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 /**
  25  * @ingroup Cache Parser
  26  * @todo document
  27  */
  28 class ParserCache {
  29         /** @var BagOStuff */
  30         private $mMemc;
  31         /**
  32          * Get an instance of this object
  33          *
  34          * @return ParserCache
  35          */
  36         public static function singleton() {
  37                 static $instance;
  38                 if ( !isset( $instance ) ) {
  39                         global $parserMemc;
  40                         $instance = new ParserCache( $parserMemc );
  41                 }
  42                 return $instance;
  43         }
  44
  45         /**
  46          * Setup a cache pathway with a given back-end storage mechanism.
  47          *
  48          * This class use an invalidation strategy that is compatible with
  49          * MultiWriteBagOStuff in async replication mode.
  50          *
  51          * @param BagOStuff $memCached
  52          * @throws MWException
  53          */
  54         protected function __construct( BagOStuff $memCached ) {
  55                 $this->mMemc = $memCached;
  56         }
  57
  58         /**
  59          * @param WikiPage $article
  60          * @param string $hash
  61          * @return mixed|string
  62          */
  63         protected function getParserOutputKey( $article, $hash ) {
  64                 global $wgRequest;
  65
  66                 // idhash seem to mean 'page id' + 'rendering hash' (r3710)
  67                 $pageid = $article->getId();
  68                 $renderkey = (int)( $wgRequest->getVal( 'action' ) == 'render' );
  69
  70                 $key = wfMemcKey( 'pcache', 'idhash', "{$pageid}-{$renderkey}!{$hash}" );
  71                 return $key;
  72         }
  73
  74         /**
  75          * @param WikiPage $page
  76          * @return mixed|string
  77          */
  78         protected function getOptionsKey( $page ) {
  79                 return wfMemcKey( 'pcache', 'idoptions', $page->getId() );
  80         }
  81
  82         /**
  83          * @param WikiPage $page
  84          * @since 1.28
  85          */
  86         public function deleteOptionsKey( $page ) {
  87                 $this->mMemc->delete( $this->getOptionsKey( $page ) );
  88         }
  89
  90         /**
  91          * Provides an E-Tag suitable for the whole page. Note that $article
  92          * is just the main wikitext. The E-Tag has to be unique to the whole
  93          * page, even if the article itself is the same, so it uses the
  94          * complete set of user options. We don't want to use the preference
  95          * of a different user on a message just because it wasn't used in
  96          * $article. For example give a Chinese interface to a user with
  97          * English preferences. That's why we take into account *all* user
  98          * options. (r70809 CR)
  99          *
 100          * @param WikiPage $article
 101          * @param ParserOptions $popts
 102          * @return string
 103          */
 104         public function getETag( $article, $popts ) {
 105                 return 'W/"' . $this->getParserOutputKey( $article,
 106                         $popts->optionsHash( ParserOptions::legacyOptions(), $article->getTitle() ) ) .
 107                                 "--" . $article->getTouched() . '"';
 108         }
 109
 110         /**
 111          * Retrieve the ParserOutput from ParserCache, even if it's outdated.
 112          * @param WikiPage $article
 113          * @param ParserOptions $popts
 114          * @return ParserOutput|bool False on failure
 115          */
 116         public function getDirty( $article, $popts ) {
 117                 $value = $this->get( $article, $popts, true );
 118                 return is_object( $value ) ? $value : false;
 119         }
 120
 121         /**
 122          * Generates a key for caching the given article considering
 123          * the given parser options.
 124          *
 125          * @note Which parser options influence the cache key
 126          * is controlled via ParserOutput::recordOption() or
 127          * ParserOptions::addExtraKey().
 128          *
 129          * @note Used by Article to provide a unique id for the PoolCounter.
 130          * It would be preferable to have this code in get()
 131          * instead of having Article looking in our internals.
 132          *
 133          * @todo Document parameter $useOutdated
 134          *
 135          * @param WikiPage $article
 136          * @param ParserOptions $popts
 137          * @param bool $useOutdated (default true)
 138          * @return bool|mixed|string
 139          */
 140         public function getKey( $article, $popts, $useOutdated = true ) {
 141                 global $wgCacheEpoch;
 142
 143                 if ( $popts instanceof User ) {
 144                         wfWarn( "Use of outdated prototype ParserCache::getKey( &\$article, &\$user )\n" );
 145                         $popts = ParserOptions::newFromUser( $popts );
 146                 }
 147
 148                 // Determine the options which affect this article
 149                 $casToken = null;
 150                 $optionsKey = $this->mMemc->get(
 151                         $this->getOptionsKey( $article ), $casToken, BagOStuff::READ_VERIFIED );
 152                 if ( $optionsKey instanceof CacheTime ) {
 153                         if ( !$useOutdated && $optionsKey->expired( $article->getTouched() ) ) {
 154                                 wfIncrStats( "pcache.miss.expired" );
 155                                 $cacheTime = $optionsKey->getCacheTime();
 156                                 wfDebugLog( "ParserCache",
 157                                         "Parser options key expired, touched " . $article->getTouched()
 158                                         . ", epoch $wgCacheEpoch, cached $cacheTime\n" );
 159                                 return false;
 160                         } elseif ( !$useOutdated && $optionsKey->isDifferentRevision( $article->getLatest() ) ) {
 161                                 wfIncrStats( "pcache.miss.revid" );
 162                                 $revId = $article->getLatest();
 163                                 $cachedRevId = $optionsKey->getCacheRevisionId();
 164                                 wfDebugLog( "ParserCache",
 165                                         "ParserOutput key is for an old revision, latest $revId, cached $cachedRevId\n"
 166                                 );
 167                                 return false;
 168                         }
 169
 170                         // $optionsKey->mUsedOptions is set by save() by calling ParserOutput::getUsedOptions()
 171                         $usedOptions = $optionsKey->mUsedOptions;
 172                         wfDebug( "Parser cache options found.\n" );
 173                 } else {
 174                         if ( !$useOutdated ) {
 175                                 return false;
 176                         }
 177                         $usedOptions = ParserOptions::legacyOptions();
 178                 }
 179
 180                 return $this->getParserOutputKey(
 181                         $article,
 182                         $popts->optionsHash( $usedOptions, $article->getTitle() )
 183                 );
 184         }
 185
 186         /**
 187          * Retrieve the ParserOutput from ParserCache.
 188          * false if not found or outdated.
 189          *
 190          * @param WikiPage|Article $article
 191          * @param ParserOptions $popts
 192          * @param bool $useOutdated (default false)
 193          *
 194          * @return ParserOutput|bool False on failure
 195          */
 196         public function get( $article, $popts, $useOutdated = false ) {
 197                 global $wgCacheEpoch;
 198
 199                 $canCache = $article->checkTouched();
 200                 if ( !$canCache ) {
 201                         // It's a redirect now
 202                         return false;
 203                 }
 204
 205                 $touched = $article->getTouched();
 206
 207                 $parserOutputKey = $this->getKey( $article, $popts, $useOutdated );
 208                 if ( $parserOutputKey === false ) {
 209                         wfIncrStats( 'pcache.miss.absent' );
 210                         return false;
 211                 }
 212
 213                 $casToken = null;
 214                 /** @var ParserOutput $value */
 215                 $value = $this->mMemc->get( $parserOutputKey, $casToken, BagOStuff::READ_VERIFIED );
 216                 if ( !$value ) {
 217                         wfDebug( "ParserOutput cache miss.\n" );
 218                         wfIncrStats( "pcache.miss.absent" );
 219                         return false;
 220                 }
 221
 222                 wfDebug( "ParserOutput cache found.\n" );
 223
 224                 // The edit section preference may not be the appropiate one in
 225                 // the ParserOutput, as we are not storing it in the parsercache
 226                 // key. Force it here. See bug 31445.
 227                 $value->setEditSectionTokens( $popts->getEditSection() );
 228
 229                 $wikiPage = method_exists( $article, 'getPage' )
 230                         ? $article->getPage()
 231                         : $article;
 232
 233                 if ( !$useOutdated && $value->expired( $touched ) ) {
 234                         wfIncrStats( "pcache.miss.expired" );
 235                         $cacheTime = $value->getCacheTime();
 236                         wfDebugLog( "ParserCache",
 237                                 "ParserOutput key expired, touched $touched, "
 238                                 . "epoch $wgCacheEpoch, cached $cacheTime\n" );
 239                         $value = false;
 240                 } elseif ( !$useOutdated && $value->isDifferentRevision( $article->getLatest() ) ) {
 241                         wfIncrStats( "pcache.miss.revid" );
 242                         $revId = $article->getLatest();
 243                         $cachedRevId = $value->getCacheRevisionId();
 244                         wfDebugLog( "ParserCache",
 245                                 "ParserOutput key is for an old revision, latest $revId, cached $cachedRevId\n"
 246                         );
 247                         $value = false;
 248                 } elseif (
 249                         Hooks::run( 'RejectParserCacheValue', [ $value, $wikiPage, $popts ] ) === false
 250                 ) {
 251                         wfIncrStats( 'pcache.miss.rejected' );
 252                         wfDebugLog( "ParserCache",
 253                                 "ParserOutput key valid, but rejected by RejectParserCacheValue hook handler.\n"
 254                         );
 255                         $value = false;
 256                 } else {
 257                         wfIncrStats( "pcache.hit" );
 258                 }
 259
 260                 return $value;
 261         }
 262
 263         /**
 264          * @param ParserOutput $parserOutput
 265          * @param WikiPage $page
 266          * @param ParserOptions $popts
 267          * @param string $cacheTime Time when the cache was generated
 268          * @param int $revId Revision ID that was parsed
 269          */
 270         public function save( $parserOutput, $page, $popts, $cacheTime = null, $revId = null ) {
 271                 $expire = $parserOutput->getCacheExpiry();
 272                 if ( $expire > 0 && !$this->mMemc instanceof EmptyBagOStuff ) {
 273                         $cacheTime = $cacheTime ?: wfTimestampNow();
 274                         if ( !$revId ) {
 275                                 $revision = $page->getRevision();
 276                                 $revId = $revision ? $revision->getId() : null;
 277                         }
 278
 279                         $optionsKey = new CacheTime;
 280                         $optionsKey->mUsedOptions = $parserOutput->getUsedOptions();
 281                         $optionsKey->updateCacheExpiry( $expire );
 282
 283                         $optionsKey->setCacheTime( $cacheTime );
 284                         $parserOutput->setCacheTime( $cacheTime );
 285                         $optionsKey->setCacheRevisionId( $revId );
 286                         $parserOutput->setCacheRevisionId( $revId );
 287
 288                         $parserOutputKey = $this->getParserOutputKey( $page,
 289                                 $popts->optionsHash( $optionsKey->mUsedOptions, $page->getTitle() ) );
 290
 291                         // Save the timestamp so that we don't have to load the revision row on view
 292                         $parserOutput->setTimestamp( $page->getTimestamp() );
 293
 294                         $msg = "Saved in parser cache with key $parserOutputKey" .
 295                                 " and timestamp $cacheTime" .
 296                                 " and revision id $revId" .
 297                                 "\n";
 298
 299                         $parserOutput->mText .= "\n<!-- $msg -->\n";
 300                         wfDebug( $msg );
 301
 302                         // Save the parser output
 303                         $this->mMemc->set( $parserOutputKey, $parserOutput, $expire );
 304
 305                         // ...and its pointer
 306                         $this->mMemc->set( $this->getOptionsKey( $page ), $optionsKey, $expire );
 307
 308                         Hooks::run(
 309                                 'ParserCacheSaveComplete',
 310                                 [ $this, $parserOutput, $page->getTitle(), $popts, $revId ]
 311                         );
 312                 } elseif ( $expire <= 0 ) {
 313                         wfDebug( "Parser output was marked as uncacheable and has not been saved.\n" );
 314                 }
 315         }
 316 }