Aaron Schulz has uploaded a new change for review.
https://gerrit.wikimedia.org/r/308310
Change subject: [WIP] objectcache: add WANObjectCacheRepear for replaying purges
......................................................................
[WIP] objectcache: add WANObjectCacheRepear for replaying purges
This triggers as a deferred updates on RC view.
Change-Id: I7f14b9ca2533032147e62b1a3cc004a23da86579
---
M autoload.php
A includes/deferred/WANCacheReapUpdate.php
M includes/libs/objectcache/WANObjectCache.php
A includes/libs/objectcache/WANObjectCacheReaper.php
M includes/specialpage/ChangesListSpecialPage.php
5 files changed, 329 insertions(+), 0 deletions(-)
git pull ssh://gerrit.wikimedia.org:29418/mediawiki/core
refs/changes/10/308310/1
diff --git a/autoload.php b/autoload.php
index 652535c..2132341 100644
--- a/autoload.php
+++ b/autoload.php
@@ -1497,7 +1497,9 @@
'ViewAction' => __DIR__ . '/includes/actions/ViewAction.php',
'VirtualRESTService' => __DIR__ .
'/includes/libs/virtualrest/VirtualRESTService.php',
'VirtualRESTServiceClient' => __DIR__ .
'/includes/libs/virtualrest/VirtualRESTServiceClient.php',
+ 'WANCacheReapUpdate' => __DIR__ .
'/includes/deferred/WANCacheReapUpdate.php',
'WANObjectCache' => __DIR__ .
'/includes/libs/objectcache/WANObjectCache.php',
+ 'WANObjectCacheRepear' => __DIR__ .
'/includes/libs/objectcache/WANObjectCacheReaper.php',
'WaitConditionLoop' => __DIR__ . '/includes/libs/WaitConditionLoop.php',
'WantedCategoriesPage' => __DIR__ .
'/includes/specials/SpecialWantedcategories.php',
'WantedFilesPage' => __DIR__ .
'/includes/specials/SpecialWantedfiles.php',
diff --git a/includes/deferred/WANCacheReapUpdate.php
b/includes/deferred/WANCacheReapUpdate.php
new file mode 100644
index 0000000..3dc3476
--- /dev/null
+++ b/includes/deferred/WANCacheReapUpdate.php
@@ -0,0 +1,108 @@
+<?php
+
+/**
+ * Class for fixing bad key entries in WANObjectCache from an event source
+ *
+ * @since 1.28
+ */
+class WANCacheReapUpdate implements DeferrableUpdate {
+ /** @var IDatabase */
+ private $db;
+
+ /**
+ * @param IDatabase $db
+ */
+ public function __construct( IDatabase $db ) {
+ $this->db = $db;
+ }
+
+ function doUpdate() {
+ $reaper = new WANObjectCacheRepear(
+ ObjectCache::getMainWANInstance(),
+ ObjectCache::getLocalClusterInstance(),
+ [ $this, 'getChangedTitles' ],
+ [ $this, 'getAffectedKeys' ],
+ [
+ 'channel' => 'table:recentchanges',
+ 'logger' =>
\MediaWiki\Logger\LoggerFactory::getInstance( 'objectcache' )
+ ]
+ );
+
+ $reaper->invoke();
+ }
+
+ /**
+ * @see WANObjectCacheRepear
+ *
+ * @param int $start
+ * @param int $id
+ * @param int $end
+ * @return array
+ */
+ public function getChangedTitles( $start, $id, $end ) {
+ $db = $this->db;
+
+ $encStart = $db->addQuotes( $db->timestamp( $start ) );
+ $encEnd = $db->addQuotes( $db->timestamp( $end ) );
+
+ $res = $db->select(
+ 'recentchanges',
+ [ 'rc_namespace', 'rc_title', 'rc_timestamp', 'rc_id' ],
+ [
+ $db->makeList( [
+ "rc_timestamp > $encStart",
+ "rc_timestamp = $encStart AND rc_id > "
. $db->addQuotes( $id )
+ ], LIST_OR ),
+ "rc_timestamp < $encEnd"
+ ],
+ __METHOD__,
+ [ 'ORDER BY' => 'rc_timestamp ASC, rc_id ASC' ]
+ );
+
+ $events = [];
+ foreach ( $res as $row ) {
+ $events[] = [
+ 'id' => (int)$row->rc_id,
+ 'pos' => wfTimestamp( TS_UNIX,
$row->rc_timestamp ),
+ 'item' => new TitleValue(
(int)$row->rc_namespace, $row->rc_title )
+ ];
+ }
+
+ return $events;
+ }
+
+ /**
+ * Gets a list of important cache keys associated with a title
+ *
+ * @see WANObjectCacheRepear
+ * @param WANObjectCache $cache
+ * @param TitleValue $t
+ * @returns string[]
+ * @TODO: avoid key generation code duplication
+ */
+ public function getAffectedKeys( WANObjectCache $cache, TitleValue $t )
{
+ $keys = [];
+ if ( $t->inNamespace( NS_FILE ) ) {
+ /** @var LocalFile $file */
+ $file =
RepoGroup::singleton()->getLocalRepo()->newFile( $t->getDBkey() );
+ $keys[] = $file->getCacheKey();
+ }
+
+ if ( $t->inNamespace( NS_FILE ) || $t->inNamespace( NS_TEMPLATE
) ) {
+ $keys[] = $cache->makeKey( 'page', $t->getNamespace(),
sha1( $t->getDBkey() ) );
+ }
+
+ if ( $t->inNamespace( NS_USER ) || $t->inNamespace(
NS_USER_TALK ) ) {
+ $id = User::idFromName( $t->getDBkey() );
+ if ( $id ) {
+ $keys[] = $cache->makeGlobalKey( 'user', 'id',
wfWikiID(), $id );
+ }
+ }
+
+ if ( $keys ) {
+ wfDebugLog( 'objectcache', __CLASS__ . ': checking
key(s) ' . implode( ', ', $keys ) );
+ }
+
+ return $keys;
+ }
+}
diff --git a/includes/libs/objectcache/WANObjectCache.php
b/includes/libs/objectcache/WANObjectCache.php
index 0d7da91..7a2541b 100644
--- a/includes/libs/objectcache/WANObjectCache.php
+++ b/includes/libs/objectcache/WANObjectCache.php
@@ -970,6 +970,37 @@
}
/**
+ * Locally destroy any value or "check" key $key if older than
$cutoffTime
+ *
+ * @param string $key Cache key
+ * @param int $cutoffTime UNIX timestamp
+ * @return bool Success
+ * @since 1.28
+ */
+ public function reap( $key, $cutoffTime ) {
+ $ok = true;
+
+ $wrapped = $this->cache->get( self::VALUE_KEY_PREFIX . $key );
+ if ( is_array( $wrapped ) && $wrapped[self::FLD_TIME] <
$cutoffTime ) {
+ $this->logger->warning( "Reaping bad value key '$key'."
);
+ $ok = $this->cache->changeTTL( self::VALUE_KEY_PREFIX .
$key, 1 ) && $ok;
+ }
+
+ $rawValue = $this->cache->get( self::TIME_KEY_PREFIX . $key );
+ $purgeValue = $this->parsePurgeValue( $rawValue );
+ if ( $purgeValue && $purgeValue[self::FLD_TIME] < $cutoffTime )
{
+ $this->logger->warning( "Reaping bad value key '$key'."
);
+ $ok = $this->cache->changeTTL( self::TIME_KEY_PREFIX .
$key, 1 ) && $ok;
+ }
+
+ if ( !$ok ) {
+ $this->logger->error( "Could not complete reap of key
'$key'." );
+ }
+
+ return $ok;
+ }
+
+ /**
* @see BagOStuff::makeKey()
* @param string ... Key component
* @return string
diff --git a/includes/libs/objectcache/WANObjectCacheReaper.php
b/includes/libs/objectcache/WANObjectCacheReaper.php
new file mode 100644
index 0000000..99f5bd2
--- /dev/null
+++ b/includes/libs/objectcache/WANObjectCacheReaper.php
@@ -0,0 +1,185 @@
+<?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
+ * @ingroup Cache
+ * @author Aaron Schulz
+ */
+
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
+
+/**
+ * Class for scanning through chronological, log-structured data or change logs
+ * and locally purging cache keys related to entities that appear in this data.
+ *
+ * This is useful for repairing cache when purges are missed by using a
reliable
+ * stream, such as Kafka or a replicated MySQL table. Purge loss between
datacenters
+ * is expected to be more common than within them.
+ *
+ * @since 1.28
+ */
+class WANObjectCacheRepear implements LoggerAwareInterface {
+ /** @var WANObjectCache */
+ protected $cache;
+ /** @var BagOStuff */
+ protected $store;
+ /** @var callable */
+ protected $logChunkCallback;
+ /** @var callable */
+ protected $keyListCallback;
+ /** @var Logger */
+ protected $logger;
+
+ /** @var string */
+ protected $channel;
+ /** @var integer */
+ protected $initialStartWindow;
+
+ /**
+ * @param WANObjectCache $cache Cache to reap bad keys from
+ * @param BagOStuff $store Cache to store positions use for locking
+ * @param callable $logCallback Callback taking arguments:
+ * - The starting position as a UNIX timestamp
+ * - The starting unique ID used for breaking timestamp
collisions
+ * - The ending position as a UNIX timestamp
+ * It returns a list of maps of (key: cache key, pos: UNIX
timestamp, id: unique ID)
+ * for each key affected, with the corrosponding event
timestamp/ID information.
+ * @param callable $keyCallback Callback taking arguments:
+ * - The WANObjectCache instance
+ * - An object from the event log
+ * It should return a list of WAN cache keys.
+ * The callback must fully duck-type test the object, since can
be any model class.
+ * @param array $params Additional options:
+ * - channel: the name of the update event stream.
+ * Default: WANObjectCache::DEFAULT_PURGE_CHANNEL.
+ * - initialStartWindow: seconds back in time to start if the
position is lost.
+ * Default: 1 hour.
+ * - logger: an SPL monolog instance [optional]
+ */
+ public function __construct(
+ WANObjectCache $cache,
+ BagOStuff $store,
+ callable $logCallback,
+ callable $keyCallback,
+ array $params
+ ) {
+ $this->cache = $cache;
+ $this->store = $store;
+
+ $this->logChunkCallback = $logCallback;
+ $this->keyListCallback = $keyCallback;
+
+ $this->channel = isset( $params['channel'] )
+ ? $params['channel']
+ : WANObjectCache::DEFAULT_PURGE_CHANNEL;
+ $this->initialStartWindow = isset(
$params['initialStartWindow'] )
+ ? $params['initialStartWindow']
+ : 3600;
+ $this->logger = isset( $params['logger'] )
+ ? $params['logger']
+ : new NullLogger();
+ }
+
+ public function setLogger( LoggerInterface $logger ) {
+ $this->logger = $logger;
+ }
+
+ /**
+ * Check and reap stale keys based on a chunk of events
+ *
+ * @param int $n Number of events
+ * @return int Number of keys checked
+ */
+ final public function invoke( $n = 100 ) {
+ $posKey = $this->store->makeGlobalKey( 'WANCache', 'reaper',
$this->channel );
+ $scopeLock = $this->store->getScopedLock( "$posKey:busy", 0 );
+ if ( !$scopeLock ) {
+ return 0;
+ }
+
+ $status = $this->store->get( $posKey );
+ if ( !$status ) {
+ $status = [ 'pos' => time() -
$this->initialStartWindow, 'id' => 1 ];
+ }
+
+ $events = call_user_func_array(
+ $this->logChunkCallback,
+ [ $status['pos'], $status['id'], time() -
WANObjectCache::HOLDOFF_TTL - 1, $n ]
+ );
+
+ $purgeCount = 0;
+ $lastEvent = null;
+ $keyEvents = [];
+ foreach ( $events as $event ) {
+ $keys = call_user_func_array(
+ $this->keyListCallback,
+ [ $this->cache, $event['item'] ]
+ );
+ foreach ( $keys as $key ) {
+ $keyEvents[$key] = [
+ 'pos' => $event['pos'],
+ 'id' => $event['id']
+ ];
+ }
+ $lastEvent = $event;
+ }
+
+ $lastKeyEvent = null;
+ foreach ( $keyEvents as $key => $keyEvent ) {
+ if ( !$this->cache->reap( $key, $keyEvent['pos'] ) ) {
+ break;
+ }
+ ++$purgeCount;
+ }
+
+ if ( $lastEvent ) {
+ $ok = $this->store->merge(
+ $posKey,
+ function ( $bag, $key, $curValue ) use (
$lastEvent ) {
+ if ( !$curValue || $lastEvent['pos'] >
$curValue['pos'] ) {
+ // Use new position
+ } elseif ( $lastEvent['id'] >=
$curValue['id'] ) {
+ // Use new position
+ } else {
+ // Keep prior position instead
of rolling it back
+ return $curValue;
+ }
+
+ return [
+ 'pos' => $lastEvent['pos'],
+ 'id' => $lastEvent['id']
+ ];
+ },
+ IExpiringStore::TTL_INDEFINITE
+ );
+
+ $pos = $lastEvent['pos'];
+ $id = $lastEvent['id'];
+ if ( $ok ) {
+ $this->logger->info( "Updated cache reap
position ($pos,$id)." );
+ } else {
+ $this->logger->error( "Could not update cache
reap position ($pos,$id)." );
+ }
+ }
+
+ ScopedCallback::consume( $scopeLock );
+
+ return $purgeCount;
+ }
+}
diff --git a/includes/specialpage/ChangesListSpecialPage.php
b/includes/specialpage/ChangesListSpecialPage.php
index 60f1dd8..d85931a 100644
--- a/includes/specialpage/ChangesListSpecialPage.php
+++ b/includes/specialpage/ChangesListSpecialPage.php
@@ -77,6 +77,9 @@
$this->webOutput( $rows, $opts );
$rows->free();
+
+ // Clean up any bad page entries for titles showing up in RC
+ DeferredUpdates::addUpdate( new WANCacheReapUpdate( wfGetDB(
DB_SLAVE ) ) );
}
/**
--
To view, visit https://gerrit.wikimedia.org/r/308310
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: I7f14b9ca2533032147e62b1a3cc004a23da86579
Gerrit-PatchSet: 1
Gerrit-Project: mediawiki/core
Gerrit-Branch: master
Gerrit-Owner: Aaron Schulz <asch...@wikimedia.org>
_______________________________________________
MediaWiki-commits mailing list
MediaWiki-commits@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/mediawiki-commits
