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          * @param WikiPage $article
 150          * @param string $metricSuffix
 151          */
 152         private function incrementStats( $article, $metricSuffix ) {
 153                 // old style global metric (can be removed once no longer used)
 154                 wfIncrStats( 'pcache.' . $metricSuffix );
 155                 // new per content model metric
 156                 $contentModel = str_replace( '.', '_', $article->getContentModel() );
 157                 $metricSuffix = str_replace( '.', '_', $metricSuffix );
 158                 wfIncrStats( 'pcache.' . $contentModel . '.' . $metricSuffix );
 159         }
 160
 161         /**
 162          * Generates a key for caching the given article considering
 163          * the given parser options.
 164          *
 165          * @note Which parser options influence the cache key
 166          * is controlled via ParserOutput::recordOption() or
 167          * ParserOptions::addExtraKey().
 168          *
 169          * @note Used by Article to provide a unique id for the PoolCounter.
 170          * It would be preferable to have this code in get()
 171          * instead of having Article looking in our internals.
 172          *
 173          * @param WikiPage $article
 174          * @param ParserOptions $popts
 175          * @param int|bool $useOutdated One of the USE constants. For backwards
 176          *  compatibility, boolean false is treated as USE_CURRENT_ONLY and
 177          *  boolean true is treated as USE_ANYTHING.
 178          * @return bool|mixed|string
 179          * @since 1.30 Changed $useOutdated to an int and added the non-boolean values
 180          */
 181         public function getKey( $article, $popts, $useOutdated = self::USE_ANYTHING ) {
 182                 if ( is_bool( $useOutdated ) ) {
 183                         $useOutdated = $useOutdated ? self::USE_ANYTHING : self::USE_CURRENT_ONLY;
 184                 }
 185
 186                 if ( $popts instanceof User ) {
 187                         wfWarn( "Use of outdated prototype ParserCache::getKey( &\$article, &\$user )\n" );
 188                         $popts = ParserOptions::newFromUser( $popts );
 189                 }
 190
 191                 // Determine the options which affect this article
 192                 $optionsKey = $this->mMemc->get(
 193                         $this->getOptionsKey( $article ), BagOStuff::READ_VERIFIED );
 194                 if ( $optionsKey instanceof CacheTime ) {
 195                         if ( $useOutdated < self::USE_EXPIRED && $optionsKey->expired( $article->getTouched() ) ) {
 196                                 $this->incrementStats( $article, "miss.expired" );
 197                                 $cacheTime = $optionsKey->getCacheTime();
 198                                 wfDebugLog( "ParserCache",
 199                                         "Parser options key expired, touched " . $article->getTouched()
 200                                         . ", epoch {$this->cacheEpoch}, cached $cacheTime\n" );
 201                                 return false;
 202                         } elseif ( $useOutdated < self::USE_OUTDATED &&
 203                                 $optionsKey->isDifferentRevision( $article->getLatest() )
 204                         ) {
 205                                 $this->incrementStats( $article, "miss.revid" );
 206                                 $revId = $article->getLatest();
 207                                 $cachedRevId = $optionsKey->getCacheRevisionId();
 208                                 wfDebugLog( "ParserCache",
 209                                         "ParserOutput key is for an old revision, latest $revId, cached $cachedRevId\n"
 210                                 );
 211                                 return false;
 212                         }
 213
 214                         // $optionsKey->mUsedOptions is set by save() by calling ParserOutput::getUsedOptions()
 215                         $usedOptions = $optionsKey->mUsedOptions;
 216                         wfDebug( "Parser cache options found.\n" );
 217                 } else {
 218                         if ( $useOutdated < self::USE_ANYTHING ) {
 219                                 return false;
 220                         }
 221                         $usedOptions = ParserOptions::allCacheVaryingOptions();
 222                 }
 223
 224                 return $this->getParserOutputKey(
 225                         $article,
 226                         $popts->optionsHash( $usedOptions, $article->getTitle() )
 227                 );
 228         }
 229
 230         /**
 231          * Retrieve the ParserOutput from ParserCache.
 232          * false if not found or outdated.
 233          *
 234          * @param WikiPage|Article $article
 235          * @param ParserOptions $popts
 236          * @param bool $useOutdated (default false)
 237          *
 238          * @return ParserOutput|bool False on failure
 239          */
 240         public function get( $article, $popts, $useOutdated = false ) {
 241                 $canCache = $article->checkTouched();
 242                 if ( !$canCache ) {
 243                         // It's a redirect now
 244                         return false;
 245                 }
 246
 247                 $touched = $article->getTouched();
 248
 249                 $parserOutputKey = $this->getKey( $article, $popts,
 250                         $useOutdated ? self::USE_OUTDATED : self::USE_CURRENT_ONLY
 251                 );
 252                 if ( $parserOutputKey === false ) {
 253                         $this->incrementStats( $article, 'miss.absent' );
 254                         return false;
 255                 }
 256
 257                 $casToken = null;
 258                 /** @var ParserOutput $value */
 259                 $value = $this->mMemc->get( $parserOutputKey, BagOStuff::READ_VERIFIED );
 260                 if ( !$value ) {
 261                         wfDebug( "ParserOutput cache miss.\n" );
 262                         $this->incrementStats( $article, "miss.absent" );
 263                         return false;
 264                 }
 265
 266                 wfDebug( "ParserOutput cache found.\n" );
 267
 268                 $wikiPage = method_exists( $article, 'getPage' )
 269                         ? $article->getPage()
 270                         : $article;
 271
 272                 if ( !$useOutdated && $value->expired( $touched ) ) {
 273                         $this->incrementStats( $article, "miss.expired" );
 274                         $cacheTime = $value->getCacheTime();
 275                         wfDebugLog( "ParserCache",
 276                                 "ParserOutput key expired, touched $touched, "
 277                                 . "epoch {$this->cacheEpoch}, cached $cacheTime\n" );
 278                         $value = false;
 279                 } elseif ( !$useOutdated && $value->isDifferentRevision( $article->getLatest() ) ) {
 280                         $this->incrementStats( $article, "miss.revid" );
 281                         $revId = $article->getLatest();
 282                         $cachedRevId = $value->getCacheRevisionId();
 283                         wfDebugLog( "ParserCache",
 284                                 "ParserOutput key is for an old revision, latest $revId, cached $cachedRevId\n"
 285                         );
 286                         $value = false;
 287                 } elseif (
 288                         Hooks::run( 'RejectParserCacheValue', [ $value, $wikiPage, $popts ] ) === false
 289                 ) {
 290                         $this->incrementStats( $article, 'miss.rejected' );
 291                         wfDebugLog( "ParserCache",
 292                                 "ParserOutput key valid, but rejected by RejectParserCacheValue hook handler.\n"
 293                         );
 294                         $value = false;
 295                 } else {
 296                         $this->incrementStats( $article, "hit" );
 297                 }
 298
 299                 return $value;
 300         }
 301
 302         /**
 303          * @param ParserOutput $parserOutput
 304          * @param WikiPage $page
 305          * @param ParserOptions $popts
 306          * @param string|null $cacheTime TS_MW timestamp when the cache was generated
 307          * @param int|null $revId Revision ID that was parsed
 308          */
 309         public function save(
 310                 ParserOutput $parserOutput,
 311                 $page,
 312                 $popts,
 313                 $cacheTime = null,
 314                 $revId = null
 315         ) {
 316                 if ( !$parserOutput->hasText() ) {
 317                         throw new InvalidArgumentException( 'Attempt to cache a ParserOutput with no text set!' );
 318                 }
 319
 320                 $expire = $parserOutput->getCacheExpiry();
 321                 if ( $expire > 0 && !$this->mMemc instanceof EmptyBagOStuff ) {
 322                         $cacheTime = $cacheTime ?: wfTimestampNow();
 323                         if ( !$revId ) {
 324                                 $revision = $page->getRevision();
 325                                 $revId = $revision ? $revision->getId() : null;
 326                         }
 327
 328                         $optionsKey = new CacheTime;
 329                         $optionsKey->mUsedOptions = $parserOutput->getUsedOptions();
 330                         $optionsKey->updateCacheExpiry( $expire );
 331
 332                         $optionsKey->setCacheTime( $cacheTime );
 333                         $parserOutput->setCacheTime( $cacheTime );
 334                         $optionsKey->setCacheRevisionId( $revId );
 335                         $parserOutput->setCacheRevisionId( $revId );
 336
 337                         $parserOutputKey = $this->getParserOutputKey( $page,
 338                                 $popts->optionsHash( $optionsKey->mUsedOptions, $page->getTitle() ) );
 339
 340                         // Save the timestamp so that we don't have to load the revision row on view
 341                         $parserOutput->setTimestamp( $page->getTimestamp() );
 342
 343                         $msg = "Saved in parser cache with key $parserOutputKey" .
 344                                 " and timestamp $cacheTime" .
 345                                 " and revision id $revId" .
 346                                 "\n";
 347
 348                         $parserOutput->mText .= "\n<!-- $msg -->\n";
 349                         wfDebug( $msg );
 350
 351                         // Save the parser output
 352                         $this->mMemc->set( $parserOutputKey, $parserOutput, $expire );
 353
 354                         // ...and its pointer
 355                         $this->mMemc->set( $this->getOptionsKey( $page ), $optionsKey, $expire );
 356
 357                         Hooks::run(
 358                                 'ParserCacheSaveComplete',
 359                                 [ $this, $parserOutput, $page->getTitle(), $popts, $revId ]
 360                         );
 361                 } elseif ( $expire <= 0 ) {
 362                         wfDebug( "Parser output was marked as uncacheable and has not been saved.\n" );
 363                 }
 364         }
 365
 366         /**
 367          * Get the backend BagOStuff instance that
 368          * powers the parser cache
 369          *
 370          * @since 1.30
 371          * @return BagOStuff
 372          */
 373         public function getCacheStorage() {
 374                 return $this->mMemc;
 375         }
 376 }