--- /dev/null
+<?php
+/**
+ * Object caching using a SQL database.
+ *
+ * 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 Cache
+ */
+
+use Wikimedia\Rdbms\Database;
+use Wikimedia\Rdbms\IDatabase;
+use Wikimedia\Rdbms\DBError;
+use Wikimedia\Rdbms\DBQueryError;
+use Wikimedia\Rdbms\DBConnectionError;
+use \MediaWiki\MediaWikiServices;
+use \Wikimedia\WaitConditionLoop;
+use \Wikimedia\Rdbms\TransactionProfiler;
+use Wikimedia\Rdbms\LoadBalancer;
+
+/**
+ * Class to store objects in the database
+ *
+ * @ingroup Cache
+ */
+class SqlBagOStuff extends BagOStuff {
+ /** @var array[] (server index => server config) */
+ protected $serverInfos;
+ /** @var string[] (server index => tag/host name) */
+ protected $serverTags;
+ /** @var int */
+ protected $numServers;
+ /** @var int */
+ protected $lastExpireAll = 0;
+ /** @var int */
+ protected $purgePeriod = 100;
+ /** @var int */
+ protected $shards = 1;
+ /** @var string */
+ protected $tableName = 'objectcache';
+ /** @var bool */
+ protected $replicaOnly = false;
+ /** @var int */
+ protected $syncTimeout = 3;
+
+ /** @var LoadBalancer|null */
+ protected $separateMainLB;
+ /** @var array */
+ protected $conns;
+ /** @var array UNIX timestamps */
+ protected $connFailureTimes = [];
+ /** @var array Exceptions */
+ protected $connFailureErrors = [];
+
+ /**
+ * Constructor. Parameters are:
+ * - server: A server info structure in the format required by each
+ * element in $wgDBServers.
+ *
+ * - servers: An array of server info structures describing a set of database servers
+ * to distribute keys to. If this is specified, the "server" option will be
+ * ignored. If string keys are used, then they will be used for consistent
+ * hashing *instead* of the host name (from the server config). This is useful
+ * when a cluster is replicated to another site (with different host names)
+ * but each server has a corresponding replica in the other cluster.
+ *
+ * - purgePeriod: The average number of object cache requests in between
+ * garbage collection operations, where expired entries
+ * are removed from the database. Or in other words, the
+ * reciprocal of the probability of purging on any given
+ * request. If this is set to zero, purging will never be
+ * done.
+ *
+ * - tableName: The table name to use, default is "objectcache".
+ *
+ * - shards: The number of tables to use for data storage on each server.
+ * If this is more than 1, table names will be formed in the style
+ * objectcacheNNN where NNN is the shard index, between 0 and
+ * shards-1. The number of digits will be the minimum number
+ * required to hold the largest shard index. Data will be
+ * distributed across all tables by key hash. This is for
+ * MySQL bugs 61735 and 61736.
+ * - slaveOnly: Whether to only use replica DBs and avoid triggering
+ * garbage collection logic of expired items. This only
+ * makes sense if the primary DB is used and only if get()
+ * calls will be used. This is used by ReplicatedBagOStuff.
+ * - syncTimeout: Max seconds to wait for replica DBs to catch up for WRITE_SYNC.
+ *
+ * @param array $params
+ */
+ public function __construct( $params ) {
+ parent::__construct( $params );
+
+ $this->attrMap[self::ATTR_EMULATION] = self::QOS_EMULATION_SQL;
+ $this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_NONE;
+
+ if ( isset( $params['servers'] ) ) {
+ $this->serverInfos = [];
+ $this->serverTags = [];
+ $this->numServers = count( $params['servers'] );
+ $index = 0;
+ foreach ( $params['servers'] as $tag => $info ) {
+ $this->serverInfos[$index] = $info;
+ if ( is_string( $tag ) ) {
+ $this->serverTags[$index] = $tag;
+ } else {
+ $this->serverTags[$index] = isset( $info['host'] ) ? $info['host'] : "#$index";
+ }
+ ++$index;
+ }
+ } elseif ( isset( $params['server'] ) ) {
+ $this->serverInfos = [ $params['server'] ];
+ $this->numServers = count( $this->serverInfos );
+ } else {
+ // Default to using the main wiki's database servers
+ $this->serverInfos = false;
+ $this->numServers = 1;
+ $this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_BE;
+ }
+ if ( isset( $params['purgePeriod'] ) ) {
+ $this->purgePeriod = intval( $params['purgePeriod'] );
+ }
+ if ( isset( $params['tableName'] ) ) {
+ $this->tableName = $params['tableName'];
+ }
+ if ( isset( $params['shards'] ) ) {
+ $this->shards = intval( $params['shards'] );
+ }
+ if ( isset( $params['syncTimeout'] ) ) {
+ $this->syncTimeout = $params['syncTimeout'];
+ }
+ $this->replicaOnly = !empty( $params['slaveOnly'] );
+ }
+
+ /**
+ * Get a connection to the specified database
+ *
+ * @param int $serverIndex
+ * @return Database
+ * @throws MWException
+ */
+ protected function getDB( $serverIndex ) {
+ if ( !isset( $this->conns[$serverIndex] ) ) {
+ if ( $serverIndex >= $this->numServers ) {
+ throw new MWException( __METHOD__ . ": Invalid server index \"$serverIndex\"" );
+ }
+
+ # Don't keep timing out trying to connect for each call if the DB is down
+ if ( isset( $this->connFailureErrors[$serverIndex] )
+ && ( time() - $this->connFailureTimes[$serverIndex] ) < 60
+ ) {
+ throw $this->connFailureErrors[$serverIndex];
+ }
+
+ if ( $this->serverInfos ) {
+ // Use custom database defined by server connection info
+ $info = $this->serverInfos[$serverIndex];
+ $type = isset( $info['type'] ) ? $info['type'] : 'mysql';
+ $host = isset( $info['host'] ) ? $info['host'] : '[unknown]';
+ $this->logger->debug( __CLASS__ . ": connecting to $host" );
+ // Use a blank trx profiler to ignore expections as this is a cache
+ $info['trxProfiler'] = new TransactionProfiler();
+ $db = Database::factory( $type, $info );
+ $db->clearFlag( DBO_TRX ); // auto-commit mode
+ } else {
+ // Use the main LB database
+ $lb = MediaWikiServices::getInstance()->getDBLoadBalancer();
+ $index = $this->replicaOnly ? DB_REPLICA : DB_MASTER;
+ if ( $lb->getServerType( $lb->getWriterIndex() ) !== 'sqlite' ) {
+ // Keep a separate connection to avoid contention and deadlocks
+ $db = $lb->getConnection( $index, [], false, $lb::CONN_TRX_AUTO );
+ // @TODO: Use a blank trx profiler to ignore expections as this is a cache
+ } else {
+ // However, SQLite has the opposite behavior due to DB-level locking.
+ // Stock sqlite MediaWiki installs use a separate sqlite cache DB instead.
+ $db = $lb->getConnection( $index );
+ }
+ }
+
+ $this->logger->debug( sprintf( "Connection %s will be used for SqlBagOStuff", $db ) );
+ $this->conns[$serverIndex] = $db;
+ }
+
+ return $this->conns[$serverIndex];
+ }
+
+ /**
+ * Get the server index and table name for a given key
+ * @param string $key
+ * @return array Server index and table name
+ */
+ protected function getTableByKey( $key ) {
+ if ( $this->shards > 1 ) {
+ $hash = hexdec( substr( md5( $key ), 0, 8 ) ) & 0x7fffffff;
+ $tableIndex = $hash % $this->shards;
+ } else {
+ $tableIndex = 0;
+ }
+ if ( $this->numServers > 1 ) {
+ $sortedServers = $this->serverTags;
+ ArrayUtils::consistentHashSort( $sortedServers, $key );
+ reset( $sortedServers );
+ $serverIndex = key( $sortedServers );
+ } else {
+ $serverIndex = 0;
+ }
+ return [ $serverIndex, $this->getTableNameByShard( $tableIndex ) ];
+ }
+
+ /**
+ * Get the table name for a given shard index
+ * @param int $index
+ * @return string
+ */
+ protected function getTableNameByShard( $index ) {
+ if ( $this->shards > 1 ) {
+ $decimals = strlen( $this->shards - 1 );
+ return $this->tableName .
+ sprintf( "%0{$decimals}d", $index );
+ } else {
+ return $this->tableName;
+ }
+ }
+
+ protected function doGet( $key, $flags = 0 ) {
+ $casToken = null;
+
+ return $this->getWithToken( $key, $casToken, $flags );
+ }
+
+ protected function getWithToken( $key, &$casToken, $flags = 0 ) {
+ $values = $this->getMulti( [ $key ] );
+ if ( array_key_exists( $key, $values ) ) {
+ $casToken = $values[$key];
+ return $values[$key];
+ }
+ return false;
+ }
+
+ public function getMulti( array $keys, $flags = 0 ) {
+ $values = []; // array of (key => value)
+
+ $keysByTable = [];
+ foreach ( $keys as $key ) {
+ list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
+ $keysByTable[$serverIndex][$tableName][] = $key;
+ }
+
+ $this->garbageCollect(); // expire old entries if any
+
+ $dataRows = [];
+ foreach ( $keysByTable as $serverIndex => $serverKeys ) {
+ try {
+ $db = $this->getDB( $serverIndex );
+ foreach ( $serverKeys as $tableName => $tableKeys ) {
+ $res = $db->select( $tableName,
+ [ 'keyname', 'value', 'exptime' ],
+ [ 'keyname' => $tableKeys ],
+ __METHOD__,
+ // Approximate write-on-the-fly BagOStuff API via blocking.
+ // This approximation fails if a ROLLBACK happens (which is rare).
+ // We do not want to flush the TRX as that can break callers.
+ $db->trxLevel() ? [ 'LOCK IN SHARE MODE' ] : []
+ );
+ if ( $res === false ) {
+ continue;
+ }
+ foreach ( $res as $row ) {
+ $row->serverIndex = $serverIndex;
+ $row->tableName = $tableName;
+ $dataRows[$row->keyname] = $row;
+ }
+ }
+ } catch ( DBError $e ) {
+ $this->handleReadError( $e, $serverIndex );
+ }
+ }
+
+ foreach ( $keys as $key ) {
+ if ( isset( $dataRows[$key] ) ) { // HIT?
+ $row = $dataRows[$key];
+ $this->debug( "get: retrieved data; expiry time is " . $row->exptime );
+ $db = null;
+ try {
+ $db = $this->getDB( $row->serverIndex );
+ if ( $this->isExpired( $db, $row->exptime ) ) { // MISS
+ $this->debug( "get: key has expired" );
+ } else { // HIT
+ $values[$key] = $this->unserialize( $db->decodeBlob( $row->value ) );
+ }
+ } catch ( DBQueryError $e ) {
+ $this->handleWriteError( $e, $db, $row->serverIndex );
+ }
+ } else { // MISS
+ $this->debug( 'get: no matching rows' );
+ }
+ }
+
+ return $values;
+ }
+
+ public function setMulti( array $data, $expiry = 0 ) {
+ $keysByTable = [];
+ foreach ( $data as $key => $value ) {
+ list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
+ $keysByTable[$serverIndex][$tableName][] = $key;
+ }
+
+ $this->garbageCollect(); // expire old entries if any
+
+ $result = true;
+ $exptime = (int)$expiry;
+ foreach ( $keysByTable as $serverIndex => $serverKeys ) {
+ $db = null;
+ try {
+ $db = $this->getDB( $serverIndex );
+ } catch ( DBError $e ) {
+ $this->handleWriteError( $e, $db, $serverIndex );
+ $result = false;
+ continue;
+ }
+
+ if ( $exptime < 0 ) {
+ $exptime = 0;
+ }
+
+ if ( $exptime == 0 ) {
+ $encExpiry = $this->getMaxDateTime( $db );
+ } else {
+ $exptime = $this->convertExpiry( $exptime );
+ $encExpiry = $db->timestamp( $exptime );
+ }
+ foreach ( $serverKeys as $tableName => $tableKeys ) {
+ $rows = [];
+ foreach ( $tableKeys as $key ) {
+ $rows[] = [
+ 'keyname' => $key,
+ 'value' => $db->encodeBlob( $this->serialize( $data[$key] ) ),
+ 'exptime' => $encExpiry,
+ ];
+ }
+
+ try {
+ $db->replace(
+ $tableName,
+ [ 'keyname' ],
+ $rows,
+ __METHOD__
+ );
+ } catch ( DBError $e ) {
+ $this->handleWriteError( $e, $db, $serverIndex );
+ $result = false;
+ }
+
+ }
+
+ }
+
+ return $result;
+ }
+
+ public function set( $key, $value, $exptime = 0, $flags = 0 ) {
+ $ok = $this->setMulti( [ $key => $value ], $exptime );
+ if ( ( $flags & self::WRITE_SYNC ) == self::WRITE_SYNC ) {
+ $ok = $this->waitForReplication() && $ok;
+ }
+
+ return $ok;
+ }
+
+ protected function cas( $casToken, $key, $value, $exptime = 0 ) {
+ list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
+ $db = null;
+ try {
+ $db = $this->getDB( $serverIndex );
+ $exptime = intval( $exptime );
+
+ if ( $exptime < 0 ) {
+ $exptime = 0;
+ }
+
+ if ( $exptime == 0 ) {
+ $encExpiry = $this->getMaxDateTime( $db );
+ } else {
+ $exptime = $this->convertExpiry( $exptime );
+ $encExpiry = $db->timestamp( $exptime );
+ }
+ // (T26425) use a replace if the db supports it instead of
+ // delete/insert to avoid clashes with conflicting keynames
+ $db->update(
+ $tableName,
+ [
+ 'keyname' => $key,
+ 'value' => $db->encodeBlob( $this->serialize( $value ) ),
+ 'exptime' => $encExpiry
+ ],
+ [
+ 'keyname' => $key,
+ 'value' => $db->encodeBlob( $this->serialize( $casToken ) )
+ ],
+ __METHOD__
+ );
+ } catch ( DBQueryError $e ) {
+ $this->handleWriteError( $e, $db, $serverIndex );
+
+ return false;
+ }
+
+ return (bool)$db->affectedRows();
+ }
+
+ public function delete( $key ) {
+ list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
+ $db = null;
+ try {
+ $db = $this->getDB( $serverIndex );
+ $db->delete(
+ $tableName,
+ [ 'keyname' => $key ],
+ __METHOD__ );
+ } catch ( DBError $e ) {
+ $this->handleWriteError( $e, $db, $serverIndex );
+ return false;
+ }
+
+ return true;
+ }
+
+ public function incr( $key, $step = 1 ) {
+ list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
+ $db = null;
+ try {
+ $db = $this->getDB( $serverIndex );
+ $step = intval( $step );
+ $row = $db->selectRow(
+ $tableName,
+ [ 'value', 'exptime' ],
+ [ 'keyname' => $key ],
+ __METHOD__,
+ [ 'FOR UPDATE' ] );
+ if ( $row === false ) {
+ // Missing
+
+ return null;
+ }
+ $db->delete( $tableName, [ 'keyname' => $key ], __METHOD__ );
+ if ( $this->isExpired( $db, $row->exptime ) ) {
+ // Expired, do not reinsert
+
+ return null;
+ }
+
+ $oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
+ $newValue = $oldValue + $step;
+ $db->insert( $tableName,
+ [
+ 'keyname' => $key,
+ 'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
+ 'exptime' => $row->exptime
+ ], __METHOD__, 'IGNORE' );
+
+ if ( $db->affectedRows() == 0 ) {
+ // Race condition. See T30611
+ $newValue = null;
+ }
+ } catch ( DBError $e ) {
+ $this->handleWriteError( $e, $db, $serverIndex );
+ return null;
+ }
+
+ return $newValue;
+ }
+
+ public function merge( $key, callable $callback, $exptime = 0, $attempts = 10, $flags = 0 ) {
+ $ok = $this->mergeViaCas( $key, $callback, $exptime, $attempts );
+ if ( ( $flags & self::WRITE_SYNC ) == self::WRITE_SYNC ) {
+ $ok = $this->waitForReplication() && $ok;
+ }
+
+ return $ok;
+ }
+
+ public function changeTTL( $key, $expiry = 0 ) {
+ list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
+ $db = null;
+ try {
+ $db = $this->getDB( $serverIndex );
+ $db->update(
+ $tableName,
+ [ 'exptime' => $db->timestamp( $this->convertExpiry( $expiry ) ) ],
+ [ 'keyname' => $key, 'exptime > ' . $db->addQuotes( $db->timestamp( time() ) ) ],
+ __METHOD__
+ );
+ if ( $db->affectedRows() == 0 ) {
+ return false;
+ }
+ } catch ( DBError $e ) {
+ $this->handleWriteError( $e, $db, $serverIndex );
+ return false;
+ }
+
+ return true;
+ }
+
+ /**
+ * @param IDatabase $db
+ * @param string $exptime
+ * @return bool
+ */
+ protected function isExpired( $db, $exptime ) {
+ return $exptime != $this->getMaxDateTime( $db ) && wfTimestamp( TS_UNIX, $exptime ) < time();
+ }
+
+ /**
+ * @param IDatabase $db
+ * @return string
+ */
+ protected function getMaxDateTime( $db ) {
+ if ( time() > 0x7fffffff ) {
+ return $db->timestamp( 1 << 62 );
+ } else {
+ return $db->timestamp( 0x7fffffff );
+ }
+ }
+
+ protected function garbageCollect() {
+ if ( !$this->purgePeriod || $this->replicaOnly ) {
+ // Disabled
+ return;
+ }
+ // Only purge on one in every $this->purgePeriod requests.
+ if ( $this->purgePeriod !== 1 && mt_rand( 0, $this->purgePeriod - 1 ) ) {
+ return;
+ }
+ $now = time();
+ // Avoid repeating the delete within a few seconds
+ if ( $now > ( $this->lastExpireAll + 1 ) ) {
+ $this->lastExpireAll = $now;
+ $this->expireAll();
+ }
+ }
+
+ public function expireAll() {
+ $this->deleteObjectsExpiringBefore( wfTimestampNow() );
+ }
+
+ /**
+ * Delete objects from the database which expire before a certain date.
+ * @param string $timestamp
+ * @param bool|callable $progressCallback
+ * @return bool
+ */
+ public function deleteObjectsExpiringBefore( $timestamp, $progressCallback = false ) {
+ for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
+ $db = null;
+ try {
+ $db = $this->getDB( $serverIndex );
+ $dbTimestamp = $db->timestamp( $timestamp );
+ $totalSeconds = false;
+ $baseConds = [ 'exptime < ' . $db->addQuotes( $dbTimestamp ) ];
+ for ( $i = 0; $i < $this->shards; $i++ ) {
+ $maxExpTime = false;
+ while ( true ) {
+ $conds = $baseConds;
+ if ( $maxExpTime !== false ) {
+ $conds[] = 'exptime >= ' . $db->addQuotes( $maxExpTime );
+ }
+ $rows = $db->select(
+ $this->getTableNameByShard( $i ),
+ [ 'keyname', 'exptime' ],
+ $conds,
+ __METHOD__,
+ [ 'LIMIT' => 100, 'ORDER BY' => 'exptime' ] );
+ if ( $rows === false || !$rows->numRows() ) {
+ break;
+ }
+ $keys = [];
+ $row = $rows->current();
+ $minExpTime = $row->exptime;
+ if ( $totalSeconds === false ) {
+ $totalSeconds = wfTimestamp( TS_UNIX, $timestamp )
+ - wfTimestamp( TS_UNIX, $minExpTime );
+ }
+ foreach ( $rows as $row ) {
+ $keys[] = $row->keyname;
+ $maxExpTime = $row->exptime;
+ }
+
+ $db->delete(
+ $this->getTableNameByShard( $i ),
+ [
+ 'exptime >= ' . $db->addQuotes( $minExpTime ),
+ 'exptime < ' . $db->addQuotes( $dbTimestamp ),
+ 'keyname' => $keys
+ ],
+ __METHOD__ );
+
+ if ( $progressCallback ) {
+ if ( intval( $totalSeconds ) === 0 ) {
+ $percent = 0;
+ } else {
+ $remainingSeconds = wfTimestamp( TS_UNIX, $timestamp )
+ - wfTimestamp( TS_UNIX, $maxExpTime );
+ if ( $remainingSeconds > $totalSeconds ) {
+ $totalSeconds = $remainingSeconds;
+ }
+ $processedSeconds = $totalSeconds - $remainingSeconds;
+ $percent = ( $i + $processedSeconds / $totalSeconds )
+ / $this->shards * 100;
+ }
+ $percent = ( $percent / $this->numServers )
+ + ( $serverIndex / $this->numServers * 100 );
+ call_user_func( $progressCallback, $percent );
+ }
+ }
+ }
+ } catch ( DBError $e ) {
+ $this->handleWriteError( $e, $db, $serverIndex );
+ return false;
+ }
+ }
+ return true;
+ }
+
+ /**
+ * Delete content of shard tables in every server.
+ * Return true if the operation is successful, false otherwise.
+ * @return bool
+ */
+ public function deleteAll() {
+ for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
+ $db = null;
+ try {
+ $db = $this->getDB( $serverIndex );
+ for ( $i = 0; $i < $this->shards; $i++ ) {
+ $db->delete( $this->getTableNameByShard( $i ), '*', __METHOD__ );
+ }
+ } catch ( DBError $e ) {
+ $this->handleWriteError( $e, $db, $serverIndex );
+ return false;
+ }
+ }
+ return true;
+ }
+
+ /**
+ * Serialize an object and, if possible, compress the representation.
+ * On typical message and page data, this can provide a 3X decrease
+ * in storage requirements.
+ *
+ * @param mixed &$data
+ * @return string
+ */
+ protected function serialize( &$data ) {
+ $serial = serialize( $data );
+
+ if ( function_exists( 'gzdeflate' ) ) {
+ return gzdeflate( $serial );
+ } else {
+ return $serial;
+ }
+ }
+
+ /**
+ * Unserialize and, if necessary, decompress an object.
+ * @param string $serial
+ * @return mixed
+ */
+ protected function unserialize( $serial ) {
+ if ( function_exists( 'gzinflate' ) ) {
+ MediaWiki\suppressWarnings();
+ $decomp = gzinflate( $serial );
+ MediaWiki\restoreWarnings();
+
+ if ( false !== $decomp ) {
+ $serial = $decomp;
+ }
+ }
+
+ $ret = unserialize( $serial );
+
+ return $ret;
+ }
+
+ /**
+ * Handle a DBError which occurred during a read operation.
+ *
+ * @param DBError $exception
+ * @param int $serverIndex
+ */
+ protected function handleReadError( DBError $exception, $serverIndex ) {
+ if ( $exception instanceof DBConnectionError ) {
+ $this->markServerDown( $exception, $serverIndex );
+ }
+ $this->logger->error( "DBError: {$exception->getMessage()}" );
+ if ( $exception instanceof DBConnectionError ) {
+ $this->setLastError( BagOStuff::ERR_UNREACHABLE );
+ $this->logger->debug( __METHOD__ . ": ignoring connection error" );
+ } else {
+ $this->setLastError( BagOStuff::ERR_UNEXPECTED );
+ $this->logger->debug( __METHOD__ . ": ignoring query error" );
+ }
+ }
+
+ /**
+ * Handle a DBQueryError which occurred during a write operation.
+ *
+ * @param DBError $exception
+ * @param IDatabase|null $db DB handle or null if connection failed
+ * @param int $serverIndex
+ * @throws Exception
+ */
+ protected function handleWriteError( DBError $exception, IDatabase $db = null, $serverIndex ) {
+ if ( !$db ) {
+ $this->markServerDown( $exception, $serverIndex );
+ } elseif ( $db->wasReadOnlyError() ) {
+ if ( $db->trxLevel() && $this->usesMainDB() ) {
+ // Errors like deadlocks and connection drops already cause rollback.
+ // For consistency, we have no choice but to throw an error and trigger
+ // complete rollback if the main DB is also being used as the cache DB.
+ throw $exception;
+ }
+ }
+
+ $this->logger->error( "DBError: {$exception->getMessage()}" );
+ if ( $exception instanceof DBConnectionError ) {
+ $this->setLastError( BagOStuff::ERR_UNREACHABLE );
+ $this->logger->debug( __METHOD__ . ": ignoring connection error" );
+ } else {
+ $this->setLastError( BagOStuff::ERR_UNEXPECTED );
+ $this->logger->debug( __METHOD__ . ": ignoring query error" );
+ }
+ }
+
+ /**
+ * Mark a server down due to a DBConnectionError exception
+ *
+ * @param DBError $exception
+ * @param int $serverIndex
+ */
+ protected function markServerDown( DBError $exception, $serverIndex ) {
+ unset( $this->conns[$serverIndex] ); // bug T103435
+
+ if ( isset( $this->connFailureTimes[$serverIndex] ) ) {
+ if ( time() - $this->connFailureTimes[$serverIndex] >= 60 ) {
+ unset( $this->connFailureTimes[$serverIndex] );
+ unset( $this->connFailureErrors[$serverIndex] );
+ } else {
+ $this->logger->debug( __METHOD__ . ": Server #$serverIndex already down" );
+ return;
+ }
+ }
+ $now = time();
+ $this->logger->info( __METHOD__ . ": Server #$serverIndex down until " . ( $now + 60 ) );
+ $this->connFailureTimes[$serverIndex] = $now;
+ $this->connFailureErrors[$serverIndex] = $exception;
+ }
+
+ /**
+ * Create shard tables. For use from eval.php.
+ */
+ public function createTables() {
+ for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
+ $db = $this->getDB( $serverIndex );
+ if ( $db->getType() !== 'mysql' ) {
+ throw new MWException( __METHOD__ . ' is not supported on this DB server' );
+ }
+
+ for ( $i = 0; $i < $this->shards; $i++ ) {
+ $db->query(
+ 'CREATE TABLE ' . $db->tableName( $this->getTableNameByShard( $i ) ) .
+ ' LIKE ' . $db->tableName( 'objectcache' ),
+ __METHOD__ );
+ }
+ }
+ }
+
+ /**
+ * @return bool Whether the main DB is used, e.g. wfGetDB( DB_MASTER )
+ */
+ protected function usesMainDB() {
+ return !$this->serverInfos;
+ }
+
+ protected function waitForReplication() {
+ if ( !$this->usesMainDB() ) {
+ // Custom DB server list; probably doesn't use replication
+ return true;
+ }
+
+ $lb = MediaWikiServices::getInstance()->getDBLoadBalancer();
+ if ( $lb->getServerCount() <= 1 ) {
+ return true; // no replica DBs
+ }
+
+ // Main LB is used; wait for any replica DBs to catch up
+ $masterPos = $lb->getMasterPos();
+
+ $loop = new WaitConditionLoop(
+ function () use ( $lb, $masterPos ) {
+ return $lb->waitForAll( $masterPos, 1 );
+ },
+ $this->syncTimeout,
+ $this->busyCallbacks
+ );
+
+ return ( $loop->invoke() === $loop::CONDITION_REACHED );
+ }
+}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff