From 4ac9fa081a7c045f6a9f1cfc529d82423f485b2e Mon Sep 17 00:00:00 2001 From: Pierre Schmitz Date: Sun, 8 Dec 2013 09:55:49 +0100 Subject: Update to MediaWiki 1.22.0 --- .../filebackend/lockmanager/QuorumLockManager.php | 140 ++++++++++++--------- 1 file changed, 78 insertions(+), 62 deletions(-) (limited to 'includes/filebackend/lockmanager/QuorumLockManager.php') diff --git a/includes/filebackend/lockmanager/QuorumLockManager.php b/includes/filebackend/lockmanager/QuorumLockManager.php index b331b540..8356d32a 100644 --- a/includes/filebackend/lockmanager/QuorumLockManager.php +++ b/includes/filebackend/lockmanager/QuorumLockManager.php @@ -31,81 +31,86 @@ abstract class QuorumLockManager extends LockManager { /** @var Array Map of bucket indexes to peer server lists */ protected $srvsByBucket = array(); // (bucket index => (lsrv1, lsrv2, ...)) + /** @var Array Map of degraded buckets */ + protected $degradedBuckets = array(); // (buckey index => UNIX timestamp) - /** - * @see LockManager::doLock() - * @param $paths array - * @param $type int - * @return Status - */ final protected function doLock( array $paths, $type ) { + return $this->doLockByType( array( $type => $paths ) ); + } + + final protected function doUnlock( array $paths, $type ) { + return $this->doUnlockByType( array( $type => $paths ) ); + } + + protected function doLockByType( array $pathsByType ) { $status = Status::newGood(); - $pathsToLock = array(); // (bucket => paths) + $pathsToLock = array(); // (bucket => type => paths) // Get locks that need to be acquired (buckets => locks)... - foreach ( $paths as $path ) { - if ( isset( $this->locksHeld[$path][$type] ) ) { - ++$this->locksHeld[$path][$type]; - } else { - $bucket = $this->getBucketFromPath( $path ); - $pathsToLock[$bucket][] = $path; + foreach ( $pathsByType as $type => $paths ) { + foreach ( $paths as $path ) { + if ( isset( $this->locksHeld[$path][$type] ) ) { + ++$this->locksHeld[$path][$type]; + } else { + $bucket = $this->getBucketFromPath( $path ); + $pathsToLock[$bucket][$type][] = $path; + } } } - $lockedPaths = array(); // files locked in this attempt + $lockedPaths = array(); // files locked in this attempt (type => paths) // Attempt to acquire these locks... - foreach ( $pathsToLock as $bucket => $paths ) { + foreach ( $pathsToLock as $bucket => $pathsToLockByType ) { // Try to acquire the locks for this bucket - $status->merge( $this->doLockingRequestBucket( $bucket, $paths, $type ) ); + $status->merge( $this->doLockingRequestBucket( $bucket, $pathsToLockByType ) ); if ( !$status->isOK() ) { - $status->merge( $this->doUnlock( $lockedPaths, $type ) ); + $status->merge( $this->doUnlockByType( $lockedPaths ) ); return $status; } // Record these locks as active - foreach ( $paths as $path ) { - $this->locksHeld[$path][$type] = 1; // locked + foreach ( $pathsToLockByType as $type => $paths ) { + foreach ( $paths as $path ) { + $this->locksHeld[$path][$type] = 1; // locked + // Keep track of what locks were made in this attempt + $lockedPaths[$type][] = $path; + } } - // Keep track of what locks were made in this attempt - $lockedPaths = array_merge( $lockedPaths, $paths ); } return $status; } - /** - * @see LockManager::doUnlock() - * @param $paths array - * @param $type int - * @return Status - */ - final protected function doUnlock( array $paths, $type ) { + protected function doUnlockByType( array $pathsByType ) { $status = Status::newGood(); - $pathsToUnlock = array(); - foreach ( $paths as $path ) { - if ( !isset( $this->locksHeld[$path][$type] ) ) { - $status->warning( 'lockmanager-notlocked', $path ); - } else { - --$this->locksHeld[$path][$type]; - // Reference count the locks held and release locks when zero - if ( $this->locksHeld[$path][$type] <= 0 ) { - unset( $this->locksHeld[$path][$type] ); - $bucket = $this->getBucketFromPath( $path ); - $pathsToUnlock[$bucket][] = $path; - } - if ( !count( $this->locksHeld[$path] ) ) { - unset( $this->locksHeld[$path] ); // no SH or EX locks left for key + $pathsToUnlock = array(); // (bucket => type => paths) + foreach ( $pathsByType as $type => $paths ) { + foreach ( $paths as $path ) { + if ( !isset( $this->locksHeld[$path][$type] ) ) { + $status->warning( 'lockmanager-notlocked', $path ); + } else { + --$this->locksHeld[$path][$type]; + // Reference count the locks held and release locks when zero + if ( $this->locksHeld[$path][$type] <= 0 ) { + unset( $this->locksHeld[$path][$type] ); + $bucket = $this->getBucketFromPath( $path ); + $pathsToUnlock[$bucket][$type][] = $path; + } + if ( !count( $this->locksHeld[$path] ) ) { + unset( $this->locksHeld[$path] ); // no SH or EX locks left for key + } } } } // Remove these specific locks if possible, or at least release // all locks once this process is currently not holding any locks. - foreach ( $pathsToUnlock as $bucket => $paths ) { - $status->merge( $this->doUnlockingRequestBucket( $bucket, $paths, $type ) ); + foreach ( $pathsToUnlock as $bucket => $pathsToUnlockByType ) { + $status->merge( $this->doUnlockingRequestBucket( $bucket, $pathsToUnlockByType ) ); } if ( !count( $this->locksHeld ) ) { $status->merge( $this->releaseAllLocks() ); + $this->degradedBuckets = array(); // safe to retry the normal quorum } return $status; @@ -116,25 +121,25 @@ abstract class QuorumLockManager extends LockManager { * This is all or nothing; if any key is locked then this totally fails. * * @param $bucket integer - * @param array $paths List of resource keys to lock - * @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH + * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths * @return Status */ - final protected function doLockingRequestBucket( $bucket, array $paths, $type ) { + final protected function doLockingRequestBucket( $bucket, array $pathsByType ) { $status = Status::newGood(); $yesVotes = 0; // locks made on trustable servers $votesLeft = count( $this->srvsByBucket[$bucket] ); // remaining peers - $quorum = floor( $votesLeft/2 + 1 ); // simple majority + $quorum = floor( $votesLeft / 2 + 1 ); // simple majority // Get votes for each peer, in order, until we have enough... foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) { if ( !$this->isServerUp( $lockSrv ) ) { --$votesLeft; $status->warning( 'lockmanager-fail-svr-acquire', $lockSrv ); + $this->degradedBuckets[$bucket] = time(); continue; // server down? } // Attempt to acquire the lock on this peer - $status->merge( $this->getLocksOnServer( $lockSrv, $paths, $type ) ); + $status->merge( $this->getLocksOnServer( $lockSrv, $pathsByType ) ); if ( !$status->isOK() ) { return $status; // vetoed; resource locked } @@ -158,21 +163,33 @@ abstract class QuorumLockManager extends LockManager { * Attempt to release locks with the peers for a bucket * * @param $bucket integer - * @param array $paths List of resource keys to lock - * @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH + * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths * @return Status */ - final protected function doUnlockingRequestBucket( $bucket, array $paths, $type ) { + final protected function doUnlockingRequestBucket( $bucket, array $pathsByType ) { $status = Status::newGood(); + $yesVotes = 0; // locks freed on trustable servers + $votesLeft = count( $this->srvsByBucket[$bucket] ); // remaining peers + $quorum = floor( $votesLeft / 2 + 1 ); // simple majority + $isDegraded = isset( $this->degradedBuckets[$bucket] ); // not the normal quorum? foreach ( $this->srvsByBucket[$bucket] as $lockSrv ) { if ( !$this->isServerUp( $lockSrv ) ) { - $status->fatal( 'lockmanager-fail-svr-release', $lockSrv ); + $status->warning( 'lockmanager-fail-svr-release', $lockSrv ); // Attempt to release the lock on this peer } else { - $status->merge( $this->freeLocksOnServer( $lockSrv, $paths, $type ) ); + $status->merge( $this->freeLocksOnServer( $lockSrv, $pathsByType ) ); + ++$yesVotes; // success for this peer + // Normally the first peers form the quorum, and the others are ignored. + // Ignore them in this case, but not when an alternative quorum was used. + if ( $yesVotes >= $quorum && !$isDegraded ) { + break; // lock released + } } } + // Set a bad status if the quorum was not met. + // Assumes the same "up" servers as during the acquire step. + $status->setResult( $yesVotes >= $quorum ); return $status; } @@ -190,7 +207,8 @@ abstract class QuorumLockManager extends LockManager { } /** - * Check if a lock server is up + * Check if a lock server is up. + * This should process cache results to reduce RTT. * * @param $lockSrv string * @return bool @@ -198,14 +216,13 @@ abstract class QuorumLockManager extends LockManager { abstract protected function isServerUp( $lockSrv ); /** - * Get a connection to a lock server and acquire locks on $paths + * Get a connection to a lock server and acquire locks * * @param $lockSrv string - * @param $paths array - * @param $type integer + * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths * @return Status */ - abstract protected function getLocksOnServer( $lockSrv, array $paths, $type ); + abstract protected function getLocksOnServer( $lockSrv, array $pathsByType ); /** * Get a connection to a lock server and release locks on $paths. @@ -213,11 +230,10 @@ abstract class QuorumLockManager extends LockManager { * Subclasses must effectively implement this or releaseAllLocks(). * * @param $lockSrv string - * @param $paths array - * @param $type integer + * @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths * @return Status */ - abstract protected function freeLocksOnServer( $lockSrv, array $paths, $type ); + abstract protected function freeLocksOnServer( $lockSrv, array $pathsByType ); /** * Release all locks that this session is holding. -- cgit v1.2.3-54-g00ecf