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 /**
  25  * Class to store objects in the database
  26  *
  27  * @ingroup Cache
  28  */
  29 class SqlBagOStuff extends BagOStuff {
  30         /** @var LoadBalancer */
  31         protected $lb;
  32
  33         /** @var array */
  34         protected $serverInfos;
  35
  36         /** @var array */
  37         protected $serverNames;
  38
  39         /** @var int */
  40         protected $numServers;
  41
  42         /** @var array */
  43         protected $conns;
  44
  45         /** @var int */
  46         protected $lastExpireAll = 0;
  47
  48         /** @var int */
  49         protected $purgePeriod = 100;
  50
  51         /** @var int */
  52         protected $shards = 1;
  53
  54         /** @var string */
  55         protected $tableName = 'objectcache';
  56
  57         /** @var bool */
  58         protected $slaveOnly = false;
  59
  60         /** @var array UNIX timestamps */
  61         protected $connFailureTimes = array();
  62
  63         /** @var array Exceptions */
  64         protected $connFailureErrors = array();
  65
  66         /**
  67          * Constructor. Parameters are:
  68          *   - server:      A server info structure in the format required by each
  69          *                  element in $wgDBServers.
  70          *
  71          *   - servers:     An array of server info structures describing a set of
  72          *                  database servers to distribute keys to. If this is
  73          *                  specified, the "server" option will be ignored.
  74          *
  75          *   - purgePeriod: The average number of object cache requests in between
  76          *                  garbage collection operations, where expired entries
  77          *                  are removed from the database. Or in other words, the
  78          *                  reciprocal of the probability of purging on any given
  79          *                  request. If this is set to zero, purging will never be
  80          *                  done.
  81          *
  82          *   - tableName:   The table name to use, default is "objectcache".
  83          *
  84          *   - shards:      The number of tables to use for data storage on each server.
  85          *                  If this is more than 1, table names will be formed in the style
  86          *                  objectcacheNNN where NNN is the shard index, between 0 and
  87          *                  shards-1. The number of digits will be the minimum number
  88          *                  required to hold the largest shard index. Data will be
  89          *                  distributed across all tables by key hash. This is for
  90          *                  MySQL bugs 61735 and 61736.
  91          *   - slaveOnly:   Whether to only use slave DBs and avoid triggering
  92          *                  garbage collection logic of expired items. This only
  93          *                  makes sense if the primary DB is used and only if get()
  94          *                  calls will be used. This is used by ReplicatedBagOStuff.
  95          *
  96          * @param array $params
  97          */
  98         public function __construct( $params ) {
  99                 parent::__construct( $params );
 100                 if ( isset( $params['servers'] ) ) {
 101                         $this->serverInfos = $params['servers'];
 102                         $this->numServers = count( $this->serverInfos );
 103                         $this->serverNames = array();
 104                         foreach ( $this->serverInfos as $i => $info ) {
 105                                 $this->serverNames[$i] = isset( $info['host'] ) ? $info['host'] : "#$i";
 106                         }
 107                 } elseif ( isset( $params['server'] ) ) {
 108                         $this->serverInfos = array( $params['server'] );
 109                         $this->numServers = count( $this->serverInfos );
 110                 } else {
 111                         $this->serverInfos = false;
 112                         $this->numServers = 1;
 113                 }
 114                 if ( isset( $params['purgePeriod'] ) ) {
 115                         $this->purgePeriod = intval( $params['purgePeriod'] );
 116                 }
 117                 if ( isset( $params['tableName'] ) ) {
 118                         $this->tableName = $params['tableName'];
 119                 }
 120                 if ( isset( $params['shards'] ) ) {
 121                         $this->shards = intval( $params['shards'] );
 122                 }
 123                 $this->slaveOnly = !empty( $params['slaveOnly'] );
 124         }
 125
 126         /**
 127          * Get a connection to the specified database
 128          *
 129          * @param int $serverIndex
 130          * @return DatabaseBase
 131          * @throws MWException
 132          */
 133         protected function getDB( $serverIndex ) {
 134                 if ( !isset( $this->conns[$serverIndex] ) ) {
 135                         if ( $serverIndex >= $this->numServers ) {
 136                                 throw new MWException( __METHOD__ . ": Invalid server index \"$serverIndex\"" );
 137                         }
 138
 139                         # Don't keep timing out trying to connect for each call if the DB is down
 140                         if ( isset( $this->connFailureErrors[$serverIndex] )
 141                                 && ( time() - $this->connFailureTimes[$serverIndex] ) < 60
 142                         ) {
 143                                 throw $this->connFailureErrors[$serverIndex];
 144                         }
 145
 146                         # If server connection info was given, use that
 147                         if ( $this->serverInfos ) {
 148                                 $info = $this->serverInfos[$serverIndex];
 149                                 $type = isset( $info['type'] ) ? $info['type'] : 'mysql';
 150                                 $host = isset( $info['host'] ) ? $info['host'] : '[unknown]';
 151                                 $this->logger->debug( __CLASS__ . ": connecting to $host" );
 152                                 // Use a blank trx profiler to ignore expections as this is a cache
 153                                 $info['trxProfiler'] = new TransactionProfiler();
 154                                 $db = DatabaseBase::factory( $type, $info );
 155                                 $db->clearFlag( DBO_TRX );
 156                         } else {
 157                                 /*
 158                                  * We must keep a separate connection to MySQL in order to avoid deadlocks
 159                                  * However, SQLite has an opposite behavior. And PostgreSQL needs to know
 160                                  * if we are in transaction or no
 161                                  */
 162                                 $index = $this->slaveOnly ? DB_SLAVE : DB_MASTER;
 163                                 if ( wfGetDB( $index )->getType() == 'mysql' ) {
 164                                         $this->lb = wfGetLBFactory()->newMainLB();
 165                                         $db = $this->lb->getConnection( $index );
 166                                         $db->clearFlag( DBO_TRX ); // auto-commit mode
 167                                 } else {
 168                                         $db = wfGetDB( $index );
 169                                 }
 170                         }
 171                         $this->logger->debug( sprintf( "Connection %s will be used for SqlBagOStuff", $db ) );
 172                         $this->conns[$serverIndex] = $db;
 173                 }
 174
 175                 return $this->conns[$serverIndex];
 176         }
 177
 178         /**
 179          * Get the server index and table name for a given key
 180          * @param string $key
 181          * @return array Server index and table name
 182          */
 183         protected function getTableByKey( $key ) {
 184                 if ( $this->shards > 1 ) {
 185                         $hash = hexdec( substr( md5( $key ), 0, 8 ) ) & 0x7fffffff;
 186                         $tableIndex = $hash % $this->shards;
 187                 } else {
 188                         $tableIndex = 0;
 189                 }
 190                 if ( $this->numServers > 1 ) {
 191                         $sortedServers = $this->serverNames;
 192                         ArrayUtils::consistentHashSort( $sortedServers, $key );
 193                         reset( $sortedServers );
 194                         $serverIndex = key( $sortedServers );
 195                 } else {
 196                         $serverIndex = 0;
 197                 }
 198                 return array( $serverIndex, $this->getTableNameByShard( $tableIndex ) );
 199         }
 200
 201         /**
 202          * Get the table name for a given shard index
 203          * @param int $index
 204          * @return string
 205          */
 206         protected function getTableNameByShard( $index ) {
 207                 if ( $this->shards > 1 ) {
 208                         $decimals = strlen( $this->shards - 1 );
 209                         return $this->tableName .
 210                                 sprintf( "%0{$decimals}d", $index );
 211                 } else {
 212                         return $this->tableName;
 213                 }
 214         }
 215
 216         public function get( $key, &$casToken = null, $flags = 0 ) {
 217                 $values = $this->getMulti( array( $key ) );
 218                 if ( array_key_exists( $key, $values ) ) {
 219                         $casToken = $values[$key];
 220                         return $values[$key];
 221                 }
 222                 return false;
 223         }
 224
 225         public function getMulti( array $keys, $flags = 0 ) {
 226                 $values = array(); // array of (key => value)
 227
 228                 $keysByTable = array();
 229                 foreach ( $keys as $key ) {
 230                         list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 231                         $keysByTable[$serverIndex][$tableName][] = $key;
 232                 }
 233
 234                 $this->garbageCollect(); // expire old entries if any
 235
 236                 $dataRows = array();
 237                 foreach ( $keysByTable as $serverIndex => $serverKeys ) {
 238                         try {
 239                                 $db = $this->getDB( $serverIndex );
 240                                 foreach ( $serverKeys as $tableName => $tableKeys ) {
 241                                         $res = $db->select( $tableName,
 242                                                 array( 'keyname', 'value', 'exptime' ),
 243                                                 array( 'keyname' => $tableKeys ),
 244                                                 __METHOD__,
 245                                                 // Approximate write-on-the-fly BagOStuff API via blocking.
 246                                                 // This approximation fails if a ROLLBACK happens (which is rare).
 247                                                 // We do not want to flush the TRX as that can break callers.
 248                                                 $db->trxLevel() ? array( 'LOCK IN SHARE MODE' ) : array()
 249                                         );
 250                                         if ( $res === false ) {
 251                                                 continue;
 252                                         }
 253                                         foreach ( $res as $row ) {
 254                                                 $row->serverIndex = $serverIndex;
 255                                                 $row->tableName = $tableName;
 256                                                 $dataRows[$row->keyname] = $row;
 257                                         }
 258                                 }
 259                         } catch ( DBError $e ) {
 260                                 $this->handleReadError( $e, $serverIndex );
 261                         }
 262                 }
 263
 264                 foreach ( $keys as $key ) {
 265                         if ( isset( $dataRows[$key] ) ) { // HIT?
 266                                 $row = $dataRows[$key];
 267                                 $this->debug( "get: retrieved data; expiry time is " . $row->exptime );
 268                                 try {
 269                                         $db = $this->getDB( $row->serverIndex );
 270                                         if ( $this->isExpired( $db, $row->exptime ) ) { // MISS
 271                                                 $this->debug( "get: key has expired" );
 272                                         } else { // HIT
 273                                                 $values[$key] = $this->unserialize( $db->decodeBlob( $row->value ) );
 274                                         }
 275                                 } catch ( DBQueryError $e ) {
 276                                         $this->handleWriteError( $e, $row->serverIndex );
 277                                 }
 278                         } else { // MISS
 279                                 $this->debug( 'get: no matching rows' );
 280                         }
 281                 }
 282
 283                 return $values;
 284         }
 285
 286         /**
 287          * @param array $data
 288          * @param int $expiry
 289          * @return bool
 290          */
 291         public function setMulti( array $data, $expiry = 0 ) {
 292                 $keysByTable = array();
 293                 foreach ( $data as $key => $value ) {
 294                         list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 295                         $keysByTable[$serverIndex][$tableName][] = $key;
 296                 }
 297
 298                 $this->garbageCollect(); // expire old entries if any
 299
 300                 $result = true;
 301                 $exptime = (int)$expiry;
 302                 foreach ( $keysByTable as $serverIndex => $serverKeys ) {
 303                         try {
 304                                 $db = $this->getDB( $serverIndex );
 305                         } catch ( DBError $e ) {
 306                                 $this->handleWriteError( $e, $serverIndex );
 307                                 $result = false;
 308                                 continue;
 309                         }
 310
 311                         if ( $exptime < 0 ) {
 312                                 $exptime = 0;
 313                         }
 314
 315                         if ( $exptime == 0 ) {
 316                                 $encExpiry = $this->getMaxDateTime( $db );
 317                         } else {
 318                                 $exptime = $this->convertExpiry( $exptime );
 319                                 $encExpiry = $db->timestamp( $exptime );
 320                         }
 321                         foreach ( $serverKeys as $tableName => $tableKeys ) {
 322                                 $rows = array();
 323                                 foreach ( $tableKeys as $key ) {
 324                                         $rows[] = array(
 325                                                 'keyname' => $key,
 326                                                 'value' => $db->encodeBlob( $this->serialize( $data[$key] ) ),
 327                                                 'exptime' => $encExpiry,
 328                                         );
 329                                 }
 330
 331                                 try {
 332                                         $db->replace(
 333                                                 $tableName,
 334                                                 array( 'keyname' ),
 335                                                 $rows,
 336                                                 __METHOD__
 337                                         );
 338                                 } catch ( DBError $e ) {
 339                                         $this->handleWriteError( $e, $serverIndex );
 340                                         $result = false;
 341                                 }
 342
 343                         }
 344
 345                 }
 346
 347                 return $result;
 348         }
 349
 350         /**
 351          * @param string $key
 352          * @param mixed $value
 353          * @param int $exptime
 354          * @return bool
 355          */
 356         public function set( $key, $value, $exptime = 0 ) {
 357                 return $this->setMulti( array( $key => $value ), $exptime );
 358         }
 359
 360         /**
 361          * @param mixed $casToken
 362          * @param string $key
 363          * @param mixed $value
 364          * @param int $exptime
 365          * @return bool
 366          */
 367         protected function cas( $casToken, $key, $value, $exptime = 0 ) {
 368                 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 369                 try {
 370                         $db = $this->getDB( $serverIndex );
 371                         $exptime = intval( $exptime );
 372
 373                         if ( $exptime < 0 ) {
 374                                 $exptime = 0;
 375                         }
 376
 377                         if ( $exptime == 0 ) {
 378                                 $encExpiry = $this->getMaxDateTime( $db );
 379                         } else {
 380                                 $exptime = $this->convertExpiry( $exptime );
 381                                 $encExpiry = $db->timestamp( $exptime );
 382                         }
 383                         // (bug 24425) use a replace if the db supports it instead of
 384                         // delete/insert to avoid clashes with conflicting keynames
 385                         $db->update(
 386                                 $tableName,
 387                                 array(
 388                                         'keyname' => $key,
 389                                         'value' => $db->encodeBlob( $this->serialize( $value ) ),
 390                                         'exptime' => $encExpiry
 391                                 ),
 392                                 array(
 393                                         'keyname' => $key,
 394                                         'value' => $db->encodeBlob( $this->serialize( $casToken ) )
 395                                 ),
 396                                 __METHOD__
 397                         );
 398                 } catch ( DBQueryError $e ) {
 399                         $this->handleWriteError( $e, $serverIndex );
 400
 401                         return false;
 402                 }
 403
 404                 return (bool)$db->affectedRows();
 405         }
 406
 407         /**
 408          * @param string $key
 409          * @return bool
 410          */
 411         public function delete( $key ) {
 412                 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 413                 try {
 414                         $db = $this->getDB( $serverIndex );
 415                         $db->delete(
 416                                 $tableName,
 417                                 array( 'keyname' => $key ),
 418                                 __METHOD__ );
 419                 } catch ( DBError $e ) {
 420                         $this->handleWriteError( $e, $serverIndex );
 421                         return false;
 422                 }
 423
 424                 return true;
 425         }
 426
 427         /**
 428          * @param string $key
 429          * @param int $step
 430          * @return int|null
 431          */
 432         public function incr( $key, $step = 1 ) {
 433                 list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
 434                 try {
 435                         $db = $this->getDB( $serverIndex );
 436                         $step = intval( $step );
 437                         $row = $db->selectRow(
 438                                 $tableName,
 439                                 array( 'value', 'exptime' ),
 440                                 array( 'keyname' => $key ),
 441                                 __METHOD__,
 442                                 array( 'FOR UPDATE' ) );
 443                         if ( $row === false ) {
 444                                 // Missing
 445
 446                                 return null;
 447                         }
 448                         $db->delete( $tableName, array( 'keyname' => $key ), __METHOD__ );
 449                         if ( $this->isExpired( $db, $row->exptime ) ) {
 450                                 // Expired, do not reinsert
 451
 452                                 return null;
 453                         }
 454
 455                         $oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
 456                         $newValue = $oldValue + $step;
 457                         $db->insert( $tableName,
 458                                 array(
 459                                         'keyname' => $key,
 460                                         'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
 461                                         'exptime' => $row->exptime
 462                                 ), __METHOD__, 'IGNORE' );
 463
 464                         if ( $db->affectedRows() == 0 ) {
 465                                 // Race condition. See bug 28611
 466                                 $newValue = null;
 467                         }
 468                 } catch ( DBError $e ) {
 469                         $this->handleWriteError( $e, $serverIndex );
 470                         return null;
 471                 }
 472
 473                 return $newValue;
 474         }
 475
 476         public function merge( $key, $callback, $exptime = 0, $attempts = 10 ) {
 477                 if ( !is_callable( $callback ) ) {
 478                         throw new Exception( "Got invalid callback." );
 479                 }
 480
 481                 return $this->mergeViaCas( $key, $callback, $exptime, $attempts );
 482         }
 483
 484         /**
 485          * @param DatabaseBase $db
 486          * @param string $exptime
 487          * @return bool
 488          */
 489         protected function isExpired( $db, $exptime ) {
 490                 return $exptime != $this->getMaxDateTime( $db ) && wfTimestamp( TS_UNIX, $exptime ) < time();
 491         }
 492
 493         /**
 494          * @param DatabaseBase $db
 495          * @return string
 496          */
 497         protected function getMaxDateTime( $db ) {
 498                 if ( time() > 0x7fffffff ) {
 499                         return $db->timestamp( 1 << 62 );
 500                 } else {
 501                         return $db->timestamp( 0x7fffffff );
 502                 }
 503         }
 504
 505         protected function garbageCollect() {
 506                 if ( !$this->purgePeriod || $this->slaveOnly ) {
 507                         // Disabled
 508                         return;
 509                 }
 510                 // Only purge on one in every $this->purgePeriod requests.
 511                 if ( $this->purgePeriod !== 1 && mt_rand( 0, $this->purgePeriod - 1 ) ) {
 512                         return;
 513                 }
 514                 $now = time();
 515                 // Avoid repeating the delete within a few seconds
 516                 if ( $now > ( $this->lastExpireAll + 1 ) ) {
 517                         $this->lastExpireAll = $now;
 518                         $this->expireAll();
 519                 }
 520         }
 521
 522         public function expireAll() {
 523                 $this->deleteObjectsExpiringBefore( wfTimestampNow() );
 524         }
 525
 526         /**
 527          * Delete objects from the database which expire before a certain date.
 528          * @param string $timestamp
 529          * @param bool|callable $progressCallback
 530          * @return bool
 531          */
 532         public function deleteObjectsExpiringBefore( $timestamp, $progressCallback = false ) {
 533                 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
 534                         try {
 535                                 $db = $this->getDB( $serverIndex );
 536                                 $dbTimestamp = $db->timestamp( $timestamp );
 537                                 $totalSeconds = false;
 538                                 $baseConds = array( 'exptime < ' . $db->addQuotes( $dbTimestamp ) );
 539                                 for ( $i = 0; $i < $this->shards; $i++ ) {
 540                                         $maxExpTime = false;
 541                                         while ( true ) {
 542                                                 $conds = $baseConds;
 543                                                 if ( $maxExpTime !== false ) {
 544                                                         $conds[] = 'exptime > ' . $db->addQuotes( $maxExpTime );
 545                                                 }
 546                                                 $rows = $db->select(
 547                                                         $this->getTableNameByShard( $i ),
 548                                                         array( 'keyname', 'exptime' ),
 549                                                         $conds,
 550                                                         __METHOD__,
 551                                                         array( 'LIMIT' => 100, 'ORDER BY' => 'exptime' ) );
 552                                                 if ( $rows === false || !$rows->numRows() ) {
 553                                                         break;
 554                                                 }
 555                                                 $keys = array();
 556                                                 $row = $rows->current();
 557                                                 $minExpTime = $row->exptime;
 558                                                 if ( $totalSeconds === false ) {
 559                                                         $totalSeconds = wfTimestamp( TS_UNIX, $timestamp )
 560                                                                 - wfTimestamp( TS_UNIX, $minExpTime );
 561                                                 }
 562                                                 foreach ( $rows as $row ) {
 563                                                         $keys[] = $row->keyname;
 564                                                         $maxExpTime = $row->exptime;
 565                                                 }
 566
 567                                                 $db->delete(
 568                                                         $this->getTableNameByShard( $i ),
 569                                                         array(
 570                                                                 'exptime >= ' . $db->addQuotes( $minExpTime ),
 571                                                                 'exptime < ' . $db->addQuotes( $dbTimestamp ),
 572                                                                 'keyname' => $keys
 573                                                         ),
 574                                                         __METHOD__ );
 575
 576                                                 if ( $progressCallback ) {
 577                                                         if ( intval( $totalSeconds ) === 0 ) {
 578                                                                 $percent = 0;
 579                                                         } else {
 580                                                                 $remainingSeconds = wfTimestamp( TS_UNIX, $timestamp )
 581                                                                         - wfTimestamp( TS_UNIX, $maxExpTime );
 582                                                                 if ( $remainingSeconds > $totalSeconds ) {
 583                                                                         $totalSeconds = $remainingSeconds;
 584                                                                 }
 585                                                                 $processedSeconds = $totalSeconds - $remainingSeconds;
 586                                                                 $percent = ( $i + $processedSeconds / $totalSeconds )
 587                                                                         / $this->shards * 100;
 588                                                         }
 589                                                         $percent = ( $percent / $this->numServers )
 590                                                                 + ( $serverIndex / $this->numServers * 100 );
 591                                                         call_user_func( $progressCallback, $percent );
 592                                                 }
 593                                         }
 594                                 }
 595                         } catch ( DBError $e ) {
 596                                 $this->handleWriteError( $e, $serverIndex );
 597                                 return false;
 598                         }
 599                 }
 600                 return true;
 601         }
 602
 603         /**
 604          * Delete content of shard tables in every server.
 605          * Return true if the operation is successful, false otherwise.
 606          * @return bool
 607          */
 608         public function deleteAll() {
 609                 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
 610                         try {
 611                                 $db = $this->getDB( $serverIndex );
 612                                 for ( $i = 0; $i < $this->shards; $i++ ) {
 613                                         $db->delete( $this->getTableNameByShard( $i ), '*', __METHOD__ );
 614                                 }
 615                         } catch ( DBError $e ) {
 616                                 $this->handleWriteError( $e, $serverIndex );
 617                                 return false;
 618                         }
 619                 }
 620                 return true;
 621         }
 622
 623         /**
 624          * Serialize an object and, if possible, compress the representation.
 625          * On typical message and page data, this can provide a 3X decrease
 626          * in storage requirements.
 627          *
 628          * @param mixed $data
 629          * @return string
 630          */
 631         protected function serialize( &$data ) {
 632                 $serial = serialize( $data );
 633
 634                 if ( function_exists( 'gzdeflate' ) ) {
 635                         return gzdeflate( $serial );
 636                 } else {
 637                         return $serial;
 638                 }
 639         }
 640
 641         /**
 642          * Unserialize and, if necessary, decompress an object.
 643          * @param string $serial
 644          * @return mixed
 645          */
 646         protected function unserialize( $serial ) {
 647                 if ( function_exists( 'gzinflate' ) ) {
 648                         MediaWiki\suppressWarnings();
 649                         $decomp = gzinflate( $serial );
 650                         MediaWiki\restoreWarnings();
 651
 652                         if ( false !== $decomp ) {
 653                                 $serial = $decomp;
 654                         }
 655                 }
 656
 657                 $ret = unserialize( $serial );
 658
 659                 return $ret;
 660         }
 661
 662         /**
 663          * Handle a DBError which occurred during a read operation.
 664          *
 665          * @param DBError $exception
 666          * @param int $serverIndex
 667          */
 668         protected function handleReadError( DBError $exception, $serverIndex ) {
 669                 if ( $exception instanceof DBConnectionError ) {
 670                         $this->markServerDown( $exception, $serverIndex );
 671                 }
 672                 $this->logger->error( "DBError: {$exception->getMessage()}" );
 673                 if ( $exception instanceof DBConnectionError ) {
 674                         $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 675                         $this->logger->debug( __METHOD__ . ": ignoring connection error" );
 676                 } else {
 677                         $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 678                         $this->logger->debug( __METHOD__ . ": ignoring query error" );
 679                 }
 680         }
 681
 682         /**
 683          * Handle a DBQueryError which occurred during a write operation.
 684          *
 685          * @param DBError $exception
 686          * @param int $serverIndex
 687          */
 688         protected function handleWriteError( DBError $exception, $serverIndex ) {
 689                 if ( $exception instanceof DBConnectionError ) {
 690                         $this->markServerDown( $exception, $serverIndex );
 691                 }
 692                 if ( $exception->db && $exception->db->wasReadOnlyError() ) {
 693                         if ( $exception->db->trxLevel() ) {
 694                                 try {
 695                                         $exception->db->rollback( __METHOD__ );
 696                                 } catch ( DBError $e ) {
 697                                 }
 698                         }
 699                 }
 700
 701                 $this->logger->error( "DBError: {$exception->getMessage()}" );
 702                 if ( $exception instanceof DBConnectionError ) {
 703                         $this->setLastError( BagOStuff::ERR_UNREACHABLE );
 704                         $this->logger->debug( __METHOD__ . ": ignoring connection error" );
 705                 } else {
 706                         $this->setLastError( BagOStuff::ERR_UNEXPECTED );
 707                         $this->logger->debug( __METHOD__ . ": ignoring query error" );
 708                 }
 709         }
 710
 711         /**
 712          * Mark a server down due to a DBConnectionError exception
 713          *
 714          * @param DBError $exception
 715          * @param int $serverIndex
 716          */
 717         protected function markServerDown( $exception, $serverIndex ) {
 718                 unset( $this->conns[$serverIndex] ); // bug T103435
 719
 720                 if ( isset( $this->connFailureTimes[$serverIndex] ) ) {
 721                         if ( time() - $this->connFailureTimes[$serverIndex] >= 60 ) {
 722                                 unset( $this->connFailureTimes[$serverIndex] );
 723                                 unset( $this->connFailureErrors[$serverIndex] );
 724                         } else {
 725                                 $this->logger->debug( __METHOD__ . ": Server #$serverIndex already down" );
 726                                 return;
 727                         }
 728                 }
 729                 $now = time();
 730                 $this->logger->info( __METHOD__ . ": Server #$serverIndex down until " . ( $now + 60 ) );
 731                 $this->connFailureTimes[$serverIndex] = $now;
 732                 $this->connFailureErrors[$serverIndex] = $exception;
 733         }
 734
 735         /**
 736          * Create shard tables. For use from eval.php.
 737          */
 738         public function createTables() {
 739                 for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
 740                         $db = $this->getDB( $serverIndex );
 741                         if ( $db->getType() !== 'mysql' ) {
 742                                 throw new MWException( __METHOD__ . ' is not supported on this DB server' );
 743                         }
 744
 745                         for ( $i = 0; $i < $this->shards; $i++ ) {
 746                                 $db->query(
 747                                         'CREATE TABLE ' . $db->tableName( $this->getTableNameByShard( $i ) ) .
 748                                         ' LIKE ' . $db->tableName( 'objectcache' ),
 749                                         __METHOD__ );
 750                         }
 751                 }
 752         }
 753 }