includes/objectcache/SqlBagOStuff.php

   1 <?php
   2 /**
   3  * Object caching using a SQL database.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Cache
  22  */
  23
  24 use Wikimedia\Rdbms\Database;
  25 use Wikimedia\Rdbms\IDatabase;
  26 use Wikimedia\Rdbms\DBError;
  27 use Wikimedia\Rdbms\DBQueryError;
  28 use Wikimedia\Rdbms\DBConnectionError;
  29 use \MediaWiki\MediaWikiServices;
  30 use \Wikimedia\WaitConditionLoop;
  31 use \Wikimedia\Rdbms\TransactionProfiler;
  32 use Wikimedia\Rdbms\LoadBalancer;
  33
  34 /**
  35  * Class to store objects in the database
  36  *
  37  * @ingroup Cache
  38  */
  39 class SqlBagOStuff extends BagOStuff {
  40         /** @var array[] (server index => server config) */
  41         protected $serverInfos;
  42         /** @var string[] (server index => tag/host name) */
  43         protected $serverTags;
  44         /** @var int */
  45         protected $numServers;
  46         /** @var int */
  47         protected $lastExpireAll = 0;
  48         /** @var int */
  49         protected $purgePeriod = 100;
  50         /** @var int */
  51         protected $shards = 1;
  52         /** @var string */
  53         protected $tableName = 'objectcache';
  54         /** @var bool */
  55         protected $replicaOnly = false;
  56         /** @var int */
  57         protected $syncTimeout = 3;
  58
  59         /** @var LoadBalancer|null */
  60         protected $separateMainLB;
  61         /** @var array */
  62         protected $conns;
  63         /** @var array UNIX timestamps */
  64         protected $connFailureTimes = [];
  65         /** @var array Exceptions */
  66         protected $connFailureErrors = [];
  67
  68         /**
  69          * Constructor. Parameters are:
  70          *   - server:      A server info structure in the format required by each
  71          *                  element in $wgDBServers.
  72          *
  73          *   - servers:     An array of server info structures describing a set of database servers
  74          *                  to distribute keys to. If this is specified, the "server" option will be
  75          *                  ignored. If string keys are used, then they will be used for consistent
  76          *                  hashing *instead* of the host name (from the server config). This is useful
  77          *                  when a cluster is replicated to another site (with different host names)
  78          *                  but each server has a corresponding replica in the other cluster.
  79          *
  80          *   - purgePeriod: The average number of object cache requests in between
  81          *                  garbage collection operations, where expired entries
  82          *                  are removed from the database. Or in other words, the
  83          *                  reciprocal of the probability of purging on any given
  84          *                  request. If this is set to zero, purging will never be
  85          *                  done.
  86          *
  87          *   - tableName:   The table name to use, default is "objectcache".
  88          *
  89          *   - shards:      The number of tables to use for data storage on each server.
  90          *                  If this is more than 1, table names will be formed in the style
  91          *                  objectcacheNNN where NNN is the shard index, between 0 and
  92          *                  shards-1. The number of digits will be the minimum number
  93          *                  required to hold the largest shard index. Data will be
  94          *                  distributed across all tables by key hash. This is for
  95          *                  MySQL bugs 61735 and 61736.
  96          *   - slaveOnly:   Whether to only use replica DBs and avoid triggering
  97          *                  garbage collection logic of expired items. This only
  98          *                  makes sense if the primary DB is used and only if get()
  99          *                  calls will be used. This is used by ReplicatedBagOStuff.
 100          *   - syncTimeout: Max seconds to wait for replica DBs to catch up for WRITE_SYNC.
 101          *
 102          * @param array $params
 103          */
 104         public function __construct( $params ) {
 105                 parent::__construct( $params );
 106
 107                 $this->attrMap[self::ATTR_EMULATION] = self::QOS_EMULATION_SQL;
 108                 $this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_NONE;
 109
 110                 if ( isset( $params['servers'] ) ) {
 111                         $this->serverInfos = [];
 112                         $this->serverTags = [];
 113                         $this->numServers = count( $params['servers'] );
 114                         $index = 0;
 115                         foreach ( $params['servers'] as $tag => $info ) {
 116                                 $this->serverInfos[$index] = $info;
 117                                 if ( is_string( $tag ) ) {
 118                                         $this->serverTags[$index] = $tag;
 119                                 } else {
 120                                         $this->serverTags[$index] = isset( $info['host'] ) ? $info['host'] : "#$index";
 121                                 }
 122                                 ++$index;
 123                         }
 124                 } elseif ( isset( $params['server'] ) ) {
 125                         $this->serverInfos = [ $params['server'] ];
 126                         $this->numServers = count( $this->serverInfos );
 127                 } else {
 128                         // Default to using the main wiki's database servers
 129                         $this->serverInfos = false;
 130                         $this->numServers = 1;
 131                         $this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_BE;
 132                 }
 133                 if ( isset( $params['purgePeriod'] ) ) {
 134                         $this->purgePeriod = intval( $params['purgePeriod'] );
 135                 }
 136                 if ( isset( $params['tableName'] ) ) {
 137                         $this->tableName = $params['tableName'];
 138                 }
 139                 if ( isset( $params['shards'] ) ) {
 140                         $this->shards = intval( $params['shards'] );
 141                 }
 142                 if ( isset( $params['syncTimeout'] ) ) {
 143                         $this->syncTimeout = $params['syncTimeout'];
 144                 }
 145                 $this->replicaOnly = !empty( $params['slaveOnly'] );
 146         }
 147
 148         protected function getSeparateMainLB() {
 149                 global $wgDBtype;
 150
 151                 if ( $wgDBtype === 'mysql' && $this->usesMainDB() ) {
 152                         if ( !$this->separateMainLB ) {
 153                                 // We must keep a separate connection to MySQL in order to avoid deadlocks
 154                                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 155                                 $this->separateMainLB = $lbFactory->newMainLB();
 156                         }
 157                         return $this->separateMainLB;
 158                 } else {
 159                         // However, SQLite has an opposite behavior. And PostgreSQL needs to know
 160                         // if we are in transaction or not (@TODO: find some PostgreSQL work-around).
 161                         return null;
 162                 }
 163         }
 164
 165         /**
 166          * Get a connection to the specified database
 167          *
 168          * @param int $serverIndex
 169          * @return IDatabase
 170          * @throws MWException
 171          */
 172         protected function getDB( $serverIndex ) {
 173                 if ( !isset( $this->conns[$serverIndex] ) ) {
 174                         if ( $serverIndex >= $this->numServers ) {
 175                                 throw new MWException( __METHOD__ . ": Invalid server index \"$serverIndex\"" );
 176                         }
 177
 178                         # Don't keep timing out trying to connect for each call if the DB is down
 179                         if ( isset( $this->connFailureErrors[$serverIndex] )
 180                                 && ( time() - $this->connFailureTimes[$serverIndex] ) < 60
 181                         ) {
 182                                 throw $this->connFailureErrors[$serverIndex];
 183                         }
 184
 185                         # If server connection info was given, use that
 186                         if ( $this->serverInfos ) {
 187                                 $info = $this->serverInfos[$serverIndex];
 188                                 $type = isset( $info['type'] ) ? $info['type'] : 'mysql';
 189                                 $host = isset( $info['host'] ) ? $info['host'] : '[unknown]';
 190                                 $this->logger->debug( __CLASS__ . ": connecting to $host" );
 191                                 // Use a blank trx profiler to ignore expections as this is a cache
 192                                 $info['trxProfiler'] = new TransactionProfiler();
 193                                 $db = Database::factory( $type, $info );
 194                                 $db->clearFlag( DBO_TRX );
 195                         } else {
 196                                 $index = $this->replicaOnly ? DB_REPLICA : DB_MASTER;
 197                                 if ( $this->getSeparateMainLB() ) {
 198                                         $db = $this->getSeparateMainLB()->getConnection( $index );
 199                                         $db->clearFlag( DBO_TRX ); // auto-commit mode
 200                                 } else {
 201                                         $db = wfGetDB( $index );
 202                                         // Can't mess with transaction rounds (DBO_TRX) :(
 203                                 }
 204                         }
 205                         $this->logger->debug( sprintf( "Connection %s will be used for SqlBagOStuff", $db ) );
 206                         $this->conns[$serverIndex] = $db;
 207                 }
 208
 209                 return $this->conns[$serverIndex];
 210         }
 211
 212         /**
 213          * Get the server index and table name for a given key
 214          * @param string $key
 215          * @return array Server index and table name
 216          */
 217         protected function getTableByKey( $key ) {
 218                 if ( $this->shards > 1 ) {
 219                         $hash = hexdec( substr( md5( $key ), 0, 8 ) ) & 0x7fffffff;
 220                         $tableIndex = $hash % $this->shards;
 221                 } else {
 222                         $tableIndex = 0;
 223                 }
 224                 if ( $this->numServers > 1 ) {
 225                         $sortedServers = $this->serverTags;
 226                         ArrayUtils::consistentHashSort( $sortedServers, $key );
 227                         reset( $sortedServers );
 228                         $serverIndex = key( $sortedServers );
 229                 } else {
 230                         $serverIndex = 0;
 231                 }
 232                 return [ $serverIndex, $this->getTableNameByShard( $tableIndex ) ];
 233         }
 234
 235         /**
 236          * Get the table name for a given shard index
 237          * @param int $index
 238          * @return string
 239          */
 240         protected function getTableNameByShard( $index ) {
 241                 if ( $this->shards > 1 ) {
 242                         $decimals = strlen( $this->shards - 1 );
 243                         return $this->tableName .
 244                                 sprintf( "%0{$decimals}d", $index );
 245                 } else {
 246                         return $this->tableName;
 247                 }
 248         }
 249
 250         protected function doGet( $key, $flags = 0 ) {
 251                 $casToken = null;
 252
 253                 return $this->getWithToken( $key, $casToken, $flags );
 254         }
 255
 256         protected function getWithToken( $key, &$casToken, $flags = 0 ) {
 257                 $values = $this->getMulti( [ $key ] );
 258                 if ( array_key_exists( $key, $values ) ) {
 259                         $casToken = $values[$key];
 260                         return $values[$key];
 261                 }
 262                 return false;
 263         }
 264
 265         public function getMulti( array $keys, $flags = 0 ) {
 266                 $values = []; // array of (key => value)
 267
 268                 $keysByTable = [];
 269                 foreach ( $keys as $key ) {
 270                         list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 271                         $keysByTable[$serverIndex][$tableName][] = $key;
 272                 }
 273
 274                 $this->garbageCollect(); // expire old entries if any
 275
 276                 $dataRows = [];
 277                 foreach ( $keysByTable as $serverIndex => $serverKeys ) {
 278                         try {
 279                                 $db = $this->getDB( $serverIndex );
 280                                 foreach ( $serverKeys as $tableName => $tableKeys ) {
 281                                         $res = $db->select( $tableName,
 282                                                 [ 'keyname', 'value', 'exptime' ],
 283                                                 [ 'keyname' => $tableKeys ],
 284                                                 __METHOD__,
 285                                                 // Approximate write-on-the-fly BagOStuff API via blocking.
 286                                                 // This approximation fails if a ROLLBACK happens (which is rare).
 287                                                 // We do not want to flush the TRX as that can break callers.
 288                                                 $db->trxLevel() ? [ 'LOCK IN SHARE MODE' ] : []
 289                                         );
 290                                         if ( $res === false ) {
 291                                                 continue;
 292                                         }
 293                                         foreach ( $res as $row ) {
 294                                                 $row->serverIndex = $serverIndex;
 295                                                 $row->tableName = $tableName;
 296                                                 $dataRows[$row->keyname] = $row;
 297                                         }
 298                                 }
 299                         } catch ( DBError $e ) {
 300                                 $this->handleReadError( $e, $serverIndex );
 301                         }
 302                 }
 303
 304                 foreach ( $keys as $key ) {
 305                         if ( isset( $dataRows[$key] ) ) { // HIT?
 306                                 $row = $dataRows[$key];
 307                                 $this->debug( "get: retrieved data; expiry time is " . $row->exptime );
 308                                 $db = null;
 309                                 try {
 310                                         $db = $this->getDB( $row->serverIndex );
 311                                         if ( $this->isExpired( $db, $row->exptime ) ) { // MISS
 312                                                 $this->debug( "get: key has expired" );
 313                                         } else { // HIT
 314                                                 $values[$key] = $this->unserialize( $db->decodeBlob( $row->value ) );
 315                                         }
 316                                 } catch ( DBQueryError $e ) {
 317                                         $this->handleWriteError( $e, $db, $row->serverIndex );
 318                                 }
 319                         } else { // MISS
 320                                 $this->debug( 'get: no matching rows' );
 321                         }
 322                 }
 323
 324                 return $values;
 325         }
 326
 327         public function setMulti( array $data, $expiry = 0 ) {
 328                 $keysByTable = [];
 329                 foreach ( $data as $key => $value ) {
 330                         list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 331                         $keysByTable[$serverIndex][$tableName][] = $key;
 332                 }
 333
 334                 $this->garbageCollect(); // expire old entries if any
 335
 336                 $result = true;
 337                 $exptime = (int)$expiry;
 338                 foreach ( $keysByTable as $serverIndex => $serverKeys ) {
 339                         $db = null;
 340                         try {
 341                                 $db = $this->getDB( $serverIndex );
 342                         } catch ( DBError $e ) {
 343                                 $this->handleWriteError( $e, $db, $serverIndex );
 344                                 $result = false;
 345                                 continue;
 346                         }
 347
 348                         if ( $exptime < 0 ) {
 349                                 $exptime = 0;
 350                         }
 351
 352                         if ( $exptime == 0 ) {
 353                                 $encExpiry = $this->getMaxDateTime( $db );
 354                         } else {
 355                                 $exptime = $this->convertExpiry( $exptime );
 356                                 $encExpiry = $db->timestamp( $exptime );
 357                         }
 358                         foreach ( $serverKeys as $tableName => $tableKeys ) {
 359                                 $rows = [];
 360                                 foreach ( $tableKeys as $key ) {
 361                                         $rows[] = [
 362                                                 'keyname' => $key,
 363                                                 'value' => $db->encodeBlob( $this->serialize( $data[$key] ) ),
 364                                                 'exptime' => $encExpiry,
 365                                         ];
 366                                 }
 367
 368                                 try {
 369                                         $db->replace(
 370                                                 $tableName,
 371                                                 [ 'keyname' ],
 372                                                 $rows,
 373                                                 __METHOD__
 374                                         );
 375                                 } catch ( DBError $e ) {
 376                                         $this->handleWriteError( $e, $db, $serverIndex );
 377                                         $result = false;
 378                                 }
 379
 380                         }
 381
 382                 }
 383
 384                 return $result;
 385         }
 386
 387         public function set( $key, $value, $exptime = 0, $flags = 0 ) {
 388                 $ok = $this->setMulti( [ $key => $value ], $exptime );
 389                 if ( ( $flags & self::WRITE_SYNC ) == self::WRITE_SYNC ) {
 390                         $ok = $this->waitForReplication() && $ok;
 391                 }
 392
 393                 return $ok;
 394         }
 395
 396         protected function cas( $casToken, $key, $value, $exptime = 0 ) {
 397                 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 398                 $db = null;
 399                 try {
 400                         $db = $this->getDB( $serverIndex );
 401                         $exptime = intval( $exptime );
 402
 403                         if ( $exptime < 0 ) {
 404                                 $exptime = 0;
 405                         }
 406
 407                         if ( $exptime == 0 ) {
 408                                 $encExpiry = $this->getMaxDateTime( $db );
 409                         } else {
 410                                 $exptime = $this->convertExpiry( $exptime );
 411                                 $encExpiry = $db->timestamp( $exptime );
 412                         }
 413                         // (T26425) use a replace if the db supports it instead of
 414                         // delete/insert to avoid clashes with conflicting keynames
 415                         $db->update(
 416                                 $tableName,
 417                                 [
 418                                         'keyname' => $key,
 419                                         'value' => $db->encodeBlob( $this->serialize( $value ) ),
 420                                         'exptime' => $encExpiry
 421                                 ],
 422                                 [
 423                                         'keyname' => $key,
 424                                         'value' => $db->encodeBlob( $this->serialize( $casToken ) )
 425                                 ],
 426                                 __METHOD__
 427                         );
 428                 } catch ( DBQueryError $e ) {
 429                         $this->handleWriteError( $e, $db, $serverIndex );
 430
 431                         return false;
 432                 }
 433
 434                 return (bool)$db->affectedRows();
 435         }
 436
 437         public function delete( $key ) {
 438                 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 439                 $db = null;
 440                 try {
 441                         $db = $this->getDB( $serverIndex );
 442                         $db->delete(
 443                                 $tableName,
 444                                 [ 'keyname' => $key ],
 445                                 __METHOD__ );
 446                 } catch ( DBError $e ) {
 447                         $this->handleWriteError( $e, $db, $serverIndex );
 448                         return false;
 449                 }
 450
 451                 return true;
 452         }
 453
 454         public function incr( $key, $step = 1 ) {
 455                 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 456                 $db = null;
 457                 try {
 458                         $db = $this->getDB( $serverIndex );
 459                         $step = intval( $step );
 460                         $row = $db->selectRow(
 461                                 $tableName,
 462                                 [ 'value', 'exptime' ],
 463                                 [ 'keyname' => $key ],
 464                                 __METHOD__,
 465                                 [ 'FOR UPDATE' ] );
 466                         if ( $row === false ) {
 467                                 // Missing
 468
 469                                 return null;
 470                         }
 471                         $db->delete( $tableName, [ 'keyname' => $key ], __METHOD__ );
 472                         if ( $this->isExpired( $db, $row->exptime ) ) {
 473                                 // Expired, do not reinsert
 474
 475                                 return null;
 476                         }
 477
 478                         $oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
 479                         $newValue = $oldValue + $step;
 480                         $db->insert( $tableName,
 481                                 [
 482                                         'keyname' => $key,
 483                                         'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
 484                                         'exptime' => $row->exptime
 485                                 ], __METHOD__, 'IGNORE' );
 486
 487                         if ( $db->affectedRows() == 0 ) {
 488                                 // Race condition. See T30611
 489                                 $newValue = null;
 490                         }
 491                 } catch ( DBError $e ) {
 492                         $this->handleWriteError( $e, $db, $serverIndex );
 493                         return null;
 494                 }
 495
 496                 return $newValue;
 497         }
 498
 499         public function merge( $key, callable $callback, $exptime = 0, $attempts = 10, $flags = 0 ) {
 500                 $ok = $this->mergeViaCas( $key, $callback, $exptime, $attempts );
 501                 if ( ( $flags & self::WRITE_SYNC ) == self::WRITE_SYNC ) {
 502                         $ok = $this->waitForReplication() && $ok;
 503                 }
 504
 505                 return $ok;
 506         }
 507
 508         public function changeTTL( $key, $expiry = 0 ) {
 509                 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 510                 $db = null;
 511                 try {
 512                         $db = $this->getDB( $serverIndex );
 513                         $db->update(
 514                                 $tableName,
 515                                 [ 'exptime' => $db->timestamp( $this->convertExpiry( $expiry ) ) ],
 516                                 [ 'keyname' => $key, 'exptime > ' . $db->addQuotes( $db->timestamp( time() ) ) ],
 517                                 __METHOD__
 518                         );
 519                         if ( $db->affectedRows() == 0 ) {
 520                                 return false;
 521                         }
 522                 } catch ( DBError $e ) {
 523                         $this->handleWriteError( $e, $db, $serverIndex );
 524                         return false;
 525                 }
 526
 527                 return true;
 528         }
 529
 530         /**
 531          * @param IDatabase $db
 532          * @param string $exptime
 533          * @return bool
 534          */
 535         protected function isExpired( $db, $exptime ) {
 536                 return $exptime != $this->getMaxDateTime( $db ) && wfTimestamp( TS_UNIX, $exptime ) < time();
 537         }
 538
 539         /**
 540          * @param IDatabase $db
 541          * @return string
 542          */
 543         protected function getMaxDateTime( $db ) {
 544                 if ( time() > 0x7fffffff ) {
 545                         return $db->timestamp( 1 << 62 );
 546                 } else {
 547                         return $db->timestamp( 0x7fffffff );
 548                 }
 549         }
 550
 551         protected function garbageCollect() {
 552                 if ( !$this->purgePeriod || $this->replicaOnly ) {
 553                         // Disabled
 554                         return;
 555                 }
 556                 // Only purge on one in every $this->purgePeriod requests.
 557                 if ( $this->purgePeriod !== 1 && mt_rand( 0, $this->purgePeriod - 1 ) ) {
 558                         return;
 559                 }
 560                 $now = time();
 561                 // Avoid repeating the delete within a few seconds
 562                 if ( $now > ( $this->lastExpireAll + 1 ) ) {
 563                         $this->lastExpireAll = $now;
 564                         $this->expireAll();
 565                 }
 566         }
 567
 568         public function expireAll() {
 569                 $this->deleteObjectsExpiringBefore( wfTimestampNow() );
 570         }
 571
 572         /**
 573          * Delete objects from the database which expire before a certain date.
 574          * @param string $timestamp
 575          * @param bool|callable $progressCallback
 576          * @return bool
 577          */
 578         public function deleteObjectsExpiringBefore( $timestamp, $progressCallback = false ) {
 579                 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
 580                         $db = null;
 581                         try {
 582                                 $db = $this->getDB( $serverIndex );
 583                                 $dbTimestamp = $db->timestamp( $timestamp );
 584                                 $totalSeconds = false;
 585                                 $baseConds = [ 'exptime < ' . $db->addQuotes( $dbTimestamp ) ];
 586                                 for ( $i = 0; $i < $this->shards; $i++ ) {
 587                                         $maxExpTime = false;
 588                                         while ( true ) {
 589                                                 $conds = $baseConds;
 590                                                 if ( $maxExpTime !== false ) {
 591                                                         $conds[] = 'exptime >= ' . $db->addQuotes( $maxExpTime );
 592                                                 }
 593                                                 $rows = $db->select(
 594                                                         $this->getTableNameByShard( $i ),
 595                                                         [ 'keyname', 'exptime' ],
 596                                                         $conds,
 597                                                         __METHOD__,
 598                                                         [ 'LIMIT' => 100, 'ORDER BY' => 'exptime' ] );
 599                                                 if ( $rows === false || !$rows->numRows() ) {
 600                                                         break;
 601                                                 }
 602                                                 $keys = [];
 603                                                 $row = $rows->current();
 604                                                 $minExpTime = $row->exptime;
 605                                                 if ( $totalSeconds === false ) {
 606                                                         $totalSeconds = wfTimestamp( TS_UNIX, $timestamp )
 607                                                                 - wfTimestamp( TS_UNIX, $minExpTime );
 608                                                 }
 609                                                 foreach ( $rows as $row ) {
 610                                                         $keys[] = $row->keyname;
 611                                                         $maxExpTime = $row->exptime;
 612                                                 }
 613
 614                                                 $db->delete(
 615                                                         $this->getTableNameByShard( $i ),
 616                                                         [
 617                                                                 'exptime >= ' . $db->addQuotes( $minExpTime ),
 618                                                                 'exptime < ' . $db->addQuotes( $dbTimestamp ),
 619                                                                 'keyname' => $keys
 620                                                         ],
 621                                                         __METHOD__ );
 622
 623                                                 if ( $progressCallback ) {
 624                                                         if ( intval( $totalSeconds ) === 0 ) {
 625                                                                 $percent = 0;
 626                                                         } else {
 627                                                                 $remainingSeconds = wfTimestamp( TS_UNIX, $timestamp )
 628                                                                         - wfTimestamp( TS_UNIX, $maxExpTime );
 629                                                                 if ( $remainingSeconds > $totalSeconds ) {
 630                                                                         $totalSeconds = $remainingSeconds;
 631                                                                 }
 632                                                                 $processedSeconds = $totalSeconds - $remainingSeconds;
 633                                                                 $percent = ( $i + $processedSeconds / $totalSeconds )
 634                                                                         / $this->shards * 100;
 635                                                         }
 636                                                         $percent = ( $percent / $this->numServers )
 637                                                                 + ( $serverIndex / $this->numServers * 100 );
 638                                                         call_user_func( $progressCallback, $percent );
 639                                                 }
 640                                         }
 641                                 }
 642                         } catch ( DBError $e ) {
 643                                 $this->handleWriteError( $e, $db, $serverIndex );
 644                                 return false;
 645                         }
 646                 }
 647                 return true;
 648         }
 649
 650         /**
 651          * Delete content of shard tables in every server.
 652          * Return true if the operation is successful, false otherwise.
 653          * @return bool
 654          */
 655         public function deleteAll() {
 656                 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
 657                         $db = null;
 658                         try {
 659                                 $db = $this->getDB( $serverIndex );
 660                                 for ( $i = 0; $i < $this->shards; $i++ ) {
 661                                         $db->delete( $this->getTableNameByShard( $i ), '*', __METHOD__ );
 662                                 }
 663                         } catch ( DBError $e ) {
 664                                 $this->handleWriteError( $e, $db, $serverIndex );
 665                                 return false;
 666                         }
 667                 }
 668                 return true;
 669         }
 670
 671         /**
 672          * Serialize an object and, if possible, compress the representation.
 673          * On typical message and page data, this can provide a 3X decrease
 674          * in storage requirements.
 675          *
 676          * @param mixed $data
 677          * @return string
 678          */
 679         protected function serialize( &$data ) {
 680                 $serial = serialize( $data );
 681
 682                 if ( function_exists( 'gzdeflate' ) ) {
 683                         return gzdeflate( $serial );
 684                 } else {
 685                         return $serial;
 686                 }
 687         }
 688
 689         /**
 690          * Unserialize and, if necessary, decompress an object.
 691          * @param string $serial
 692          * @return mixed
 693          */
 694         protected function unserialize( $serial ) {
 695                 if ( function_exists( 'gzinflate' ) ) {
 696                         MediaWiki\suppressWarnings();
 697                         $decomp = gzinflate( $serial );
 698                         MediaWiki\restoreWarnings();
 699
 700                         if ( false !== $decomp ) {
 701                                 $serial = $decomp;
 702                         }
 703                 }
 704
 705                 $ret = unserialize( $serial );
 706
 707                 return $ret;
 708         }
 709
 710         /**
 711          * Handle a DBError which occurred during a read operation.
 712          *
 713          * @param DBError $exception
 714          * @param int $serverIndex
 715          */
 716         protected function handleReadError( DBError $exception, $serverIndex ) {
 717                 if ( $exception instanceof DBConnectionError ) {
 718                         $this->markServerDown( $exception, $serverIndex );
 719                 }
 720                 $this->logger->error( "DBError: {$exception->getMessage()}" );
 721                 if ( $exception instanceof DBConnectionError ) {
 722                         $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 723                         $this->logger->debug( __METHOD__ . ": ignoring connection error" );
 724                 } else {
 725                         $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 726                         $this->logger->debug( __METHOD__ . ": ignoring query error" );
 727                 }
 728         }
 729
 730         /**
 731          * Handle a DBQueryError which occurred during a write operation.
 732          *
 733          * @param DBError $exception
 734          * @param IDatabase|null $db DB handle or null if connection failed
 735          * @param int $serverIndex
 736          * @throws Exception
 737          */
 738         protected function handleWriteError( DBError $exception, IDatabase $db = null, $serverIndex ) {
 739                 if ( !$db ) {
 740                         $this->markServerDown( $exception, $serverIndex );
 741                 } elseif ( $db->wasReadOnlyError() ) {
 742                         if ( $db->trxLevel() && $this->usesMainDB() ) {
 743                                 // Errors like deadlocks and connection drops already cause rollback.
 744                                 // For consistency, we have no choice but to throw an error and trigger
 745                                 // complete rollback if the main DB is also being used as the cache DB.
 746                                 throw $exception;
 747                         }
 748                 }
 749
 750                 $this->logger->error( "DBError: {$exception->getMessage()}" );
 751                 if ( $exception instanceof DBConnectionError ) {
 752                         $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 753                         $this->logger->debug( __METHOD__ . ": ignoring connection error" );
 754                 } else {
 755                         $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 756                         $this->logger->debug( __METHOD__ . ": ignoring query error" );
 757                 }
 758         }
 759
 760         /**
 761          * Mark a server down due to a DBConnectionError exception
 762          *
 763          * @param DBError $exception
 764          * @param int $serverIndex
 765          */
 766         protected function markServerDown( DBError $exception, $serverIndex ) {
 767                 unset( $this->conns[$serverIndex] ); // bug T103435
 768
 769                 if ( isset( $this->connFailureTimes[$serverIndex] ) ) {
 770                         if ( time() - $this->connFailureTimes[$serverIndex] >= 60 ) {
 771                                 unset( $this->connFailureTimes[$serverIndex] );
 772                                 unset( $this->connFailureErrors[$serverIndex] );
 773                         } else {
 774                                 $this->logger->debug( __METHOD__ . ": Server #$serverIndex already down" );
 775                                 return;
 776                         }
 777                 }
 778                 $now = time();
 779                 $this->logger->info( __METHOD__ . ": Server #$serverIndex down until " . ( $now + 60 ) );
 780                 $this->connFailureTimes[$serverIndex] = $now;
 781                 $this->connFailureErrors[$serverIndex] = $exception;
 782         }
 783
 784         /**
 785          * Create shard tables. For use from eval.php.
 786          */
 787         public function createTables() {
 788                 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
 789                         $db = $this->getDB( $serverIndex );
 790                         if ( $db->getType() !== 'mysql' ) {
 791                                 throw new MWException( __METHOD__ . ' is not supported on this DB server' );
 792                         }
 793
 794                         for ( $i = 0; $i < $this->shards; $i++ ) {
 795                                 $db->query(
 796                                         'CREATE TABLE ' . $db->tableName( $this->getTableNameByShard( $i ) ) .
 797                                         ' LIKE ' . $db->tableName( 'objectcache' ),
 798                                         __METHOD__ );
 799                         }
 800                 }
 801         }
 802
 803         /**
 804          * @return bool Whether the main DB is used, e.g. wfGetDB( DB_MASTER )
 805          */
 806         protected function usesMainDB() {
 807                 return !$this->serverInfos;
 808         }
 809
 810         protected function waitForReplication() {
 811                 if ( !$this->usesMainDB() ) {
 812                         // Custom DB server list; probably doesn't use replication
 813                         return true;
 814                 }
 815
 816                 $lb = $this->getSeparateMainLB()
 817                         ?: MediaWikiServices::getInstance()->getDBLoadBalancer();
 818
 819                 if ( $lb->getServerCount() <= 1 ) {
 820                         return true; // no replica DBs
 821                 }
 822
 823                 // Main LB is used; wait for any replica DBs to catch up
 824                 $masterPos = $lb->getMasterPos();
 825
 826                 $loop = new WaitConditionLoop(
 827                         function () use ( $lb, $masterPos ) {
 828                                 return $lb->waitForAll( $masterPos, 1 );
 829                         },
 830                         $this->syncTimeout,
 831                         $this->busyCallbacks
 832                 );
 833
 834                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
 835         }
 836 }