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;
  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         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'] ?? '';
 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                 # Close/unset connection handle
 126                 $this->close();
 127
 128                 $this->server = $server;
 129                 $this->user = $user;
 130                 $this->password = $password;
 131
 132                 $this->installErrorHandler();
 133                 try {
 134                         $this->conn = $this->mysqlConnect( $this->server, $dbName );
 135                 } catch ( Exception $ex ) {
 136                         $this->restoreErrorHandler();
 137                         throw $ex;
 138                 }
 139                 $error = $this->restoreErrorHandler();
 140
 141                 # Always log connection errors
 142                 if ( !$this->conn ) {
 143                         $error = $error ?: $this->lastError();
 144                         $this->connLogger->error(
 145                                 "Error connecting to {db_server}: {error}",
 146                                 $this->getLogContext( [
 147                                         'method' => __METHOD__,
 148                                         'error' => $error,
 149                                 ] )
 150                         );
 151                         $this->connLogger->debug( "DB connection error\n" .
 152                                 "Server: $server, User: $user, Password: " .
 153                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 154
 155                         throw new DBConnectionError( $this, $error );
 156                 }
 157
 158                 if ( strlen( $dbName ) ) {
 159                         $this->selectDomain( new DatabaseDomain( $dbName, null, $tablePrefix ) );
 160                 } else {
 161                         $this->currentDomain = new DatabaseDomain( null, null, $tablePrefix );
 162                 }
 163
 164                 // Tell the server what we're communicating with
 165                 if ( !$this->connectInitCharset() ) {
 166                         $error = $this->lastError();
 167                         $this->queryLogger->error(
 168                                 "Error setting character set: {error}",
 169                                 $this->getLogContext( [
 170                                         'method' => __METHOD__,
 171                                         'error' => $this->lastError(),
 172                                 ] )
 173                         );
 174                         throw new DBConnectionError( $this, "Error setting character set: $error" );
 175                 }
 176
 177                 // Abstract over any insane MySQL defaults
 178                 $set = [ 'group_concat_max_len = 262144' ];
 179                 // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 180                 if ( is_string( $this->sqlMode ) ) {
 181                         $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 182                 }
 183                 // Set any custom settings defined by site config
 184                 // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 185                 foreach ( $this->sessionVars as $var => $val ) {
 186                         // Escape strings but not numbers to avoid MySQL complaining
 187                         if ( !is_int( $val ) && !is_float( $val ) ) {
 188                                 $val = $this->addQuotes( $val );
 189                         }
 190                         $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 191                 }
 192
 193                 if ( $set ) {
 194                         // Use doQuery() to avoid opening implicit transactions (DBO_TRX)
 195                         $success = $this->doQuery( 'SET ' . implode( ', ', $set ) );
 196                         if ( !$success ) {
 197                                 $error = $this->lastError();
 198                                 $this->queryLogger->error(
 199                                         'Error setting MySQL variables on server {db_server}: {error}',
 200                                         $this->getLogContext( [
 201                                                 'method' => __METHOD__,
 202                                                 'error' => $error,
 203                                         ] )
 204                                 );
 205                                 throw new DBConnectionError( $this, "Error setting MySQL variables: $error" );
 206                         }
 207                 }
 208
 209                 $this->opened = true;
 210
 211                 return true;
 212         }
 213
 214         /**
 215          * Set the character set information right after connection
 216          * @return bool
 217          */
 218         protected function connectInitCharset() {
 219                 if ( $this->utf8Mode ) {
 220                         // Tell the server we're communicating with it in UTF-8.
 221                         // This may engage various charset conversions.
 222                         return $this->mysqlSetCharset( 'utf8' );
 223                 } else {
 224                         return $this->mysqlSetCharset( 'binary' );
 225                 }
 226         }
 227
 228         /**
 229          * Open a connection to a MySQL server
 230          *
 231          * @param string $realServer
 232          * @param string|null $dbName
 233          * @return mixed Raw connection
 234          * @throws DBConnectionError
 235          */
 236         abstract protected function mysqlConnect( $realServer, $dbName );
 237
 238         /**
 239          * Set the character set of the MySQL link
 240          *
 241          * @param string $charset
 242          * @return bool
 243          */
 244         abstract protected function mysqlSetCharset( $charset );
 245
 246         /**
 247          * @param ResultWrapper|resource $res
 248          * @throws DBUnexpectedError
 249          */
 250         public function freeResult( $res ) {
 251                 if ( $res instanceof ResultWrapper ) {
 252                         $res = $res->result;
 253                 }
 254                 Wikimedia\suppressWarnings();
 255                 $ok = $this->mysqlFreeResult( $res );
 256                 Wikimedia\restoreWarnings();
 257                 if ( !$ok ) {
 258                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 259                 }
 260         }
 261
 262         /**
 263          * Free result memory
 264          *
 265          * @param resource $res Raw result
 266          * @return bool
 267          */
 268         abstract protected function mysqlFreeResult( $res );
 269
 270         /**
 271          * @param ResultWrapper|resource $res
 272          * @return stdClass|bool
 273          * @throws DBUnexpectedError
 274          */
 275         public function fetchObject( $res ) {
 276                 if ( $res instanceof ResultWrapper ) {
 277                         $res = $res->result;
 278                 }
 279                 Wikimedia\suppressWarnings();
 280                 $row = $this->mysqlFetchObject( $res );
 281                 Wikimedia\restoreWarnings();
 282
 283                 $errno = $this->lastErrno();
 284                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 285                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 286                 // these are the only errors mysql_fetch_object can cause.
 287                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 288                 if ( $errno == 2000 || $errno == 2013 ) {
 289                         throw new DBUnexpectedError(
 290                                 $this,
 291                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 292                         );
 293                 }
 294
 295                 return $row;
 296         }
 297
 298         /**
 299          * Fetch a result row as an object
 300          *
 301          * @param resource $res Raw result
 302          * @return stdClass
 303          */
 304         abstract protected function mysqlFetchObject( $res );
 305
 306         /**
 307          * @param IResultWrapper|resource $res
 308          * @return array|bool
 309          * @throws DBUnexpectedError
 310          */
 311         public function fetchRow( $res ) {
 312                 if ( $res instanceof ResultWrapper ) {
 313                         $res = $res->result;
 314                 }
 315                 Wikimedia\suppressWarnings();
 316                 $row = $this->mysqlFetchArray( $res );
 317                 Wikimedia\restoreWarnings();
 318
 319                 $errno = $this->lastErrno();
 320                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 321                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 322                 // these are the only errors mysql_fetch_array can cause.
 323                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 324                 if ( $errno == 2000 || $errno == 2013 ) {
 325                         throw new DBUnexpectedError(
 326                                 $this,
 327                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 328                         );
 329                 }
 330
 331                 return $row;
 332         }
 333
 334         /**
 335          * Fetch a result row as an associative and numeric array
 336          *
 337          * @param resource $res Raw result
 338          * @return array
 339          */
 340         abstract protected function mysqlFetchArray( $res );
 341
 342         /**
 343          * @throws DBUnexpectedError
 344          * @param ResultWrapper|resource $res
 345          * @return int
 346          */
 347         function numRows( $res ) {
 348                 if ( $res instanceof ResultWrapper ) {
 349                         $res = $res->result;
 350                 }
 351                 Wikimedia\suppressWarnings();
 352                 $n = !is_bool( $res ) ? $this->mysqlNumRows( $res ) : 0;
 353                 Wikimedia\restoreWarnings();
 354
 355                 // Unfortunately, mysql_num_rows does not reset the last errno.
 356                 // We are not checking for any errors here, since
 357                 // there are no errors mysql_num_rows can cause.
 358                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 359                 // See https://phabricator.wikimedia.org/T44430
 360                 return $n;
 361         }
 362
 363         /**
 364          * Get number of rows in result
 365          *
 366          * @param resource $res Raw result
 367          * @return int
 368          */
 369         abstract protected function mysqlNumRows( $res );
 370
 371         /**
 372          * @param ResultWrapper|resource $res
 373          * @return int
 374          */
 375         public function numFields( $res ) {
 376                 if ( $res instanceof ResultWrapper ) {
 377                         $res = $res->result;
 378                 }
 379
 380                 return $this->mysqlNumFields( $res );
 381         }
 382
 383         /**
 384          * Get number of fields in result
 385          *
 386          * @param resource $res Raw result
 387          * @return int
 388          */
 389         abstract protected function mysqlNumFields( $res );
 390
 391         /**
 392          * @param ResultWrapper|resource $res
 393          * @param int $n
 394          * @return string
 395          */
 396         public function fieldName( $res, $n ) {
 397                 if ( $res instanceof ResultWrapper ) {
 398                         $res = $res->result;
 399                 }
 400
 401                 return $this->mysqlFieldName( $res, $n );
 402         }
 403
 404         /**
 405          * Get the name of the specified field in a result
 406          *
 407          * @param ResultWrapper|resource $res
 408          * @param int $n
 409          * @return string
 410          */
 411         abstract protected function mysqlFieldName( $res, $n );
 412
 413         /**
 414          * mysql_field_type() wrapper
 415          * @param ResultWrapper|resource $res
 416          * @param int $n
 417          * @return string
 418          */
 419         public function fieldType( $res, $n ) {
 420                 if ( $res instanceof ResultWrapper ) {
 421                         $res = $res->result;
 422                 }
 423
 424                 return $this->mysqlFieldType( $res, $n );
 425         }
 426
 427         /**
 428          * Get the type of the specified field in a result
 429          *
 430          * @param ResultWrapper|resource $res
 431          * @param int $n
 432          * @return string
 433          */
 434         abstract protected function mysqlFieldType( $res, $n );
 435
 436         /**
 437          * @param ResultWrapper|resource $res
 438          * @param int $row
 439          * @return bool
 440          */
 441         public function dataSeek( $res, $row ) {
 442                 if ( $res instanceof ResultWrapper ) {
 443                         $res = $res->result;
 444                 }
 445
 446                 return $this->mysqlDataSeek( $res, $row );
 447         }
 448
 449         /**
 450          * Move internal result pointer
 451          *
 452          * @param ResultWrapper|resource $res
 453          * @param int $row
 454          * @return bool
 455          */
 456         abstract protected function mysqlDataSeek( $res, $row );
 457
 458         /**
 459          * @return string
 460          */
 461         public function lastError() {
 462                 if ( $this->conn ) {
 463                         # Even if it's non-zero, it can still be invalid
 464                         Wikimedia\suppressWarnings();
 465                         $error = $this->mysqlError( $this->conn );
 466                         if ( !$error ) {
 467                                 $error = $this->mysqlError();
 468                         }
 469                         Wikimedia\restoreWarnings();
 470                 } else {
 471                         $error = $this->mysqlError();
 472                 }
 473                 if ( $error ) {
 474                         $error .= ' (' . $this->server . ')';
 475                 }
 476
 477                 return $error;
 478         }
 479
 480         /**
 481          * Returns the text of the error message from previous MySQL operation
 482          *
 483          * @param resource|null $conn Raw connection
 484          * @return string
 485          */
 486         abstract protected function mysqlError( $conn = null );
 487
 488         protected function wasQueryTimeout( $error, $errno ) {
 489                 return $errno == 2062;
 490         }
 491
 492         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 493                 $this->nativeReplace( $table, $rows, $fname );
 494         }
 495
 496         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
 497                 $row = $this->getReplicationSafetyInfo();
 498                 // For row-based-replication, the resulting changes will be relayed, not the query
 499                 if ( $row->binlog_format === 'ROW' ) {
 500                         return true;
 501                 }
 502                 // LIMIT requires ORDER BY on a unique key or it is non-deterministic
 503                 if ( isset( $selectOptions['LIMIT'] ) ) {
 504                         return false;
 505                 }
 506                 // In MySQL, an INSERT SELECT is only replication safe with row-based
 507                 // replication or if innodb_autoinc_lock_mode is 0. When those
 508                 // conditions aren't met, use non-native mode.
 509                 // While we could try to determine if the insert is safe anyway by
 510                 // checking if the target table has an auto-increment column that
 511                 // isn't set in $varMap, that seems unlikely to be worth the extra
 512                 // complexity.
 513                 return (
 514                         in_array( 'NO_AUTO_COLUMNS', $insertOptions ) ||
 515                         (int)$row->innodb_autoinc_lock_mode === 0
 516                 );
 517         }
 518
 519         /**
 520          * @return stdClass Process cached row
 521          */
 522         protected function getReplicationSafetyInfo() {
 523                 if ( $this->replicationInfoRow === null ) {
 524                         $this->replicationInfoRow = $this->selectRow(
 525                                 false,
 526                                 [
 527                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 528                                         'binlog_format' => '@@binlog_format',
 529                                 ],
 530                                 [],
 531                                 __METHOD__
 532                         );
 533                 }
 534
 535                 return $this->replicationInfoRow;
 536         }
 537
 538         /**
 539          * Estimate rows in dataset
 540          * Returns estimated count, based on EXPLAIN output
 541          * Takes same arguments as Database::select()
 542          *
 543          * @param string|array $table
 544          * @param string|array $var
 545          * @param string|array $conds
 546          * @param string $fname
 547          * @param string|array $options
 548          * @param array $join_conds
 549          * @return bool|int
 550          */
 551         public function estimateRowCount( $table, $var = '*', $conds = '',
 552                 $fname = __METHOD__, $options = [], $join_conds = []
 553         ) {
 554                 $conds = $this->normalizeConditions( $conds, $fname );
 555                 $column = $this->extractSingleFieldFromList( $var );
 556                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 557                         $conds[] = "$column IS NOT NULL";
 558                 }
 559
 560                 $options['EXPLAIN'] = true;
 561                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 562                 if ( $res === false ) {
 563                         return false;
 564                 }
 565                 if ( !$this->numRows( $res ) ) {
 566                         return 0;
 567                 }
 568
 569                 $rows = 1;
 570                 foreach ( $res as $plan ) {
 571                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 572                 }
 573
 574                 return (int)$rows;
 575         }
 576
 577         public function tableExists( $table, $fname = __METHOD__ ) {
 578                 // Split database and table into proper variables as Database::tableName() returns
 579                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 580                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 581                 $tableName = "{$prefix}{$table}";
 582
 583                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 584                         return true; // already known to exist and won't show in SHOW TABLES anyway
 585                 }
 586
 587                 // We can't use buildLike() here, because it specifies an escape character
 588                 // other than the backslash, which is the only one supported by SHOW TABLES
 589                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 590
 591                 // If the database has been specified (such as for shared tables), use "FROM"
 592                 if ( $database !== '' ) {
 593                         $encDatabase = $this->addIdentifierQuotes( $database );
 594                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 595                 } else {
 596                         $query = "SHOW TABLES LIKE '$encLike'";
 597                 }
 598
 599                 return $this->query( $query, $fname )->numRows() > 0;
 600         }
 601
 602         /**
 603          * @param string $table
 604          * @param string $field
 605          * @return bool|MySQLField
 606          */
 607         public function fieldInfo( $table, $field ) {
 608                 $table = $this->tableName( $table );
 609                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 610                 if ( !$res ) {
 611                         return false;
 612                 }
 613                 $n = $this->mysqlNumFields( $res->result );
 614                 for ( $i = 0; $i < $n; $i++ ) {
 615                         $meta = $this->mysqlFetchField( $res->result, $i );
 616                         if ( $field == $meta->name ) {
 617                                 return new MySQLField( $meta );
 618                         }
 619                 }
 620
 621                 return false;
 622         }
 623
 624         /**
 625          * Get column information from a result
 626          *
 627          * @param resource $res Raw result
 628          * @param int $n
 629          * @return stdClass
 630          */
 631         abstract protected function mysqlFetchField( $res, $n );
 632
 633         /**
 634          * Get information about an index into an object
 635          * Returns false if the index does not exist
 636          *
 637          * @param string $table
 638          * @param string $index
 639          * @param string $fname
 640          * @return bool|array|null False or null on failure
 641          */
 642         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 643                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 644                 # SHOW INDEX should work for 3.x and up:
 645                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 646                 $table = $this->tableName( $table );
 647                 $index = $this->indexName( $index );
 648
 649                 $sql = 'SHOW INDEX FROM ' . $table;
 650                 $res = $this->query( $sql, $fname );
 651
 652                 if ( !$res ) {
 653                         return null;
 654                 }
 655
 656                 $result = [];
 657
 658                 foreach ( $res as $row ) {
 659                         if ( $row->Key_name == $index ) {
 660                                 $result[] = $row;
 661                         }
 662                 }
 663
 664                 return $result ?: false;
 665         }
 666
 667         /**
 668          * @param string $s
 669          * @return string
 670          */
 671         public function strencode( $s ) {
 672                 return $this->mysqlRealEscapeString( $s );
 673         }
 674
 675         /**
 676          * @param string $s
 677          * @return mixed
 678          */
 679         abstract protected function mysqlRealEscapeString( $s );
 680
 681         public function addQuotes( $s ) {
 682                 if ( is_bool( $s ) ) {
 683                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 684                         // When searching for an int in a string column, the strings are cast to int, which
 685                         // means false would match any string not starting with a number.
 686                         $s = (string)(int)$s;
 687                 }
 688                 return parent::addQuotes( $s );
 689         }
 690
 691         /**
 692          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 693          *
 694          * @param string $s
 695          * @return string
 696          */
 697         public function addIdentifierQuotes( $s ) {
 698                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 699                 // Remove NUL bytes and escape backticks by doubling
 700                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 701         }
 702
 703         /**
 704          * @param string $name
 705          * @return bool
 706          */
 707         public function isQuotedIdentifier( $name ) {
 708                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 709         }
 710
 711         public function getLag() {
 712                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 713                         return $this->getLagFromPtHeartbeat();
 714                 } else {
 715                         return $this->getLagFromSlaveStatus();
 716                 }
 717         }
 718
 719         /**
 720          * @return string
 721          */
 722         protected function getLagDetectionMethod() {
 723                 return $this->lagDetectionMethod;
 724         }
 725
 726         /**
 727          * @return bool|int
 728          */
 729         protected function getLagFromSlaveStatus() {
 730                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 731                 $row = $res ? $res->fetchObject() : false;
 732                 // If the server is not replicating, there will be no row
 733                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 734                         return intval( $row->Seconds_Behind_Master );
 735                 }
 736
 737                 return false;
 738         }
 739
 740         /**
 741          * @return bool|float
 742          */
 743         protected function getLagFromPtHeartbeat() {
 744                 $options = $this->lagDetectionOptions;
 745
 746                 $currentTrxInfo = $this->getRecordedTransactionLagStatus();
 747                 if ( $currentTrxInfo ) {
 748                         // There is an active transaction and the initial lag was already queried
 749                         $staleness = microtime( true ) - $currentTrxInfo['since'];
 750                         if ( $staleness > self::LAG_STALE_WARN_THRESHOLD ) {
 751                                 // Avoid returning higher and higher lag value due to snapshot age
 752                                 // given that the isolation level will typically be REPEATABLE-READ
 753                                 $this->queryLogger->warning(
 754                                         "Using cached lag value for {db_server} due to active transaction",
 755                                         $this->getLogContext( [
 756                                                 'method' => __METHOD__,
 757                                                 'age' => $staleness,
 758                                                 'trace' => ( new RuntimeException() )->getTraceAsString()
 759                                         ] )
 760                                 );
 761                         }
 762
 763                         return $currentTrxInfo['lag'];
 764                 }
 765
 766                 if ( isset( $options['conds'] ) ) {
 767                         // Best method for multi-DC setups: use logical channel names
 768                         $data = $this->getHeartbeatData( $options['conds'] );
 769                 } else {
 770                         // Standard method: use master server ID (works with stock pt-heartbeat)
 771                         $masterInfo = $this->getMasterServerInfo();
 772                         if ( !$masterInfo ) {
 773                                 $this->queryLogger->error(
 774                                         "Unable to query master of {db_server} for server ID",
 775                                         $this->getLogContext( [
 776                                                 'method' => __METHOD__
 777                                         ] )
 778                                 );
 779
 780                                 return false; // could not get master server ID
 781                         }
 782
 783                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 784                         $data = $this->getHeartbeatData( $conds );
 785                 }
 786
 787                 list( $time, $nowUnix ) = $data;
 788                 if ( $time !== null ) {
 789                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 790                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 791                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 792
 793                         return max( $nowUnix - $timeUnix, 0.0 );
 794                 }
 795
 796                 $this->queryLogger->error(
 797                         "Unable to find pt-heartbeat row for {db_server}",
 798                         $this->getLogContext( [
 799                                 'method' => __METHOD__
 800                         ] )
 801                 );
 802
 803                 return false;
 804         }
 805
 806         protected function getMasterServerInfo() {
 807                 $cache = $this->srvCache;
 808                 $key = $cache->makeGlobalKey(
 809                         'mysql',
 810                         'master-info',
 811                         // Using one key for all cluster replica DBs is preferable
 812                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 813                 );
 814                 $fname = __METHOD__;
 815
 816                 return $cache->getWithSetCallback(
 817                         $key,
 818                         $cache::TTL_INDEFINITE,
 819                         function () use ( $cache, $key, $fname ) {
 820                                 // Get and leave a lock key in place for a short period
 821                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 822                                         return false; // avoid master connection spike slams
 823                                 }
 824
 825                                 $conn = $this->getLazyMasterHandle();
 826                                 if ( !$conn ) {
 827                                         return false; // something is misconfigured
 828                                 }
 829
 830                                 // Connect to and query the master; catch errors to avoid outages
 831                                 try {
 832                                         $res = $conn->query( 'SELECT @@server_id AS id', $fname );
 833                                         $row = $res ? $res->fetchObject() : false;
 834                                         $id = $row ? (int)$row->id : 0;
 835                                 } catch ( DBError $e ) {
 836                                         $id = 0;
 837                                 }
 838
 839                                 // Cache the ID if it was retrieved
 840                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 841                         }
 842                 );
 843         }
 844
 845         /**
 846          * @param array $conds WHERE clause conditions to find a row
 847          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 848          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 849          */
 850         protected function getHeartbeatData( array $conds ) {
 851                 // Query time and trip time are not counted
 852                 $nowUnix = microtime( true );
 853                 // Do not bother starting implicit transactions here
 854                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 855                 try {
 856                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 857                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 858                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 859                         // percision field is not supported in MySQL <= 5.5.
 860                         $res = $this->query(
 861                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1",
 862                                 __METHOD__
 863                         );
 864                         $row = $res ? $res->fetchObject() : false;
 865                 } finally {
 866                         $this->restoreFlags();
 867                 }
 868
 869                 return [ $row ? $row->ts : null, $nowUnix ];
 870         }
 871
 872         protected function getApproximateLagStatus() {
 873                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 874                         // Disable caching since this is fast enough and we don't wan't
 875                         // to be *too* pessimistic by having both the cache TTL and the
 876                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 877                         return parent::getApproximateLagStatus();
 878                 }
 879
 880                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 881                 $approxLag = $this->srvCache->get( $key );
 882                 if ( !$approxLag ) {
 883                         $approxLag = parent::getApproximateLagStatus();
 884                         $this->srvCache->set( $key, $approxLag, 1 );
 885                 }
 886
 887                 return $approxLag;
 888         }
 889
 890         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 891                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 892                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 893                 }
 894
 895                 if ( $this->getLBInfo( 'is static' ) === true ) {
 896                         return 0; // this is a copy of a read-only dataset with no master DB
 897                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 898                         return 0; // already reached this point for sure
 899                 }
 900
 901                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 902                 if ( $pos->getGTIDs() ) {
 903                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 904                         $rpos = $this->getReplicaPos();
 905                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 906                         if ( !$gtidsWait ) {
 907                                 $this->queryLogger->error(
 908                                         "No GTIDs with the same domain between master ($pos) and replica ($rpos)",
 909                                         $this->getLogContext( [
 910                                                 'method' => __METHOD__,
 911                                         ] )
 912                                 );
 913
 914                                 return -1; // $pos is from the wrong cluster?
 915                         }
 916                         // Wait on the GTID set (MariaDB only)
 917                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 918                         if ( strpos( $gtidArg, ':' ) !== false ) {
 919                                 // MySQL GTIDs, e.g "source_id:transaction_id"
 920                                 $res = $this->doQuery( "SELECT WAIT_FOR_EXECUTED_GTID_SET($gtidArg, $timeout)" );
 921                         } else {
 922                                 // MariaDB GTIDs, e.g."domain:server:sequence"
 923                                 $res = $this->doQuery( "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)" );
 924                         }
 925                 } else {
 926                         // Wait on the binlog coordinates
 927                         $encFile = $this->addQuotes( $pos->getLogFile() );
 928                         $encPos = intval( $pos->getLogPosition()[$pos::CORD_EVENT] );
 929                         $res = $this->doQuery( "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)" );
 930                 }
 931
 932                 $row = $res ? $this->fetchRow( $res ) : false;
 933                 if ( !$row ) {
 934                         throw new DBExpectedError( $this, "Replication wait failed: {$this->lastError()}" );
 935                 }
 936
 937                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 938                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 939                 if ( $status === null ) {
 940                         if ( !$pos->getGTIDs() ) {
 941                                 // T126436: jobs programmed to wait on master positions might be referencing
 942                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 943                                 // Try to detect this case and treat the replica DB as having reached the given
 944                                 // position (any master switchover already requires that the new master be caught
 945                                 // up before the switch).
 946                                 $replicationPos = $this->getReplicaPos();
 947                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 948                                         $this->lastKnownReplicaPos = $replicationPos;
 949                                         $status = 0;
 950                                 }
 951                         }
 952                 } elseif ( $status >= 0 ) {
 953                         // Remember that this position was reached to save queries next time
 954                         $this->lastKnownReplicaPos = $pos;
 955                 }
 956
 957                 return $status;
 958         }
 959
 960         /**
 961          * Get the position of the master from SHOW SLAVE STATUS
 962          *
 963          * @return MySQLMasterPos|bool
 964          */
 965         public function getReplicaPos() {
 966                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 967
 968                 if ( $this->useGTIDs() ) {
 969                         // Try to use GTIDs, fallbacking to binlog positions if not possible
 970                         $data = $this->getServerGTIDs( __METHOD__ );
 971                         // Use gtid_slave_pos for MariaDB and gtid_executed for MySQL
 972                         foreach ( [ 'gtid_slave_pos', 'gtid_executed' ] as $name ) {
 973                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
 974                                         return new MySQLMasterPos( $data[$name], $now );
 975                                 }
 976                         }
 977                 }
 978
 979                 $data = $this->getServerRoleStatus( 'SLAVE', __METHOD__ );
 980                 if ( $data && strlen( $data['Relay_Master_Log_File'] ) ) {
 981                         return new MySQLMasterPos(
 982                                 "{$data['Relay_Master_Log_File']}/{$data['Exec_Master_Log_Pos']}",
 983                                 $now
 984                         );
 985                 }
 986
 987                 return false;
 988         }
 989
 990         /**
 991          * Get the position of the master from SHOW MASTER STATUS
 992          *
 993          * @return MySQLMasterPos|bool
 994          */
 995         public function getMasterPos() {
 996                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 997
 998                 $pos = false;
 999                 if ( $this->useGTIDs() ) {
1000                         // Try to use GTIDs, fallbacking to binlog positions if not possible
1001                         $data = $this->getServerGTIDs( __METHOD__ );
1002                         // Use gtid_binlog_pos for MariaDB and gtid_executed for MySQL
1003                         foreach ( [ 'gtid_binlog_pos', 'gtid_executed' ] as $name ) {
1004                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1005                                         $pos = new MySQLMasterPos( $data[$name], $now );
1006                                         break;
1007                                 }
1008                         }
1009                         // Filter domains that are inactive or not relevant to the session
1010                         if ( $pos ) {
1011                                 $pos->setActiveOriginServerId( $this->getServerId() );
1012                                 $pos->setActiveOriginServerUUID( $this->getServerUUID() );
1013                                 if ( isset( $data['gtid_domain_id'] ) ) {
1014                                         $pos->setActiveDomain( $data['gtid_domain_id'] );
1015                                 }
1016                         }
1017                 }
1018
1019                 if ( !$pos ) {
1020                         $data = $this->getServerRoleStatus( 'MASTER', __METHOD__ );
1021                         if ( $data && strlen( $data['File'] ) ) {
1022                                 $pos = new MySQLMasterPos( "{$data['File']}/{$data['Position']}", $now );
1023                         }
1024                 }
1025
1026                 return $pos;
1027         }
1028
1029         /**
1030          * @return int
1031          * @throws DBQueryError If the variable doesn't exist for some reason
1032          */
1033         protected function getServerId() {
1034                 $fname = __METHOD__;
1035                 return $this->srvCache->getWithSetCallback(
1036                         $this->srvCache->makeGlobalKey( 'mysql-server-id', $this->getServer() ),
1037                         self::SERVER_ID_CACHE_TTL,
1038                         function () use ( $fname ) {
1039                                 $res = $this->query( "SELECT @@server_id AS id", $fname );
1040                                 return intval( $this->fetchObject( $res )->id );
1041                         }
1042                 );
1043         }
1044
1045         /**
1046          * @return string|null
1047          */
1048         protected function getServerUUID() {
1049                 return $this->srvCache->getWithSetCallback(
1050                         $this->srvCache->makeGlobalKey( 'mysql-server-uuid', $this->getServer() ),
1051                         self::SERVER_ID_CACHE_TTL,
1052                         function () {
1053                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'server_uuid'" );
1054                                 $row = $this->fetchObject( $res );
1055
1056                                 return $row ? $row->Value : null;
1057                         }
1058                 );
1059         }
1060
1061         /**
1062          * @param string $fname
1063          * @return string[]
1064          */
1065         protected function getServerGTIDs( $fname = __METHOD__ ) {
1066                 $map = [];
1067                 // Get global-only variables like gtid_executed
1068                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_%'", $fname );
1069                 foreach ( $res as $row ) {
1070                         $map[$row->Variable_name] = $row->Value;
1071                 }
1072                 // Get session-specific (e.g. gtid_domain_id since that is were writes will log)
1073                 $res = $this->query( "SHOW SESSION VARIABLES LIKE 'gtid_%'", $fname );
1074                 foreach ( $res as $row ) {
1075                         $map[$row->Variable_name] = $row->Value;
1076                 }
1077
1078                 return $map;
1079         }
1080
1081         /**
1082          * @param string $role One of "MASTER"/"SLAVE"
1083          * @param string $fname
1084          * @return string[] Latest available server status row
1085          */
1086         protected function getServerRoleStatus( $role, $fname = __METHOD__ ) {
1087                 return $this->query( "SHOW $role STATUS", $fname )->fetchRow() ?: [];
1088         }
1089
1090         public function serverIsReadOnly() {
1091                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
1092                 $row = $this->fetchObject( $res );
1093
1094                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
1095         }
1096
1097         /**
1098          * @param string $index
1099          * @return string
1100          */
1101         function useIndexClause( $index ) {
1102                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1103         }
1104
1105         /**
1106          * @param string $index
1107          * @return string
1108          */
1109         function ignoreIndexClause( $index ) {
1110                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1111         }
1112
1113         /**
1114          * @return string
1115          */
1116         function lowPriorityOption() {
1117                 return 'LOW_PRIORITY';
1118         }
1119
1120         /**
1121          * @return string
1122          */
1123         public function getSoftwareLink() {
1124                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1125                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1126                 // in libmysql/libmysql.c).
1127                 $version = $this->getServerVersion();
1128                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1129                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1130                 }
1131
1132                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1133                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1134                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1135                 return '[{{int:version-db-mysql-url}} MySQL]';
1136         }
1137
1138         /**
1139          * @return string
1140          */
1141         public function getServerVersion() {
1142                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1143                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1144                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1145                 if ( $this->serverVersion === null ) {
1146                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1147                 }
1148                 return $this->serverVersion;
1149         }
1150
1151         /**
1152          * @param array $options
1153          */
1154         public function setSessionOptions( array $options ) {
1155                 if ( isset( $options['connTimeout'] ) ) {
1156                         $timeout = (int)$options['connTimeout'];
1157                         $this->query( "SET net_read_timeout=$timeout" );
1158                         $this->query( "SET net_write_timeout=$timeout" );
1159                 }
1160         }
1161
1162         /**
1163          * @param string &$sql
1164          * @param string &$newLine
1165          * @return bool
1166          */
1167         public function streamStatementEnd( &$sql, &$newLine ) {
1168                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1169                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1170                         $this->delimiter = $m[1];
1171                         $newLine = '';
1172                 }
1173
1174                 return parent::streamStatementEnd( $sql, $newLine );
1175         }
1176
1177         /**
1178          * Check to see if a named lock is available. This is non-blocking.
1179          *
1180          * @param string $lockName Name of lock to poll
1181          * @param string $method Name of method calling us
1182          * @return bool
1183          * @since 1.20
1184          */
1185         public function lockIsFree( $lockName, $method ) {
1186                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1187                         return false; // already held
1188                 }
1189
1190                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1191                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1192                 $row = $this->fetchObject( $result );
1193
1194                 return ( $row->lockstatus == 1 );
1195         }
1196
1197         /**
1198          * @param string $lockName
1199          * @param string $method
1200          * @param int $timeout
1201          * @return bool
1202          */
1203         public function lock( $lockName, $method, $timeout = 5 ) {
1204                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1205                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1206                 $row = $this->fetchObject( $result );
1207
1208                 if ( $row->lockstatus == 1 ) {
1209                         parent::lock( $lockName, $method, $timeout ); // record
1210                         return true;
1211                 }
1212
1213                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1214                         [ 'lockname' => $lockName ] );
1215
1216                 return false;
1217         }
1218
1219         /**
1220          * FROM MYSQL DOCS:
1221          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1222          * @param string $lockName
1223          * @param string $method
1224          * @return bool
1225          */
1226         public function unlock( $lockName, $method ) {
1227                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1228                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1229                 $row = $this->fetchObject( $result );
1230
1231                 if ( $row->lockstatus == 1 ) {
1232                         parent::unlock( $lockName, $method ); // record
1233                         return true;
1234                 }
1235
1236                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1237
1238                 return false;
1239         }
1240
1241         private function makeLockName( $lockName ) {
1242                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1243                 // Newer version enforce a 64 char length limit.
1244                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1245         }
1246
1247         public function namedLocksEnqueue() {
1248                 return true;
1249         }
1250
1251         public function tableLocksHaveTransactionScope() {
1252                 return false; // tied to TCP connection
1253         }
1254
1255         protected function doLockTables( array $read, array $write, $method ) {
1256                 $items = [];
1257                 foreach ( $write as $table ) {
1258                         $items[] = $this->tableName( $table ) . ' WRITE';
1259                 }
1260                 foreach ( $read as $table ) {
1261                         $items[] = $this->tableName( $table ) . ' READ';
1262                 }
1263
1264                 $sql = "LOCK TABLES " . implode( ',', $items );
1265                 $this->query( $sql, $method );
1266
1267                 return true;
1268         }
1269
1270         protected function doUnlockTables( $method ) {
1271                 $this->query( "UNLOCK TABLES", $method );
1272
1273                 return true;
1274         }
1275
1276         /**
1277          * @param bool $value
1278          */
1279         public function setBigSelects( $value = true ) {
1280                 if ( $value === 'default' ) {
1281                         if ( $this->defaultBigSelects === null ) {
1282                                 # Function hasn't been called before so it must already be set to the default
1283                                 return;
1284                         } else {
1285                                 $value = $this->defaultBigSelects;
1286                         }
1287                 } elseif ( $this->defaultBigSelects === null ) {
1288                         $this->defaultBigSelects =
1289                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1290                 }
1291                 $encValue = $value ? '1' : '0';
1292                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1293         }
1294
1295         /**
1296          * DELETE where the condition is a join. MySql uses multi-table deletes.
1297          * @param string $delTable
1298          * @param string $joinTable
1299          * @param string $delVar
1300          * @param string $joinVar
1301          * @param array|string $conds
1302          * @param bool|string $fname
1303          * @throws DBUnexpectedError
1304          */
1305         public function deleteJoin(
1306                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1307         ) {
1308                 if ( !$conds ) {
1309                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1310                 }
1311
1312                 $delTable = $this->tableName( $delTable );
1313                 $joinTable = $this->tableName( $joinTable );
1314                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1315
1316                 if ( $conds != '*' ) {
1317                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1318                 }
1319
1320                 $this->query( $sql, $fname );
1321         }
1322
1323         public function upsert(
1324                 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1325         ) {
1326                 if ( $rows === [] ) {
1327                         return true; // nothing to do
1328                 }
1329
1330                 if ( !is_array( reset( $rows ) ) ) {
1331                         $rows = [ $rows ];
1332                 }
1333
1334                 $table = $this->tableName( $table );
1335                 $columns = array_keys( $rows[0] );
1336
1337                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1338                 $rowTuples = [];
1339                 foreach ( $rows as $row ) {
1340                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1341                 }
1342                 $sql .= implode( ',', $rowTuples );
1343                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1344
1345                 $this->query( $sql, $fname );
1346
1347                 return true;
1348         }
1349
1350         /**
1351          * Determines how long the server has been up
1352          *
1353          * @return int
1354          */
1355         public function getServerUptime() {
1356                 $vars = $this->getMysqlStatus( 'Uptime' );
1357
1358                 return (int)$vars['Uptime'];
1359         }
1360
1361         /**
1362          * Determines if the last failure was due to a deadlock
1363          *
1364          * @return bool
1365          */
1366         public function wasDeadlock() {
1367                 return $this->lastErrno() == 1213;
1368         }
1369
1370         /**
1371          * Determines if the last failure was due to a lock timeout
1372          *
1373          * @return bool
1374          */
1375         public function wasLockTimeout() {
1376                 return $this->lastErrno() == 1205;
1377         }
1378
1379         /**
1380          * Determines if the last failure was due to the database being read-only.
1381          *
1382          * @return bool
1383          */
1384         public function wasReadOnlyError() {
1385                 return $this->lastErrno() == 1223 ||
1386                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1387         }
1388
1389         public function wasConnectionError( $errno ) {
1390                 return $errno == 2013 || $errno == 2006;
1391         }
1392
1393         protected function wasKnownStatementRollbackError() {
1394                 $errno = $this->lastErrno();
1395
1396                 if ( $errno === 1205 ) { // lock wait timeout
1397                         // Note that this is uncached to avoid stale values of SET is used
1398                         $row = $this->selectRow(
1399                                 false,
1400                                 [ 'innodb_rollback_on_timeout' => '@@innodb_rollback_on_timeout' ],
1401                                 [],
1402                                 __METHOD__
1403                         );
1404                         // https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1405                         // https://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html
1406                         return $row->innodb_rollback_on_timeout ? false : true;
1407                 }
1408
1409                 // See https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
1410                 return in_array( $errno, [ 1022, 1216, 1217, 1137, 1146, 1051, 1054 ], true );
1411         }
1412
1413         /**
1414          * @param string $oldName
1415          * @param string $newName
1416          * @param bool $temporary
1417          * @param string $fname
1418          * @return bool
1419          */
1420         public function duplicateTableStructure(
1421                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1422         ) {
1423                 $tmp = $temporary ? 'TEMPORARY ' : '';
1424                 $newName = $this->addIdentifierQuotes( $newName );
1425                 $oldName = $this->addIdentifierQuotes( $oldName );
1426                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1427
1428                 return $this->query( $query, $fname );
1429         }
1430
1431         /**
1432          * List all tables on the database
1433          *
1434          * @param string|null $prefix Only show tables with this prefix, e.g. mw_
1435          * @param string $fname Calling function name
1436          * @return array
1437          */
1438         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1439                 $result = $this->query( "SHOW TABLES", $fname );
1440
1441                 $endArray = [];
1442
1443                 foreach ( $result as $table ) {
1444                         $vars = get_object_vars( $table );
1445                         $table = array_pop( $vars );
1446
1447                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1448                                 $endArray[] = $table;
1449                         }
1450                 }
1451
1452                 return $endArray;
1453         }
1454
1455         /**
1456          * @param string $tableName
1457          * @param string $fName
1458          * @return bool|ResultWrapper
1459          */
1460         public function dropTable( $tableName, $fName = __METHOD__ ) {
1461                 if ( !$this->tableExists( $tableName, $fName ) ) {
1462                         return false;
1463                 }
1464
1465                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1466         }
1467
1468         /**
1469          * Get status information from SHOW STATUS in an associative array
1470          *
1471          * @param string $which
1472          * @return array
1473          */
1474         private function getMysqlStatus( $which = "%" ) {
1475                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1476                 $status = [];
1477
1478                 foreach ( $res as $row ) {
1479                         $status[$row->Variable_name] = $row->Value;
1480                 }
1481
1482                 return $status;
1483         }
1484
1485         /**
1486          * Lists VIEWs in the database
1487          *
1488          * @param string|null $prefix Only show VIEWs with this prefix, eg.
1489          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1490          * @param string $fname Name of calling function
1491          * @return array
1492          * @since 1.22
1493          */
1494         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1495                 // The name of the column containing the name of the VIEW
1496                 $propertyName = 'Tables_in_' . $this->getDBname();
1497
1498                 // Query for the VIEWS
1499                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1500                 $allViews = [];
1501                 foreach ( $res as $row ) {
1502                         array_push( $allViews, $row->$propertyName );
1503                 }
1504
1505                 if ( is_null( $prefix ) || $prefix === '' ) {
1506                         return $allViews;
1507                 }
1508
1509                 $filteredViews = [];
1510                 foreach ( $allViews as $viewName ) {
1511                         // Does the name of this VIEW start with the table-prefix?
1512                         if ( strpos( $viewName, $prefix ) === 0 ) {
1513                                 array_push( $filteredViews, $viewName );
1514                         }
1515                 }
1516
1517                 return $filteredViews;
1518         }
1519
1520         /**
1521          * Differentiates between a TABLE and a VIEW.
1522          *
1523          * @param string $name Name of the TABLE/VIEW to test
1524          * @param string|null $prefix
1525          * @return bool
1526          * @since 1.22
1527          */
1528         public function isView( $name, $prefix = null ) {
1529                 return in_array( $name, $this->listViews( $prefix ) );
1530         }
1531
1532         protected function isTransactableQuery( $sql ) {
1533                 return parent::isTransactableQuery( $sql ) &&
1534                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1535         }
1536
1537         public function buildStringCast( $field ) {
1538                 return "CAST( $field AS BINARY )";
1539         }
1540
1541         /**
1542          * @param string $field Field or column to cast
1543          * @return string
1544          */
1545         public function buildIntegerCast( $field ) {
1546                 return 'CAST( ' . $field . ' AS SIGNED )';
1547         }
1548
1549         /*
1550          * @return bool Whether GTID support is used (mockable for testing)
1551          */
1552         protected function useGTIDs() {
1553                 return $this->useGTIDs;
1554         }
1555 }
1556
1557 /**
1558  * @deprecated since 1.29
1559  */
1560 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );