jenkins-bot has submitted this change and it was merged.
Change subject: Account for DB lag when refreshing cached ChoiceData
......................................................................
Account for DB lag when refreshing cached ChoiceData
This fixes an apparent race condition in which ObjectCache-cached ChoiceData
is invalidated following a change in campaign or banner settings, then a
client request has a cache miss and re-sets the cache using data form a laggy
DB slave, causing stale ChoiceData to be cached and served. For details about
the solution, see the inline documentation for
WANObjectCache::getWithSetCallback(), in MediaWiki core.
Bug: T144393
Change-Id: Id4e46b653554d39ac5721c4327774ccfce63b734
---
M includes/ChoiceDataProvider.php
1 file changed, 21 insertions(+), 4 deletions(-)
Approvals:
Ejegg: Looks good to me, approved
jenkins-bot: Verified
diff --git a/includes/ChoiceDataProvider.php b/includes/ChoiceDataProvider.php
index 0d765fb..715e450 100644
--- a/includes/ChoiceDataProvider.php
+++ b/includes/ChoiceDataProvider.php
@@ -42,10 +42,26 @@
$choices = $cache->getWithSetCallback(
$dataKey,
self::CACHE_TTL,
- function () use ( $project, $language ) {
- return self::fetchChoices( $project, $language
);
+ function ( $oldValue, &$ttl, array &$setOpts )
+ use ( $project, $language ) {
+
+ $dbr = CNDatabase::getDb( DB_SLAVE );
+
+ // Account for slave lag to prevent a race
condition when
+ // campaigns are updated, the cache is
invalidated, and
+ // a client queries a yet-unsynced slave DB.
Also, gracefully
+ // fail if we're running an old version of core
(<1.27).
+ if ( method_exists( 'Database',
'getCacheSetOptions') ) {
+ $setOpts +=
Database::getCacheSetOptions( $dbr );
+ }
+
+ return self::fetchChoices( $project, $language,
$dbr );
},
[
+ // We don't bother with the lockTSE option
because the only
+ // potentially high-volume requests that would
ask for this
+ // object are heavily cached by Varnish, for
all users. (Those
+ // requests are for load.php.)
'checkKeys' => [ $checkKey ],
'pcTTL' => $cache::TTL_PROC_LONG,
]
@@ -59,11 +75,12 @@
} );
}
- private static function fetchChoices( $project, $language ) {
+ private static function fetchChoices( $project, $language,
+ IDatabase $dbr ) {
+
// For speed, we'll do our own queries instead of using methods
in
// Campaign and Banner.
- $dbr = CNDatabase::getDb( DB_SLAVE );
$cache = ObjectCache::getMainWANInstance();
// Set up conditions
--
To view, visit https://gerrit.wikimedia.org/r/308126
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: merged
Gerrit-Change-Id: Id4e46b653554d39ac5721c4327774ccfce63b734
Gerrit-PatchSet: 7
Gerrit-Project: mediawiki/extensions/CentralNotice
Gerrit-Branch: master
Gerrit-Owner: AndyRussG <andrew.green...@gmail.com>
Gerrit-Reviewer: Aaron Schulz <asch...@wikimedia.org>
Gerrit-Reviewer: AndyRussG <andrew.green...@gmail.com>
Gerrit-Reviewer: Awight <awi...@wikimedia.org>
Gerrit-Reviewer: Cdentinger <cdentin...@wikimedia.org>
Gerrit-Reviewer: Ejegg <eeggles...@wikimedia.org>
Gerrit-Reviewer: Ssmith <ssm...@wikimedia.org>
Gerrit-Reviewer: XenoRyet <dkozlow...@wikimedia.org>
Gerrit-Reviewer: jenkins-bot <>
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