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         /**
  62          * Get an instance of this object
  63          *
  64          * @deprecated since 1.30, use MediaWikiServices instead
  65          * @return ParserCache
  66          */
  67         public static function singleton() {
  68                 return MediaWikiServices::getInstance()->getParserCache();
  69         }
  70
  71         /**
  72          * Setup a cache pathway with a given back-end storage mechanism.
  73          *
  74          * This class use an invalidation strategy that is compatible with
  75          * MultiWriteBagOStuff in async replication mode.
  76          *
  77          * @param BagOStuff $cache
  78          * @param string $cacheEpoch Anything before this timestamp is invalidated
  79          * @throws MWException
  80          */
  81         public function __construct( BagOStuff $cache, $cacheEpoch = '20030516000000' ) {
  82                 $this->mMemc = $cache;
  83                 $this->cacheEpoch = $cacheEpoch;
  84         }
  85
  86         /**
  87          * @param WikiPage $article
  88          * @param string $hash
  89          * @return mixed|string
  90          */
  91         protected function getParserOutputKey( $article, $hash ) {
  92                 global $wgRequest;
  93
  94                 // idhash seem to mean 'page id' + 'rendering hash' (r3710)
  95                 $pageid = $article->getId();
  96                 $renderkey = (int)( $wgRequest->getVal( 'action' ) == 'render' );
  97
  98                 $key = $this->mMemc->makeKey( 'pcache', 'idhash', "{$pageid}-{$renderkey}!{$hash}" );
  99                 return $key;
 100         }
 101
 102         /**
 103          * @param WikiPage $page
 104          * @return mixed|string
 105          */
 106         protected function getOptionsKey( $page ) {
 107                 return $this->mMemc->makeKey( 'pcache', 'idoptions', $page->getId() );
 108         }
 109
 110         /**
 111          * @param WikiPage $page
 112          * @since 1.28
 113          */
 114         public function deleteOptionsKey( $page ) {
 115                 $this->mMemc->delete( $this->getOptionsKey( $page ) );
 116         }
 117
 118         /**
 119          * Provides an E-Tag suitable for the whole page. Note that $article
 120          * is just the main wikitext. The E-Tag has to be unique to the whole
 121          * page, even if the article itself is the same, so it uses the
 122          * complete set of user options. We don't want to use the preference
 123          * of a different user on a message just because it wasn't used in
 124          * $article. For example give a Chinese interface to a user with
 125          * English preferences. That's why we take into account *all* user
 126          * options. (r70809 CR)
 127          *
 128          * @param WikiPage $article
 129          * @param ParserOptions $popts
 130          * @return string
 131          */
 132         public function getETag( $article, $popts ) {
 133                 return 'W/"' . $this->getParserOutputKey( $article,
 134                         $popts->optionsHash( ParserOptions::allCacheVaryingOptions(), $article->getTitle() ) ) .
 135                                 "--" . $article->getTouched() . '"';
 136         }
 137
 138         /**
 139          * Retrieve the ParserOutput from ParserCache, even if it's outdated.
 140          * @param WikiPage $article
 141          * @param ParserOptions $popts
 142          * @return ParserOutput|bool False on failure
 143          */
 144         public function getDirty( $article, $popts ) {
 145                 $value = $this->get( $article, $popts, true );
 146                 return is_object( $value ) ? $value : false;
 147         }
 148
 149         /**
 150          * @param WikiPage $article
 151          * @param string $metricSuffix
 152          */
 153         private function incrementStats( $article, $metricSuffix ) {
 154                 // old style global metric (can be removed once no longer used)
 155                 wfIncrStats( 'pcache.' . $metricSuffix );
 156                 // new per content model metric
 157                 $contentModel = str_replace( '.', '_', $article->getContentModel() );
 158                 $metricSuffix = str_replace( '.', '_', $metricSuffix );
 159                 wfIncrStats( 'pcache.' . $contentModel . '.' . $metricSuffix );
 160         }
 161
 162         /**
 163          * Generates a key for caching the given article considering
 164          * the given parser options.
 165          *
 166          * @note Which parser options influence the cache key
 167          * is controlled via ParserOutput::recordOption() or
 168          * ParserOptions::addExtraKey().
 169          *
 170          * @note Used by Article to provide a unique id for the PoolCounter.
 171          * It would be preferable to have this code in get()
 172          * instead of having Article looking in our internals.
 173          *
 174          * @param WikiPage $article
 175          * @param ParserOptions $popts
 176          * @param int|bool $useOutdated One of the USE constants. For backwards
 177          *  compatibility, boolean false is treated as USE_CURRENT_ONLY and
 178          *  boolean true is treated as USE_ANYTHING.
 179          * @return bool|mixed|string
 180          * @since 1.30 Changed $useOutdated to an int and added the non-boolean values
 181          */
 182         public function getKey( $article, $popts, $useOutdated = self::USE_ANYTHING ) {
 183                 if ( is_bool( $useOutdated ) ) {
 184                         $useOutdated = $useOutdated ? self::USE_ANYTHING : self::USE_CURRENT_ONLY;
 185                 }
 186
 187                 if ( $popts instanceof User ) {
 188                         wfWarn( "Use of outdated prototype ParserCache::getKey( &\$article, &\$user )\n" );
 189                         $popts = ParserOptions::newFromUser( $popts );
 190                 }
 191
 192                 // Determine the options which affect this article
 193                 $optionsKey = $this->mMemc->get(
 194                         $this->getOptionsKey( $article ), BagOStuff::READ_VERIFIED );
 195                 if ( $optionsKey instanceof CacheTime ) {
 196                         if ( $useOutdated < self::USE_EXPIRED && $optionsKey->expired( $article->getTouched() ) ) {
 197                                 $this->incrementStats( $article, "miss.expired" );
 198                                 $cacheTime = $optionsKey->getCacheTime();
 199                                 wfDebugLog( "ParserCache",
 200                                         "Parser options key expired, touched " . $article->getTouched()
 201                                         . ", epoch {$this->cacheEpoch}, cached $cacheTime\n" );
 202                                 return false;
 203                         } elseif ( $useOutdated < self::USE_OUTDATED &&
 204                                 $optionsKey->isDifferentRevision( $article->getLatest() )
 205                         ) {
 206                                 $this->incrementStats( $article, "miss.revid" );
 207                                 $revId = $article->getLatest();
 208                                 $cachedRevId = $optionsKey->getCacheRevisionId();
 209                                 wfDebugLog( "ParserCache",
 210                                         "ParserOutput key is for an old revision, latest $revId, cached $cachedRevId\n"
 211                                 );
 212                                 return false;
 213                         }
 214
 215                         // $optionsKey->mUsedOptions is set by save() by calling ParserOutput::getUsedOptions()
 216                         $usedOptions = $optionsKey->mUsedOptions;
 217                         wfDebug( "Parser cache options found.\n" );
 218                 } else {
 219                         if ( $useOutdated < self::USE_ANYTHING ) {
 220                                 return false;
 221                         }
 222                         $usedOptions = ParserOptions::allCacheVaryingOptions();
 223                 }
 224
 225                 return $this->getParserOutputKey(
 226                         $article,
 227                         $popts->optionsHash( $usedOptions, $article->getTitle() )
 228                 );
 229         }
 230
 231         /**
 232          * Retrieve the ParserOutput from ParserCache.
 233          * false if not found or outdated.
 234          *
 235          * @param WikiPage|Article $article
 236          * @param ParserOptions $popts
 237          * @param bool $useOutdated (default false)
 238          *
 239          * @return ParserOutput|bool False on failure
 240          */
 241         public function get( $article, $popts, $useOutdated = false ) {
 242                 $canCache = $article->checkTouched();
 243                 if ( !$canCache ) {
 244                         // It's a redirect now
 245                         return false;
 246                 }
 247
 248                 $touched = $article->getTouched();
 249
 250                 $parserOutputKey = $this->getKey( $article, $popts,
 251                         $useOutdated ? self::USE_OUTDATED : self::USE_CURRENT_ONLY
 252                 );
 253                 if ( $parserOutputKey === false ) {
 254                         $this->incrementStats( $article, 'miss.absent' );
 255                         return false;
 256                 }
 257
 258                 $casToken = null;
 259                 /** @var ParserOutput $value */
 260                 $value = $this->mMemc->get( $parserOutputKey, BagOStuff::READ_VERIFIED );
 261                 if ( !$value ) {
 262                         wfDebug( "ParserOutput cache miss.\n" );
 263                         $this->incrementStats( $article, "miss.absent" );
 264                         return false;
 265                 }
 266
 267                 wfDebug( "ParserOutput cache found.\n" );
 268
 269                 $wikiPage = method_exists( $article, 'getPage' )
 270                         ? $article->getPage()
 271                         : $article;
 272
 273                 if ( !$useOutdated && $value->expired( $touched ) ) {
 274                         $this->incrementStats( $article, "miss.expired" );
 275                         $cacheTime = $value->getCacheTime();
 276                         wfDebugLog( "ParserCache",
 277                                 "ParserOutput key expired, touched $touched, "
 278                                 . "epoch {$this->cacheEpoch}, cached $cacheTime\n" );
 279                         $value = false;
 280                 } elseif ( !$useOutdated && $value->isDifferentRevision( $article->getLatest() ) ) {
 281                         $this->incrementStats( $article, "miss.revid" );
 282                         $revId = $article->getLatest();
 283                         $cachedRevId = $value->getCacheRevisionId();
 284                         wfDebugLog( "ParserCache",
 285                                 "ParserOutput key is for an old revision, latest $revId, cached $cachedRevId\n"
 286                         );
 287                         $value = false;
 288                 } elseif (
 289                         Hooks::run( 'RejectParserCacheValue', [ $value, $wikiPage, $popts ] ) === false
 290                 ) {
 291                         $this->incrementStats( $article, 'miss.rejected' );
 292                         wfDebugLog( "ParserCache",
 293                                 "ParserOutput key valid, but rejected by RejectParserCacheValue hook handler.\n"
 294                         );
 295                         $value = false;
 296                 } else {
 297                         $this->incrementStats( $article, "hit" );
 298                 }
 299
 300                 return $value;
 301         }
 302
 303         /**
 304          * @param ParserOutput $parserOutput
 305          * @param WikiPage $page
 306          * @param ParserOptions $popts
 307          * @param string|null $cacheTime TS_MW timestamp when the cache was generated
 308          * @param int|null $revId Revision ID that was parsed
 309          */
 310         public function save(
 311                 ParserOutput $parserOutput,
 312                 $page,
 313                 $popts,
 314                 $cacheTime = null,
 315                 $revId = null
 316         ) {
 317                 if ( !$parserOutput->hasText() ) {
 318                         throw new InvalidArgumentException( 'Attempt to cache a ParserOutput with no text set!' );
 319                 }
 320
 321                 $expire = $parserOutput->getCacheExpiry();
 322                 if ( $expire > 0 && !$this->mMemc instanceof EmptyBagOStuff ) {
 323                         $cacheTime = $cacheTime ?: wfTimestampNow();
 324                         if ( !$revId ) {
 325                                 $revision = $page->getRevision();
 326                                 $revId = $revision ? $revision->getId() : null;
 327                         }
 328
 329                         $optionsKey = new CacheTime;
 330                         $optionsKey->mUsedOptions = $parserOutput->getUsedOptions();
 331                         $optionsKey->updateCacheExpiry( $expire );
 332
 333                         $optionsKey->setCacheTime( $cacheTime );
 334                         $parserOutput->setCacheTime( $cacheTime );
 335                         $optionsKey->setCacheRevisionId( $revId );
 336                         $parserOutput->setCacheRevisionId( $revId );
 337
 338                         $parserOutputKey = $this->getParserOutputKey( $page,
 339                                 $popts->optionsHash( $optionsKey->mUsedOptions, $page->getTitle() ) );
 340
 341                         // Save the timestamp so that we don't have to load the revision row on view
 342                         $parserOutput->setTimestamp( $page->getTimestamp() );
 343
 344                         $msg = "Saved in parser cache with key $parserOutputKey" .
 345                                 " and timestamp $cacheTime" .
 346                                 " and revision id $revId" .
 347                                 "\n";
 348
 349                         $parserOutput->mText .= "\n<!-- $msg -->\n";
 350                         wfDebug( $msg );
 351
 352                         // Save the parser output
 353                         $this->mMemc->set( $parserOutputKey, $parserOutput, $expire );
 354
 355                         // ...and its pointer
 356                         $this->mMemc->set( $this->getOptionsKey( $page ), $optionsKey, $expire );
 357
 358                         Hooks::run(
 359                                 'ParserCacheSaveComplete',
 360                                 [ $this, $parserOutput, $page->getTitle(), $popts, $revId ]
 361                         );
 362                 } elseif ( $expire <= 0 ) {
 363                         wfDebug( "Parser output was marked as uncacheable and has not been saved.\n" );
 364                 }
 365         }
 366
 367         /**
 368          * Get the backend BagOStuff instance that
 369          * powers the parser cache
 370          *
 371          * @since 1.30
 372          * @return BagOStuff
 373          */
 374         public function getCacheStorage() {
 375                 return $this->mMemc;
 376         }
 377 }