includes/parser/ParserCache.php

   1 <?php
   2 /**
   3  * Cache for outputs of the PHP parser
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Cache Parser
  22  */
  23
  24 use MediaWiki\MediaWikiServices;
  25
  26 /**
  27  * @ingroup Cache Parser
  28  * @todo document
  29  */
  30 class ParserCache {
  31         /**
  32          * Constants for self::getKey()
  33          * @since 1.30
  34          */
  35
  36         /** Use only current data */
  37         const USE_CURRENT_ONLY = 0;
  38
  39         /** Use expired data if current data is unavailable */
  40         const USE_EXPIRED = 1;
  41
  42         /** Use expired data or data from different revisions if current data is unavailable */
  43         const USE_OUTDATED = 2;
  44
  45         /**
  46          * Use expired data and data from different revisions, and if all else
  47          * fails vary on all variable options
  48          */
  49         const USE_ANYTHING = 3;
  50
  51         /** @var BagOStuff */
  52         private $mMemc;
  53
  54         /**
  55          * Anything cached prior to this is invalidated
  56          *
  57          * @var string
  58          */
  59         private $cacheEpoch;
  60         /**
  61          * Get an instance of this object
  62          *
  63          * @deprecated since 1.30, use MediaWikiServices instead
  64          * @return ParserCache
  65          */
  66         public static function singleton() {
  67                 return MediaWikiServices::getInstance()->getParserCache();
  68         }
  69
  70         /**
  71          * Setup a cache pathway with a given back-end storage mechanism.
  72          *
  73          * This class use an invalidation strategy that is compatible with
  74          * MultiWriteBagOStuff in async replication mode.
  75          *
  76          * @param BagOStuff $cache
  77          * @param string $cacheEpoch Anything before this timestamp is invalidated
  78          * @throws MWException
  79          */
  80         public function __construct( BagOStuff $cache, $cacheEpoch = '20030516000000' ) {
  81                 $this->mMemc = $cache;
  82                 $this->cacheEpoch = $cacheEpoch;
  83         }
  84
  85         /**
  86          * @param WikiPage $article
  87          * @param string $hash
  88          * @return mixed|string
  89          */
  90         protected function getParserOutputKey( $article, $hash ) {
  91                 global $wgRequest;
  92
  93                 // idhash seem to mean 'page id' + 'rendering hash' (r3710)
  94                 $pageid = $article->getId();
  95                 $renderkey = (int)( $wgRequest->getVal( 'action' ) == 'render' );
  96
  97                 $key = $this->mMemc->makeKey( 'pcache', 'idhash', "{$pageid}-{$renderkey}!{$hash}" );
  98                 return $key;
  99         }
 100
 101         /**
 102          * @param WikiPage $page
 103          * @return mixed|string
 104          */
 105         protected function getOptionsKey( $page ) {
 106                 return $this->mMemc->makeKey( 'pcache', 'idoptions', $page->getId() );
 107         }
 108
 109         /**
 110          * @param WikiPage $page
 111          * @since 1.28
 112          */
 113         public function deleteOptionsKey( $page ) {
 114                 $this->mMemc->delete( $this->getOptionsKey( $page ) );
 115         }
 116
 117         /**
 118          * Provides an E-Tag suitable for the whole page. Note that $article
 119          * is just the main wikitext. The E-Tag has to be unique to the whole
 120          * page, even if the article itself is the same, so it uses the
 121          * complete set of user options. We don't want to use the preference
 122          * of a different user on a message just because it wasn't used in
 123          * $article. For example give a Chinese interface to a user with
 124          * English preferences. That's why we take into account *all* user
 125          * options. (r70809 CR)
 126          *
 127          * @param WikiPage $article
 128          * @param ParserOptions $popts
 129          * @return string
 130          */
 131         public function getETag( $article, $popts ) {
 132                 return 'W/"' . $this->getParserOutputKey( $article,
 133                         $popts->optionsHash( ParserOptions::allCacheVaryingOptions(), $article->getTitle() ) ) .
 134                                 "--" . $article->getTouched() . '"';
 135         }
 136
 137         /**
 138          * Retrieve the ParserOutput from ParserCache, even if it's outdated.
 139          * @param WikiPage $article
 140          * @param ParserOptions $popts
 141          * @return ParserOutput|bool False on failure
 142          */
 143         public function getDirty( $article, $popts ) {
 144                 $value = $this->get( $article, $popts, true );
 145                 return is_object( $value ) ? $value : false;
 146         }
 147
 148         /**
 149          * Generates a key for caching the given article considering
 150          * the given parser options.
 151          *
 152          * @note Which parser options influence the cache key
 153          * is controlled via ParserOutput::recordOption() or
 154          * ParserOptions::addExtraKey().
 155          *
 156          * @note Used by Article to provide a unique id for the PoolCounter.
 157          * It would be preferable to have this code in get()
 158          * instead of having Article looking in our internals.
 159          *
 160          * @param WikiPage $article
 161          * @param ParserOptions $popts
 162          * @param int|bool $useOutdated One of the USE constants. For backwards
 163          *  compatibility, boolean false is treated as USE_CURRENT_ONLY and
 164          *  boolean true is treated as USE_ANYTHING.
 165          * @return bool|mixed|string
 166          * @since 1.30 Changed $useOutdated to an int and added the non-boolean values
 167          */
 168         public function getKey( $article, $popts, $useOutdated = self::USE_ANYTHING ) {
 169                 if ( is_bool( $useOutdated ) ) {
 170                         $useOutdated = $useOutdated ? self::USE_ANYTHING : self::USE_CURRENT_ONLY;
 171                 }
 172
 173                 if ( $popts instanceof User ) {
 174                         wfWarn( "Use of outdated prototype ParserCache::getKey( &\$article, &\$user )\n" );
 175                         $popts = ParserOptions::newFromUser( $popts );
 176                 }
 177
 178                 // Determine the options which affect this article
 179                 $casToken = null;
 180                 $optionsKey = $this->mMemc->get(
 181                         $this->getOptionsKey( $article ), $casToken, BagOStuff::READ_VERIFIED );
 182                 if ( $optionsKey instanceof CacheTime ) {
 183                         if ( $useOutdated < self::USE_EXPIRED && $optionsKey->expired( $article->getTouched() ) ) {
 184                                 wfIncrStats( "pcache.miss.expired" );
 185                                 $cacheTime = $optionsKey->getCacheTime();
 186                                 wfDebugLog( "ParserCache",
 187                                         "Parser options key expired, touched " . $article->getTouched()
 188                                         . ", epoch {$this->cacheEpoch}, cached $cacheTime\n" );
 189                                 return false;
 190                         } elseif ( $useOutdated < self::USE_OUTDATED &&
 191                                 $optionsKey->isDifferentRevision( $article->getLatest() )
 192                         ) {
 193                                 wfIncrStats( "pcache.miss.revid" );
 194                                 $revId = $article->getLatest();
 195                                 $cachedRevId = $optionsKey->getCacheRevisionId();
 196                                 wfDebugLog( "ParserCache",
 197                                         "ParserOutput key is for an old revision, latest $revId, cached $cachedRevId\n"
 198                                 );
 199                                 return false;
 200                         }
 201
 202                         // $optionsKey->mUsedOptions is set by save() by calling ParserOutput::getUsedOptions()
 203                         $usedOptions = $optionsKey->mUsedOptions;
 204                         wfDebug( "Parser cache options found.\n" );
 205                 } else {
 206                         if ( $useOutdated < self::USE_ANYTHING ) {
 207                                 return false;
 208                         }
 209                         $usedOptions = ParserOptions::allCacheVaryingOptions();
 210                 }
 211
 212                 return $this->getParserOutputKey(
 213                         $article,
 214                         $popts->optionsHash( $usedOptions, $article->getTitle() )
 215                 );
 216         }
 217
 218         /**
 219          * Retrieve the ParserOutput from ParserCache.
 220          * false if not found or outdated.
 221          *
 222          * @param WikiPage|Article $article
 223          * @param ParserOptions $popts
 224          * @param bool $useOutdated (default false)
 225          *
 226          * @return ParserOutput|bool False on failure
 227          */
 228         public function get( $article, $popts, $useOutdated = false ) {
 229                 $canCache = $article->checkTouched();
 230                 if ( !$canCache ) {
 231                         // It's a redirect now
 232                         return false;
 233                 }
 234
 235                 $touched = $article->getTouched();
 236
 237                 $parserOutputKey = $this->getKey( $article, $popts,
 238                         $useOutdated ? self::USE_OUTDATED : self::USE_CURRENT_ONLY
 239                 );
 240                 if ( $parserOutputKey === false ) {
 241                         wfIncrStats( 'pcache.miss.absent' );
 242                         return false;
 243                 }
 244
 245                 $casToken = null;
 246                 /** @var ParserOutput $value */
 247                 $value = $this->mMemc->get( $parserOutputKey, $casToken, BagOStuff::READ_VERIFIED );
 248                 if ( !$value ) {
 249                         wfDebug( "ParserOutput cache miss.\n" );
 250                         wfIncrStats( "pcache.miss.absent" );
 251                         return false;
 252                 }
 253
 254                 wfDebug( "ParserOutput cache found.\n" );
 255
 256                 // The edit section preference may not be the appropiate one in
 257                 // the ParserOutput, as we are not storing it in the parsercache
 258                 // key. Force it here. See T33445.
 259                 $value->setEditSectionTokens( $popts->getEditSection() );
 260
 261                 $wikiPage = method_exists( $article, 'getPage' )
 262                         ? $article->getPage()
 263                         : $article;
 264
 265                 if ( !$useOutdated && $value->expired( $touched ) ) {
 266                         wfIncrStats( "pcache.miss.expired" );
 267                         $cacheTime = $value->getCacheTime();
 268                         wfDebugLog( "ParserCache",
 269                                 "ParserOutput key expired, touched $touched, "
 270                                 . "epoch {$this->cacheEpoch}, cached $cacheTime\n" );
 271                         $value = false;
 272                 } elseif ( !$useOutdated && $value->isDifferentRevision( $article->getLatest() ) ) {
 273                         wfIncrStats( "pcache.miss.revid" );
 274                         $revId = $article->getLatest();
 275                         $cachedRevId = $value->getCacheRevisionId();
 276                         wfDebugLog( "ParserCache",
 277                                 "ParserOutput key is for an old revision, latest $revId, cached $cachedRevId\n"
 278                         );
 279                         $value = false;
 280                 } elseif (
 281                         Hooks::run( 'RejectParserCacheValue', [ $value, $wikiPage, $popts ] ) === false
 282                 ) {
 283                         wfIncrStats( 'pcache.miss.rejected' );
 284                         wfDebugLog( "ParserCache",
 285                                 "ParserOutput key valid, but rejected by RejectParserCacheValue hook handler.\n"
 286                         );
 287                         $value = false;
 288                 } else {
 289                         wfIncrStats( "pcache.hit" );
 290                 }
 291
 292                 return $value;
 293         }
 294
 295         /**
 296          * @param ParserOutput $parserOutput
 297          * @param WikiPage $page
 298          * @param ParserOptions $popts
 299          * @param string $cacheTime Time when the cache was generated
 300          * @param int $revId Revision ID that was parsed
 301          */
 302         public function save( $parserOutput, $page, $popts, $cacheTime = null, $revId = null ) {
 303                 $expire = $parserOutput->getCacheExpiry();
 304                 if ( $expire > 0 && !$this->mMemc instanceof EmptyBagOStuff ) {
 305                         $cacheTime = $cacheTime ?: wfTimestampNow();
 306                         if ( !$revId ) {
 307                                 $revision = $page->getRevision();
 308                                 $revId = $revision ? $revision->getId() : null;
 309                         }
 310
 311                         $optionsKey = new CacheTime;
 312                         $optionsKey->mUsedOptions = $parserOutput->getUsedOptions();
 313                         $optionsKey->updateCacheExpiry( $expire );
 314
 315                         $optionsKey->setCacheTime( $cacheTime );
 316                         $parserOutput->setCacheTime( $cacheTime );
 317                         $optionsKey->setCacheRevisionId( $revId );
 318                         $parserOutput->setCacheRevisionId( $revId );
 319
 320                         $parserOutputKey = $this->getParserOutputKey( $page,
 321                                 $popts->optionsHash( $optionsKey->mUsedOptions, $page->getTitle() ) );
 322
 323                         // Save the timestamp so that we don't have to load the revision row on view
 324                         $parserOutput->setTimestamp( $page->getTimestamp() );
 325
 326                         $msg = "Saved in parser cache with key $parserOutputKey" .
 327                                 " and timestamp $cacheTime" .
 328                                 " and revision id $revId" .
 329                                 "\n";
 330
 331                         $parserOutput->mText .= "\n<!-- $msg -->\n";
 332                         wfDebug( $msg );
 333
 334                         // Save the parser output
 335                         $this->mMemc->set( $parserOutputKey, $parserOutput, $expire );
 336
 337                         // ...and its pointer
 338                         $this->mMemc->set( $this->getOptionsKey( $page ), $optionsKey, $expire );
 339
 340                         Hooks::run(
 341                                 'ParserCacheSaveComplete',
 342                                 [ $this, $parserOutput, $page->getTitle(), $popts, $revId ]
 343                         );
 344                 } elseif ( $expire <= 0 ) {
 345                         wfDebug( "Parser output was marked as uncacheable and has not been saved.\n" );
 346                 }
 347         }
 348
 349         /**
 350          * Get the backend BagOStuff instance that
 351          * powers the parser cache
 352          *
 353          * @since 1.30
 354          * @return BagOStuff
 355          */
 356         public function getCacheStorage() {
 357                 return $this->mMemc;
 358         }
 359 }