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