* @ingroup LockManager
* @since 1.19
*/
- class DBLockManager extends LockManager {
+ class DBLockManager extends QuorumLockManager {
/** @var Array Map of DB names to server config */
protected $dbServers; // (DB name => server config array)
- /** @var Array Map of bucket indexes to peer DB lists */
- protected $dbsByBucket; // (bucket index => (ldb1, ldb2, ...))
/** @var BagOStuff */
protected $statusCache;
/**
* Construct a new instance from configuration.
- *
+ *
* $config paramaters include:
* 'dbServers' : Associative array of DB names to server configuration.
* Configuration is an associative array that includes:
* This tells the DB server how long to wait before assuming
* connection failure and releasing all the locks for a session.
*
- * @param Array $config
+ * @param Array $config
*/
public function __construct( array $config ) {
parent::__construct( $config );
$this->dbServers = isset( $config['dbServers'] )
? $config['dbServers']
: array(); // likely just using 'localDBMaster'
- // Sanitize dbsByBucket config to prevent PHP errors
- $this->dbsByBucket = array_filter( $config['dbsByBucket'], 'is_array' );
- $this->dbsByBucket = array_values( $this->dbsByBucket ); // consecutive
+ // Sanitize srvsByBucket config to prevent PHP errors
+ $this->srvsByBucket = array_filter( $config['dbsByBucket'], 'is_array' );
+ $this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive
if ( isset( $config['lockExpiry'] ) ) {
$this->lockExpiry = $config['lockExpiry'];
? 60 // pick a safe-ish number to match DB timeout default
: $this->lockExpiry; // cover worst case
- foreach ( $this->dbsByBucket as $bucket ) {
- if ( count( $bucket ) > 1 ) {
+ foreach ( $this->srvsByBucket as $bucket ) {
+ if ( count( $bucket ) > 1 ) { // multiple peers
// Tracks peers that couldn't be queried recently to avoid lengthy
// connection timeouts. This is useless if each bucket has one peer.
- $this->statusCache = wfGetMainCache();
+ try {
+ $this->statusCache = ObjectCache::newAccelerator( array() );
+ } catch ( MWException $e ) {
+ trigger_error( __CLASS__ .
+ " using multiple DB peers without apc, xcache, or wincache." );
+ }
break;
}
}
- $this->session = '';
- for ( $i = 0; $i < 5; $i++ ) {
- $this->session .= mt_rand( 0, 2147483647 );
- }
- $this->session = wfBaseConvert( sha1( $this->session ), 16, 36, 31 );
+ $this->session = wfRandomString( 31 );
}
/**
- * @see LockManager::doLock()
- * @param $paths array
- * @param $type int
+ * Get a connection to a lock DB and acquire locks on $paths.
+ * This does not use GET_LOCK() per http://bugs.mysql.com/bug.php?id=1118.
+ *
+ * @see QuorumLockManager::getLocksOnServer()
* @return Status
*/
- protected function doLock( array $paths, $type ) {
+ protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
$status = Status::newGood();
- $pathsToLock = array();
- // Get locks that need to be acquired (buckets => locks)...
- foreach ( $paths as $path ) {
- if ( isset( $this->locksHeld[$path][$type] ) ) {
- ++$this->locksHeld[$path][$type];
- } elseif ( isset( $this->locksHeld[$path][self::LOCK_EX] ) ) {
- $this->locksHeld[$path][$type] = 1;
- } else {
- $bucket = $this->getBucketFromKey( $path );
- $pathsToLock[$bucket][] = $path;
- }
- }
-
- $lockedPaths = array(); // files locked in this attempt
- // Attempt to acquire these locks...
- foreach ( $pathsToLock as $bucket => $paths ) {
- // Try to acquire the locks for this bucket
- $res = $this->doLockingQueryAll( $bucket, $paths, $type );
- if ( $res === 'cantacquire' ) {
- // Resources already locked by another process.
- // Abort and unlock everything we just locked.
+ if ( $type == self::LOCK_EX ) { // writer locks
+ try {
+ $keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
+ # Build up values for INSERT clause
+ $data = array();
+ foreach ( $keys as $key ) {
+ $data[] = array( 'fle_key' => $key );
+ }
+ # Wait on any existing writers and block new ones if we get in
+ $db = $this->getConnection( $lockSrv ); // checked in isServerUp()
+ $db->insert( 'filelocks_exclusive', $data, __METHOD__ );
+ } catch ( DBError $e ) {
foreach ( $paths as $path ) {
$status->fatal( 'lockmanager-fail-acquirelock', $path );
}
- $status->merge( $this->doUnlock( $lockedPaths, $type ) );
- return $status;
- } elseif ( $res !== true ) {
- // Couldn't contact any DBs for this bucket.
- // Abort and unlock everything we just locked.
- $status->fatal( 'lockmanager-fail-db-bucket', $bucket );
- $status->merge( $this->doUnlock( $lockedPaths, $type ) );
- return $status;
}
- // Record these locks as active
- foreach ( $paths as $path ) {
- $this->locksHeld[$path][$type] = 1; // locked
- }
- // 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
+ * @see QuorumLockManager::freeLocksOnServer()
* @return Status
*/
- protected function doUnlock( array $paths, $type ) {
+ protected function freeLocksOnServer( $lockSrv, array $paths, $type ) {
+ return Status::newGood(); // not supported
+ }
+
+ /**
+ * @see QuorumLockManager::releaseAllLocks()
+ * @return Status
+ */
+ protected function releaseAllLocks() {
$status = Status::newGood();
- foreach ( $paths as $path ) {
- if ( !isset( $this->locksHeld[$path] ) ) {
- $status->warning( 'lockmanager-notlocked', $path );
- } elseif ( !isset( $this->locksHeld[$path][$type] ) ) {
- $status->warning( 'lockmanager-notlocked', $path );
- } else {
- --$this->locksHeld[$path][$type];
- if ( $this->locksHeld[$path][$type] <= 0 ) {
- unset( $this->locksHeld[$path][$type] );
- }
- if ( !count( $this->locksHeld[$path] ) ) {
- unset( $this->locksHeld[$path] ); // no SH or EX locks left for key
+ foreach ( $this->conns as $lockDb => $db ) {
+ if ( $db->trxLevel() ) { // in transaction
+ try {
+ $db->rollback( __METHOD__ ); // finish transaction and kill any rows
+ } catch ( DBError $e ) {
+ $status->fatal( 'lockmanager-fail-db-release', $lockDb );
}
}
}
- // Reference count the locks held and COMMIT when zero
- if ( !count( $this->locksHeld ) ) {
- $status->merge( $this->finishLockTransactions() );
- }
-
return $status;
}
/**
- * Get a connection to a lock DB and acquire locks on $paths.
- * This does not use GET_LOCK() per http://bugs.mysql.com/bug.php?id=1118.
- *
- * @param $lockDb string
- * @param $paths Array
- * @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
- * @return bool Resources able to be locked
- * @throws DBError
+ * @see QuorumLockManager::isServerUp()
+ * @return bool
*/
- protected function doLockingQuery( $lockDb, array $paths, $type ) {
- if ( $type == self::LOCK_EX ) { // writer locks
- $db = $this->getConnection( $lockDb );
- if ( !$db ) {
- return false; // bad config
- }
- $keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
- # Build up values for INSERT clause
- $data = array();
- foreach ( $keys as $key ) {
- $data[] = array( 'fle_key' => $key );
- }
- # Wait on any existing writers and block new ones if we get in
- $db->insert( 'filelocks_exclusive', $data, __METHOD__ );
+ protected function isServerUp( $lockSrv ) {
+ if ( !$this->cacheCheckFailures( $lockSrv ) ) {
+ return false; // recent failure to connect
}
- return true;
- }
-
- /**
- * Attempt to acquire locks with the peers for a bucket.
- * This should avoid throwing any exceptions.
- *
- * @param $bucket integer
- * @param $paths Array List of resource keys to lock
- * @param $type integer LockManager::LOCK_EX or LockManager::LOCK_SH
- * @return bool|string One of (true, 'cantacquire', 'dberrors')
- */
- protected function doLockingQueryAll( $bucket, array $paths, $type ) {
- $yesVotes = 0; // locks made on trustable DBs
- $votesLeft = count( $this->dbsByBucket[$bucket] ); // remaining DBs
- $quorum = floor( $votesLeft/2 + 1 ); // simple majority
- // Get votes for each DB, in order, until we have enough...
- foreach ( $this->dbsByBucket[$bucket] as $lockDb ) {
- // Check that DB is not *known* to be down
- if ( $this->cacheCheckFailures( $lockDb ) ) {
- try {
- // Attempt to acquire the lock on this DB
- if ( !$this->doLockingQuery( $lockDb, $paths, $type ) ) {
- return 'cantacquire'; // vetoed; resource locked
- }
- ++$yesVotes; // success for this peer
- if ( $yesVotes >= $quorum ) {
- return true; // lock obtained
- }
- } catch ( DBConnectionError $e ) {
- $this->cacheRecordFailure( $lockDb );
- } catch ( DBError $e ) {
- if ( $this->lastErrorIndicatesLocked( $lockDb ) ) {
- return 'cantacquire'; // vetoed; resource locked
- }
- }
- }
- --$votesLeft;
- $votesNeeded = $quorum - $yesVotes;
- if ( $votesNeeded > $votesLeft ) {
- // In "trust cache" mode we don't have to meet the quorum
- break; // short-circuit
- }
+ try {
+ $this->getConnection( $lockSrv );
+ } catch ( DBError $e ) {
+ $this->cacheRecordFailure( $lockSrv );
+ return false; // failed to connect
}
- // At this point, we must not have meet the quorum
- return 'dberrors'; // not enough votes to ensure correctness
+ return true;
}
/**
*/
protected function initConnection( $lockDb, DatabaseBase $db ) {}
- /**
- * Commit all changes to lock-active databases.
- * This should avoid throwing any exceptions.
- *
- * @return Status
- */
- protected function finishLockTransactions() {
- $status = Status::newGood();
- foreach ( $this->conns as $lockDb => $db ) {
- if ( $db->trxLevel() ) { // in transaction
- try {
- $db->rollback( __METHOD__ ); // finish transaction and kill any rows
- } catch ( DBError $e ) {
- $status->fatal( 'lockmanager-fail-db-release', $lockDb );
- }
- }
- }
- return $status;
- }
-
- /**
- * Check if the last DB error for $lockDb indicates
- * that a requested resource was locked by another process.
- * This should avoid throwing any exceptions.
- *
- * @param $lockDb string
- * @return bool
- */
- protected function lastErrorIndicatesLocked( $lockDb ) {
- if ( isset( $this->conns[$lockDb] ) ) { // sanity
- $db = $this->conns[$lockDb];
- return ( $db->wasDeadlock() || $db->wasLockTimeout() );
- }
- return false;
- }
-
/**
* Checks if the DB has not recently had connection/query errors.
* This just avoids wasting time on doomed connection attempts.
- *
+ *
* @param $lockDb string
* @return bool
*/
protected function cacheCheckFailures( $lockDb ) {
- if ( $this->statusCache && $this->safeDelay > 0 ) {
- $path = $this->getMissKey( $lockDb );
- $misses = $this->statusCache->get( $path );
- return !$misses;
- }
- return true;
+ return ( $this->statusCache && $this->safeDelay > 0 )
+ ? !$this->statusCache->get( $this->getMissKey( $lockDb ) )
+ : true;
}
/**
* @return bool Success
*/
protected function cacheRecordFailure( $lockDb ) {
- if ( $this->statusCache && $this->safeDelay > 0 ) {
- $path = $this->getMissKey( $lockDb );
- $misses = $this->statusCache->get( $path );
- if ( $misses ) {
- return $this->statusCache->incr( $path );
- } else {
- return $this->statusCache->add( $path, 1, $this->safeDelay );
- }
- }
- return true;
+ return ( $this->statusCache && $this->safeDelay > 0 )
+ ? $this->statusCache->set( $this->getMissKey( $lockDb ), 1, $this->safeDelay )
+ : true;
}
/**
* @return string
*/
protected function getMissKey( $lockDb ) {
- return 'lockmanager:querymisses:' . str_replace( ' ', '_', $lockDb );
- }
-
- /**
- * Get the bucket for resource path.
- * This should avoid throwing any exceptions.
- *
- * @param $path string
- * @return integer
- */
- protected function getBucketFromKey( $path ) {
- $prefix = substr( sha1( $path ), 0, 2 ); // first 2 hex chars (8 bits)
- return intval( base_convert( $prefix, 16, 10 ) ) % count( $this->dbsByBucket );
+ $lockDb = ( $lockDb === 'localDBMaster' ) ? wfWikiID() : $lockDb; // non-relative
+ return 'dblockmanager:downservers:' . str_replace( ' ', '_', $lockDb );
}
/**
* Make sure remaining locks get cleared for sanity
*/
function __destruct() {
- foreach ( $this->conns as $lockDb => $db ) {
+ foreach ( $this->conns as $db ) {
if ( $db->trxLevel() ) { // in transaction
try {
$db->rollback( __METHOD__ ); // finish transaction and kill any rows
}
/**
- * @param $lockDb string
- * @param $paths array
- * @param $type int
- * @return bool
+ * Get a connection to a lock DB and acquire locks on $paths.
+ * This does not use GET_LOCK() per http://bugs.mysql.com/bug.php?id=1118.
+ *
+ * @see DBLockManager::getLocksOnServer()
+ * @return Status
*/
- protected function doLockingQuery( $lockDb, array $paths, $type ) {
- $db = $this->getConnection( $lockDb );
- if ( !$db ) {
- return false;
- }
+ protected function getLocksOnServer( $lockSrv, array $paths, $type ) {
+ $status = Status::newGood();
+
+ $db = $this->getConnection( $lockSrv ); // checked in isServerUp()
$keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) );
# Build up values for INSERT clause
$data = array();
);
}
}
- return !$blocked;
+
+ if ( $blocked ) {
+ foreach ( $paths as $path ) {
+ $status->fatal( 'lockmanager-fail-acquirelock', $path );
+ }
+ }
+
+ return $status;
}
}
dépôts / lhc / web / wiklou.git / commitdiff