* @since 1.20
*/
abstract class QuorumLockManager extends LockManager {
- /** @var Array Map of bucket indexes to peer server lists */
+ /** @var array Map of bucket indexes to peer server lists */
protected $srvsByBucket = array(); // (bucket index => (lsrv1, lsrv2, ...))
- /**
- * @see LockManager::doLock()
- * @param $paths array
- * @param $type int
- * @return Status
- */
+ /** @var array Map of degraded buckets */
+ protected $degradedBuckets = array(); // (buckey index => UNIX timestamp)
+
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;
* Attempt to acquire locks with the peers for a bucket.
* 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 int $bucket
+ * @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();
$yesVotes = 0; // locks made on trustable servers
if ( !$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
}
/**
* 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 int $bucket
+ * @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;
}
* Get the bucket for resource path.
* This should avoid throwing any exceptions.
*
- * @param $path string
- * @return integer
+ * @param string $path
+ * @return int
*/
protected function getBucketFromPath( $path ) {
$prefix = substr( sha1( $path ), 0, 2 ); // first 2 hex chars (8 bits)
}
/**
- * 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
+ * @param string $lockSrv
* @return bool
*/
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 string $lockSrv
+ * @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.
*
* Subclasses must effectively implement this or releaseAllLocks().
*
- * @param $lockSrv string
- * @param $paths array
- * @param $type integer
+ * @param string $lockSrv
+ * @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.
dépôts / lhc / web / wiklou.git / blobdiff