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Avoid self-deadlocks in MessageCache::replace()

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* This makes use of the $rclass flag in BagOStuff

Bug: T109183
Change-Id: I305f51e744aac53876e5865f860c282aa2efbd8b
This commit is contained in:
Aaron Schulz 2015-08-21 14:46:44 -07:00 committed by Ori.livneh
parent ad1fb276de
commit a88e9ba007
1 changed files with 16 additions and 3 deletions
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19
includes/cache/MessageCache.php vendored
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@ -346,7 +346,7 @@ class MessageCache {
# Wait for the other thread to finish, then retry. Normally,
# the memcached get() will then yeild the other thread's result.
$where[] = 'waited for other thread to complete';
$this->mMemc->getScopedLock( $cacheKey, self::WAIT_SEC, self::LOCK_TTL );
$this->getReentrantScopedLock( $cacheKey );
}
}
}
@ -400,7 +400,7 @@ class MessageCache {
# If this lock fails, it doesn't really matter, it just means the
# write is potentially non-atomic, e.g. the results of a replace()
# may be discarded.
$mainUnlocker = $memCache->getScopedLock( $cacheKey, self::WAIT_SEC, self::LOCK_TTL );
$mainUnlocker = $this->getReentrantScopedLock( $cacheKey );
if ( !$mainUnlocker ) {
$where[] = 'could not acquire main lock';
}
@ -548,8 +548,13 @@ class MessageCache {
return;
}
# Note that if the cache is volatile, load() may trigger a DB fetch.
# In that case we reenter/reuse the existing cache key lock to avoid
# a self-deadlock. This is safe as no reads happen *directly* in this
# method between getReentrantScopedLock() and load() below. There is
# no risk of data "changing under our feet" for replace().
$cacheKey = wfMemcKey( 'messages', $code );
$scopedLock = $this->mMemc->getScopedLock( $cacheKey, self::WAIT_SEC, self::LOCK_TTL );
$scopedLock = $this->getReentrantScopedLock( $cacheKey );
$this->load( $code, self::FOR_UPDATE );
$titleKey = wfMemcKey( 'messages', 'individual', $title );
@ -673,6 +678,14 @@ class MessageCache {
);
}
/**
* @param string $key A language message cache key that stores blobs
* @return null|ScopedCallback
*/
protected function getReentrantScopedLock( $key ) {
return $this->mMemc->getScopedLock( $key, self::WAIT_SEC, self::LOCK_TTL, __METHOD__ );
}
/**
* Get a message from either the content language or the user language.
*