<?php
/**
* Cache for outputs of the PHP parser
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Cache Parser
*/
/**
* @ingroup Cache Parser
* @todo document
*/
class ParserCache {
private $mMemc;
const try116cache = false; /* Only useful $wgParserCacheExpireTime after updating to 1.17 */
/**
* Get an instance of this object
*
* @return ParserCache
*/
public static function singleton() {
static $instance;
if ( !isset( $instance ) ) {
global $parserMemc;
$instance = new ParserCache( $parserMemc );
}
return $instance;
}
/**
* Setup a cache pathway with a given back-end storage mechanism.
* May be a memcached client or a BagOStuff derivative.
*
* @param $memCached Object
* @throws MWException
*/
protected function __construct( $memCached ) {
if ( !$memCached ) {
throw new MWException( "Tried to create a ParserCache with an invalid memcached" );
}
$this->mMemc = $memCached;
}
/**
* @param $article Article
* @param $hash string
* @return mixed|string
*/
protected function getParserOutputKey( $article, $hash ) {
global $wgRequest;
// idhash seem to mean 'page id' + 'rendering hash' (r3710)
$pageid = $article->getID();
$renderkey = (int)( $wgRequest->getVal( 'action' ) == 'render' );
$key = wfMemcKey( 'pcache', 'idhash', "{$pageid}-{$renderkey}!{$hash}" );
return $key;
}
/**
* @param $article Article
* @return mixed|string
*/
protected function getOptionsKey( $article ) {
$pageid = $article->getID();
return wfMemcKey( 'pcache', 'idoptions', "{$pageid}" );
}
/**
* Provides an E-Tag suitable for the whole page. Note that $article
* is just the main wikitext. The E-Tag has to be unique to the whole
* page, even if the article itself is the same, so it uses the
* complete set of user options. We don't want to use the preference
* of a different user on a message just because it wasn't used in
* $article. For example give a Chinese interface to a user with
* English preferences. That's why we take into account *all* user
* options. (r70809 CR)
*
* @param $article Article
* @param $popts ParserOptions
* @return string
*/
function getETag( $article, $popts ) {
return 'W/"' . $this->getParserOutputKey( $article,
$popts->optionsHash( ParserOptions::legacyOptions(), $article->getTitle() ) ) .
"--" . $article->getTouched() . '"';
}
/**
* Retrieve the ParserOutput from ParserCache, even if it's outdated.
* @param $article Article
* @param $popts ParserOptions
* @return ParserOutput|bool False on failure
*/
public function getDirty( $article, $popts ) {
$value = $this->get( $article, $popts, true );
return is_object( $value ) ? $value : false;
}
/**
* Used to provide a unique id for the PoolCounter.
* It would be preferable to have this code in get()
* instead of having Article looking in our internals.
*
* @todo Document parameter $useOutdated
*
* @param $article Article
* @param $popts ParserOptions
* @param $useOutdated Boolean (default true)
* @return bool|mixed|string
*/
public function getKey( $article, $popts, $useOutdated = true ) {
global $wgCacheEpoch;
if ( $popts instanceof User ) {
wfWarn( "Use of outdated prototype ParserCache::getKey( &\$article, &\$user )\n" );
$popts = ParserOptions::newFromUser( $popts );
}
// Determine the options which affect this article
$optionsKey = $this->mMemc->get( $this->getOptionsKey( $article ) );
if ( $optionsKey != false ) {
if ( !$useOutdated && $optionsKey->expired( $article->getTouched() ) ) {
wfIncrStats( "pcache_miss_expired" );
$cacheTime = $optionsKey->getCacheTime();
wfDebug( "Parser options key expired, touched " . $article->getTouched() . ", epoch $wgCacheEpoch, cached $cacheTime\n" );
return false;
}
$usedOptions = $optionsKey->mUsedOptions;
wfDebug( "Parser cache options found.\n" );
} else {
if ( !$useOutdated && !self::try116cache ) {
return false;
}
$usedOptions = ParserOptions::legacyOptions();
}
return $this->getParserOutputKey( $article, $popts->optionsHash( $usedOptions, $article->getTitle() ) );
}
/**
* Retrieve the ParserOutput from ParserCache.
* false if not found or outdated.
*
* @param $article Article
* @param $popts ParserOptions
* @param $useOutdated Boolean (default false)
*
* @return ParserOutput|bool False on failure
*/
public function get( $article, $popts, $useOutdated = false ) {
global $wgCacheEpoch;
wfProfileIn( __METHOD__ );
$canCache = $article->checkTouched();
if ( !$canCache ) {
// It's a redirect now
wfProfileOut( __METHOD__ );
return false;
}
$touched = $article->getTouched();
$parserOutputKey = $this->getKey( $article, $popts, $useOutdated );
if ( $parserOutputKey === false ) {
wfIncrStats( 'pcache_miss_absent' );
wfProfileOut( __METHOD__ );
return false;
}
$value = $this->mMemc->get( $parserOutputKey );
if ( self::try116cache && !$value && strpos( $value, '*' ) !== -1 ) {
wfDebug( "New format parser cache miss.\n" );
$parserOutputKey = $this->getParserOutputKey( $article,
$popts->optionsHash( ParserOptions::legacyOptions(), $article->getTitle() ) );
$value = $this->mMemc->get( $parserOutputKey );
}
if ( !$value ) {
wfDebug( "ParserOutput cache miss.\n" );
wfIncrStats( "pcache_miss_absent" );
wfProfileOut( __METHOD__ );
return false;
}
wfDebug( "ParserOutput cache found.\n" );
// The edit section preference may not be the appropiate one in
// the ParserOutput, as we are not storing it in the parsercache
// key. Force it here. See bug 31445.
$value->setEditSectionTokens( $popts->getEditSection() );
if ( !$useOutdated && $value->expired( $touched ) ) {
wfIncrStats( "pcache_miss_expired" );
$cacheTime = $value->getCacheTime();
wfDebug( "ParserOutput key expired, touched $touched, epoch $wgCacheEpoch, cached $cacheTime\n" );
$value = false;
} else {
wfIncrStats( "pcache_hit" );
}
wfProfileOut( __METHOD__ );
return $value;
}
/**
* @param $parserOutput ParserOutput
* @param $article Article
* @param $popts ParserOptions
* @param $cacheTime Time when the cache was generated
*/
public function save( $parserOutput, $article, $popts, $cacheTime = null ) {
$expire = $parserOutput->getCacheExpiry();
if ( $expire > 0 ) {
$cacheTime = $cacheTime ?: wfTimestampNow();
$optionsKey = new CacheTime;
$optionsKey->mUsedOptions = $parserOutput->getUsedOptions();
$optionsKey->updateCacheExpiry( $expire );
$optionsKey->setCacheTime( $cacheTime );
$parserOutput->setCacheTime( $cacheTime );
$optionsKey->setContainsOldMagic( $parserOutput->containsOldMagic() );
$parserOutputKey = $this->getParserOutputKey( $article,
$popts->optionsHash( $optionsKey->mUsedOptions, $article->getTitle() ) );
// Save the timestamp so that we don't have to load the revision row on view
$parserOutput->setTimestamp( $article->getTimestamp() );
$parserOutput->mText .= "\n<!-- Saved in parser cache with key $parserOutputKey and timestamp $cacheTime\n -->\n";
wfDebug( "Saved in parser cache with key $parserOutputKey and timestamp $cacheTime\n" );
// Save the parser output
$this->mMemc->set( $parserOutputKey, $parserOutput, $expire );
// ...and its pointer
$this->mMemc->set( $this->getOptionsKey( $article ), $optionsKey, $expire );
} else {
wfDebug( "Parser output was marked as uncacheable and has not been saved.\n" );
}
}
}