*/
/**
- * Version of LockManager based on using DB table row 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
* @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 */
$this->session = wfRandomString( 31 );
}
- /**
- * 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( array( $this, 'sha1Base36Absolute' ), $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
* 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();
}
}
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;
+ }
}