  fallback).
 589          * @param $isFullKey Boolean: specifies whether $key is a two part key
 590          *                   "msg/lang".
 591          *
 592          * @return string|bool
 593          */
 594         function get( $key, $useDB = true, $langcode = true, $isFullKey = false ) {
 595                 global $wgLanguageCode, $wgContLang;
 596
 597                 if ( is_int( $key ) ) {
 598                         // "Non-string key given" exception sometimes happens for numerical strings that become ints somewhere on their way here
 599                         $key = strval( $key );
 600                 }
 601
 602                 if ( !is_string( $key ) ) {
 603                         throw new MWException( 'Non-string key given' );
 604                 }
 605
 606                 if ( strval( $key ) === '' ) {
 607                         # Shortcut: the empty key is always missing
 608                         return false;
 609                 }
 610
 611                 $lang = wfGetLangObj( $langcode );
 612                 if ( !$lang ) {
 613                         throw new MWException( "Bad lang code $langcode given" );
 614                 }
 615
 616                 $langcode = $lang->getCode();
 617
 618                 $message = false;
 619
 620                 # Normalise title-case input (with some inlining)
 621                 $lckey = str_replace( ' ', '_', $key );
 622                 if ( ord( $key ) < 128 ) {
 623                         $lckey[0] = strtolower( $lckey[0] );
 624                         $uckey = ucfirst( $lckey );
 625                 } else {
 626                         $lckey = $wgContLang->lcfirst( $lckey );
 627                         $uckey = $wgContLang->ucfirst( $lckey );
 628                 }
 629
 630                 /**
 631                  * Record each message request, but only once per request.
 632                  * This information is not used unless $wgAdaptiveMessageCache
 633                  * is enabled.
 634                  */
 635                 $this->mRequestedMessages[$uckey] = true;
 636
 637                 # Try the MediaWiki namespace
 638                 if( !$this->mDisable && $useDB ) {
 639                         $title = $uckey;
 640                         if( !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 641                                 $title .= '/' . $langcode;
 642                         }
 643                         $message = $this->getMsgFromNamespace( $title, $langcode );
 644                 }
 645
 646                 # Try the array in the language object
 647                 if ( $message === false ) {
 648                         $message = $lang->getMessage( $lckey );
 649                         if ( is_null( $message ) ) {
 650                                 $message = false;
 651                         }
 652                 }
 653
 654                 # Try the array of another language
 655                 if( $message === false ) {
 656                         $parts = explode( '/', $lckey );
 657                         # We may get calls for things that are http-urls from sidebar
 658                         # Let's not load nonexistent languages for those
 659                         # They usually have more than one slash.
 660                         if ( count( $parts ) == 2 && $parts[1] !== '' ) {
 661                                 $message = Language::getMessageFor( $parts[0], $parts[1] );
 662                                 if ( is_null( $message ) ) {
 663                                         $message = false;
 664                                 }
 665                         }
 666                 }
 667
 668                 # Is this a custom message? Try the default language in the db...
 669                 if( ( $message === false || $message === '-' ) &&
 670                         !$this->mDisable && $useDB &&
 671                         !$isFullKey && ( $langcode != $wgLanguageCode ) ) {
 672                         $message = $this->getMsgFromNamespace( $uckey, $wgLanguageCode );
 673                 }
 674
 675                 # Final fallback
 676                 if( $message === false ) {
 677                         return false;
 678                 }
 679
 680                 # Fix whitespace
 681                 $message = strtr( $message,
 682                         array(
 683                                 # Fix for trailing whitespace, removed by textarea
 684                                 '&#32;' => ' ',
 685                                 # Fix for NBSP, converted to space by firefox
 686                                 '&nbsp;' => "\xc2\xa0",
 687                                 '&#160;' => "\xc2\xa0",
 688                         ) );
 689
 690                 return $message;
 691         }
 692
 693         /**
 694          * Get a message from the MediaWiki namespace, with caching. The key must
 695          * first be converted to two-part lang/msg form if necessary.
 696          *
 697          * @param $title String: Message cache key with initial uppercase letter.
 698          * @param $code String: code denoting the language to try.
 699          *
 700          * @return string|bool False on failure
 701          */
 702         function getMsgFromNamespace( $title, $code ) {
 703                 global $wgAdaptiveMessageCache;
 704
 705                 $this->load( $code );
 706                 if ( isset( $this->mCache[$code][$title] ) ) {
 707                         $entry = $this->mCache[$code][$title];
 708                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 709                                 return substr( $entry, 1 );
 710                         } elseif ( $entry === '!NONEXISTENT' ) {
 711                                 return false;
 712                         } elseif( $entry === '!TOO BIG' ) {
 713                                 // Fall through and try invididual message cache below
 714                         }
 715                 } else {
 716                         // XXX: This is not cached in process cache, should it?
 717                         $message = false;
 718                         wfRunHooks( 'MessagesPreLoad', array( $title, &$message ) );
 719                         if ( $message !== false ) {
 720                                 return $message;
 721                         }
 722
 723                         /**
 724                          * If message cache is in normal mode, it is guaranteed
 725                          * (except bugs) that there is always entry (or placeholder)
 726                          * in the cache if message exists. Thus we can do minor
 727                          * performance improvement and return false early.
 728                          */
 729                         if ( !$wgAdaptiveMessageCache ) {
 730                                 return false;
 731                         }
 732                 }
 733
 734                 # Try the individual message cache
 735                 $titleKey = wfMemcKey( 'messages', 'individual', $title );
 736                 $entry = $this->mMemc->get( $titleKey );
 737                 if ( $entry ) {
 738                         if ( substr( $entry, 0, 1 ) === ' ' ) {
 739                                 $this->mCache[$code][$title] = $entry;
 740                                 return substr( $entry, 1 );
 741                         } elseif ( $entry === '!NONEXISTENT' ) {
 742                                 $this->mCache[$code][$title] = '!NONEXISTENT';
 743                                 return false;
 744                         } else {
 745                                 # Corrupt/obsolete entry, delete it
 746                                 $this->mMemc->delete( $titleKey );
 747                         }
 748                 }
 749
 750                 # Try loading it from the database
 751                 $revision = Revision::newFromTitle( Title::makeTitle( NS_MEDIAWIKI, $title ) );
 752                 if ( $revision ) {
 753                         $message = $revision->getText();
 754                         if ($message === false) {
 755                                 // A possibly temporary loading failure.
 756                                 wfDebugLog( 'MessageCache', __METHOD__ . ": failed to load message page text for {$title} ($code)" );
 757                         } else {
 758                                 $this->mCache[$code][$title] = ' ' . $message;
 759                                 $this->mMemc->set( $titleKey, ' ' . $message, $this->mExpiry );
 760                         }
 761                 } else {
 762                         $message = false;
 763                         $this->mCache[$code][$title] = '!NONEXISTENT';
 764                         $this->mMemc->set( $titleKey, '!NONEXISTENT', $this->mExpiry );
 765                 }
 766
 767                 return $message;
 768         }
 769
 770         /**
 771          * @param $message string
 772          * @param $interface bool
 773          * @param $language
 774          * @param $title Title
 775          * @return string
 776          */
 777         function transform( $message, $interface = false, $language = null, $title = null ) {
 778                 // Avoid creating parser if nothing to transform
 779                 if( strpos( $message, '{{' ) === false ) {
 780                         return $message;
 781                 }
 782
 783                 if ( $this->mInParser ) {
 784                         return $message;
 785                 }
 786
 787                 $parser = $this->getParser();
 788                 if ( $parser ) {
 789                         $popts = $this->getParserOptions();
 790                         $popts->setInterfaceMessage( $interface );
 791                         $popts->setTargetLanguage( $language );
 792
 793                         $userlang = $popts->setUserLang( $language );
 794                         $this->mInParser = true;
 795                         $message = $parser->transformMsg( $message, $popts, $title );
 796                         $this->mInParser = false;
 797                         $popts->setUserLang( $userlang );
 798                 }
 799                 return $message;
 800         }
 801
 802         /**
 803          * @return Parser
 804          */
 805         function getParser() {
 806                 global $wgParser, $wgParserConf;
 807                 if ( !$this->mParser && isset( $wgParser ) ) {
 808                         # Do some initialisation so that we don't have to do it twice
 809                         $wgParser->firstCallInit();
 810                         # Clone it and store it
 811                         $class = $wgParserConf['class'];
 812                         if ( $class == 'Parser_DiffTest' ) {
 813                                 # Uncloneable
 814                                 $this->mParser = new $class( $wgParserConf );
 815                         } else {
 816                                 $this->mParser = clone $wgParser;
 817                         }
 818                 }
 819                 return $this->mParser;
 820         }
 821
 822         /**
 823          * @param $text string
 824          * @param $title Title
 825          * @param $linestart bool
 826          * @param $interface bool
 827          * @param $language
 828          * @return ParserOutput
 829          */
 830         public function parse( $text, $title = null, $linestart = true, $interface = false, $language = null  ) {
 831                 if ( $this->mInParser ) {
 832                         return htmlspecialchars( $text );
 833                 }
 834
 835                 $parser = $this->getParser();
 836                 $popts = $this->getParserOptions();
 837
 838                 if ( $interface ) {
 839                         $popts->setInterfaceMessage( true );
 840                 }
 841                 if ( $language !== null ) {
 842                         $popts->setTargetLanguage( $language );
 843                 }
 844
 845                 wfProfileIn( __METHOD__ );
 846                 if ( !$title || !$title instanceof Title ) {
 847                         global $wgTitle;
 848                         $title = $wgTitle;
 849                 }
 850                 // Sometimes $wgTitle isn't set either...
 851                 if ( !$title ) {
 852                         # It's not uncommon having a null $wgTitle in scripts. See r80898
 853                         # Create a ghost title in such case
 854                         $title = Title::newFromText( 'Dwimmerlaik' );
 855                 }
 856
 857                 $this->mInParser = true;
 858                 $res = $parser->parse( $text, $title, $popts, $linestart );
 859                 $this->mInParser = false;
 860
 861                 wfProfileOut( __METHOD__ );
 862                 return $res;
 863         }
 864
 865         function disable() {
 866                 $this->mDisable = true;
 867         }
 868
 869         function enable() {
 870                 $this->mDisable = false;
 871         }
 872
 873         /**
 874          * Clear all stored messages. Mainly used after a mass rebuild.
 875          */
 876         function clear() {
 877                 $langs = Language::getLanguageNames( false );
 878                 foreach ( array_keys($langs) as $code ) {
 879                         # Global cache
 880                         $this->mMemc->delete( wfMemcKey( 'messages', $code ) );
 881                         # Invalidate all local caches
 882                         $this->mMemc->delete( wfMemcKey( 'messages', $code, 'hash' ) );
 883                 }
 884                 $this->mLoadedLanguages = array();
 885         }
 886
 887         /**
 888          * @param $key
 889          * @return array
 890          */
 891         public function figureMessage( $key ) {
 892                 global $wgLanguageCode;
 893                 $pieces = explode( '/', $key );
 894                 if( count( $pieces ) < 2 ) {
 895                         return array( $key, $wgLanguageCode );
 896                 }
 897
 898                 $lang = array_pop( $pieces );
 899                 $validCodes = Language::getLanguageNames();
 900                 if( !array_key_exists( $lang, $validCodes ) ) {
 901                         return array( $key, $wgLanguageCode );
 902                 }
 903
 904                 $message = implode( '/', $pieces );
 905                 return array( $message, $lang );
 906         }
 907
 908         public static function logMessages() {
 909                 wfProfileIn( __METHOD__ );
 910                 global $wgAdaptiveMessageCache;
 911                 if ( !$wgAdaptiveMessageCache || !self::$instance instanceof MessageCache ) {
 912                         wfProfileOut( __METHOD__ );
 913                         return;
 914                 }
 915
 916                 $cachekey = wfMemckey( 'message-profiling' );
 917                 $cache = wfGetCache( CACHE_DB );
 918                 $data = $cache->get( $cachekey );
 919
 920                 if ( !$data ) {
 921                         $data = array();
 922                 }
 923
 924                 $age = self::$mAdaptiveDataAge;
 925                 $filterDate = substr( wfTimestamp( TS_MW, time() - $age ), 0, 8 );
 926                 foreach ( array_keys( $data ) as $key ) {
 927                         if ( $key < $filterDate ) {
 928                                 unset( $data[$key] );
 929                         }
 930                 }
 931
 932                 $index = substr( wfTimestampNow(), 0, 8 );
 933                 if ( !isset( $data[$index] ) ) {
 934                         $data[$index] = array();
 935                 }
 936
 937                 foreach ( self::$instance->mRequestedMessages as $message => $_ ) {
 938                         if ( !isset( $data[$index][$message] ) ) {
 939                                 $data[$index][$message] = 0;
 940                         }
 941                         $data[$index][$message]++;
 942                 }
 943
 944                 $cache->set( $cachekey, $data );
 945                 wfProfileOut( __METHOD__ );
 946         }
 947
 948         /**
 949          * @return array
 950          */
 951         public function getMostUsedMessages() {
 952                 wfProfileIn( __METHOD__ );
 953                 $cachekey = wfMemcKey( 'message-profiling' );
 954                 $cache = wfGetCache( CACHE_DB );
 955                 $data = $cache->get( $cachekey );
 956                 if ( !$data ) {
 957                         wfProfileOut( __METHOD__ );
 958                         return array();
 959                 }
 960
 961                 $list = array();
 962
 963                 foreach( $data as $messages ) {
 964                         foreach( $messages as $message => $count ) {
 965                                 $key = $message;
 966                                 if ( !isset( $list[$key] ) ) {
 967                                         $list[$key] = 0;
 968                                 }
 969                                 $list[$key] += $count;
 970                         }
 971                 }
 972
 973                 $max = max( $list );
 974                 foreach ( $list as $message => $count ) {
 975                         if ( $count < intval( $max * self::$mAdaptiveInclusionThreshold ) ) {
 976                                 unset( $list[$message] );
 977                         }
 978                 }
 979
 980                 wfProfileOut( __METHOD__ );
 981                 return array_keys( $list );
 982         }
 983
 984         /**
 985          * Get all message keys stored in the message cache for a given language.
 986          * If $code is the content language code, this will return all message keys
 987          * for which MediaWiki:msgkey exists. If $code is another language code, this
 988          * will ONLY return message keys for which MediaWiki:msgkey/$code exists.
 989          * @param $code string
 990          * @return array of message keys (strings)
 991          */
 992         public function getAllMessageKeys( $code ) {
 993                 global $wgContLang;
 994                 $this->load( $code );
 995                 if ( !isset( $this->mCache[$code] ) ) {
 996                         // Apparently load() failed
 997                         return null;
 998                 }
 999                 $cache = $this->mCache[$code]; // Copy the cache
1000                 unset( $cache['VERSION'] ); // Remove the VERSION key
1001                 $cache = array_diff( $cache, array( '!NONEXISTENT' ) ); // Remove any !NONEXISTENT keys
1002                 // Keys may appear with a capital first letter. lcfirst them.
1003                 return array_map( array( $wgContLang, 'lcfirst' ), array_keys( $cache ) );
1004         }
1005 }