includes/libs/rdbms/database/DatabaseMysqlBase.php

   1 <?php
   2 /**
   3  * This is the MySQL database abstraction layer.
   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 Database
  22  */
  23 namespace Wikimedia\Rdbms;
  24
  25 use DateTime;
  26 use DateTimeZone;
  27 use Wikimedia\AtEase\AtEase;
  28 use InvalidArgumentException;
  29 use Exception;
  30 use RuntimeException;
  31 use stdClass;
  32
  33 /**
  34  * Database abstraction object for MySQL.
  35  * Defines methods independent on used MySQL extension.
  36  *
  37  * @ingroup Database
  38  * @since 1.22
  39  * @see Database
  40  */
  41 abstract class DatabaseMysqlBase extends Database {
  42         /** @var MysqlMasterPos */
  43         protected $lastKnownReplicaPos;
  44         /** @var string Method to detect replica DB lag */
  45         protected $lagDetectionMethod;
  46         /** @var array Method to detect replica DB lag */
  47         protected $lagDetectionOptions = [];
  48         /** @var bool bool Whether to use GTID methods */
  49         protected $useGTIDs = false;
  50         /** @var string|null */
  51         protected $sslKeyPath;
  52         /** @var string|null */
  53         protected $sslCertPath;
  54         /** @var string|null */
  55         protected $sslCAFile;
  56         /** @var string|null */
  57         protected $sslCAPath;
  58         /** @var string[]|null */
  59         protected $sslCiphers;
  60         /** @var string sql_mode value to send on connection */
  61         protected $sqlMode;
  62         /** @var bool Use experimental UTF-8 transmission encoding */
  63         protected $utf8Mode;
  64         /** @var bool|null */
  65         protected $defaultBigSelects = null;
  66
  67         /** @var string|null */
  68         private $serverVersion = null;
  69         /** @var bool|null */
  70         private $insertSelectIsSafe = null;
  71         /** @var stdClass|null */
  72         private $replicationInfoRow = null;
  73
  74         // Cache getServerId() for 24 hours
  75         const SERVER_ID_CACHE_TTL = 86400;
  76
  77         /** @var float Warn if lag estimates are made for transactions older than this many seconds */
  78         const LAG_STALE_WARN_THRESHOLD = 0.100;
  79
  80         /**
  81          * Additional $params include:
  82          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  83          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  84          *       and uses UTC timestamps in the heartbeat.ts column.
  85          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  86          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  87          *       the default behavior. Normally, the heartbeat row with the server
  88          *       ID of this server's master will be used. Set the "conds" field to
  89          *       override the query conditions, e.g. ['shard' => 's1'].
  90          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  91          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  92          *   - sslKeyPath : path to key file [default: null]
  93          *   - sslCertPath : path to certificate file [default: null]
  94          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  95          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  96          *   - sslCiphers : array list of allowable ciphers [default: null]
  97          * @param array $params
  98          */
  99         public function __construct( array $params ) {
 100                 $this->lagDetectionMethod = $params['lagDetectionMethod'] ?? 'Seconds_Behind_Master';
 101                 $this->lagDetectionOptions = $params['lagDetectionOptions'] ?? [];
 102                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
 103                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
 104                         $var = "ssl{$name}";
 105                         if ( isset( $params[$var] ) ) {
 106                                 $this->$var = $params[$var];
 107                         }
 108                 }
 109                 $this->sqlMode = $params['sqlMode'] ?? null;
 110                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 111                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 112                         ? (bool)$params['insertSelectIsSafe'] : null;
 113
 114                 parent::__construct( $params );
 115         }
 116
 117         /**
 118          * @return string
 119          */
 120         public function getType() {
 121                 return 'mysql';
 122         }
 123
 124         protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix ) {
 125                 $this->close();
 126
 127                 if ( $schema !== null ) {
 128                         throw $this->newExceptionAfterConnectError( "Got schema '$schema'; not supported." );
 129                 }
 130
 131                 $this->server = $server;
 132                 $this->user = $user;
 133                 $this->password = $password;
 134
 135                 $this->installErrorHandler();
 136                 try {
 137                         $this->conn = $this->mysqlConnect( $this->server, $dbName );
 138                 } catch ( Exception $e ) {
 139                         $this->restoreErrorHandler();
 140                         throw $this->newExceptionAfterConnectError( $e->getMessage() );
 141                 }
 142                 $error = $this->restoreErrorHandler();
 143
 144                 if ( !$this->conn ) {
 145                         throw $this->newExceptionAfterConnectError( $error ?: $this->lastError() );
 146                 }
 147
 148                 try {
 149                         $this->currentDomain = new DatabaseDomain(
 150                                 strlen( $dbName ) ? $dbName : null,
 151                                 null,
 152                                 $tablePrefix
 153                         );
 154                         // Abstract over any insane MySQL defaults
 155                         $set = [ 'group_concat_max_len = 262144' ];
 156                         // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 157                         if ( is_string( $this->sqlMode ) ) {
 158                                 $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 159                         }
 160                         // Set any custom settings defined by site config
 161                         // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 162                         foreach ( $this->connectionVariables as $var => $val ) {
 163                                 // Escape strings but not numbers to avoid MySQL complaining
 164                                 if ( !is_int( $val ) && !is_float( $val ) ) {
 165                                         $val = $this->addQuotes( $val );
 166                                 }
 167                                 $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 168                         }
 169
 170                         if ( $set ) {
 171                                 $this->query(
 172                                         'SET ' . implode( ', ', $set ),
 173                                         __METHOD__,
 174                                         self::QUERY_IGNORE_DBO_TRX | self::QUERY_NO_RETRY
 175                                 );
 176                         }
 177                 } catch ( Exception $e ) {
 178                         throw $this->newExceptionAfterConnectError( $e->getMessage() );
 179                 }
 180         }
 181
 182         protected function doSelectDomain( DatabaseDomain $domain ) {
 183                 if ( $domain->getSchema() !== null ) {
 184                         throw new DBExpectedError(
 185                                 $this,
 186                                 __CLASS__ . ": domain '{$domain->getId()}' has a schema component"
 187                         );
 188                 }
 189
 190                 $database = $domain->getDatabase();
 191                 // A null database means "don't care" so leave it as is and update the table prefix
 192                 if ( $database === null ) {
 193                         $this->currentDomain = new DatabaseDomain(
 194                                 $this->currentDomain->getDatabase(),
 195                                 null,
 196                                 $domain->getTablePrefix()
 197                         );
 198
 199                         return true;
 200                 }
 201
 202                 if ( $database !== $this->getDBname() ) {
 203                         $sql = 'USE ' . $this->addIdentifierQuotes( $database );
 204                         list( $res, $err, $errno ) =
 205                                 $this->executeQuery( $sql, __METHOD__, self::QUERY_IGNORE_DBO_TRX );
 206
 207                         if ( $res === false ) {
 208                                 $this->reportQueryError( $err, $errno, $sql, __METHOD__ );
 209                                 return false; // unreachable
 210                         }
 211                 }
 212
 213                 // Update that domain fields on success (no exception thrown)
 214                 $this->currentDomain = $domain;
 215
 216                 return true;
 217         }
 218
 219         /**
 220          * Open a connection to a MySQL server
 221          *
 222          * @param string $realServer
 223          * @param string|null $dbName
 224          * @return mixed|null Driver connection handle
 225          * @throws DBConnectionError
 226          */
 227         abstract protected function mysqlConnect( $realServer, $dbName );
 228
 229         /**
 230          * @param IResultWrapper|resource $res
 231          * @throws DBUnexpectedError
 232          */
 233         public function freeResult( $res ) {
 234                 AtEase::suppressWarnings();
 235                 $ok = $this->mysqlFreeResult( ResultWrapper::unwrap( $res ) );
 236                 AtEase::restoreWarnings();
 237                 if ( !$ok ) {
 238                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 239                 }
 240         }
 241
 242         /**
 243          * Free result memory
 244          *
 245          * @param resource $res Raw result
 246          * @return bool
 247          */
 248         abstract protected function mysqlFreeResult( $res );
 249
 250         /**
 251          * @param IResultWrapper|resource $res
 252          * @return stdClass|bool
 253          * @throws DBUnexpectedError
 254          */
 255         public function fetchObject( $res ) {
 256                 AtEase::suppressWarnings();
 257                 $row = $this->mysqlFetchObject( ResultWrapper::unwrap( $res ) );
 258                 AtEase::restoreWarnings();
 259
 260                 $errno = $this->lastErrno();
 261                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 262                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 263                 // these are the only errors mysql_fetch_object can cause.
 264                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 265                 if ( $errno == 2000 || $errno == 2013 ) {
 266                         throw new DBUnexpectedError(
 267                                 $this,
 268                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 269                         );
 270                 }
 271
 272                 return $row;
 273         }
 274
 275         /**
 276          * Fetch a result row as an object
 277          *
 278          * @param resource $res Raw result
 279          * @return stdClass
 280          */
 281         abstract protected function mysqlFetchObject( $res );
 282
 283         /**
 284          * @param IResultWrapper|resource $res
 285          * @return array|bool
 286          * @throws DBUnexpectedError
 287          */
 288         public function fetchRow( $res ) {
 289                 AtEase::suppressWarnings();
 290                 $row = $this->mysqlFetchArray( ResultWrapper::unwrap( $res ) );
 291                 AtEase::restoreWarnings();
 292
 293                 $errno = $this->lastErrno();
 294                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 295                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 296                 // these are the only errors mysql_fetch_array can cause.
 297                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 298                 if ( $errno == 2000 || $errno == 2013 ) {
 299                         throw new DBUnexpectedError(
 300                                 $this,
 301                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 302                         );
 303                 }
 304
 305                 return $row;
 306         }
 307
 308         /**
 309          * Fetch a result row as an associative and numeric array
 310          *
 311          * @param resource $res Raw result
 312          * @return array|false
 313          */
 314         abstract protected function mysqlFetchArray( $res );
 315
 316         /**
 317          * @throws DBUnexpectedError
 318          * @param IResultWrapper|resource $res
 319          * @return int
 320          */
 321         function numRows( $res ) {
 322                 if ( is_bool( $res ) ) {
 323                         $n = 0;
 324                 } else {
 325                         AtEase::suppressWarnings();
 326                         $n = $this->mysqlNumRows( ResultWrapper::unwrap( $res ) );
 327                         AtEase::restoreWarnings();
 328                 }
 329
 330                 // Unfortunately, mysql_num_rows does not reset the last errno.
 331                 // We are not checking for any errors here, since
 332                 // there are no errors mysql_num_rows can cause.
 333                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 334                 // See https://phabricator.wikimedia.org/T44430
 335                 return $n;
 336         }
 337
 338         /**
 339          * Get number of rows in result
 340          *
 341          * @param resource $res Raw result
 342          * @return int
 343          */
 344         abstract protected function mysqlNumRows( $res );
 345
 346         /**
 347          * @param IResultWrapper|resource $res
 348          * @return int
 349          */
 350         public function numFields( $res ) {
 351                 return $this->mysqlNumFields( ResultWrapper::unwrap( $res ) );
 352         }
 353
 354         /**
 355          * Get number of fields in result
 356          *
 357          * @param resource $res Raw result
 358          * @return int
 359          */
 360         abstract protected function mysqlNumFields( $res );
 361
 362         /**
 363          * @param IResultWrapper|resource $res
 364          * @param int $n
 365          * @return string
 366          */
 367         public function fieldName( $res, $n ) {
 368                 return $this->mysqlFieldName( ResultWrapper::unwrap( $res ), $n );
 369         }
 370
 371         /**
 372          * Get the name of the specified field in a result
 373          *
 374          * @param IResultWrapper|resource $res
 375          * @param int $n
 376          * @return string
 377          */
 378         abstract protected function mysqlFieldName( $res, $n );
 379
 380         /**
 381          * mysql_field_type() wrapper
 382          * @param IResultWrapper|resource $res
 383          * @param int $n
 384          * @return string
 385          */
 386         public function fieldType( $res, $n ) {
 387                 return $this->mysqlFieldType( ResultWrapper::unwrap( $res ), $n );
 388         }
 389
 390         /**
 391          * Get the type of the specified field in a result
 392          *
 393          * @param IResultWrapper|resource $res
 394          * @param int $n
 395          * @return string
 396          */
 397         abstract protected function mysqlFieldType( $res, $n );
 398
 399         /**
 400          * @param IResultWrapper|resource $res
 401          * @param int $row
 402          * @return bool
 403          */
 404         public function dataSeek( $res, $row ) {
 405                 return $this->mysqlDataSeek( ResultWrapper::unwrap( $res ), $row );
 406         }
 407
 408         /**
 409          * Move internal result pointer
 410          *
 411          * @param IResultWrapper|resource $res
 412          * @param int $row
 413          * @return bool
 414          */
 415         abstract protected function mysqlDataSeek( $res, $row );
 416
 417         /**
 418          * @return string
 419          */
 420         public function lastError() {
 421                 if ( $this->conn ) {
 422                         # Even if it's non-zero, it can still be invalid
 423                         AtEase::suppressWarnings();
 424                         $error = $this->mysqlError( $this->conn );
 425                         if ( !$error ) {
 426                                 $error = $this->mysqlError();
 427                         }
 428                         AtEase::restoreWarnings();
 429                 } else {
 430                         $error = $this->mysqlError();
 431                 }
 432                 if ( $error ) {
 433                         $error .= ' (' . $this->server . ')';
 434                 }
 435
 436                 return $error;
 437         }
 438
 439         /**
 440          * Returns the text of the error message from previous MySQL operation
 441          *
 442          * @param resource|null $conn Raw connection
 443          * @return string
 444          */
 445         abstract protected function mysqlError( $conn = null );
 446
 447         protected function wasQueryTimeout( $error, $errno ) {
 448                 // https://dev.mysql.com/doc/refman/8.0/en/client-error-reference.html
 449                 // https://phabricator.wikimedia.org/T170638
 450                 return in_array( $errno, [ 2062, 3024 ] );
 451         }
 452
 453         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 454                 $this->nativeReplace( $table, $rows, $fname );
 455         }
 456
 457         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
 458                 $row = $this->getReplicationSafetyInfo();
 459                 // For row-based-replication, the resulting changes will be relayed, not the query
 460                 if ( $row->binlog_format === 'ROW' ) {
 461                         return true;
 462                 }
 463                 // LIMIT requires ORDER BY on a unique key or it is non-deterministic
 464                 if ( isset( $selectOptions['LIMIT'] ) ) {
 465                         return false;
 466                 }
 467                 // In MySQL, an INSERT SELECT is only replication safe with row-based
 468                 // replication or if innodb_autoinc_lock_mode is 0. When those
 469                 // conditions aren't met, use non-native mode.
 470                 // While we could try to determine if the insert is safe anyway by
 471                 // checking if the target table has an auto-increment column that
 472                 // isn't set in $varMap, that seems unlikely to be worth the extra
 473                 // complexity.
 474                 return (
 475                         in_array( 'NO_AUTO_COLUMNS', $insertOptions ) ||
 476                         (int)$row->innodb_autoinc_lock_mode === 0
 477                 );
 478         }
 479
 480         /**
 481          * @return stdClass Process cached row
 482          */
 483         protected function getReplicationSafetyInfo() {
 484                 if ( $this->replicationInfoRow === null ) {
 485                         $this->replicationInfoRow = $this->selectRow(
 486                                 false,
 487                                 [
 488                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 489                                         'binlog_format' => '@@binlog_format',
 490                                 ],
 491                                 [],
 492                                 __METHOD__
 493                         );
 494                 }
 495
 496                 return $this->replicationInfoRow;
 497         }
 498
 499         /**
 500          * Estimate rows in dataset
 501          * Returns estimated count, based on EXPLAIN output
 502          * Takes same arguments as Database::select()
 503          *
 504          * @param string|array $table
 505          * @param string|array $var
 506          * @param string|array $conds
 507          * @param string $fname
 508          * @param string|array $options
 509          * @param array $join_conds
 510          * @return bool|int
 511          */
 512         public function estimateRowCount( $table, $var = '*', $conds = '',
 513                 $fname = __METHOD__, $options = [], $join_conds = []
 514         ) {
 515                 $conds = $this->normalizeConditions( $conds, $fname );
 516                 $column = $this->extractSingleFieldFromList( $var );
 517                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 518                         $conds[] = "$column IS NOT NULL";
 519                 }
 520
 521                 $options['EXPLAIN'] = true;
 522                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 523                 if ( $res === false ) {
 524                         return false;
 525                 }
 526                 if ( !$this->numRows( $res ) ) {
 527                         return 0;
 528                 }
 529
 530                 $rows = 1;
 531                 foreach ( $res as $plan ) {
 532                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 533                 }
 534
 535                 return (int)$rows;
 536         }
 537
 538         public function tableExists( $table, $fname = __METHOD__ ) {
 539                 // Split database and table into proper variables as Database::tableName() returns
 540                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 541                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 542                 $tableName = "{$prefix}{$table}";
 543
 544                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 545                         return true; // already known to exist and won't show in SHOW TABLES anyway
 546                 }
 547
 548                 // We can't use buildLike() here, because it specifies an escape character
 549                 // other than the backslash, which is the only one supported by SHOW TABLES
 550                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 551
 552                 // If the database has been specified (such as for shared tables), use "FROM"
 553                 if ( $database !== '' ) {
 554                         $encDatabase = $this->addIdentifierQuotes( $database );
 555                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 556                 } else {
 557                         $query = "SHOW TABLES LIKE '$encLike'";
 558                 }
 559
 560                 return $this->query( $query, $fname )->numRows() > 0;
 561         }
 562
 563         /**
 564          * @param string $table
 565          * @param string $field
 566          * @return bool|MySQLField
 567          */
 568         public function fieldInfo( $table, $field ) {
 569                 $table = $this->tableName( $table );
 570                 $flags = self::QUERY_SILENCE_ERRORS;
 571                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, $flags );
 572                 if ( !$res ) {
 573                         return false;
 574                 }
 575                 $n = $this->mysqlNumFields( ResultWrapper::unwrap( $res ) );
 576                 for ( $i = 0; $i < $n; $i++ ) {
 577                         $meta = $this->mysqlFetchField( ResultWrapper::unwrap( $res ), $i );
 578                         if ( $field == $meta->name ) {
 579                                 return new MySQLField( $meta );
 580                         }
 581                 }
 582
 583                 return false;
 584         }
 585
 586         /**
 587          * Get column information from a result
 588          *
 589          * @param resource $res Raw result
 590          * @param int $n
 591          * @return stdClass
 592          */
 593         abstract protected function mysqlFetchField( $res, $n );
 594
 595         /**
 596          * Get information about an index into an object
 597          * Returns false if the index does not exist
 598          *
 599          * @param string $table
 600          * @param string $index
 601          * @param string $fname
 602          * @return bool|array|null False or null on failure
 603          */
 604         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 605                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 606                 # SHOW INDEX should work for 3.x and up:
 607                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 608                 $table = $this->tableName( $table );
 609                 $index = $this->indexName( $index );
 610
 611                 $sql = 'SHOW INDEX FROM ' . $table;
 612                 $res = $this->query( $sql, $fname );
 613
 614                 if ( !$res ) {
 615                         return null;
 616                 }
 617
 618                 $result = [];
 619
 620                 foreach ( $res as $row ) {
 621                         if ( $row->Key_name == $index ) {
 622                                 $result[] = $row;
 623                         }
 624                 }
 625
 626                 return $result ?: false;
 627         }
 628
 629         /**
 630          * @param string $s
 631          * @return string
 632          */
 633         public function strencode( $s ) {
 634                 return $this->mysqlRealEscapeString( $s );
 635         }
 636
 637         /**
 638          * @param string $s
 639          * @return mixed
 640          */
 641         abstract protected function mysqlRealEscapeString( $s );
 642
 643         public function addQuotes( $s ) {
 644                 if ( is_bool( $s ) ) {
 645                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 646                         // When searching for an int in a string column, the strings are cast to int, which
 647                         // means false would match any string not starting with a number.
 648                         $s = (string)(int)$s;
 649                 }
 650                 return parent::addQuotes( $s );
 651         }
 652
 653         /**
 654          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 655          *
 656          * @param string $s
 657          * @return string
 658          */
 659         public function addIdentifierQuotes( $s ) {
 660                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 661                 // Remove NUL bytes and escape backticks by doubling
 662                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 663         }
 664
 665         /**
 666          * @param string $name
 667          * @return bool
 668          */
 669         public function isQuotedIdentifier( $name ) {
 670                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 671         }
 672
 673         protected function doGetLag() {
 674                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 675                         return $this->getLagFromPtHeartbeat();
 676                 } else {
 677                         return $this->getLagFromSlaveStatus();
 678                 }
 679         }
 680
 681         /**
 682          * @return string
 683          */
 684         protected function getLagDetectionMethod() {
 685                 return $this->lagDetectionMethod;
 686         }
 687
 688         /**
 689          * @return bool|int
 690          */
 691         protected function getLagFromSlaveStatus() {
 692                 $flags = self::QUERY_SILENCE_ERRORS | self::QUERY_IGNORE_DBO_TRX;
 693                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__, $flags );
 694                 $row = $res ? $res->fetchObject() : false;
 695                 // If the server is not replicating, there will be no row
 696                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 697                         return intval( $row->Seconds_Behind_Master );
 698                 }
 699
 700                 return false;
 701         }
 702
 703         /**
 704          * @return bool|float
 705          */
 706         protected function getLagFromPtHeartbeat() {
 707                 $options = $this->lagDetectionOptions;
 708
 709                 $currentTrxInfo = $this->getRecordedTransactionLagStatus();
 710                 if ( $currentTrxInfo ) {
 711                         // There is an active transaction and the initial lag was already queried
 712                         $staleness = microtime( true ) - $currentTrxInfo['since'];
 713                         if ( $staleness > self::LAG_STALE_WARN_THRESHOLD ) {
 714                                 // Avoid returning higher and higher lag value due to snapshot age
 715                                 // given that the isolation level will typically be REPEATABLE-READ
 716                                 $this->queryLogger->warning(
 717                                         "Using cached lag value for {db_server} due to active transaction",
 718                                         $this->getLogContext( [
 719                                                 'method' => __METHOD__,
 720                                                 'age' => $staleness,
 721                                                 'trace' => ( new RuntimeException() )->getTraceAsString()
 722                                         ] )
 723                                 );
 724                         }
 725
 726                         return $currentTrxInfo['lag'];
 727                 }
 728
 729                 if ( isset( $options['conds'] ) ) {
 730                         // Best method for multi-DC setups: use logical channel names
 731                         $data = $this->getHeartbeatData( $options['conds'] );
 732                 } else {
 733                         // Standard method: use master server ID (works with stock pt-heartbeat)
 734                         $masterInfo = $this->getMasterServerInfo();
 735                         if ( !$masterInfo ) {
 736                                 $this->queryLogger->error(
 737                                         "Unable to query master of {db_server} for server ID",
 738                                         $this->getLogContext( [
 739                                                 'method' => __METHOD__
 740                                         ] )
 741                                 );
 742
 743                                 return false; // could not get master server ID
 744                         }
 745
 746                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 747                         $data = $this->getHeartbeatData( $conds );
 748                 }
 749
 750                 list( $time, $nowUnix ) = $data;
 751                 if ( $time !== null ) {
 752                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 753                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 754                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 755
 756                         return max( $nowUnix - $timeUnix, 0.0 );
 757                 }
 758
 759                 $this->queryLogger->error(
 760                         "Unable to find pt-heartbeat row for {db_server}",
 761                         $this->getLogContext( [
 762                                 'method' => __METHOD__
 763                         ] )
 764                 );
 765
 766                 return false;
 767         }
 768
 769         protected function getMasterServerInfo() {
 770                 $cache = $this->srvCache;
 771                 $key = $cache->makeGlobalKey(
 772                         'mysql',
 773                         'master-info',
 774                         // Using one key for all cluster replica DBs is preferable
 775                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 776                 );
 777                 $fname = __METHOD__;
 778
 779                 return $cache->getWithSetCallback(
 780                         $key,
 781                         $cache::TTL_INDEFINITE,
 782                         function () use ( $cache, $key, $fname ) {
 783                                 // Get and leave a lock key in place for a short period
 784                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 785                                         return false; // avoid master connection spike slams
 786                                 }
 787
 788                                 $conn = $this->getLazyMasterHandle();
 789                                 if ( !$conn ) {
 790                                         return false; // something is misconfigured
 791                                 }
 792
 793                                 // Connect to and query the master; catch errors to avoid outages
 794                                 try {
 795                                         $flags = self::QUERY_SILENCE_ERRORS | self::QUERY_IGNORE_DBO_TRX;
 796                                         $res = $conn->query( 'SELECT @@server_id AS id', $fname, $flags );
 797                                         $row = $res ? $res->fetchObject() : false;
 798                                         $id = $row ? (int)$row->id : 0;
 799                                 } catch ( DBError $e ) {
 800                                         $id = 0;
 801                                 }
 802
 803                                 // Cache the ID if it was retrieved
 804                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 805                         }
 806                 );
 807         }
 808
 809         /**
 810          * @param array $conds WHERE clause conditions to find a row
 811          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 812          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 813          */
 814         protected function getHeartbeatData( array $conds ) {
 815                 // Query time and trip time are not counted
 816                 $nowUnix = microtime( true );
 817                 // Do not bother starting implicit transactions here
 818                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 819                 try {
 820                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 821                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 822                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 823                         // percision field is not supported in MySQL <= 5.5.
 824                         $res = $this->query(
 825                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1",
 826                                 __METHOD__,
 827                                 self::QUERY_SILENCE_ERRORS | self::QUERY_IGNORE_DBO_TRX
 828                         );
 829                         $row = $res ? $res->fetchObject() : false;
 830                 } finally {
 831                         $this->restoreFlags();
 832                 }
 833
 834                 return [ $row ? $row->ts : null, $nowUnix ];
 835         }
 836
 837         protected function getApproximateLagStatus() {
 838                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 839                         // Disable caching since this is fast enough and we don't wan't
 840                         // to be *too* pessimistic by having both the cache TTL and the
 841                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 842                         return parent::getApproximateLagStatus();
 843                 }
 844
 845                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 846                 $approxLag = $this->srvCache->get( $key );
 847                 if ( !$approxLag ) {
 848                         $approxLag = parent::getApproximateLagStatus();
 849                         $this->srvCache->set( $key, $approxLag, 1 );
 850                 }
 851
 852                 return $approxLag;
 853         }
 854
 855         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 856                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 857                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 858                 }
 859
 860                 if ( $this->getLBInfo( 'is static' ) === true ) {
 861                         return 0; // this is a copy of a read-only dataset with no master DB
 862                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 863                         return 0; // already reached this point for sure
 864                 }
 865
 866                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 867                 if ( $pos->getGTIDs() ) {
 868                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 869                         $rpos = $this->getReplicaPos();
 870                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 871                         if ( !$gtidsWait ) {
 872                                 $this->queryLogger->error(
 873                                         "No GTIDs with the same domain between master ($pos) and replica ($rpos)",
 874                                         $this->getLogContext( [
 875                                                 'method' => __METHOD__,
 876                                         ] )
 877                                 );
 878
 879                                 return -1; // $pos is from the wrong cluster?
 880                         }
 881                         // Wait on the GTID set (MariaDB only)
 882                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 883                         if ( strpos( $gtidArg, ':' ) !== false ) {
 884                                 // MySQL GTIDs, e.g "source_id:transaction_id"
 885                                 $sql = "SELECT WAIT_FOR_EXECUTED_GTID_SET($gtidArg, $timeout)";
 886                         } else {
 887                                 // MariaDB GTIDs, e.g."domain:server:sequence"
 888                                 $sql = "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)";
 889                         }
 890                 } else {
 891                         // Wait on the binlog coordinates
 892                         $encFile = $this->addQuotes( $pos->getLogFile() );
 893                         $encPos = intval( $pos->getLogPosition()[$pos::CORD_EVENT] );
 894                         $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
 895                 }
 896
 897                 list( $res, $err ) = $this->executeQuery( $sql, __METHOD__, self::QUERY_IGNORE_DBO_TRX );
 898                 $row = $res ? $this->fetchRow( $res ) : false;
 899                 if ( !$row ) {
 900                         throw new DBExpectedError( $this, "Replication wait failed: {$err}" );
 901                 }
 902
 903                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 904                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 905                 if ( $status === null ) {
 906                         if ( !$pos->getGTIDs() ) {
 907                                 // T126436: jobs programmed to wait on master positions might be referencing
 908                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 909                                 // Try to detect this case and treat the replica DB as having reached the given
 910                                 // position (any master switchover already requires that the new master be caught
 911                                 // up before the switch).
 912                                 $replicationPos = $this->getReplicaPos();
 913                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 914                                         $this->lastKnownReplicaPos = $replicationPos;
 915                                         $status = 0;
 916                                 }
 917                         }
 918                 } elseif ( $status >= 0 ) {
 919                         // Remember that this position was reached to save queries next time
 920                         $this->lastKnownReplicaPos = $pos;
 921                 }
 922
 923                 return $status;
 924         }
 925
 926         /**
 927          * Get the position of the master from SHOW SLAVE STATUS
 928          *
 929          * @return MySQLMasterPos|bool
 930          */
 931         public function getReplicaPos() {
 932                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 933
 934                 if ( $this->useGTIDs() ) {
 935                         // Try to use GTIDs, fallbacking to binlog positions if not possible
 936                         $data = $this->getServerGTIDs( __METHOD__ );
 937                         // Use gtid_slave_pos for MariaDB and gtid_executed for MySQL
 938                         foreach ( [ 'gtid_slave_pos', 'gtid_executed' ] as $name ) {
 939                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
 940                                         return new MySQLMasterPos( $data[$name], $now );
 941                                 }
 942                         }
 943                 }
 944
 945                 $data = $this->getServerRoleStatus( 'SLAVE', __METHOD__ );
 946                 if ( $data && strlen( $data['Relay_Master_Log_File'] ) ) {
 947                         return new MySQLMasterPos(
 948                                 "{$data['Relay_Master_Log_File']}/{$data['Exec_Master_Log_Pos']}",
 949                                 $now
 950                         );
 951                 }
 952
 953                 return false;
 954         }
 955
 956         /**
 957          * Get the position of the master from SHOW MASTER STATUS
 958          *
 959          * @return MySQLMasterPos|bool
 960          */
 961         public function getMasterPos() {
 962                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 963
 964                 $pos = false;
 965                 if ( $this->useGTIDs() ) {
 966                         // Try to use GTIDs, fallbacking to binlog positions if not possible
 967                         $data = $this->getServerGTIDs( __METHOD__ );
 968                         // Use gtid_binlog_pos for MariaDB and gtid_executed for MySQL
 969                         foreach ( [ 'gtid_binlog_pos', 'gtid_executed' ] as $name ) {
 970                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
 971                                         $pos = new MySQLMasterPos( $data[$name], $now );
 972                                         break;
 973                                 }
 974                         }
 975                         // Filter domains that are inactive or not relevant to the session
 976                         if ( $pos ) {
 977                                 $pos->setActiveOriginServerId( $this->getServerId() );
 978                                 $pos->setActiveOriginServerUUID( $this->getServerUUID() );
 979                                 if ( isset( $data['gtid_domain_id'] ) ) {
 980                                         $pos->setActiveDomain( $data['gtid_domain_id'] );
 981                                 }
 982                         }
 983                 }
 984
 985                 if ( !$pos ) {
 986                         $data = $this->getServerRoleStatus( 'MASTER', __METHOD__ );
 987                         if ( $data && strlen( $data['File'] ) ) {
 988                                 $pos = new MySQLMasterPos( "{$data['File']}/{$data['Position']}", $now );
 989                         }
 990                 }
 991
 992                 return $pos;
 993         }
 994
 995         /**
 996          * @return int
 997          * @throws DBQueryError If the variable doesn't exist for some reason
 998          */
 999         protected function getServerId() {
1000                 $fname = __METHOD__;
1001                 return $this->srvCache->getWithSetCallback(
1002                         $this->srvCache->makeGlobalKey( 'mysql-server-id', $this->getServer() ),
1003                         self::SERVER_ID_CACHE_TTL,
1004                         function () use ( $fname ) {
1005                                 $flags = self::QUERY_IGNORE_DBO_TRX;
1006                                 $res = $this->query( "SELECT @@server_id AS id", $fname, $flags );
1007
1008                                 return intval( $this->fetchObject( $res )->id );
1009                         }
1010                 );
1011         }
1012
1013         /**
1014          * @return string|null
1015          */
1016         protected function getServerUUID() {
1017                 $fname = __METHOD__;
1018                 return $this->srvCache->getWithSetCallback(
1019                         $this->srvCache->makeGlobalKey( 'mysql-server-uuid', $this->getServer() ),
1020                         self::SERVER_ID_CACHE_TTL,
1021                         function () use ( $fname ) {
1022                                 $flags = self::QUERY_IGNORE_DBO_TRX;
1023                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'server_uuid'", $fname, $flags );
1024                                 $row = $this->fetchObject( $res );
1025
1026                                 return $row ? $row->Value : null;
1027                         }
1028                 );
1029         }
1030
1031         /**
1032          * @param string $fname
1033          * @return string[]
1034          */
1035         protected function getServerGTIDs( $fname = __METHOD__ ) {
1036                 $map = [];
1037
1038                 $flags = self::QUERY_IGNORE_DBO_TRX;
1039                 // Get global-only variables like gtid_executed
1040                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_%'", $fname, $flags );
1041                 foreach ( $res as $row ) {
1042                         $map[$row->Variable_name] = $row->Value;
1043                 }
1044                 // Get session-specific (e.g. gtid_domain_id since that is were writes will log)
1045                 $res = $this->query( "SHOW SESSION VARIABLES LIKE 'gtid_%'", $fname, $flags );
1046                 foreach ( $res as $row ) {
1047                         $map[$row->Variable_name] = $row->Value;
1048                 }
1049
1050                 return $map;
1051         }
1052
1053         /**
1054          * @param string $role One of "MASTER"/"SLAVE"
1055          * @param string $fname
1056          * @return string[] Latest available server status row
1057          */
1058         protected function getServerRoleStatus( $role, $fname = __METHOD__ ) {
1059                 $flags = self::QUERY_IGNORE_DBO_TRX;
1060
1061                 return $this->query( "SHOW $role STATUS", $fname, $flags )->fetchRow() ?: [];
1062         }
1063
1064         public function serverIsReadOnly() {
1065                 $flags = self::QUERY_IGNORE_DBO_TRX;
1066                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__, $flags );
1067                 $row = $this->fetchObject( $res );
1068
1069                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
1070         }
1071
1072         /**
1073          * @param string $index
1074          * @return string
1075          */
1076         function useIndexClause( $index ) {
1077                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1078         }
1079
1080         /**
1081          * @param string $index
1082          * @return string
1083          */
1084         function ignoreIndexClause( $index ) {
1085                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1086         }
1087
1088         /**
1089          * @return string
1090          */
1091         function lowPriorityOption() {
1092                 return 'LOW_PRIORITY';
1093         }
1094
1095         /**
1096          * @return string
1097          */
1098         public function getSoftwareLink() {
1099                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1100                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1101                 // in libmysql/libmysql.c).
1102                 $version = $this->getServerVersion();
1103                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1104                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1105                 }
1106
1107                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1108                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1109                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1110                 return '[{{int:version-db-mysql-url}} MySQL]';
1111         }
1112
1113         /**
1114          * @return string
1115          */
1116         public function getServerVersion() {
1117                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1118                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1119                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1120                 if ( $this->serverVersion === null ) {
1121                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1122                 }
1123                 return $this->serverVersion;
1124         }
1125
1126         /**
1127          * @param array $options
1128          */
1129         public function setSessionOptions( array $options ) {
1130                 if ( isset( $options['connTimeout'] ) ) {
1131                         $flags = self::QUERY_IGNORE_DBO_TRX;
1132                         $timeout = (int)$options['connTimeout'];
1133                         $this->query( "SET net_read_timeout=$timeout", __METHOD__, $flags );
1134                         $this->query( "SET net_write_timeout=$timeout", __METHOD__, $flags );
1135                 }
1136         }
1137
1138         /**
1139          * @param string &$sql
1140          * @param string &$newLine
1141          * @return bool
1142          */
1143         public function streamStatementEnd( &$sql, &$newLine ) {
1144                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1145                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1146                         $this->delimiter = $m[1];
1147                         $newLine = '';
1148                 }
1149
1150                 return parent::streamStatementEnd( $sql, $newLine );
1151         }
1152
1153         /**
1154          * Check to see if a named lock is available. This is non-blocking.
1155          *
1156          * @param string $lockName Name of lock to poll
1157          * @param string $method Name of method calling us
1158          * @return bool
1159          * @since 1.20
1160          */
1161         public function lockIsFree( $lockName, $method ) {
1162                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1163                         return false; // already held
1164                 }
1165
1166                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1167
1168                 $flags = self::QUERY_IGNORE_DBO_TRX;
1169                 $res = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method, $flags );
1170                 $row = $this->fetchObject( $res );
1171
1172                 return ( $row->lockstatus == 1 );
1173         }
1174
1175         /**
1176          * @param string $lockName
1177          * @param string $method
1178          * @param int $timeout
1179          * @return bool
1180          */
1181         public function lock( $lockName, $method, $timeout = 5 ) {
1182                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1183
1184                 $flags = self::QUERY_IGNORE_DBO_TRX;
1185                 $res = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method, $flags );
1186                 $row = $this->fetchObject( $res );
1187
1188                 if ( $row->lockstatus == 1 ) {
1189                         parent::lock( $lockName, $method, $timeout ); // record
1190                         return true;
1191                 }
1192
1193                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1194                         [ 'lockname' => $lockName ] );
1195
1196                 return false;
1197         }
1198
1199         /**
1200          * FROM MYSQL DOCS:
1201          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1202          * @param string $lockName
1203          * @param string $method
1204          * @return bool
1205          */
1206         public function unlock( $lockName, $method ) {
1207                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1208
1209                 $flags = self::QUERY_IGNORE_DBO_TRX;
1210                 $res = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method, $flags );
1211                 $row = $this->fetchObject( $res );
1212
1213                 if ( $row->lockstatus == 1 ) {
1214                         parent::unlock( $lockName, $method ); // record
1215                         return true;
1216                 }
1217
1218                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1219
1220                 return false;
1221         }
1222
1223         private function makeLockName( $lockName ) {
1224                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1225                 // Newer version enforce a 64 char length limit.
1226                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1227         }
1228
1229         public function namedLocksEnqueue() {
1230                 return true;
1231         }
1232
1233         public function tableLocksHaveTransactionScope() {
1234                 return false; // tied to TCP connection
1235         }
1236
1237         protected function doLockTables( array $read, array $write, $method ) {
1238                 $items = [];
1239                 foreach ( $write as $table ) {
1240                         $items[] = $this->tableName( $table ) . ' WRITE';
1241                 }
1242                 foreach ( $read as $table ) {
1243                         $items[] = $this->tableName( $table ) . ' READ';
1244                 }
1245
1246                 $sql = "LOCK TABLES " . implode( ',', $items );
1247                 $this->query( $sql, $method, self::QUERY_IGNORE_DBO_TRX );
1248
1249                 return true;
1250         }
1251
1252         protected function doUnlockTables( $method ) {
1253                 $this->query( "UNLOCK TABLES", $method, self::QUERY_IGNORE_DBO_TRX );
1254
1255                 return true;
1256         }
1257
1258         /**
1259          * @param bool $value
1260          */
1261         public function setBigSelects( $value = true ) {
1262                 if ( $value === 'default' ) {
1263                         if ( $this->defaultBigSelects === null ) {
1264                                 # Function hasn't been called before so it must already be set to the default
1265                                 return;
1266                         } else {
1267                                 $value = $this->defaultBigSelects;
1268                         }
1269                 } elseif ( $this->defaultBigSelects === null ) {
1270                         $this->defaultBigSelects =
1271                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1272                 }
1273                 $encValue = $value ? '1' : '0';
1274                 $this->query( "SET sql_big_selects=$encValue", __METHOD__, self::QUERY_IGNORE_DBO_TRX );
1275         }
1276
1277         /**
1278          * DELETE where the condition is a join. MySql uses multi-table deletes.
1279          * @param string $delTable
1280          * @param string $joinTable
1281          * @param string $delVar
1282          * @param string $joinVar
1283          * @param array|string $conds
1284          * @param bool|string $fname
1285          * @throws DBUnexpectedError
1286          */
1287         public function deleteJoin(
1288                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1289         ) {
1290                 if ( !$conds ) {
1291                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1292                 }
1293
1294                 $delTable = $this->tableName( $delTable );
1295                 $joinTable = $this->tableName( $joinTable );
1296                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1297
1298                 if ( $conds != '*' ) {
1299                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1300                 }
1301
1302                 $this->query( $sql, $fname );
1303         }
1304
1305         public function upsert(
1306                 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1307         ) {
1308                 if ( $rows === [] ) {
1309                         return true; // nothing to do
1310                 }
1311
1312                 if ( !is_array( reset( $rows ) ) ) {
1313                         $rows = [ $rows ];
1314                 }
1315
1316                 $table = $this->tableName( $table );
1317                 $columns = array_keys( $rows[0] );
1318
1319                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1320                 $rowTuples = [];
1321                 foreach ( $rows as $row ) {
1322                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1323                 }
1324                 $sql .= implode( ',', $rowTuples );
1325                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1326
1327                 $this->query( $sql, $fname );
1328
1329                 return true;
1330         }
1331
1332         /**
1333          * Determines how long the server has been up
1334          *
1335          * @return int
1336          */
1337         public function getServerUptime() {
1338                 $vars = $this->getMysqlStatus( 'Uptime' );
1339
1340                 return (int)$vars['Uptime'];
1341         }
1342
1343         /**
1344          * Determines if the last failure was due to a deadlock
1345          *
1346          * @return bool
1347          */
1348         public function wasDeadlock() {
1349                 return $this->lastErrno() == 1213;
1350         }
1351
1352         /**
1353          * Determines if the last failure was due to a lock timeout
1354          *
1355          * @return bool
1356          */
1357         public function wasLockTimeout() {
1358                 return $this->lastErrno() == 1205;
1359         }
1360
1361         /**
1362          * Determines if the last failure was due to the database being read-only.
1363          *
1364          * @return bool
1365          */
1366         public function wasReadOnlyError() {
1367                 return $this->lastErrno() == 1223 ||
1368                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1369         }
1370
1371         public function wasConnectionError( $errno ) {
1372                 return $errno == 2013 || $errno == 2006;
1373         }
1374
1375         protected function wasKnownStatementRollbackError() {
1376                 $errno = $this->lastErrno();
1377
1378                 if ( $errno === 1205 ) { // lock wait timeout
1379                         // Note that this is uncached to avoid stale values of SET is used
1380                         $row = $this->selectRow(
1381                                 false,
1382                                 [ 'innodb_rollback_on_timeout' => '@@innodb_rollback_on_timeout' ],
1383                                 [],
1384                                 __METHOD__
1385                         );
1386                         // https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1387                         // https://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html
1388                         return $row->innodb_rollback_on_timeout ? false : true;
1389                 }
1390
1391                 // See https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
1392                 return in_array( $errno, [ 1022, 1062, 1216, 1217, 1137, 1146, 1051, 1054 ], true );
1393         }
1394
1395         /**
1396          * @param string $oldName
1397          * @param string $newName
1398          * @param bool $temporary
1399          * @param string $fname
1400          * @return bool
1401          */
1402         public function duplicateTableStructure(
1403                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1404         ) {
1405                 $tmp = $temporary ? 'TEMPORARY ' : '';
1406                 $newName = $this->addIdentifierQuotes( $newName );
1407                 $oldName = $this->addIdentifierQuotes( $oldName );
1408                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1409
1410                 return $this->query( $query, $fname, $this::QUERY_PSEUDO_PERMANENT );
1411         }
1412
1413         /**
1414          * List all tables on the database
1415          *
1416          * @param string|null $prefix Only show tables with this prefix, e.g. mw_
1417          * @param string $fname Calling function name
1418          * @return array
1419          */
1420         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1421                 $result = $this->query( "SHOW TABLES", $fname );
1422
1423                 $endArray = [];
1424
1425                 foreach ( $result as $table ) {
1426                         $vars = get_object_vars( $table );
1427                         $table = array_pop( $vars );
1428
1429                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1430                                 $endArray[] = $table;
1431                         }
1432                 }
1433
1434                 return $endArray;
1435         }
1436
1437         /**
1438          * @param string $tableName
1439          * @param string $fName
1440          * @return bool|IResultWrapper
1441          */
1442         public function dropTable( $tableName, $fName = __METHOD__ ) {
1443                 if ( !$this->tableExists( $tableName, $fName ) ) {
1444                         return false;
1445                 }
1446
1447                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1448         }
1449
1450         /**
1451          * Get status information from SHOW STATUS in an associative array
1452          *
1453          * @param string $which
1454          * @return array
1455          */
1456         private function getMysqlStatus( $which = "%" ) {
1457                 $flags = self::QUERY_IGNORE_DBO_TRX;
1458                 $res = $this->query( "SHOW STATUS LIKE '{$which}'", __METHOD__, $flags );
1459                 $status = [];
1460
1461                 foreach ( $res as $row ) {
1462                         $status[$row->Variable_name] = $row->Value;
1463                 }
1464
1465                 return $status;
1466         }
1467
1468         /**
1469          * Lists VIEWs in the database
1470          *
1471          * @param string|null $prefix Only show VIEWs with this prefix, eg.
1472          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1473          * @param string $fname Name of calling function
1474          * @return array
1475          * @since 1.22
1476          */
1477         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1478                 // The name of the column containing the name of the VIEW
1479                 $propertyName = 'Tables_in_' . $this->getDBname();
1480
1481                 // Query for the VIEWS
1482                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1483                 $allViews = [];
1484                 foreach ( $res as $row ) {
1485                         array_push( $allViews, $row->$propertyName );
1486                 }
1487
1488                 if ( is_null( $prefix ) || $prefix === '' ) {
1489                         return $allViews;
1490                 }
1491
1492                 $filteredViews = [];
1493                 foreach ( $allViews as $viewName ) {
1494                         // Does the name of this VIEW start with the table-prefix?
1495                         if ( strpos( $viewName, $prefix ) === 0 ) {
1496                                 array_push( $filteredViews, $viewName );
1497                         }
1498                 }
1499
1500                 return $filteredViews;
1501         }
1502
1503         /**
1504          * Differentiates between a TABLE and a VIEW.
1505          *
1506          * @param string $name Name of the TABLE/VIEW to test
1507          * @param string|null $prefix
1508          * @return bool
1509          * @since 1.22
1510          */
1511         public function isView( $name, $prefix = null ) {
1512                 return in_array( $name, $this->listViews( $prefix ) );
1513         }
1514
1515         protected function isTransactableQuery( $sql ) {
1516                 return parent::isTransactableQuery( $sql ) &&
1517                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1518         }
1519
1520         public function buildStringCast( $field ) {
1521                 return "CAST( $field AS BINARY )";
1522         }
1523
1524         /**
1525          * @param string $field Field or column to cast
1526          * @return string
1527          */
1528         public function buildIntegerCast( $field ) {
1529                 return 'CAST( ' . $field . ' AS SIGNED )';
1530         }
1531
1532         /*
1533          * @return bool Whether GTID support is used (mockable for testing)
1534          */
1535         protected function useGTIDs() {
1536                 return $this->useGTIDs;
1537         }
1538 }
1539
1540 /**
1541  * @deprecated since 1.29
1542  */
1543 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );