--- /dev/null
+<?php
+/**
+ * Version of LockManager based on using DB table locks.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup LockManager
+ */
+
+use Wikimedia\Rdbms\Database;
+use Wikimedia\Rdbms\IDatabase;
+use Wikimedia\Rdbms\DBError;
+
+/**
+ * Version of LockManager based on using named/row DB locks.
+ *
+ * This is meant for multi-wiki systems that may share files.
+ *
+ * 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 own server.
+ * A majority of peer DBs must agree for a lock to be acquired.
+ *
+ * Caching is used to avoid hitting servers that are down.
+ *
+ * @ingroup LockManager
+ * @since 1.19
+ */
+abstract class DBLockManager extends QuorumLockManager {
+ /** @var array[]|IDatabase[] Map of (DB names => server config or IDatabase) */
+ protected $dbServers; // (DB name => server config array)
+ /** @var BagOStuff */
+ protected $statusCache;
+
+ protected $lockExpiry; // integer number of seconds
+ protected $safeDelay; // integer number of seconds
+ /** @var IDatabase[] Map Database connections (DB name => Database) */
+ protected $conns = [];
+
+ /**
+ * Construct a new instance from configuration.
+ *
+ * @param array $config Parameters include:
+ * - dbServers : Associative array of DB names to server configuration.
+ * Configuration is an associative array that includes:
+ * - host : DB server name
+ * - dbname : DB name
+ * - type : DB type (mysql,postgres,...)
+ * - user : DB user
+ * - password : DB user password
+ * - tablePrefix : DB table prefix
+ * - flags : DB flags; bitfield of IDatabase::DBO_* constants
+ * - dbsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
+ * each having an odd-numbered list of DB names (peers) as values.
+ * - 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.
+ * - srvCache : A BagOStuff instance using APC or the like.
+ */
+ public function __construct( array $config ) {
+ parent::__construct( $config );
+
+ $this->dbServers = $config['dbServers'];
+ // 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'];
+ } else {
+ $met = ini_get( 'max_execution_time' );
+ $this->lockExpiry = $met ? $met : 60; // use some sane amount if 0
+ }
+ $this->safeDelay = ( $this->lockExpiry <= 0 )
+ ? 60 // pick a safe-ish number to match DB timeout default
+ : $this->lockExpiry; // cover worst case
+
+ // Tracks peers that couldn't be queried recently to avoid lengthy
+ // connection timeouts. This is useless if each bucket has one peer.
+ $this->statusCache = isset( $config['srvCache'] )
+ ? $config['srvCache']
+ : new HashBagOStuff();
+ }
+
+ /**
+ * @TODO change this code to work in one batch
+ * @param string $lockSrv
+ * @param array $pathsByType
+ * @return StatusValue
+ */
+ protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
+ $status = StatusValue::newGood();
+ foreach ( $pathsByType as $type => $paths ) {
+ $status->merge( $this->doGetLocksOnServer( $lockSrv, $paths, $type ) );
+ }
+
+ return $status;
+ }
+
+ abstract protected function doGetLocksOnServer( $lockSrv, array $paths, $type );
+
+ protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
+ return StatusValue::newGood();
+ }
+
+ /**
+ * @see QuorumLockManager::isServerUp()
+ * @param string $lockSrv
+ * @return bool
+ */
+ protected function isServerUp( $lockSrv ) {
+ if ( !$this->cacheCheckFailures( $lockSrv ) ) {
+ return false; // recent failure to connect
+ }
+ try {
+ $this->getConnection( $lockSrv );
+ } catch ( DBError $e ) {
+ $this->cacheRecordFailure( $lockSrv );
+
+ return false; // failed to connect
+ }
+
+ return true;
+ }
+
+ /**
+ * Get (or reuse) a connection to a lock DB
+ *
+ * @param string $lockDb
+ * @return IDatabase
+ * @throws DBError
+ * @throws UnexpectedValueException
+ */
+ protected function getConnection( $lockDb ) {
+ if ( !isset( $this->conns[$lockDb] ) ) {
+ if ( $this->dbServers[$lockDb] instanceof IDatabase ) {
+ // Direct injected connection hande for $lockDB
+ $db = $this->dbServers[$lockDb];
+ } elseif ( is_array( $this->dbServers[$lockDb] ) ) {
+ // Parameters to construct a new database connection
+ $config = $this->dbServers[$lockDb];
+ $db = Database::factory( $config['type'], $config );
+ } else {
+ throw new UnexpectedValueException( "No server called '$lockDb'." );
+ }
+
+ $db->clearFlag( DBO_TRX );
+ # If the connection drops, try to avoid letting the DB rollback
+ # and release the locks before the file operations are finished.
+ # This won't handle the case of DB server restarts however.
+ $options = [];
+ if ( $this->lockExpiry > 0 ) {
+ $options['connTimeout'] = $this->lockExpiry;
+ }
+ $db->setSessionOptions( $options );
+ $this->initConnection( $lockDb, $db );
+
+ $this->conns[$lockDb] = $db;
+ }
+
+ return $this->conns[$lockDb];
+ }
+
+ /**
+ * Do additional initialization for new lock DB connection
+ *
+ * @param string $lockDb
+ * @param IDatabase $db
+ * @throws DBError
+ */
+ protected function initConnection( $lockDb, IDatabase $db ) {
+ }
+
+ /**
+ * Checks if the DB has not recently had connection/query errors.
+ * This just avoids wasting time on doomed connection attempts.
+ *
+ * @param string $lockDb
+ * @return bool
+ */
+ protected function cacheCheckFailures( $lockDb ) {
+ return ( $this->safeDelay > 0 )
+ ? !$this->statusCache->get( $this->getMissKey( $lockDb ) )
+ : true;
+ }
+
+ /**
+ * Log a lock request failure to the cache
+ *
+ * @param string $lockDb
+ * @return bool Success
+ */
+ protected function cacheRecordFailure( $lockDb ) {
+ return ( $this->safeDelay > 0 )
+ ? $this->statusCache->set( $this->getMissKey( $lockDb ), 1, $this->safeDelay )
+ : true;
+ }
+
+ /**
+ * Get a cache key for recent query misses for a DB
+ *
+ * @param string $lockDb
+ * @return string
+ */
+ protected function getMissKey( $lockDb ) {
+ return 'dblockmanager:downservers:' . str_replace( ' ', '_', $lockDb );
+ }
+
+ /**
+ * Make sure remaining locks get cleared for sanity
+ */
+ function __destruct() {
+ $this->releaseAllLocks();
+ foreach ( $this->conns as $db ) {
+ $db->close();
+ }
+ }
+}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff