diff options
Diffstat (limited to 'includes/filebackend/lockmanager/DBLockManager.php')
| -rw-r--r-- | includes/filebackend/lockmanager/DBLockManager.php | 227 |
1 files changed, 143 insertions, 84 deletions
diff --git a/includes/filebackend/lockmanager/DBLockManager.php b/includes/filebackend/lockmanager/DBLockManager.php index a8fe258b..f02387dc 100644 --- a/includes/filebackend/lockmanager/DBLockManager.php +++ b/includes/filebackend/lockmanager/DBLockManager.php @@ -22,10 +22,9 @@ */ /** - * Version of LockManager based on using DB table locks. + * Version of LockManager based on using named/row DB locks. + * * This is meant for multi-wiki systems that may share files. - * All locks are blocking, so it might be useful to set a small - * lock-wait timeout via server config to curtail deadlocks. * * All lock requests for a resource, identified by a hash string, will map * to one bucket. Each bucket maps to one or several peer DBs, each on their @@ -37,7 +36,7 @@ * @ingroup LockManager * @since 1.19 */ -class DBLockManager extends QuorumLockManager { +abstract class DBLockManager extends QuorumLockManager { /** @var Array Map of DB names to server config */ protected $dbServers; // (DB name => server config array) /** @var BagOStuff */ @@ -67,11 +66,12 @@ class DBLockManager extends QuorumLockManager { * each having an odd-numbered list of DB names (peers) as values. * Any DB named 'localDBMaster' will automatically use the DB master * settings for this wiki (without the need for a dbServers entry). + * Only use 'localDBMaster' if the domain is a valid wiki ID. * - lockExpiry : Lock timeout (seconds) for dropped connections. [optional] * 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 ); @@ -111,65 +111,6 @@ class DBLockManager extends QuorumLockManager { } /** - * 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 getLocksOnServer( $lockSrv, array $paths, $type ) { - $status = Status::newGood(); - - 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 ); - } - } - } - - return $status; - } - - /** - * @see QuorumLockManager::freeLocksOnServer() - * @return Status - */ - protected function freeLocksOnServer( $lockSrv, array $paths, $type ) { - return Status::newGood(); // not supported - } - - /** - * @see QuorumLockManager::releaseAllLocks() - * @return Status - */ - protected function releaseAllLocks() { - $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; - } - - /** * @see QuorumLockManager::isServerUp() * @return bool */ @@ -197,8 +138,8 @@ class DBLockManager extends QuorumLockManager { if ( !isset( $this->conns[$lockDb] ) ) { $db = null; if ( $lockDb === 'localDBMaster' ) { - $lb = wfGetLBFactory()->newMainLB(); - $db = $lb->getConnection( DB_MASTER ); + $lb = wfGetLBFactory()->getMainLB( $this->domain ); + $db = $lb->getConnection( DB_MASTER, array(), $this->domain ); } elseif ( isset( $this->dbServers[$lockDb] ) ) { $config = $this->dbServers[$lockDb]; $db = DatabaseBase::factory( $config['type'], $config ); @@ -274,14 +215,8 @@ class DBLockManager extends QuorumLockManager { * Make sure remaining locks get cleared for sanity */ function __destruct() { + $this->releaseAllLocks(); foreach ( $this->conns as $db ) { - if ( $db->trxLevel() ) { // in transaction - try { - $db->rollback( __METHOD__ ); // finish transaction and kill any rows - } catch ( DBError $e ) { - // oh well - } - } $db->close(); } } @@ -321,27 +256,38 @@ class MySqlLockManager extends DBLockManager { $status = Status::newGood(); $db = $this->getConnection( $lockSrv ); // checked in isServerUp() - $keys = array_unique( array_map( 'LockManager::sha1Base36', $paths ) ); + + $keys = array(); // list of hash keys for the paths + $data = array(); // list of rows to insert + $checkEXKeys = array(); // list of hash keys that this has no EX lock on # Build up values for INSERT clause - $data = array(); - foreach ( $keys as $key ) { + foreach ( $paths as $path ) { + $key = $this->sha1Base36Absolute( $path ); + $keys[] = $key; $data[] = array( 'fls_key' => $key, 'fls_session' => $this->session ); + if ( !isset( $this->locksHeld[$path][self::LOCK_EX] ) ) { + $checkEXKeys[] = $key; + } } - # Block new writers... + + # Block new writers (both EX and SH locks leave entries here)... $db->insert( 'filelocks_shared', $data, __METHOD__, array( 'IGNORE' ) ); # Actually do the locking queries... if ( $type == self::LOCK_SH ) { // reader locks + $blocked = false; # Bail if there are any existing writers... - $blocked = $db->selectField( 'filelocks_exclusive', '1', - array( 'fle_key' => $keys ), - __METHOD__ - ); - # Prospective writers that haven't yet updated filelocks_exclusive - # will recheck filelocks_shared after doing so and bail due to our entry. + if ( count( $checkEXKeys ) ) { + $blocked = $db->selectField( 'filelocks_exclusive', '1', + array( 'fle_key' => $checkEXKeys ), + __METHOD__ + ); + } + # Other prospective writers that haven't yet updated filelocks_exclusive + # will recheck filelocks_shared after doing so and bail due to this entry. } else { // writer locks $encSession = $db->addQuotes( $this->session ); # Bail if there are any existing writers... - # The may detect readers, but the safe check for them is below. + # This may detect readers, but the safe check for them is below. # Note: if two writers come at the same time, both bail :) $blocked = $db->selectField( 'filelocks_shared', '1', array( 'fls_key' => $keys, "fls_session != $encSession" ), @@ -371,4 +317,117 @@ class MySqlLockManager extends DBLockManager { return $status; } + + /** + * @see QuorumLockManager::freeLocksOnServer() + * @return Status + */ + protected function freeLocksOnServer( $lockSrv, array $paths, $type ) { + return Status::newGood(); // not supported + } + + /** + * @see QuorumLockManager::releaseAllLocks() + * @return Status + */ + protected function releaseAllLocks() { + $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; + } +} + +/** + * PostgreSQL version of DBLockManager that supports shared locks. + * All locks are non-blocking, which avoids deadlocks. + * + * @ingroup LockManager + */ +class PostgreSqlLockManager extends DBLockManager { + /** @var Array Mapping of lock types to the type actually used */ + protected $lockTypeMap = array( + self::LOCK_SH => self::LOCK_SH, + self::LOCK_UW => self::LOCK_SH, + self::LOCK_EX => self::LOCK_EX + ); + + protected function getLocksOnServer( $lockSrv, array $paths, $type ) { + $status = Status::newGood(); + if ( !count( $paths ) ) { + return $status; // nothing to lock + } + + $db = $this->getConnection( $lockSrv ); // checked in isServerUp() + $bigints = array_unique( array_map( + function( $key ) { return wfBaseConvert( substr( $key, 0, 15 ), 16, 10 ); }, + array_map( array( $this, 'sha1Base16Absolute' ), $paths ) + ) ); + + // Try to acquire all the locks... + $fields = array(); + foreach ( $bigints as $bigint ) { + $fields[] = ( $type == self::LOCK_SH ) + ? "pg_try_advisory_lock_shared({$db->addQuotes( $bigint )}) AS K$bigint" + : "pg_try_advisory_lock({$db->addQuotes( $bigint )}) AS K$bigint"; + } + $res = $db->query( 'SELECT ' . implode( ', ', $fields ), __METHOD__ ); + $row = (array)$res->fetchObject(); + + if ( in_array( 'f', $row ) ) { + // Release any acquired locks if some could not be acquired... + $fields = array(); + foreach ( $row as $kbigint => $ok ) { + if ( $ok === 't' ) { // locked + $bigint = substr( $kbigint, 1 ); // strip off the "K" + $fields[] = ( $type == self::LOCK_SH ) + ? "pg_advisory_unlock_shared({$db->addQuotes( $bigint )})" + : "pg_advisory_unlock({$db->addQuotes( $bigint )})"; + } + } + if ( count( $fields ) ) { + $db->query( 'SELECT ' . implode( ', ', $fields ), __METHOD__ ); + } + foreach ( $paths as $path ) { + $status->fatal( 'lockmanager-fail-acquirelock', $path ); + } + } + + return $status; + } + + /** + * @see QuorumLockManager::freeLocksOnServer() + * @return Status + */ + protected function freeLocksOnServer( $lockSrv, array $paths, $type ) { + return Status::newGood(); // not supported + } + + /** + * @see QuorumLockManager::releaseAllLocks() + * @return Status + */ + protected function releaseAllLocks() { + $status = Status::newGood(); + + foreach ( $this->conns as $lockDb => $db ) { + try { + $db->query( "SELECT pg_advisory_unlock_all()", __METHOD__ ); + } catch ( DBError $e ) { + $status->fatal( 'lockmanager-fail-db-release', $lockDb ); + } + } + + return $status; + } } |