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<?php
/**
* 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
*/
use MediaWiki\HookContainer\HookContainer;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\Page\PageIdentity;
use MediaWiki\Page\PageReference;
use MediaWiki\Title\TitleFactory;
/**
* Class to invalidate the CDN and HTMLFileCache entries associated with URLs/titles
*
* @ingroup Cache
* @since 1.35
*/
class HtmlCacheUpdater {
/** @var int Seconds between initial and rebound purges; 0 if disabled */
private $reboundDelay;
/** @var bool Whether filesystem-based HTML output caching is enabled */
private $useFileCache;
/** @var int Max seconds for CDN to served cached objects without revalidation */
private $cdnMaxAge;
/** @var HookRunner */
private $hookRunner;
/** @var int Issue purge immediately and do not schedule a rebound purge */
public const PURGE_NAIVE = 0;
/**
* @var int Defer purge via PRESEND deferred updates. The pending DeferrableUpdate instances
* will combined/de-duplicated into a single DeferrableUpdate instance; this lowers overhead
* and improves HTTP PURGE request pipelining.
*/
public const PURGE_PRESEND = 1;
/**
* @var int Upon purge, schedule a delayed CDN purge if rebound purges are enabled
* ($wgCdnReboundPurgeDelay). Rebound purges are schedule via the job queue.
*/
public const PURGE_REBOUND = 2;
/**
* @var int Defer purge until no LBFactory transaction round is pending and then schedule
* a delayed rebound purge if rebound purges are enabled ($wgCdnReboundPurgeDelay). This is
* useful for CDN purges triggered by data changes in the current or last transaction round.
* Even if the origin server uses lagged replicas, the use of rebound purges corrects the
* cache in cases where lag is less than the rebound delay. If the lag is anywhere near the
* rebound delay, then auxiliary mechanisms should lower the cache TTL ($wgCdnMaxageLagged).
*/
public const PURGE_INTENT_TXROUND_REFLECTED = self::PURGE_PRESEND | self::PURGE_REBOUND;
/**
* Reduce set of URLs to be purged to only those that may be affected by
* change propagation from LinksUpdate (e.g. after a used template was edited).
*
* Specifically, this means URLs only affected by direct revision edits,
* will not be purged.
* @var int
*/
public const PURGE_URLS_LINKSUPDATE_ONLY = 4;
/**
* Do not bother purging cache items if the default max cache TTL implies that no objects
* can still be in cache from before the given timestamp.
*
* @var string
*/
public const UNLESS_CACHE_MTIME_AFTER = 'unless-timestamp-exceeds';
/** @var TitleFactory */
private $titleFactory;
/**
* @param HookContainer $hookContainer
* @param TitleFactory $titleFactory
* @param int $reboundDelay $wgCdnReboundPurgeDelay
* @param bool $useFileCache $wgUseFileCache
* @param int $cdnMaxAge $wgCdnMaxAge
*
* @internal For use with MediaWikiServices->getHtmlCacheUpdater()
*/
public function __construct(
HookContainer $hookContainer,
TitleFactory $titleFactory,
$reboundDelay,
$useFileCache,
$cdnMaxAge
) {
$this->hookRunner = new HookRunner( $hookContainer );
$this->titleFactory = $titleFactory;
$this->reboundDelay = $reboundDelay;
$this->useFileCache = $useFileCache;
$this->cdnMaxAge = $cdnMaxAge;
}
/**
* @param int $flags Bit field
* @param int $flag Constant to check for
* @return bool If $flags contains $flag
*/
private function fieldHasFlag( $flags, $flag ) {
return ( ( $flags & $flag ) === $flag );
}
/**
* Purge the CDN for a URL or list of URLs
*
* @param string[]|string $urls URL or list of URLs
* @param int $flags Bit field of class PURGE_* constants
* [Default: HtmlCacheUpdater::PURGE_PRESEND]
* @param mixed[] $unless Optional map of (HtmlCacheUpdater::UNLESS_* constant => value)
*/
public function purgeUrls( $urls, $flags = self::PURGE_PRESEND, array $unless = [] ) {
$minFreshCacheMtime = $unless[self::UNLESS_CACHE_MTIME_AFTER] ?? null;
if ( $minFreshCacheMtime && time() > ( $minFreshCacheMtime + $this->cdnMaxAge ) ) {
return;
}
$urls = is_string( $urls ) ? [ $urls ] : $urls;
$reboundDelay = $this->fieldHasFlag( $flags, self::PURGE_REBOUND )
? $this->reboundDelay
: 0; // no second purge
$update = new CdnCacheUpdate( $urls, [ 'reboundDelay' => $reboundDelay ] );
if ( $this->fieldHasFlag( $flags, self::PURGE_PRESEND ) ) {
DeferredUpdates::addUpdate( $update, DeferredUpdates::PRESEND );
} else {
$update->doUpdate();
}
}
/**
* Purge the CDN/HTMLFileCache for a title or the titles yielded by an iterator
*
* All cacheable canonical URLs associated with the titles will be purged from CDN.
* All cacheable actions associated with the titles will be purged from HTMLFileCache.
*
* @param Traversable|PageReference[]|PageReference $pages PageReference or iterator yielding
* PageReference instances
* @param int $flags Bit field of class PURGE_* constants
* [Default: HtmlCacheUpdater::PURGE_PRESEND]
* @param mixed[] $unless Optional map of (HtmlCacheUpdater::UNLESS_* constant => value)
*/
public function purgeTitleUrls( $pages, $flags = self::PURGE_PRESEND, array $unless = [] ) {
$pages = is_iterable( $pages ) ? $pages : [ $pages ];
$pageIdentities = [];
foreach ( $pages as $page ) {
// TODO: We really only need to cast to PageIdentity. We could use a LinkBatch for that.
$title = $this->titleFactory->newFromPageReference( $page );
if ( $title->canExist() ) {
$pageIdentities[] = $title;
}
}
if ( !$pageIdentities ) {
return;
}
if ( $this->useFileCache ) {
$update = HtmlFileCacheUpdate::newFromPages( $pageIdentities );
if ( $this->fieldHasFlag( $flags, self::PURGE_PRESEND ) ) {
DeferredUpdates::addUpdate( $update, DeferredUpdates::PRESEND );
} else {
$update->doUpdate();
}
}
$minFreshCacheMtime = $unless[self::UNLESS_CACHE_MTIME_AFTER] ?? null;
if ( !$minFreshCacheMtime || time() <= ( $minFreshCacheMtime + $this->cdnMaxAge ) ) {
$urls = [];
foreach ( $pageIdentities as $pi ) {
/** @var PageIdentity $pi */
$urls = array_merge( $urls, $this->getUrls( $pi, $flags ) );
}
$this->purgeUrls( $urls, $flags );
}
}
/**
* Get a list of URLs to purge from the CDN cache when this page changes.
*
* @param PageReference $page
* @param int $flags Bit field of `PURGE_URLS_*` class constants (optional).
* @return string[] URLs
*/
public function getUrls( PageReference $page, int $flags = 0 ): array {
$title = $this->titleFactory->newFromPageReference( $page );
if ( !$title->canExist() ) {
return [];
}
// These urls are affected both by direct revisions as well,
// as re-rendering of the same content during a LinksUpdate.
$urls = [
$title->getInternalURL()
];
// Language variant page views are currently not cached
// and thus not purged (T250511).
// These urls are only affected by direct revisions, and do not require
// purging when a LinksUpdate merely rerenders the same content.
// This exists to avoid large amounts of redundant PURGE traffic (T250261).
if ( !$this->fieldHasFlag( $flags, self::PURGE_URLS_LINKSUPDATE_ONLY ) ) {
$urls[] = $title->getInternalURL( 'action=history' );
// Canonical action=raw URLs for user and site config pages (T58874, T261371).
if ( $title->isUserJsConfigPage() || $title->isSiteJsConfigPage() ) {
$urls[] = $title->getInternalURL( 'action=raw&ctype=text/javascript' );
} elseif ( $title->isUserJsonConfigPage() || $title->isSiteJsonConfigPage() ) {
$urls[] = $title->getInternalURL( 'action=raw&ctype=application/json' );
} elseif ( $title->isUserCssConfigPage() || $title->isSiteCssConfigPage() ) {
$urls[] = $title->getInternalURL( 'action=raw&ctype=text/css' );
}
}
// Extensions may add novel ways to access this content
$append = [];
$mode = $flags & self::PURGE_URLS_LINKSUPDATE_ONLY;
$this->hookRunner->onHtmlCacheUpdaterAppendUrls( $title, $mode, $append );
$urls = array_merge( $urls, $append );
// Extensions may add novel ways to access the site overall
$append = [];
$this->hookRunner->onHtmlCacheUpdaterVaryUrls( $urls, $append );
$urls = array_merge( $urls, $append );
// Legacy. TODO: Deprecate this
$this->hookRunner->onTitleSquidURLs( $title, $urls );
return $urls;
}
}